add package.json

.air.toml

@@ -1,46 +0,0 @@
-root = "./"
-testdata_dir = "testdata"
-tmp_dir = "tmp"
-
-[build]
-  args_bin = []
-  bin = "./tmp/main"
-  cmd = "go build -o ./tmp/main ./cmd"
-  delay = 1000
-  exclude_dir = ["assets", "tmp", "vendor", "testdata"]
-  exclude_file = []
-  exclude_regex = ["_test.go"]
-  exclude_unchanged = false
-  follow_symlink = false
-  full_bin = "RULESET=./ruleset.yaml ./tmp/main"
-  include_dir = []
-  include_ext = ["go", "tpl", "tmpl", "yaml", "html"]
-  include_file = []
-  kill_delay = "0s"
-  log = "build-errors.log"
-  poll = false
-  poll_interval = 0
-  post_cmd = []
-  pre_cmd = ["echo 'dev' > handlers/VERSION"]
-  rerun = false
-  rerun_delay = 500
-  send_interrupt = false
-  stop_on_error = false
-
-[color]
-  app = ""
-  build = "yellow"
-  main = "magenta"
-  runner = "green"
-  watcher = "cyan"
-
-[log]
-  main_only = false
-  time = false
-
-[misc]
-  clean_on_exit = true
-
-[screen]
-  clear_on_rebuild = true
-  keep_scroll = true

Makefile

@@ -1,6 +1,6 @@
 lint:
 	gofumpt -l -w .
-	golangci-lint run -c .golangci-lint.yaml --fix
+	golangci-lint run -c .golangci-lint.yaml
 
 	go mod tidy
 	go clean

README.md

@@ -14,18 +14,6 @@ Freedom of information is an essential pillar of democracy and informed decision
 
 > **Disclaimer:** This project is intended for educational purposes only. The author does not endorse or encourage any unethical or illegal activity. Use this tool at your own risk.
 
-### How it works
-
-```mermaid
-sequenceDiagram
-    client->>+ladder: GET
-    ladder-->>ladder: apply RequestModifications
-    ladder->>+website: GET
-    website->>-ladder: 200 OK
-    ladder-->>ladder: apply ResultModifications
-    ladder->>-client: 200 OK
-```
-
 ### Features
 - [x] Bypass Paywalls
 - [x] Remove CORS headers from responses, assets, and images ...
@@ -193,14 +181,4 @@ echo "dev" > handlers/VERSION
 RULESET="./ruleset.yaml" go run cmd/main.go
 ```
 
-### Optional: Live reloading development server with [cosmtrek/air](https://github.com/cosmtrek/air)
-
-Install air according to the [installation instructions](https://github.com/cosmtrek/air#installation). 
-
-Run a development server at http://localhost:8080:
-
-```bash
-air # or the path to air if you haven't added a path alias to your .bashrc or .zshrc
-```
-
 This project uses [pnpm](https://pnpm.io/) to build a stylesheet with the [Tailwind CSS](https://tailwindcss.com/) classes. For local development, if you modify styles in `form.html`, run `pnpm build` to generate a new stylesheet.

cmd/main.go

@@ -8,7 +8,7 @@ import (
 	"strings"
 
 	"ladder/handlers"
-	"ladder/handlers/cli"
+	"ladder/internal/cli"
 
 	"github.com/akamensky/argparse"
 	"github.com/gofiber/fiber/v2"
@@ -29,7 +29,6 @@ func main() {
 	if os.Getenv("PORT") == "" {
 		portEnv = "8080"
 	}
-
 	port := parser.String("p", "port", &argparse.Options{
 		Required: false,
 		Default:  portEnv,
@@ -41,6 +40,13 @@ func main() {
 		Help:     "This will spawn multiple processes listening",
 	})
 
+	verbose := parser.Flag("v", "verbose", &argparse.Options{
+		Required: false,
+		Help:     "Adds verbose logging",
+	})
+
+	// TODO: add version flag that reads from handers/VERSION
+
 	ruleset := parser.String("r", "ruleset", &argparse.Options{
 		Required: false,
 		Help:     "File, Directory or URL to a ruleset.yaml. Overrides RULESET environment variable.",
@@ -50,12 +56,10 @@ func main() {
 		Required: false,
 		Help:     "Compiles a directory of yaml files into a single ruleset.yaml. Requires --ruleset arg.",
 	})
-
 	mergeRulesetsGzip := parser.Flag("", "merge-rulesets-gzip", &argparse.Options{
 		Required: false,
 		Help:     "Compiles a directory of yaml files into a single ruleset.gz Requires --ruleset arg.",
 	})
-
 	mergeRulesetsOutput := parser.String("", "merge-rulesets-output", &argparse.Options{
 		Required: false,
 		Help:     "Specify output file for --merge-rulesets and --merge-rulesets-gzip. Requires --ruleset and --merge-rulesets args.",
@@ -68,18 +72,7 @@ func main() {
 
 	// utility cli flag to compile ruleset directory into single ruleset.yaml
 	if *mergeRulesets || *mergeRulesetsGzip {
-		output := os.Stdout
+		err = cli.HandleRulesetMerge(ruleset, mergeRulesets, mergeRulesetsGzip, mergeRulesetsOutput)
-
-		if *mergeRulesetsOutput != "" {
-			output, err = os.Create(*mergeRulesetsOutput)
-			
-			if err != nil {
-				fmt.Println(err)
-				os.Exit(1)
-			}
-		}
-
-		err = cli.HandleRulesetMerge(*ruleset, *mergeRulesets, *mergeRulesetsGzip, output)
 		if err != nil {
 			fmt.Println(err)
 			os.Exit(1)
@@ -94,14 +87,15 @@ func main() {
 	app := fiber.New(
 		fiber.Config{
 			Prefork:        *prefork,
-			GETOnly: true,
+			GETOnly:        false,
+			ReadBufferSize: 4096 * 4, // increase max header size
 		},
 	)
 
+	// TODO: move to cmd/auth.go
 	userpass := os.Getenv("USERPASS")
 	if userpass != "" {
 		userpass := strings.Split(userpass, ":")
-
 		app.Use(basicauth.New(basicauth.Config{
 			Users: map[string]string{
 				userpass[0]: userpass[1],
@@ -109,6 +103,7 @@ func main() {
 		}))
 	}
 
+	// TODO: move to handlers/favicon.go
 	app.Use(favicon.New(favicon.Config{
 		Data: []byte(faviconData),
 		URL:  "/favicon.ico",
@@ -117,28 +112,33 @@ func main() {
 	if os.Getenv("NOLOGS") != "true" {
 		app.Use(func(c *fiber.Ctx) error {
 			log.Println(c.Method(), c.Path())
-
 			return c.Next()
 		})
 	}
 
 	app.Get("/", handlers.Form)
 
+	// TODO: move this logic to handers/styles.go
 	app.Get("/styles.css", func(c *fiber.Ctx) error {
 		cssData, err := cssData.ReadFile("styles.css")
 		if err != nil {
 			return c.Status(fiber.StatusInternalServerError).SendString("Internal Server Error")
 		}
-
 		c.Set("Content-Type", "text/css")
-
 		return c.Send(cssData)
 	})
 
 	app.Get("ruleset", handlers.Ruleset)
+
 	app.Get("raw/*", handlers.Raw)
 	app.Get("api/*", handlers.Api)
-	app.Get("/*", handlers.ProxySite(*ruleset))
 
+	proxyOpts := &handlers.ProxyOptions{
+		Verbose:     *verbose,
+		RulesetPath: *ruleset,
+	}
+
+	app.Get("/*", handlers.NewProxySiteHandler(proxyOpts))
+	app.Post("/*", handlers.NewProxySiteHandler(proxyOpts))
 	log.Fatal(app.Listen(":" + *port))
 }

go.mod

@@ -24,7 +24,7 @@ require (
 	github.com/valyala/bytebufferpool v1.0.0 // indirect
 	github.com/valyala/fasthttp v1.50.0 // indirect
 	github.com/valyala/tcplisten v1.0.0 // indirect
-	golang.org/x/net v0.18.0 // indirect
+	golang.org/x/net v0.18.0
 	golang.org/x/sys v0.14.0 // indirect
 	golang.org/x/term v0.14.0
 )

handlers/proxy.go

@@ -11,6 +11,9 @@ import (
 	"strings"
 
 	"ladder/pkg/ruleset"
+	"ladder/proxychain"
+	rx "ladder/proxychain/requestmodifers"
+	tx "ladder/proxychain/responsemodifers"
 
 	"github.com/PuerkitoBio/goquery"
 	"github.com/gofiber/fiber/v2"
@@ -30,88 +33,45 @@ func init() {
 	}
 }
 
-// extracts a URL from the request ctx. If the URL in the request
+type ProxyOptions struct {
-// is a relative path, it reconstructs the full URL using the referer header.
+	RulesetPath string
-func extractUrl(c *fiber.Ctx) (string, error) {
+	Verbose     bool
-	// try to extract url-encoded
-	reqUrl, err := url.QueryUnescape(c.Params("*"))
-	if err != nil {
-		// fallback
-		reqUrl = c.Params("*")
-	}
-
-	// Extract the actual path from req ctx
-	urlQuery, err := url.Parse(reqUrl)
-	if err != nil {
-		return "", fmt.Errorf("error parsing request URL '%s': %v", reqUrl, err)
-	}
-
-	isRelativePath := urlQuery.Scheme == ""
-
-	// eg: https://localhost:8080/images/foobar.jpg -> https://realsite.com/images/foobar.jpg
-	if isRelativePath {
-		// Parse the referer URL from the request header.
-		refererUrl, err := url.Parse(c.Get("referer"))
-		if err != nil {
-			return "", fmt.Errorf("error parsing referer URL from req: '%s': %v", reqUrl, err)
-		}
-
-		// Extract the real url from referer path
-		realUrl, err := url.Parse(strings.TrimPrefix(refererUrl.Path, "/"))
-		if err != nil {
-			return "", fmt.Errorf("error parsing real URL from referer '%s': %v", refererUrl.Path, err)
-		}
-
-		// reconstruct the full URL using the referer's scheme, host, and the relative path / queries
-		fullUrl := &url.URL{
-			Scheme:   realUrl.Scheme,
-			Host:     realUrl.Host,
-			Path:     urlQuery.Path,
-			RawQuery: urlQuery.RawQuery,
-		}
-
-		if os.Getenv("LOG_URLS") == "true" {
-			log.Printf("modified relative URL: '%s' -> '%s'", reqUrl, fullUrl.String())
-		}
-		return fullUrl.String(), nil
-
-	}
-
-	// default behavior:
-	// eg: https://localhost:8080/https://realsite.com/images/foobar.jpg -> https://realsite.com/images/foobar.jpg
-	return urlQuery.String(), nil
 }
 
-func ProxySite(rulesetPath string) fiber.Handler {
+func NewProxySiteHandler(opts *ProxyOptions) fiber.Handler {
-	if rulesetPath != "" {
+	/*
-		rs, err := ruleset.NewRuleset(rulesetPath)
+		var rs ruleset.RuleSet
+		if opts.RulesetPath != "" {
+			r, err := ruleset.NewRuleset(opts.RulesetPath)
 			if err != nil {
 				panic(err)
 			}
-		rulesSet = rs
+			rs = r
 		}
+	*/
 
 	return func(c *fiber.Ctx) error {
-		// Get the url from the URL
+		proxychain := proxychain.
-		url, err := extractUrl(c)
+			NewProxyChain().
-		if err != nil {
+			SetFiberCtx(c).
-			log.Println("ERROR In URL extraction:", err)
+			SetDebugLogging(opts.Verbose).
+			SetRequestModifications(
+				rx.DeleteOutgoingCookies(),
+				//rx.RequestArchiveIs(),
+				rx.MasqueradeAsGoogleBot(),
+			).
+			AddResponseModifications(
+				tx.BypassCORS(),
+				tx.BypassContentSecurityPolicy(),
+				tx.DeleteIncomingCookies(),
+				tx.RewriteHTMLResourceURLs(),
+				tx.PatchDynamicResourceURLs(),
+			).
+			Execute()
+
+		return proxychain
 	}
 
-		queries := c.Queries()
-		body, _, resp, err := fetchSite(url, queries)
-		if err != nil {
-			log.Println("ERROR:", err)
-			c.SendStatus(fiber.StatusInternalServerError)
-			return c.SendString(err.Error())
-		}
-
-		c.Cookie(&fiber.Cookie{})
-		c.Set("Content-Type", resp.Header.Get("Content-Type"))
-		c.Set("Content-Security-Policy", resp.Header.Get("Content-Security-Policy"))
-
-		return c.SendString(body)
-	}
 }
 
 func modifyURL(uri string, rule ruleset.Rule) (string, error) {
@@ -120,18 +80,18 @@ func modifyURL(uri string, rule ruleset.Rule) (string, error) {
 		return "", err
 	}
 
-	for _, urlMod := range rule.URLMods.Domain {
+	for _, urlMod := range rule.UrlMods.Domain {
 		re := regexp.MustCompile(urlMod.Match)
 		newUrl.Host = re.ReplaceAllString(newUrl.Host, urlMod.Replace)
 	}
 
-	for _, urlMod := range rule.URLMods.Path {
+	for _, urlMod := range rule.UrlMods.Path {
 		re := regexp.MustCompile(urlMod.Match)
 		newUrl.Path = re.ReplaceAllString(newUrl.Path, urlMod.Replace)
 	}
 
 	v := newUrl.Query()
-	for _, query := range rule.URLMods.Query {
+	for _, query := range rule.UrlMods.Query {
 		if query.Value == "" {
 			v.Del(query.Key)
 			continue
@@ -222,11 +182,11 @@ func fetchSite(urlpath string, queries map[string]string) (string, *http.Request
 	}
 
 	if rule.Headers.CSP != "" {
-		// log.Println(rule.Headers.CSP)
+		//log.Println(rule.Headers.CSP)
 		resp.Header.Set("Content-Security-Policy", rule.Headers.CSP)
 	}
 
-	// log.Print("rule", rule) TODO: Add a debug mode to print the rule
+	//log.Print("rule", rule) TODO: Add a debug mode to print the rule
 	body := rewriteHtml(bodyB, u, rule)
 	return body, req, resp, nil
 }

handlers/proxy.test.go

@@ -2,20 +2,19 @@
 package handlers
 
 import (
+	"ladder/pkg/ruleset"
 	"net/http"
 	"net/http/httptest"
 	"net/url"
 	"testing"
 
-	"ladder/pkg/ruleset"
-
 	"github.com/gofiber/fiber/v2"
 	"github.com/stretchr/testify/assert"
 )
 
 func TestProxySite(t *testing.T) {
 	app := fiber.New()
-	app.Get("/:url", ProxySite(""))
+	app.Get("/:url", NewProxySiteHandler(nil))
 
 	req := httptest.NewRequest("GET", "/https://example.com", nil)
 	resp, err := app.Test(req)

internal/cli/ruleset_merge.go

@@ -3,9 +3,9 @@ package cli
 import (
 	"fmt"
 	"io"
-	"os"
+	"io/fs"
-
 	"ladder/pkg/ruleset"
+	"os"
 
 	"golang.org/x/term"
 )
@@ -14,38 +14,32 @@ import (
 // Exits the program with an error message if the ruleset path is not provided or if loading the ruleset fails.
 //
 // Parameters:
-// - rulesetPath: Specifies the path to the ruleset file.
+// - rulesetPath: A pointer to a string specifying the path to the ruleset file.
-// - mergeRulesets: Indicates if a merge operation should be performed.
+// - mergeRulesets: A pointer to a boolean indicating if a merge operation should be performed.
-// - useGzip: Indicates if the merged rulesets should be gzip-ped.
+// - mergeRulesetsGzip: A pointer to a boolean indicating if the merge should be in Gzip format.
-// - output: Specifies the output file. If nil, stdout will be used.
+// - mergeRulesetsOutput: A pointer to a string specifying the output file path. If empty, the output is printed to stdout.
 //
 // Returns:
 // - An error if the ruleset loading or merging process fails, otherwise nil.
-func HandleRulesetMerge(rulesetPath string, mergeRulesets bool, useGzip bool, output *os.File) error {
+func HandleRulesetMerge(rulesetPath *string, mergeRulesets *bool, mergeRulesetsGzip *bool, mergeRulesetsOutput *string) error {
-	if !mergeRulesets {
+	if *rulesetPath == "" {
-		return nil
+		*rulesetPath = os.Getenv("RULESET")
 	}
-
+	if *rulesetPath == "" {
-	if rulesetPath == "" {
+		fmt.Println("ERROR: no ruleset provided. Try again with --ruleset <ruleset.yaml>")
-		rulesetPath = os.Getenv("RULESET")
-	}
-
-	if rulesetPath == "" {
-		fmt.Println("error: no ruleset provided. Try again with --ruleset <ruleset.yaml>")
 		os.Exit(1)
 	}
 
-	rs, err := ruleset.NewRuleset(rulesetPath)
+	rs, err := ruleset.NewRuleset(*rulesetPath)
 	if err != nil {
 		fmt.Println(err)
 		os.Exit(1)
 	}
 
-	if useGzip {
+	if *mergeRulesetsGzip {
-		return gzipMerge(rs, output)
+		return gzipMerge(rs, mergeRulesetsOutput)
 	}
-
+	return yamlMerge(rs, mergeRulesetsOutput)
-	return yamlMerge(rs, output)
 }
 
 // gzipMerge takes a RuleSet and an optional output file path pointer. It compresses the RuleSet into Gzip format.
@@ -54,33 +48,33 @@ func HandleRulesetMerge(rulesetPath string, mergeRulesets bool, useGzip bool, ou
 //
 // Parameters:
 // - rs: The ruleset.RuleSet to be compressed.
-// - output: The output for the gzip data. If nil, stdout will be used.
+// - mergeRulesetsOutput: A pointer to a string specifying the output file path. If empty, the output is directed to stdout.
 //
 // Returns:
 // - An error if compression or file writing fails, otherwise nil.
-func gzipMerge(rs ruleset.RuleSet, output io.Writer) error {
+func gzipMerge(rs ruleset.RuleSet, mergeRulesetsOutput *string) error {
 	gzip, err := rs.GzipYaml()
 	if err != nil {
 		return err
 	}
 
-	if output != nil {
+	if *mergeRulesetsOutput != "" {
-		_, err = io.Copy(output, gzip)
+		out, err := os.Create(*mergeRulesetsOutput)
+		defer out.Close()
+		_, err = io.Copy(out, gzip)
 		if err != nil {
 			return err
 		}
 	}
 
 	if term.IsTerminal(int(os.Stdout.Fd())) {
-		println("warning: binary output can mess up your terminal. Use '--merge-rulesets-output <ruleset.gz>' or pipe it to a file.")
+		println("WARNING: binary output can mess up your terminal. Use '--merge-rulesets-output <ruleset.gz>' or pipe it to a file.")
 		os.Exit(1)
 	}
-
 	_, err = io.Copy(os.Stdout, gzip)
 	if err != nil {
 		return err
 	}
-
 	return nil
 }
 
@@ -89,25 +83,23 @@ func gzipMerge(rs ruleset.RuleSet, output io.Writer) error {
 //
 // Parameters:
 // - rs: The ruleset.RuleSet to be converted to YAML.
-// - output: The output for the merged data. If nil, stdout will be used.
+// - mergeRulesetsOutput: A pointer to a string specifying the output file path. If empty, the output is printed to stdout.
 //
 // Returns:
 // - An error if YAML conversion or file writing fails, otherwise nil.
-func yamlMerge(rs ruleset.RuleSet, output io.Writer) error {
+func yamlMerge(rs ruleset.RuleSet, mergeRulesetsOutput *string) error {
 	yaml, err := rs.Yaml()
 	if err != nil {
 		return err
 	}
-
+	if *mergeRulesetsOutput == "" {
-	if output == nil {
+		fmt.Printf(yaml)
-		fmt.Println(yaml)
 		os.Exit(0)
 	}
 
-	_, err = io.WriteString(output, yaml)
+	err = os.WriteFile(*mergeRulesetsOutput, []byte(yaml), fs.FileMode(os.O_RDWR))
 	if err != nil {
-		return fmt.Errorf("failed to write merged YAML ruleset: %v", err)
+		return fmt.Errorf("ERROR: failed to write merged YAML ruleset to '%s'\n", *mergeRulesetsOutput)
 	}
-
 	return nil
 }

pkg/ruleset/ruleset.go

@@ -1,7 +1,6 @@
 package ruleset
 
 import (
-	"compress/gzip"
 	"errors"
 	"fmt"
 	"io"
@@ -12,6 +11,8 @@ import (
 	"regexp"
 	"strings"
 
+	"compress/gzip"
+
 	"gopkg.in/yaml.v3"
 )
 
@@ -40,7 +41,7 @@ type Rule struct {
 	GoogleCache bool    `yaml:"googleCache,omitempty"`
 	RegexRules  []Regex `yaml:"regexRules,omitempty"`
 
-	URLMods struct {
+	UrlMods struct {
 		Domain []Regex `yaml:"domain,omitempty"`
 		Path   []Regex `yaml:"path,omitempty"`
 		Query  []KV    `yaml:"query,omitempty"`
@@ -54,8 +55,6 @@ type Rule struct {
 	} `yaml:"injections,omitempty"`
 }
 
-var remoteRegex = regexp.MustCompile(`^https?:\/\/(www\.)?[-a-zA-Z0-9@:%._\+~#=]{1,256}\.[a-zA-Z0-9()]{1,6}\b([-a-zA-Z0-9()!@:%_\+.~#?&\/\/=]*)`)
-
 // NewRulesetFromEnv creates a new RuleSet based on the RULESET environment variable.
 // It logs a warning and returns an empty RuleSet if the RULESET environment variable is not set.
 // If the RULESET is set but the rules cannot be loaded, it panics.
@@ -65,12 +64,10 @@ func NewRulesetFromEnv() RuleSet {
 		log.Printf("WARN: No ruleset specified. Set the `RULESET` environment variable to load one for a better success rate.")
 		return RuleSet{}
 	}
-
 	ruleSet, err := NewRuleset(rulesPath)
 	if err != nil {
 		log.Println(err)
 	}
-
 	return ruleSet
 }
 
@@ -78,17 +75,16 @@ func NewRulesetFromEnv() RuleSet {
 // It supports loading rules from both local file paths and remote URLs.
 // Returns a RuleSet and an error if any issues occur during loading.
 func NewRuleset(rulePaths string) (RuleSet, error) {
-	var ruleSet RuleSet
+	ruleSet := RuleSet{}
-
+	errs := []error{}
-	var errs []error
 
 	rp := strings.Split(rulePaths, ";")
+	var remoteRegex = regexp.MustCompile(`^https?:\/\/(www\.)?[-a-zA-Z0-9@:%._\+~#=]{1,256}\.[a-zA-Z0-9()]{1,6}\b([-a-zA-Z0-9()!@:%_\+.~#?&\/\/=]*)`)
 	for _, rule := range rp {
+		rulePath := strings.Trim(rule, " ")
 		var err error
 
-		rulePath := strings.Trim(rule, " ")
 		isRemote := remoteRegex.MatchString(rulePath)
-
 		if isRemote {
 			err = ruleSet.loadRulesFromRemoteFile(rulePath)
 		} else {
@@ -98,7 +94,6 @@ func NewRuleset(rulePaths string) (RuleSet, error) {
 		if err != nil {
 			e := fmt.Errorf("WARN: failed to load ruleset from '%s'", rulePath)
 			errs = append(errs, errors.Join(e, err))
-
 			continue
 		}
 	}
@@ -106,7 +101,6 @@ func NewRuleset(rulePaths string) (RuleSet, error) {
 	if len(errs) != 0 {
 		e := fmt.Errorf("WARN: failed to load %d rulesets", len(rp))
 		errs = append(errs, e)
-
 		// panic if the user specified a local ruleset, but it wasn't found on disk
 		// don't fail silently
 		for _, err := range errs {
@@ -115,13 +109,10 @@ func NewRuleset(rulePaths string) (RuleSet, error) {
 				panic(errors.Join(e, err))
 			}
 		}
-
 		// else, bubble up any errors, such as syntax or remote host issues
 		return ruleSet, errors.Join(errs...)
 	}
-
 	ruleSet.PrintStats()
-
 	return ruleSet, nil
 }
 
@@ -155,16 +146,13 @@ func (rs *RuleSet) loadRulesFromLocalDir(path string) error {
 			log.Printf("WARN: failed to load directory ruleset '%s': %s, skipping", path, err)
 			return nil
 		}
-
 		log.Printf("INFO: loaded ruleset %s\n", path)
-
 		return nil
 	})
 
 	if err != nil {
 		return err
 	}
-
 	return nil
 }
 
@@ -179,51 +167,42 @@ func (rs *RuleSet) loadRulesFromLocalFile(path string) error {
 
 	var r RuleSet
 	err = yaml.Unmarshal(yamlFile, &r)
-
 	if err != nil {
 		e := fmt.Errorf("failed to load rules from local file, possible syntax error in '%s'", path)
 		ee := errors.Join(e, err)
-
 		if _, ok := os.LookupEnv("DEBUG"); ok {
 			debugPrintRule(string(yamlFile), ee)
 		}
-
 		return ee
 	}
-
 	*rs = append(*rs, r...)
-
 	return nil
 }
 
 // loadRulesFromRemoteFile loads rules from a remote URL.
 // It supports plain and gzip compressed content.
 // Returns an error if there's an issue accessing the URL or if there's a syntax error in the YAML.
-func (rs *RuleSet) loadRulesFromRemoteFile(rulesURL string) error {
+func (rs *RuleSet) loadRulesFromRemoteFile(rulesUrl string) error {
 	var r RuleSet
-
+	resp, err := http.Get(rulesUrl)
-	resp, err := http.Get(rulesURL)
 	if err != nil {
-		e := fmt.Errorf("failed to load rules from remote url '%s'", rulesURL)
+		e := fmt.Errorf("failed to load rules from remote url '%s'", rulesUrl)
 		return errors.Join(e, err)
 	}
-
 	defer resp.Body.Close()
 
 	if resp.StatusCode >= 400 {
-		e := fmt.Errorf("failed to load rules from remote url (%s) on '%s'", resp.Status, rulesURL)
+		e := fmt.Errorf("failed to load rules from remote url (%s) on '%s'", resp.Status, rulesUrl)
 		return errors.Join(e, err)
 	}
 
 	var reader io.Reader
-
+	isGzip := strings.HasSuffix(rulesUrl, ".gz") || strings.HasSuffix(rulesUrl, ".gzip") || resp.Header.Get("content-encoding") == "gzip"
-	isGzip := strings.HasSuffix(rulesURL, ".gz") || strings.HasSuffix(rulesURL, ".gzip") || resp.Header.Get("content-encoding") == "gzip"
 
 	if isGzip {
 		reader, err = gzip.NewReader(resp.Body)
-
 		if err != nil {
-			return fmt.Errorf("failed to create gzip reader for URL '%s' with status code '%s': %w", rulesURL, resp.Status, err)
+			return fmt.Errorf("failed to create gzip reader for URL '%s' with status code '%s': %w", rulesUrl, resp.Status, err)
 		}
 	} else {
 		reader = resp.Body
@@ -232,14 +211,12 @@ func (rs *RuleSet) loadRulesFromRemoteFile(rulesURL string) error {
 	err = yaml.NewDecoder(reader).Decode(&r)
 
 	if err != nil {
-		e := fmt.Errorf("failed to load rules from remote url '%s' with status code '%s' and possible syntax error", rulesURL, resp.Status)
+		e := fmt.Errorf("failed to load rules from remote url '%s' with status code '%s' and possible syntax error", rulesUrl, resp.Status)
 		ee := errors.Join(e, err)
-
 		return ee
 	}
 
 	*rs = append(*rs, r...)
-
 	return nil
 }
 
@@ -251,7 +228,6 @@ func (rs *RuleSet) Yaml() (string, error) {
 	if err != nil {
 		return "", err
 	}
-
 	return string(y), nil
 }
 

pkg/ruleset/ruleset_test.go

@@ -33,7 +33,6 @@ func TestLoadRulesFromRemoteFile(t *testing.T) {
 		c.SendString(validYAML)
 		return nil
 	})
-
 	app.Get("/invalid-config.yml", func(c *fiber.Ctx) error {
 		c.SendString(invalidYAML)
 		return nil
@@ -41,12 +40,10 @@ func TestLoadRulesFromRemoteFile(t *testing.T) {
 
 	app.Get("/valid-config.gz", func(c *fiber.Ctx) error {
 		c.Set("Content-Type", "application/octet-stream")
-
 		rs, err := loadRuleFromString(validYAML)
 		if err != nil {
 			t.Errorf("failed to load valid yaml from string: %s", err.Error())
 		}
-
 		s, err := rs.GzipYaml()
 		if err != nil {
 			t.Errorf("failed to load gzip serialize yaml: %s", err.Error())
@@ -73,18 +70,15 @@ func TestLoadRulesFromRemoteFile(t *testing.T) {
 	if err != nil {
 		t.Errorf("failed to load plaintext ruleset from http server: %s", err.Error())
 	}
-
 	assert.Equal(t, rs[0].Domain, "example.com")
 
 	rs, err = NewRuleset("http://127.0.0.1:9999/valid-config.gz")
 	if err != nil {
 		t.Errorf("failed to load gzipped ruleset from http server: %s", err.Error())
 	}
-
 	assert.Equal(t, rs[0].Domain, "example.com")
 
 	os.Setenv("RULESET", "http://127.0.0.1:9999/valid-config.gz")
-
 	rs = NewRulesetFromEnv()
 	if !assert.Equal(t, rs[0].Domain, "example.com") {
 		t.Error("expected no errors loading ruleset from gzip url using environment variable, but got one")
@@ -94,14 +88,10 @@ func TestLoadRulesFromRemoteFile(t *testing.T) {
 func loadRuleFromString(yaml string) (RuleSet, error) {
 	// Create a temporary file and load it
 	tmpFile, _ := os.CreateTemp("", "ruleset*.yaml")
-
 	defer os.Remove(tmpFile.Name())
-
 	tmpFile.WriteString(yaml)
-
 	rs := RuleSet{}
 	err := rs.loadRulesFromLocalFile(tmpFile.Name())
-
 	return rs, err
 }
 
@@ -111,7 +101,6 @@ func TestLoadRulesFromLocalFile(t *testing.T) {
 	if err != nil {
 		t.Errorf("Failed to load rules from valid YAML: %s", err)
 	}
-
 	assert.Equal(t, rs[0].Domain, "example.com")
 	assert.Equal(t, rs[0].RegexRules[0].Match, "^http:")
 	assert.Equal(t, rs[0].RegexRules[0].Replace, "https:")
@@ -129,39 +118,30 @@ func TestLoadRulesFromLocalDir(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Failed to create temporary directory: %s", err)
 	}
-
 	defer os.RemoveAll(baseDir)
 
 	// Create a nested subdirectory
 	nestedDir := filepath.Join(baseDir, "nested")
-	err = os.Mkdir(nestedDir, 0o755)
+	err = os.Mkdir(nestedDir, 0755)
-
 	if err != nil {
 		t.Fatalf("Failed to create nested directory: %s", err)
 	}
 
 	// Create a nested subdirectory
 	nestedTwiceDir := filepath.Join(nestedDir, "nestedTwice")
-	err = os.Mkdir(nestedTwiceDir, 0o755)
+	err = os.Mkdir(nestedTwiceDir, 0755)
-	if err != nil {
-		t.Fatalf("Failed to create twice-nested directory: %s", err)
-	}
 
 	testCases := []string{"test.yaml", "test2.yaml", "test-3.yaml", "test 4.yaml", "1987.test.yaml.yml", "foobar.example.com.yaml", "foobar.com.yml"}
 	for _, fileName := range testCases {
 		filePath := filepath.Join(nestedDir, "2x-"+fileName)
-		os.WriteFile(filePath, []byte(validYAML), 0o644)
+		os.WriteFile(filePath, []byte(validYAML), 0644)
-
 		filePath = filepath.Join(nestedDir, fileName)
-		os.WriteFile(filePath, []byte(validYAML), 0o644)
+		os.WriteFile(filePath, []byte(validYAML), 0644)
-
 		filePath = filepath.Join(baseDir, "base-"+fileName)
-		os.WriteFile(filePath, []byte(validYAML), 0o644)
+		os.WriteFile(filePath, []byte(validYAML), 0644)
 	}
-
 	rs := RuleSet{}
 	err = rs.loadRulesFromLocalDir(baseDir)
-
 	assert.NoError(t, err)
 	assert.Equal(t, rs.Count(), len(testCases)*3)
 

proxychain/proxychain.go

@@ -0,0 +1,427 @@
+package proxychain
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"log"
+	"net/http"
+	"net/url"
+	"strings"
+
+	"ladder/pkg/ruleset"
+	rr "ladder/proxychain/responsemodifers/rewriters"
+
+	"github.com/gofiber/fiber/v2"
+)
+
+/*
+ProxyChain manages the process of forwarding an HTTP request to an upstream server,
+applying request and response modifications along the way.
+
+  - It accepts incoming HTTP requests (as a Fiber *ctx), and applies
+    request modifiers (ReqMods) and response modifiers (ResMods) before passing the
+    upstream response back to the client.
+
+  - ProxyChains can be reused to avoid memory allocations. However, they are not concurrent-safe
+    so a ProxyChainPool should be used with mutexes to avoid memory errors.
+
+---
+
+# EXAMPLE
+
+```
+
+import (
+
+	rx "ladder/pkg/proxychain/requestmodifers"
+	tx "ladder/pkg/proxychain/responsemodifers"
+	"ladder/pkg/proxychain/responsemodifers/rewriters"
+	"ladder/internal/proxychain"
+
+)
+
+proxychain.NewProxyChain().
+
+	SetFiberCtx(c).
+	SetRequestModifications(
+		rx.BlockOutgoingCookies(),
+		rx.SpoofOrigin(),
+		rx.SpoofReferrer(),
+	).
+	SetResultModifications(
+		tx.BlockIncomingCookies(),
+		tx.RewriteHTMLResourceURLs()
+	).
+	Execute()
+
+```
+
+	client            ladder service            upstream
+
+┌─────────┐    ┌────────────────────────┐    ┌─────────┐
+│         │GET │                        │    │         │
+│       req────┼───► ProxyChain         │    │         │
+│         │    │       │                │    │         │
+│         │    │       ▼                │    │         │
+│         │    │     apply              │    │         │
+│         │    │ RequestModifications   │    │         │
+│         │    │       │                │    │         │
+│         │    │       ▼                │    │         │
+│         │    │     send        GET    │    │         │
+│         │    │     Request req────────┼─►  │         │
+│         │    │                        │    │         │
+│         │    │                 200 OK │    │         │
+│         │    │       ┌────────────────┼─response     │
+│         │    │       ▼                │    │         │
+│         │    │     apply              │    │         │
+│         │    │ ResultModifications    │    │         │
+│         │    │       │                │    │         │
+│         │◄───┼───────┘                │    │         │
+│         │    │ 200 OK                 │    │         │
+│         │    │                        │    │         │
+└─────────┘    └────────────────────────┘    └─────────┘
+*/
+type ProxyChain struct {
+	Context              *fiber.Ctx
+	Client               *http.Client
+	Request              *http.Request
+	Response             *http.Response
+	requestModifications []RequestModification
+	resultModifications  []ResponseModification
+	htmlTokenRewriters   []rr.IHTMLTokenRewriter
+	Ruleset              *ruleset.RuleSet
+	debugMode            bool
+	abortErr             error
+}
+
+// a ProxyStrategy is a pre-built proxychain with purpose-built defaults
+type ProxyStrategy ProxyChain
+
+// A RequestModification is a function that should operate on the
+// ProxyChain Req or Client field, using the fiber ctx as needed.
+type RequestModification func(*ProxyChain) error
+
+// A ResponseModification is a function that should operate on the
+// ProxyChain Res (http result) & Body (buffered http response body) field
+type ResponseModification func(*ProxyChain) error
+
+// SetRequestModifications sets the ProxyChain's request modifers
+// the modifier will not fire until ProxyChain.Execute() is run.
+func (chain *ProxyChain) SetRequestModifications(mods ...RequestModification) *ProxyChain {
+	chain.requestModifications = mods
+	return chain
+}
+
+// AddRequestModifications sets the ProxyChain's request modifers
+// the modifier will not fire until ProxyChain.Execute() is run.
+func (chain *ProxyChain) AddRequestModifications(mods ...RequestModification) *ProxyChain {
+	chain.requestModifications = append(chain.requestModifications, mods...)
+	return chain
+}
+
+// AddResponseModifications sets the ProxyChain's response modifers
+// the modifier will not fire until ProxyChain.Execute() is run.
+func (chain *ProxyChain) AddResponseModifications(mods ...ResponseModification) *ProxyChain {
+	chain.resultModifications = mods
+	return chain
+}
+
+// Adds a ruleset to ProxyChain
+func (chain *ProxyChain) AddRuleset(rs *ruleset.RuleSet) *ProxyChain {
+	chain.Ruleset = rs
+	// TODO: add _applyRuleset method
+	return chain
+}
+
+func (chain *ProxyChain) _initialize_request() (*http.Request, error) {
+	if chain.Context == nil {
+		chain.abortErr = chain.abort(errors.New("no context set"))
+		return nil, chain.abortErr
+	}
+	// initialize a request (without url)
+	req, err := http.NewRequest(chain.Context.Method(), "", nil)
+	if err != nil {
+		return nil, err
+	}
+	chain.Request = req
+	switch chain.Context.Method() {
+	case "GET":
+	case "DELETE":
+	case "HEAD":
+	case "OPTIONS":
+		break
+	case "POST":
+	case "PUT":
+	case "PATCH":
+		// stream content of body from client request to upstream request
+		chain.Request.Body = io.NopCloser(chain.Context.Request().BodyStream())
+	default:
+		return nil, fmt.Errorf("unsupported request method from client: '%s'", chain.Context.Method())
+	}
+
+	/*
+		// copy client request headers to upstream request headers
+		forwardHeaders := func(key []byte, val []byte) {
+			req.Header.Set(string(key), string(val))
+		}
+		clientHeaders := &chain.Context.Request().Header
+		clientHeaders.VisitAll(forwardHeaders)
+	*/
+
+	return req, nil
+}
+
+// reconstructUrlFromReferer reconstructs the URL using the referer's scheme, host, and the relative path / queries
+func reconstructUrlFromReferer(referer *url.URL, relativeUrl *url.URL) (*url.URL, error) {
+
+	// Extract the real url from referer path
+	realUrl, err := url.Parse(strings.TrimPrefix(referer.Path, "/"))
+	if err != nil {
+		return nil, fmt.Errorf("error parsing real URL from referer '%s': %v", referer.Path, err)
+	}
+
+	if realUrl.Scheme == "" || realUrl.Host == "" {
+		return nil, fmt.Errorf("invalid referer URL: '%s' on request '%s", referer.String(), relativeUrl.String())
+	}
+
+	log.Printf("rewrite relative URL using referer: '%s' -> '%s'\n", relativeUrl.String(), realUrl.String())
+
+	return &url.URL{
+		Scheme:   referer.Scheme,
+		Host:     referer.Host,
+		Path:     realUrl.Path,
+		RawQuery: realUrl.RawQuery,
+	}, nil
+}
+
+// prevents calls like: http://localhost:8080/http://localhost:8080
+func preventRecursiveProxyRequest(urlQuery *url.URL, baseProxyURL string) *url.URL {
+	u := urlQuery.String()
+	isRecursive := strings.HasPrefix(u, baseProxyURL) || u == baseProxyURL
+	if !isRecursive {
+		return urlQuery
+	}
+
+	fixedURL, err := url.Parse(strings.TrimPrefix(strings.TrimPrefix(urlQuery.String(), baseProxyURL), "/"))
+	if err != nil {
+		log.Printf("proxychain: failed to fix recursive request: '%s' -> '%s\n'", baseProxyURL, u)
+		return urlQuery
+	}
+	return preventRecursiveProxyRequest(fixedURL, baseProxyURL)
+}
+
+// extractUrl extracts a URL from the request ctx. If the URL in the request
+// is a relative path, it reconstructs the full URL using the referer header.
+func (chain *ProxyChain) extractUrl() (*url.URL, error) {
+	reqUrl := chain.Context.Params("*")
+
+	// sometimes client requests doubleroot '//'
+	// there is a bug somewhere else, but this is a workaround until we find it
+	if strings.HasPrefix(reqUrl, "/") || strings.HasPrefix(reqUrl, `%2F`) {
+		reqUrl = strings.TrimPrefix(reqUrl, "/")
+		reqUrl = strings.TrimPrefix(reqUrl, `%2F`)
+	}
+
+	// unescape url query
+	uReqUrl, err := url.QueryUnescape(reqUrl)
+	if err == nil {
+		reqUrl = uReqUrl
+	}
+
+	urlQuery, err := url.Parse(reqUrl)
+	if err != nil {
+		return nil, fmt.Errorf("error parsing request URL '%s': %v", reqUrl, err)
+	}
+
+	// prevent recursive proxy requests
+	fullURL := chain.Context.Request().URI()
+	proxyURL := fmt.Sprintf("%s://%s", fullURL.Scheme(), fullURL.Host())
+	urlQuery = preventRecursiveProxyRequest(urlQuery, proxyURL)
+
+	// Handle standard paths
+	// eg: https://localhost:8080/https://realsite.com/images/foobar.jpg -> https://realsite.com/images/foobar.jpg
+	isRelativePath := urlQuery.Scheme == ""
+	if !isRelativePath {
+		return urlQuery, nil
+	}
+
+	// Handle relative URLs
+	// eg: https://localhost:8080/images/foobar.jpg -> https://realsite.com/images/foobar.jpg
+	referer, err := url.Parse(chain.Context.Get("referer"))
+	relativePath := urlQuery
+	if err != nil {
+		return nil, fmt.Errorf("error parsing referer URL from req: '%s': %v", relativePath, err)
+	}
+	return reconstructUrlFromReferer(referer, relativePath)
+}
+
+// AddBodyRewriter adds a HTMLTokenRewriter to the chain.
+//   - HTMLTokenRewriters modify the body response by parsing the HTML
+//     and making changes to the DOM as it streams to the client
+//   - In most cases, you don't need to use this method. It's usually called by
+//     a ResponseModifier to batch queue changes for performance reasons.
+func (chain *ProxyChain) AddHTMLTokenRewriter(rr rr.IHTMLTokenRewriter) *ProxyChain {
+	chain.htmlTokenRewriters = append(chain.htmlTokenRewriters, rr)
+	return chain
+}
+
+// SetFiberCtx takes the request ctx from the client
+// for the modifiers and execute function to use.
+// it must be set everytime a new request comes through
+// if the upstream request url cannot be extracted from the ctx,
+// a 500 error will be sent back to the client
+func (chain *ProxyChain) SetFiberCtx(ctx *fiber.Ctx) *ProxyChain {
+	chain.Context = ctx
+
+	// initialize the request and prepare it for modification
+	req, err := chain._initialize_request()
+	if err != nil {
+		chain.abortErr = chain.abort(err)
+	}
+	chain.Request = req
+
+	// extract the URL for the request and add it to the new request
+	url, err := chain.extractUrl()
+	if err != nil {
+		chain.abortErr = chain.abort(err)
+	}
+	chain.Request.URL = url
+	fmt.Printf("extracted URL: %s\n", chain.Request.URL)
+
+	return chain
+}
+
+func (chain *ProxyChain) validateCtxIsSet() error {
+	if chain.Context != nil {
+		return nil
+	}
+	err := errors.New("proxyChain was called without setting a fiber Ctx. Use ProxyChain.SetCtx()")
+	chain.abortErr = chain.abort(err)
+	return chain.abortErr
+}
+
+// SetHttpClient sets a new upstream http client transport
+// useful for modifying TLS
+func (chain *ProxyChain) SetHttpClient(httpClient *http.Client) *ProxyChain {
+	chain.Client = httpClient
+	return chain
+}
+
+// SetVerbose changes the logging behavior to print
+// the modification steps and applied rulesets for debugging
+func (chain *ProxyChain) SetDebugLogging(isDebugMode bool) *ProxyChain {
+	chain.debugMode = isDebugMode
+	return chain
+}
+
+// abort proxychain and return 500 error to client
+// this will prevent Execute from firing and reset the state
+// returns the initial error enriched with context
+func (chain *ProxyChain) abort(err error) error {
+	//defer chain._reset()
+	chain.abortErr = err
+	chain.Context.Response().SetStatusCode(500)
+	e := fmt.Errorf("ProxyChain error for '%s': %s", chain.Request.URL.String(), err.Error())
+	chain.Context.SendString(e.Error())
+	log.Println(e.Error())
+	return e
+}
+
+// internal function to reset state of ProxyChain for reuse
+func (chain *ProxyChain) _reset() {
+	chain.abortErr = nil
+	chain.Request = nil
+	//chain.Response = nil
+	chain.Context = nil
+}
+
+// NewProxyChain initializes a new ProxyChain
+func NewProxyChain() *ProxyChain {
+	chain := new(ProxyChain)
+	chain.Client = http.DefaultClient
+	return chain
+}
+
+/// ========================================================================================================
+
+// _execute sends the request for the ProxyChain and returns the raw body only
+// the caller is responsible for returning a response back to the requestor
+// the caller is also responsible for calling chain._reset() when they are done with the body
+func (chain *ProxyChain) _execute() (io.Reader, error) {
+	if chain.validateCtxIsSet() != nil || chain.abortErr != nil {
+		return nil, chain.abortErr
+	}
+	if chain.Request == nil {
+		return nil, errors.New("proxychain request not yet initialized")
+	}
+	if chain.Request.URL.Scheme == "" {
+		return nil, errors.New("request url not set or invalid. Check ProxyChain ReqMods for issues")
+	}
+
+	// Apply requestModifications to proxychain
+	for _, applyRequestModificationsTo := range chain.requestModifications {
+		err := applyRequestModificationsTo(chain)
+		if err != nil {
+			return nil, chain.abort(err)
+		}
+	}
+
+	// Send Request Upstream
+	resp, err := chain.Client.Do(chain.Request)
+	if err != nil {
+		return nil, chain.abort(err)
+	}
+	chain.Response = resp
+
+	/* todo: move to rsm
+	for k, v := range resp.Header {
+		chain.Context.Set(k, resp.Header.Get(k))
+	}
+	*/
+
+	// Apply ResponseModifiers to proxychain
+	for _, applyResultModificationsTo := range chain.resultModifications {
+		err := applyResultModificationsTo(chain)
+		if err != nil {
+			return nil, chain.abort(err)
+		}
+	}
+
+	// stream request back to client, possibly rewriting the body
+	if len(chain.htmlTokenRewriters) == 0 {
+		return chain.Response.Body, nil
+	}
+
+	ct := chain.Response.Header.Get("content-type")
+	switch {
+	case strings.HasPrefix(ct, "text/html"):
+		fmt.Println("fooox")
+		return rr.NewHTMLRewriter(chain.Response.Body, chain.htmlTokenRewriters), nil
+	default:
+		return chain.Response.Body, nil
+	}
+
+}
+
+// Execute sends the request for the ProxyChain and returns the request to the sender
+// and resets the fields so that the ProxyChain can be reused.
+// if any step in the ProxyChain fails, the request will abort and a 500 error will
+// be returned to the client
+func (chain *ProxyChain) Execute() error {
+	defer chain._reset()
+	body, err := chain._execute()
+	if err != nil {
+		log.Println(err)
+		return err
+	}
+	if chain.Context == nil {
+		return errors.New("no context set")
+	}
+
+	// Return request back to client
+	chain.Context.Set("content-type", chain.Response.Header.Get("content-type"))
+	return chain.Context.SendStream(body)
+
+	//return chain.Context.SendStream(body)
+}

proxychain/proxychain_pool.go

@@ -0,0 +1,11 @@
+package proxychain
+
+import (
+	"net/url"
+)
+
+type ProxyChainPool map[url.URL]ProxyChain
+
+func NewProxyChainPool() ProxyChainPool {
+	return map[url.URL]ProxyChain{}
+}

proxychain/requestmodifers/masquerade_as_trusted_bot.go

@@ -0,0 +1,33 @@
+package requestmodifers
+
+import (
+	"ladder/proxychain"
+)
+
+// MasqueradeAsGoogleBot modifies user agent and x-forwarded for
+// to appear to be a Google Bot
+func MasqueradeAsGoogleBot() proxychain.RequestModification {
+	const botUA string = "Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko; compatible; Googlebot/2.1; http://www.google.com/bot.html) Chrome/79.0.3945.120 Safari/537.36"
+	const botIP string = "66.249.78.8" // TODO: create a random ip pool from https://developers.google.com/static/search/apis/ipranges/googlebot.json
+	return masqueradeAsTrustedBot(botUA, botIP)
+}
+
+// MasqueradeAsBingBot modifies user agent and x-forwarded for
+// to appear to be a Bing Bot
+func MasqueradeAsBingBot() proxychain.RequestModification {
+	const botUA string = "Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko; compatible; bingbot/2.0; +http://www.bing.com/bingbot.htm) Chrome/79.0.3945.120 Safari/537.36"
+	const botIP string = "13.66.144.9" // https://www.bing.com/toolbox/bingbot.json
+	return masqueradeAsTrustedBot(botUA, botIP)
+}
+
+func masqueradeAsTrustedBot(botUA string, botIP string) proxychain.RequestModification {
+	return func(px *proxychain.ProxyChain) error {
+		px.AddRequestModifications(
+			SpoofUserAgent(botUA),
+			SpoofXForwardedFor(botIP),
+			SpoofReferrer(""),
+			SpoofOrigin(""),
+		)
+		return nil
+	}
+}

proxychain/requestmodifers/modify_domain_with_regex.go

@@ -0,0 +1,13 @@
+package requestmodifers
+
+import (
+	"ladder/proxychain"
+	"regexp"
+)
+
+func ModifyDomainWithRegex(match regexp.Regexp, replacement string) proxychain.RequestModification {
+	return func(px *proxychain.ProxyChain) error {
+		px.Request.URL.Host = match.ReplaceAllString(px.Request.URL.Host, replacement)
+		return nil
+	}
+}

proxychain/requestmodifers/modify_outgoing_cookies.go

@@ -0,0 +1,97 @@
+package requestmodifers
+
+import (
+	"ladder/proxychain"
+	"net/http"
+)
+
+// SetOutgoingCookie modifes a specific cookie name
+// by modifying the request cookie headers going to the upstream server.
+// If the cookie name does not already exist, it is created.
+func SetOutgoingCookie(name string, val string) proxychain.RequestModification {
+	return func(chain *proxychain.ProxyChain) error {
+		cookies := chain.Request.Cookies()
+		hasCookie := false
+		for _, cookie := range cookies {
+			if cookie.Name != name {
+				continue
+			}
+			hasCookie = true
+			cookie.Value = val
+		}
+
+		if hasCookie {
+			return nil
+		}
+
+		chain.Request.AddCookie(&http.Cookie{
+			Domain: chain.Request.URL.Host,
+			Name:   name,
+			Value:  val,
+		})
+
+		return nil
+	}
+}
+
+// SetOutgoingCookies modifies a client request's cookie header
+// to a raw Cookie string, overwriting existing cookies
+func SetOutgoingCookies(cookies string) proxychain.RequestModification {
+	return func(chain *proxychain.ProxyChain) error {
+		chain.Request.Header.Set("Cookies", cookies)
+		return nil
+	}
+}
+
+// DeleteOutgoingCookie modifies the http request's cookies header to
+// delete a specific request cookie going to the upstream server.
+// If the cookie does not exist, it does not do anything.
+func DeleteOutgoingCookie(name string) proxychain.RequestModification {
+	return func(chain *proxychain.ProxyChain) error {
+		cookies := chain.Request.Cookies()
+		chain.Request.Header.Del("Cookies")
+
+		for _, cookie := range cookies {
+			if cookie.Name == name {
+				chain.Request.AddCookie(cookie)
+			}
+		}
+		return nil
+	}
+}
+
+// DeleteOutgoingCookies removes the cookie header entirely,
+// preventing any cookies from reaching the upstream server.
+func DeleteOutgoingCookies() proxychain.RequestModification {
+	return func(px *proxychain.ProxyChain) error {
+		px.Request.Header.Del("Cookie")
+		return nil
+	}
+}
+
+// DeleteOutGoingCookiesExcept prevents non-whitelisted cookies from being sent from the client
+// to the upstream proxy server. Cookies whose names are in the whitelist are not removed.
+func DeleteOutgoingCookiesExcept(whitelist ...string) proxychain.RequestModification {
+	return func(px *proxychain.ProxyChain) error {
+		// Convert whitelist slice to a map for efficient lookups
+		whitelistMap := make(map[string]struct{})
+		for _, cookieName := range whitelist {
+			whitelistMap[cookieName] = struct{}{}
+		}
+
+		// Get all cookies from the request header
+		cookies := px.Request.Cookies()
+
+		// Clear the original Cookie header
+		px.Request.Header.Del("Cookie")
+
+		// Re-add cookies that are in the whitelist
+		for _, cookie := range cookies {
+			if _, found := whitelistMap[cookie.Name]; found {
+				px.Request.AddCookie(cookie)
+			}
+		}
+
+		return nil
+	}
+}

proxychain/requestmodifers/modify_path_with_regex.go

@@ -0,0 +1,13 @@
+package requestmodifers
+
+import (
+	"ladder/proxychain"
+	"regexp"
+)
+
+func ModifyPathWithRegex(match regexp.Regexp, replacement string) proxychain.RequestModification {
+	return func(px *proxychain.ProxyChain) error {
+		px.Request.URL.Path = match.ReplaceAllString(px.Request.URL.Path, replacement)
+		return nil
+	}
+}

proxychain/requestmodifers/modify_query_params.go

@@ -0,0 +1,20 @@
+package requestmodifers
+
+import (
+	"ladder/proxychain"
+)
+
+// ModifyQueryParams replaces query parameter values in URL's query params in a ProxyChain's URL.
+// If the query param key doesn't exist, it is created.
+func ModifyQueryParams(key string, value string) proxychain.RequestModification {
+	return func(px *proxychain.ProxyChain) error {
+		q := px.Request.URL.Query()
+		if value == "" {
+			q.Del(key)
+			return nil
+		}
+		q.Set(key, value)
+		px.Request.URL.RawQuery = q.Encode()
+		return nil
+	}
+}

proxychain/requestmodifers/modify_request_headers.go

@@ -0,0 +1,23 @@
+package requestmodifers
+
+import (
+	"ladder/proxychain"
+)
+
+// SetRequestHeader modifies a specific outgoing header
+// This is the header that the upstream server will see.
+func SetRequestHeader(name string, val string) proxychain.RequestModification {
+	return func(px *proxychain.ProxyChain) error {
+		px.Request.Header.Set(name, val)
+		return nil
+	}
+}
+
+// DeleteRequestHeader modifies a specific outgoing header
+// This is the header that the upstream server will see.
+func DeleteRequestHeader(name string) proxychain.RequestModification {
+	return func(px *proxychain.ProxyChain) error {
+		px.Request.Header.Del(name)
+		return nil
+	}
+}

proxychain/requestmodifers/request_archive_is.go

@@ -0,0 +1,27 @@
+package requestmodifers
+
+import (
+	"ladder/proxychain"
+	"net/url"
+)
+
+const archivistUrl string = "https://archive.is/latest/"
+
+// RequestArchiveIs modifies a ProxyChain's URL to request an archived version from archive.is
+func RequestArchiveIs() proxychain.RequestModification {
+	return func(px *proxychain.ProxyChain) error {
+		px.Request.URL.RawQuery = ""
+		newURLString := archivistUrl + px.Request.URL.String()
+		newURL, err := url.Parse(newURLString)
+		if err != nil {
+			return err
+		}
+
+		// archivist seems to sabotage requests from cloudflare's DNS
+		// bypass this just in case
+		px.AddRequestModifications(ResolveWithGoogleDoH())
+
+		px.Request.URL = newURL
+		return nil
+	}
+}

proxychain/requestmodifers/request_google_cache.go

@@ -0,0 +1,21 @@
+package requestmodifers
+
+import (
+	"ladder/proxychain"
+	"net/url"
+)
+
+const googleCacheUrl string = "https://webcache.googleusercontent.com/search?q=cache:"
+
+// RequestGoogleCache modifies a ProxyChain's URL to request its Google Cache version.
+func RequestGoogleCache() proxychain.RequestModification {
+	return func(px *proxychain.ProxyChain) error {
+		encodedURL := url.QueryEscape(px.Request.URL.String())
+		newURL, err := url.Parse(googleCacheUrl + encodedURL)
+		if err != nil {
+			return err
+		}
+		px.Request.URL = newURL
+		return nil
+	}
+}

proxychain/requestmodifers/request_wayback_machine.go

@@ -0,0 +1,22 @@
+package requestmodifers
+
+import (
+	"ladder/proxychain"
+	"net/url"
+)
+
+const waybackUrl string = "https://web.archive.org/web/"
+
+// RequestWaybackMachine modifies a ProxyChain's URL to request the wayback machine (archive.org) version.
+func RequestWaybackMachine() proxychain.RequestModification {
+	return func(px *proxychain.ProxyChain) error {
+		px.Request.URL.RawQuery = ""
+		newURLString := waybackUrl + px.Request.URL.String()
+		newURL, err := url.Parse(newURLString)
+		if err != nil {
+			return err
+		}
+		px.Request.URL = newURL
+		return nil
+	}
+}

proxychain/requestmodifers/resolve_with_google_doh.go

@@ -0,0 +1,80 @@
+package requestmodifers
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"ladder/proxychain"
+	"net"
+	"net/http"
+	"time"
+)
+
+// resolveWithGoogleDoH resolves DNS using Google's DNS-over-HTTPS
+func resolveWithGoogleDoH(host string) (string, error) {
+	url := "https://dns.google/resolve?name=" + host + "&type=A"
+	resp, err := http.Get(url)
+	if err != nil {
+		return "", err
+	}
+	defer resp.Body.Close()
+
+	var result struct {
+		Answer []struct {
+			Data string `json:"data"`
+		} `json:"Answer"`
+	}
+	err = json.NewDecoder(resp.Body).Decode(&result)
+	if err != nil {
+		return "", err
+	}
+
+	// Get the first A record
+	if len(result.Answer) > 0 {
+		return result.Answer[0].Data, nil
+	}
+	return "", fmt.Errorf("no DoH DNS record found for %s", host)
+}
+
+// ResolveWithGoogleDoH modifies a ProxyChain's client to make the request by resolving the URL
+// using Google's DNS over HTTPs service
+func ResolveWithGoogleDoH() proxychain.RequestModification {
+	return func(px *proxychain.ProxyChain) error {
+		client := &http.Client{
+			Timeout: px.Client.Timeout,
+		}
+
+		dialer := &net.Dialer{
+			Timeout:   5 * time.Second,
+			KeepAlive: 5 * time.Second,
+		}
+
+		customDialContext := func(ctx context.Context, network, addr string) (net.Conn, error) {
+			host, port, err := net.SplitHostPort(addr)
+			if err != nil {
+				// If the addr doesn't include a port, determine it based on the URL scheme
+				if px.Request.URL.Scheme == "https" {
+					port = "443"
+				} else {
+					port = "80"
+				}
+				host = addr // assume the entire addr is the host
+			}
+
+			resolvedHost, err := resolveWithGoogleDoH(host)
+			if err != nil {
+				return nil, err
+			}
+
+			return dialer.DialContext(ctx, network, net.JoinHostPort(resolvedHost, port))
+		}
+
+		patchedTransportWithDoH := &http.Transport{
+			DialContext: customDialContext,
+		}
+
+		client.Transport = patchedTransportWithDoH
+		px.Client = client // Assign the modified client to the ProxyChain
+		return nil
+	}
+}

proxychain/requestmodifers/spoof_origin.go

@@ -0,0 +1,24 @@
+package requestmodifers
+
+import (
+	"ladder/proxychain"
+)
+
+// SpoofOrigin modifies the origin header
+// if the upstream server returns a Vary header
+// it means you might get a different response if you change this
+func SpoofOrigin(url string) proxychain.RequestModification {
+	return func(px *proxychain.ProxyChain) error {
+		px.Request.Header.Set("origin", url)
+		return nil
+	}
+}
+
+// HideOrigin modifies the origin header
+// so that it is the original origin, not the proxy
+func HideOrigin() proxychain.RequestModification {
+	return func(px *proxychain.ProxyChain) error {
+		px.Request.Header.Set("origin", px.Request.URL.String())
+		return nil
+	}
+}

proxychain/requestmodifers/spoof_referrer.go

@@ -0,0 +1,29 @@
+package requestmodifers
+
+import (
+	"ladder/proxychain"
+)
+
+// SpoofReferrer modifies the referrer header
+// useful if the page can be accessed from a search engine
+// or social media site, but not by browsing the website itself
+// if url is "", then the referrer header is removed
+func SpoofReferrer(url string) proxychain.RequestModification {
+	return func(px *proxychain.ProxyChain) error {
+		if url == "" {
+			px.Request.Header.Del("referrer")
+			return nil
+		}
+		px.Request.Header.Set("referrer", url)
+		return nil
+	}
+}
+
+// HideReferrer modifies the referrer header
+// so that it is the original referrer, not the proxy
+func HideReferrer() proxychain.RequestModification {
+	return func(px *proxychain.ProxyChain) error {
+		px.Request.Header.Set("referrer", px.Request.URL.String())
+		return nil
+	}
+}

proxychain/requestmodifers/spoof_referrer_from_baidu_post.go

@@ -0,0 +1,44 @@
+package requestmodifers
+
+import (
+	"fmt"
+	"ladder/proxychain"
+	"math/rand"
+	"strings"
+	"time"
+)
+
+// SpoofReferrerFromBaiduSearch modifies the referrer header
+// pretending to be from a BaiduSearch
+func SpoofReferrerFromBaiduSearch() proxychain.RequestModification {
+	return func(chain *proxychain.ProxyChain) error {
+		// https://www.baidu.com/link?url=5biIeDvUIihawf3Zbbysach2Xn4H3w3FzO6LZKgSs-B5Yt4M4RUFikokOk5zetf2&wd=&eqid=9da80d8208009b8480000706655d5ed6
+		referrer := fmt.Sprintf("https://baidu.com/link?url=%s", generateRandomBaiduURL())
+		chain.AddRequestModifications(
+			SpoofReferrer(referrer),
+			SetRequestHeader("sec-fetch-site", "cross-site"),
+			SetRequestHeader("sec-fetch-dest", "document"),
+			SetRequestHeader("sec-fetch-mode", "navigate"),
+		)
+		return nil
+	}
+}
+
+// utility functions ==================
+
+func generateRandomString(charset string, length int) string {
+	var seededRand *rand.Rand = rand.New(rand.NewSource(time.Now().UnixNano()))
+	var stringBuilder strings.Builder
+	for i := 0; i < length; i++ {
+		stringBuilder.WriteByte(charset[seededRand.Intn(len(charset))])
+	}
+	return stringBuilder.String()
+}
+
+func generateRandomBaiduURL() string {
+	const alphanumericCharset = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
+	const hexCharset = "0123456789abcdef"
+	randomAlphanumeric := generateRandomString(alphanumericCharset, 30) // Length before "-"
+	randomHex := generateRandomString(hexCharset, 16)                   // Length of eqid
+	return randomAlphanumeric + "-" + "&wd=&eqid=" + randomHex
+}

proxychain/requestmodifers/spoof_referrer_from_bing_search.go

@@ -0,0 +1,20 @@
+package requestmodifers
+
+import (
+	"ladder/proxychain"
+)
+
+// SpoofReferrerFromBingSearch modifies the referrer header
+// pretending to be from a bing search site
+func SpoofReferrerFromBingSearch() proxychain.RequestModification {
+	return func(chain *proxychain.ProxyChain) error {
+		chain.AddRequestModifications(
+			SpoofReferrer("https://www.bing.com/"),
+			SetRequestHeader("sec-fetch-site", "cross-site"),
+			SetRequestHeader("sec-fetch-dest", "document"),
+			SetRequestHeader("sec-fetch-mode", "navigate"),
+			ModifyQueryParams("utm_source", "bing"),
+		)
+		return nil
+	}
+}

proxychain/requestmodifers/spoof_referrer_from_google_search.go

@@ -0,0 +1,20 @@
+package requestmodifers
+
+import (
+	"ladder/proxychain"
+)
+
+// SpoofReferrerFromGoogleSearch modifies the referrer header
+// pretending to be from a google search site
+func SpoofReferrerFromGoogleSearch() proxychain.RequestModification {
+	return func(chain *proxychain.ProxyChain) error {
+		chain.AddRequestModifications(
+			SpoofReferrer("https://www.google.com/"),
+			SetRequestHeader("sec-fetch-site", "cross-site"),
+			SetRequestHeader("sec-fetch-dest", "document"),
+			SetRequestHeader("sec-fetch-mode", "navigate"),
+			ModifyQueryParams("utm_source", "google"),
+		)
+		return nil
+	}
+}

proxychain/requestmodifers/spoof_referrer_from_linkedin_post.go

@@ -0,0 +1,21 @@
+package requestmodifers
+
+import (
+	"ladder/proxychain"
+)
+
+// SpoofReferrerFromLinkedInPost modifies the referrer header
+// pretending to be from a linkedin post
+func SpoofReferrerFromLinkedInPost() proxychain.RequestModification {
+	return func(chain *proxychain.ProxyChain) error {
+		chain.AddRequestModifications(
+			SpoofReferrer("https://www.linkedin.com/"),
+			SetRequestHeader("sec-fetch-site", "cross-site"),
+			SetRequestHeader("sec-fetch-dest", "document"),
+			SetRequestHeader("sec-fetch-mode", "navigate"),
+			ModifyQueryParams("utm_campaign", "post"),
+			ModifyQueryParams("utm_medium", "web"),
+		)
+		return nil
+	}
+}

proxychain/requestmodifers/spoof_referrer_from_naver_post.go

@@ -0,0 +1,24 @@
+package requestmodifers
+
+import (
+	"fmt"
+	"ladder/proxychain"
+)
+
+// SpoofReferrerFromNaverSearch modifies the referrer header
+// pretending to be from a Naver search (popular in South Korea)
+func SpoofReferrerFromNaverSearch() proxychain.RequestModification {
+	return func(chain *proxychain.ProxyChain) error {
+		referrer := fmt.Sprintf(
+			"https://search.naver.com/search.naver?where=nexearch&sm=top_hty&fbm=0&ie=utf8&query=%s",
+			chain.Request.URL.Host,
+		)
+		chain.AddRequestModifications(
+			SpoofReferrer(referrer),
+			SetRequestHeader("sec-fetch-site", "cross-site"),
+			SetRequestHeader("sec-fetch-dest", "document"),
+			SetRequestHeader("sec-fetch-mode", "navigate"),
+		)
+		return nil
+	}
+}

proxychain/requestmodifers/spoof_referrer_from_pinterest_post.go

@@ -0,0 +1,19 @@
+package requestmodifers
+
+import (
+	"ladder/proxychain"
+)
+
+// SpoofReferrerFromPinterestPost modifies the referrer header
+// pretending to be from a pinterest post
+func SpoofReferrerFromPinterestPost() proxychain.RequestModification {
+	return func(chain *proxychain.ProxyChain) error {
+		chain.AddRequestModifications(
+			SpoofReferrer("https://www.pinterest.com/"),
+			SetRequestHeader("sec-fetch-site", "cross-site"),
+			SetRequestHeader("sec-fetch-dest", "document"),
+			SetRequestHeader("sec-fetch-mode", "navigate"),
+		)
+		return nil
+	}
+}

proxychain/requestmodifers/spoof_referrer_from_qq_post.go

@@ -0,0 +1,19 @@
+package requestmodifers
+
+import (
+	"ladder/proxychain"
+)
+
+// SpoofReferrerFromQQPost modifies the referrer header
+// pretending to be from a QQ post (popular social media in China)
+func SpoofReferrerFromQQPost() proxychain.RequestModification {
+	return func(chain *proxychain.ProxyChain) error {
+		chain.AddRequestModifications(
+			SpoofReferrer("https://new.qq.com/'"),
+			SetRequestHeader("sec-fetch-site", "cross-site"),
+			SetRequestHeader("sec-fetch-dest", "document"),
+			SetRequestHeader("sec-fetch-mode", "navigate"),
+		)
+		return nil
+	}
+}

proxychain/requestmodifers/spoof_referrer_from_reddit_post.go

@@ -0,0 +1,19 @@
+package requestmodifers
+
+import (
+	"ladder/proxychain"
+)
+
+// SpoofReferrerFromRedditPost modifies the referrer header
+// pretending to be from a reddit post
+func SpoofReferrerFromRedditPost() proxychain.RequestModification {
+	return func(chain *proxychain.ProxyChain) error {
+		chain.AddRequestModifications(
+			SpoofReferrer("https://www.reddit.com/"),
+			SetRequestHeader("sec-fetch-site", "cross-site"),
+			SetRequestHeader("sec-fetch-dest", "document"),
+			SetRequestHeader("sec-fetch-mode", "navigate"),
+		)
+		return nil
+	}
+}

proxychain/requestmodifers/spoof_referrer_from_tumblr_post.go

@@ -0,0 +1,19 @@
+package requestmodifers
+
+import (
+	"ladder/proxychain"
+)
+
+// SpoofReferrerFromTumblrPost modifies the referrer header
+// pretending to be from a tumblr post
+func SpoofReferrerFromTumblrPost() proxychain.RequestModification {
+	return func(chain *proxychain.ProxyChain) error {
+		chain.AddRequestModifications(
+			SpoofReferrer("https://www.tumblr.com/"),
+			SetRequestHeader("sec-fetch-site", "cross-site"),
+			SetRequestHeader("sec-fetch-dest", "document"),
+			SetRequestHeader("sec-fetch-mode", "navigate"),
+		)
+		return nil
+	}
+}

proxychain/requestmodifers/spoof_referrer_from_twitter_post.go

@@ -0,0 +1,19 @@
+package requestmodifers
+
+import (
+	"ladder/proxychain"
+)
+
+// SpoofReferrerFromTwitterPost modifies the referrer header
+// pretending to be from a twitter post
+func SpoofReferrerFromTwitterPost() proxychain.RequestModification {
+	return func(chain *proxychain.ProxyChain) error {
+		chain.AddRequestModifications(
+			SpoofReferrer("https://t.co/"),
+			SetRequestHeader("sec-fetch-site", "cross-site"),
+			SetRequestHeader("sec-fetch-dest", "document"),
+			SetRequestHeader("sec-fetch-mode", "navigate"),
+		)
+		return nil
+	}
+}

proxychain/requestmodifers/spoof_referrer_from_vkontake_post.go

@@ -0,0 +1,19 @@
+package requestmodifers
+
+import (
+	"ladder/proxychain"
+)
+
+// SpoofReferrerFromVkontaktePost modifies the referrer header
+// pretending to be from a vkontakte post (popular in Russia)
+func SpoofReferrerFromVkontaktePost() proxychain.RequestModification {
+	return func(chain *proxychain.ProxyChain) error {
+		chain.AddRequestModifications(
+			SpoofReferrer("https://away.vk.com/"),
+			SetRequestHeader("sec-fetch-site", "cross-site"),
+			SetRequestHeader("sec-fetch-dest", "document"),
+			SetRequestHeader("sec-fetch-mode", "navigate"),
+		)
+		return nil
+	}
+}

proxychain/requestmodifers/spoof_referrer_from_weibo_post.go

@@ -0,0 +1,22 @@
+package requestmodifers
+
+import (
+	"fmt"
+	"ladder/proxychain"
+	"math/rand"
+)
+
+// SpoofReferrerFromWeiboPost modifies the referrer header
+// pretending to be from a Weibo post (popular in China)
+func SpoofReferrerFromWeiboPost() proxychain.RequestModification {
+	return func(chain *proxychain.ProxyChain) error {
+		referrer := fmt.Sprintf("http://weibo.com/u/%d", rand.Intn(90001))
+		chain.AddRequestModifications(
+			SpoofReferrer(referrer),
+			SetRequestHeader("sec-fetch-site", "cross-site"),
+			SetRequestHeader("sec-fetch-dest", "document"),
+			SetRequestHeader("sec-fetch-mode", "navigate"),
+		)
+		return nil
+	}
+}

proxychain/requestmodifers/spoof_user_agent.go

@@ -0,0 +1,13 @@
+package requestmodifers
+
+import (
+	"ladder/proxychain"
+)
+
+// SpoofUserAgent modifies the user agent
+func SpoofUserAgent(ua string) proxychain.RequestModification {
+	return func(px *proxychain.ProxyChain) error {
+		px.Request.Header.Set("user-agent", ua)
+		return nil
+	}
+}

proxychain/requestmodifers/spoof_x_forwarded_for.go

@@ -0,0 +1,14 @@
+package requestmodifers
+
+import (
+	"ladder/proxychain"
+)
+
+// SpoofXForwardedFor modifies the X-Forwarded-For header
+// in some cases, a forward proxy may interpret this as the source IP
+func SpoofXForwardedFor(ip string) proxychain.RequestModification {
+	return func(px *proxychain.ProxyChain) error {
+		px.Request.Header.Set("X-FORWARDED-FOR", ip)
+		return nil
+	}
+}

proxychain/responsemodifers/bypass_cors.go

@@ -0,0 +1,21 @@
+package responsemodifers
+
+import (
+	"ladder/proxychain"
+)
+
+// BypassCORS modifies response headers to prevent the browser
+// from enforcing any CORS restrictions. This should run at the end of the chain.
+func BypassCORS() proxychain.ResponseModification {
+	return func(chain *proxychain.ProxyChain) error {
+		chain.AddResponseModifications(
+			SetResponseHeader("Access-Control-Allow-Origin", "*"),
+			SetResponseHeader("Access-Control-Expose-Headers", "*"),
+			SetResponseHeader("Access-Control-Allow-Credentials", "true"),
+			SetResponseHeader("Access-Control-Allow-Methods", "GET, PUT, POST, DELETE, HEAD, OPTIONS, PATCH"),
+			SetResponseHeader("Access-Control-Allow-Headers", "*"),
+			DeleteResponseHeader("X-Frame-Options"),
+		)
+		return nil
+	}
+}

proxychain/responsemodifers/bypass_csp.go

@@ -0,0 +1,30 @@
+package responsemodifers
+
+import (
+	"ladder/proxychain"
+)
+
+// TODO: handle edge case where CSP is specified in meta tag:
+// <meta http-equiv="Content-Security-Policy" content="default-src 'self'">
+
+// BypassContentSecurityPolicy modifies response headers to prevent the browser
+// from enforcing any CSP restrictions. This should run at the end of the chain.
+func BypassContentSecurityPolicy() proxychain.ResponseModification {
+	return func(chain *proxychain.ProxyChain) error {
+		chain.AddResponseModifications(
+			DeleteResponseHeader("Content-Security-Policy"),
+			DeleteResponseHeader("Content-Security-Policy-Report-Only"),
+			DeleteResponseHeader("X-Content-Security-Policy"),
+			DeleteResponseHeader("X-WebKit-CSP"),
+		)
+		return nil
+	}
+}
+
+// SetContentSecurityPolicy modifies response headers to a specific CSP
+func SetContentSecurityPolicy(csp string) proxychain.ResponseModification {
+	return func(chain *proxychain.ProxyChain) error {
+		chain.Response.Header.Set("Content-Security-Policy", csp)
+		return nil
+	}
+}

proxychain/responsemodifers/inject_script.go

@@ -0,0 +1,27 @@
+package responsemodifers
+
+import (
+	_ "embed"
+	"ladder/proxychain"
+	"ladder/proxychain/responsemodifers/rewriters"
+	"strings"
+)
+
+// InjectScript modifies HTTP responses
+// to execute javascript at a particular time.
+func InjectScript(js string, execTime rewriters.ScriptExecTime) proxychain.ResponseModification {
+	return func(chain *proxychain.ProxyChain) error {
+		// don't add rewriter if it's not even html
+		ct := chain.Response.Header.Get("content-type")
+		if !strings.HasPrefix(ct, "text/html") {
+			return nil
+		}
+
+		// the rewriting actually happens in chain.Execute() as the client is streaming the response body back
+		rr := rewriters.NewScriptInjectorRewriter(js, execTime)
+		// we just queue it up here
+		chain.AddHTMLTokenRewriter(rr)
+
+		return nil
+	}
+}

proxychain/responsemodifers/modify_incoming_cookies.go

@@ -0,0 +1,102 @@
+package responsemodifers
+
+import (
+	"fmt"
+	"ladder/proxychain"
+	"net/http"
+)
+
+// DeleteIncomingCookies prevents ALL cookies from being sent from the proxy server
+// back down to the client.
+func DeleteIncomingCookies(whitelist ...string) proxychain.ResponseModification {
+	return func(px *proxychain.ProxyChain) error {
+		px.Response.Header.Del("Set-Cookie")
+		return nil
+	}
+}
+
+// DeleteIncomingCookiesExcept prevents non-whitelisted cookies from being sent from the proxy server
+// to the client. Cookies whose names are in the whitelist are not removed.
+func DeleteIncomingCookiesExcept(whitelist ...string) proxychain.ResponseModification {
+	return func(px *proxychain.ProxyChain) error {
+		// Convert whitelist slice to a map for efficient lookups
+		whitelistMap := make(map[string]struct{})
+		for _, cookieName := range whitelist {
+			whitelistMap[cookieName] = struct{}{}
+		}
+
+		// If the response has no cookies, return early
+		if px.Response.Header == nil {
+			return nil
+		}
+
+		// Filter the cookies in the response
+		filteredCookies := []string{}
+		for _, cookieStr := range px.Response.Header["Set-Cookie"] {
+			cookie := parseCookie(cookieStr)
+			if _, found := whitelistMap[cookie.Name]; found {
+				filteredCookies = append(filteredCookies, cookieStr)
+			}
+		}
+
+		// Update the Set-Cookie header with the filtered cookies
+		if len(filteredCookies) > 0 {
+			px.Response.Header["Set-Cookie"] = filteredCookies
+		} else {
+			px.Response.Header.Del("Set-Cookie")
+		}
+
+		return nil
+	}
+}
+
+// parseCookie parses a cookie string and returns an http.Cookie object.
+func parseCookie(cookieStr string) *http.Cookie {
+	header := http.Header{}
+	header.Add("Set-Cookie", cookieStr)
+	request := http.Request{Header: header}
+	return request.Cookies()[0]
+}
+
+// SetIncomingCookies adds a raw cookie string being sent from the proxy server down to the client
+func SetIncomingCookies(cookies string) proxychain.ResponseModification {
+	return func(px *proxychain.ProxyChain) error {
+		px.Response.Header.Set("Set-Cookie", cookies)
+		return nil
+	}
+}
+
+// SetIncomingCookie modifies a specific cookie in the response from the proxy server to the client.
+func SetIncomingCookie(name string, val string) proxychain.ResponseModification {
+	return func(px *proxychain.ProxyChain) error {
+		if px.Response.Header == nil {
+			return nil
+		}
+
+		updatedCookies := []string{}
+		found := false
+
+		// Iterate over existing cookies and modify the one that matches the cookieName
+		for _, cookieStr := range px.Response.Header["Set-Cookie"] {
+			cookie := parseCookie(cookieStr)
+			if cookie.Name == name {
+				// Replace the cookie with the new value
+				updatedCookies = append(updatedCookies, fmt.Sprintf("%s=%s", name, val))
+				found = true
+			} else {
+				// Keep the cookie as is
+				updatedCookies = append(updatedCookies, cookieStr)
+			}
+		}
+
+		// If the specified cookie wasn't found, add it
+		if !found {
+			updatedCookies = append(updatedCookies, fmt.Sprintf("%s=%s", name, val))
+		}
+
+		// Update the Set-Cookie header
+		px.Response.Header["Set-Cookie"] = updatedCookies
+
+		return nil
+	}
+}

proxychain/responsemodifers/modify_response_header.go

@@ -0,0 +1,21 @@
+package responsemodifers
+
+import (
+	"ladder/proxychain"
+)
+
+// SetResponseHeader modifies response headers from the upstream server
+func SetResponseHeader(key string, value string) proxychain.ResponseModification {
+	return func(px *proxychain.ProxyChain) error {
+		px.Context.Response().Header.Set(key, value)
+		return nil
+	}
+}
+
+// DeleteResponseHeader removes response headers from the upstream server
+func DeleteResponseHeader(key string) proxychain.ResponseModification {
+	return func(px *proxychain.ProxyChain) error {
+		px.Context.Response().Header.Del(key)
+		return nil
+	}
+}

proxychain/responsemodifers/patch_dynamic_resource_urls.go

@@ -0,0 +1,55 @@
+package responsemodifers
+
+import (
+	_ "embed"
+	"fmt"
+	"ladder/proxychain"
+	"ladder/proxychain/responsemodifers/rewriters"
+	"strings"
+)
+
+//go:embed patch_dynamic_resource_urls.js
+var patchDynamicResourceURLsScript string
+
+// PatchDynamicResourceURLs patches the javascript runtime to rewrite URLs client-side.
+//   - This function is designed to allow the proxified page
+//     to still be browsible by routing all resource URLs through the proxy.
+//   - Native APIs capable of network requests will be hooked
+//     and the URLs arguments modified to point to the proxy instead.
+//   - fetch('/relative_path') -> fetch('/https://proxiedsite.com/relative_path')
+//   - Element.setAttribute('src', "/assets/img.jpg") -> Element.setAttribute('src', "/https://proxiedsite.com/assets/img.jpg") -> fetch('/https://proxiedsite.com/relative_path')
+func PatchDynamicResourceURLs() proxychain.ResponseModification {
+	return func(chain *proxychain.ProxyChain) error {
+		// don't add rewriter if it's not even html
+		ct := chain.Response.Header.Get("content-type")
+		if !strings.HasPrefix(ct, "text/html") {
+			return nil
+		}
+
+		// this is the original URL sent by client:
+		// http://localhost:8080/http://proxiedsite.com/foo/bar
+		originalURI := chain.Context.Request().URI()
+
+		// this is the extracted URL that the client requests to proxy
+		// http://proxiedsite.com/foo/bar
+		reqURL := chain.Request.URL
+
+		params := map[string]string{
+			// ie: http://localhost:8080
+			"{{PROXY_ORIGIN}}": fmt.Sprintf("%s://%s", originalURI.Scheme(), originalURI.Host()),
+			// ie: http://proxiedsite.com
+			"{{ORIGIN}}": fmt.Sprintf("%s://%s", reqURL.Scheme, reqURL.Host),
+		}
+
+		// the rewriting actually happens in chain.Execute() as the client is streaming the response body back
+		rr := rewriters.NewScriptInjectorRewriterWithParams(
+			patchDynamicResourceURLsScript,
+			rewriters.BeforeDOMContentLoaded,
+			params,
+		)
+		// we just queue it up here
+		chain.AddHTMLTokenRewriter(rr)
+
+		return nil
+	}
+}

proxychain/responsemodifers/patch_dynamic_resource_urls.js

@@ -0,0 +1,325 @@
+// Overrides the global fetch and XMLHttpRequest open methods to modify the request URLs.
+// Also overrides the attribute setter prototype to modify the request URLs
+// fetch("/relative_script.js") -> fetch("http://localhost:8080/relative_script.js")
+(() => {
+
+    // ============== PARAMS ===========================
+	// if the original request was: http://localhost:8080/http://proxiedsite.com/foo/bar
+	// proxyOrigin is http://localhost:8080
+    const proxyOrigin = "{{PROXY_ORIGIN}}";
+    //const proxyOrigin = globalThis.window.location.origin;
+
+	// if the original request was: http://localhost:8080/http://proxiedsite.com/foo/bar
+	// origin is http://proxiedsite.com
+    const origin = "{{ORIGIN}}";
+    //const origin = (new URL(decodeURIComponent(globalThis.window.location.pathname.substring(1)))).origin
+    // ============== END PARAMS ======================
+
+   const blacklistedSchemes = [
+    "ftp:",
+    "mailto:",
+    "tel:",
+    "file:",
+    "blob:",
+    "javascript:",
+    "about:",
+    "magnet:",
+    "ws:",
+    "wss:",
+   ];
+
+   function rewriteURL(url) {
+        const oldUrl = url 
+        if (!url) return url
+        let isStr = (typeof url.startsWith === 'function')
+        if (!isStr) return url
+
+        // don't rewrite special URIs
+        if (blacklistedSchemes.includes(url)) return url;
+
+        // don't rewrite invalid URIs
+        try { new URL(url, origin) } catch { return url }
+
+        // don't double rewrite
+        if (url.startsWith(proxyOrigin)) return url;
+        if (url.startsWith(`/${proxyOrigin}`)) return url;
+        if (url.startsWith(`/${origin}`)) return url;
+        if (url.startsWith(`/http://`)) return url;
+        if (url.startsWith(`/https://`)) return url;
+        if (url.startsWith(`/http%3A%2F%2F`)) return url;
+        if (url.startsWith(`/https%3A%2F%2F`)) return url;
+        if (url.startsWith(`/%2Fhttp`)) return url;
+
+        //console.log(`proxychain: origin: ${origin} // proxyOrigin: ${proxyOrigin} // original: ${oldUrl}`)
+
+        if (url.startsWith("//")) {
+            url = `/${origin}/${encodeURIComponent(url.substring(2))}`;
+        } else if (url.startsWith("/")) {
+            url = `/${origin}/${encodeURIComponent(url.substring(1))}`;
+        } else if (url.startsWith(origin)) {
+            url = `/${encodeURIComponent(url)}` 
+        } else if (url.startsWith("http://") || url.startsWith("https://")) {
+            url = `/${proxyOrigin}/${encodeURIComponent(url)}`;
+        }
+        console.log(`proxychain: rewrite JS URL: ${oldUrl} -> ${url}`)
+        return url;
+   };
+
+    // sometimes anti-bot protections like cloudflare or akamai bot manager check if JS is hooked
+    function hideMonkeyPatch(objectOrName, method, originalToString) {
+        let obj;
+        let isGlobalFunction = false;
+    
+        if (typeof objectOrName === 'string') {
+            obj = globalThis[objectOrName];
+            isGlobalFunction = (typeof obj === 'function') && (method === objectOrName);
+        } else {
+            obj = objectOrName;
+        }
+    
+        if (isGlobalFunction) {
+            const originalFunction = obj;
+            globalThis[objectOrName] = function(...args) {
+                return originalFunction.apply(this, args);
+            };
+            globalThis[objectOrName].toString = () => originalToString;
+        } else if (obj && typeof obj[method] === 'function') {
+            const originalMethod = obj[method];
+            obj[method] = function(...args) {
+                return originalMethod.apply(this, args);
+            };
+            obj[method].toString = () => originalToString;
+        } else {
+            console.warn(`proxychain: cannot hide monkey patch: ${method} is not a function on the provided object.`);
+        }
+    }
+
+   // monkey patch fetch
+   const oldFetch = fetch;
+   fetch = async (url, init) => {
+        return oldFetch(rewriteURL(url), init)
+   }
+   hideMonkeyPatch('fetch', 'fetch', 'function fetch() { [native code] }')
+
+   // monkey patch xmlhttprequest
+   const oldOpen = XMLHttpRequest.prototype.open;
+   XMLHttpRequest.prototype.open = function(method, url, async = true, user = null, password = null) {
+       return oldOpen.call(this, method, rewriteURL(url), async, user, password);
+   };
+   hideMonkeyPatch(XMLHttpRequest.prototype, 'open', 'function(){if("function"==typeof eo)return eo.apply(this,arguments)}');
+
+   const oldSend = XMLHttpRequest.prototype.send;
+   XMLHttpRequest.prototype.send = function(method, url) {
+       return oldSend.call(this, method, rewriteURL(url));
+   };
+   hideMonkeyPatch(XMLHttpRequest.prototype, 'send', 'function(){if("function"==typeof eo)return eo.apply(this,arguments)}');
+
+
+   // monkey patch service worker registration
+   const oldRegister = ServiceWorkerContainer.prototype.register;
+   ServiceWorkerContainer.prototype.register = function(scriptURL, options) {
+        return oldRegister.call(this, rewriteURL(scriptURL), options)
+   }
+   hideMonkeyPatch(ServiceWorkerContainer.prototype, 'register', 'function register() { [native code] }')
+
+   // monkey patch URL.toString() method 
+   const oldToString = URL.prototype.toString
+   URL.prototype.toString = function() {
+        let originalURL = oldToString.call(this)
+        return rewriteURL(originalURL)
+   }
+   hideMonkeyPatch(URL.prototype, 'toString', 'function toString() { [native code] }')
+
+   // monkey patch URL.toJSON() method 
+   const oldToJson = URL.prototype.toString
+   URL.prototype.toString = function() {
+        let originalURL = oldToJson.call(this)
+        return rewriteURL(originalURL)
+   }
+   hideMonkeyPatch(URL.prototype, 'toString', 'function toJSON() { [native code] }')
+
+   // Monkey patch URL.href getter and setter
+    const originalHrefDescriptor = Object.getOwnPropertyDescriptor(URL.prototype, 'href');
+    Object.defineProperty(URL.prototype, 'href', {
+        get: function() {
+            let originalHref = originalHrefDescriptor.get.call(this);
+            return rewriteURL(originalHref)
+        },
+        set: function(newValue) {
+            originalHrefDescriptor.set.call(this, rewriteURL(newValue));
+        }
+    });
+
+    // TODO: do one more pass of this by manually traversing the DOM
+    // AFTER all the JS and page has loaded just in case 
+
+    // Monkey patch setter 
+    const elements = [
+        { tag: 'a', attribute: 'href' },
+        { tag: 'img', attribute: 'src' },
+        // { tag: 'img', attribute: 'srcset' }, // TODO: handle srcset
+        { tag: 'script', attribute: 'src' },
+        { tag: 'link', attribute: 'href' },
+        { tag: 'link', attribute: 'icon' },
+        { tag: 'iframe', attribute: 'src' },
+        { tag: 'audio', attribute: 'src' },
+        { tag: 'video', attribute: 'src' },
+        { tag: 'source', attribute: 'src' },
+        // { tag: 'source', attribute: 'srcset' }, // TODO: handle srcset
+        { tag: 'embed', attribute: 'src' },
+        { tag: 'embed', attribute: 'pluginspage' },
+        { tag: 'html', attribute: 'manifest' },
+        { tag: 'object', attribute: 'src' },
+        { tag: 'input', attribute: 'src' },
+        { tag: 'track', attribute: 'src' },
+        { tag: 'form', attribute: 'action' },
+        { tag: 'area', attribute: 'href' },
+        { tag: 'base', attribute: 'href' },
+        { tag: 'blockquote', attribute: 'cite' },
+        { tag: 'del', attribute: 'cite' },
+        { tag: 'ins', attribute: 'cite' },
+        { tag: 'q', attribute: 'cite' },
+        { tag: 'button', attribute: 'formaction' },
+        { tag: 'input', attribute: 'formaction' },
+        { tag: 'meta', attribute: 'content' },
+        { tag: 'object', attribute: 'data' },
+    ];
+
+    elements.forEach(({ tag, attribute }) => {
+        const proto = document.createElement(tag).constructor.prototype;
+        const descriptor = Object.getOwnPropertyDescriptor(proto, attribute);
+        if (descriptor && descriptor.set) {
+            Object.defineProperty(proto, attribute, {
+                ...descriptor,
+                set(value) {
+                    // calling rewriteURL will end up calling a setter for href,
+                    // leading to a recusive loop and a Maximum call stack size exceeded
+                    // error, so we guard against this with a local semaphore flag
+                    const isRewritingSetKey = Symbol.for('isRewritingSet');
+                    if (!this[isRewritingSetKey]) {
+                        this[isRewritingSetKey] = true;
+                        descriptor.set.call(this, rewriteURL(value));
+                        //descriptor.set.call(this, value);
+                        this[isRewritingSetKey] = false;
+                    } else {
+                        // Directly set the value without rewriting
+                        descriptor.set.call(this, value);
+                    }
+                },
+                get() {
+                    const isRewritingGetKey = Symbol.for('isRewritingGet');
+                    if (!this[isRewritingGetKey]) {
+                        this[isRewritingGetKey] = true;
+                        let oldURL = descriptor.get.call(this);
+                        let newURL = rewriteURL(oldURL);
+                        this[isRewritingGetKey] = false;
+                        return newURL
+                    } else {
+                        return descriptor.get.call(this);
+                    }
+                }
+            });
+        }
+    });
+
+
+    // sometimes, libraries will set the Element.innerHTML or Element.outerHTML directly with a string instead of setters.
+    // in this case, we intercept it, create a fake DOM, parse it and then rewrite all attributes that could
+    // contain a URL. Then we return the replacement innerHTML/outerHTML with redirected links.
+    function rewriteInnerHTML(html, elements) {
+        const isRewritingHTMLKey = Symbol.for('isRewritingHTML');
+    
+        // Check if already processing
+        if (document[isRewritingHTMLKey]) {
+            return html;
+        }
+    
+        const tempContainer = document.createElement('div');
+        document[isRewritingHTMLKey] = true;
+    
+        try {
+            tempContainer.innerHTML = html;
+        
+            // Create a map for quick lookup
+            const elementsMap = new Map(elements.map(e => [e.tag, e.attribute]));
+        
+            // Loop-based DOM traversal
+            const nodes = [...tempContainer.querySelectorAll('*')];
+            for (const node of nodes) {
+                const attribute = elementsMap.get(node.tagName.toLowerCase());
+                if (attribute && node.hasAttribute(attribute)) {
+                    const originalUrl = node.getAttribute(attribute);
+                    const rewrittenUrl = rewriteURL(originalUrl);
+                    node.setAttribute(attribute, rewrittenUrl);
+                }
+            }
+    
+            return tempContainer.innerHTML;
+        } finally {
+            // Clear the flag
+            document[isRewritingHTMLKey] = false;
+        }
+    }
+
+
+    // Store original setters
+const originalSetters = {};
+
+    ['innerHTML', 'outerHTML'].forEach(property => {
+        const descriptor = Object.getOwnPropertyDescriptor(Element.prototype, property);
+        if (descriptor && descriptor.set) {
+            originalSetters[property] = descriptor.set;
+
+            Object.defineProperty(Element.prototype, property, {
+                ...descriptor,
+                set(value) {
+                    const isRewritingHTMLKey = Symbol.for('isRewritingHTML');
+                    if (!this[isRewritingHTMLKey]) {
+                        this[isRewritingHTMLKey] = true;
+                        try {
+                            // Use custom logic
+                            descriptor.set.call(this, rewriteInnerHTML(value, elements));
+                        } finally {
+                            this[isRewritingHTMLKey] = false;
+                        }
+                    } else {
+                        // Use original setter in recursive call
+                        originalSetters[property].call(this, value);
+                    }
+                }
+            });
+        }
+    });
+
+
+})();
+
+
+
+(() => {
+    document.addEventListener('DOMContentLoaded', (event) => {
+        initIdleMutationObserver();
+    });
+    
+    function initIdleMutationObserver() {
+        let debounceTimer;
+        const debounceDelay = 500; // adjust the delay as needed
+    
+        const observer = new MutationObserver((mutations) => {
+            // Clear the previous timer and set a new one
+            clearTimeout(debounceTimer);
+            debounceTimer = setTimeout(() => {
+                execute();
+                observer.disconnect(); // Disconnect after first execution
+            }, debounceDelay);
+        });
+    
+        const config = { attributes: false, childList: true, subtree: true };
+        observer.observe(document.body, config);
+    }
+    
+    function execute() {
+        console.log('DOM is now idle. Executing...');
+    }
+
+})();

proxychain/responsemodifers/rewrite_http_resource_urls.go

@@ -0,0 +1,35 @@
+package responsemodifers
+
+import (
+	_ "embed"
+	"fmt"
+	"ladder/proxychain"
+	"ladder/proxychain/responsemodifers/rewriters"
+	"strings"
+)
+
+// RewriteHTMLResourceURLs modifies HTTP responses
+// to rewrite URLs attributes in HTML content (such as src, href)
+//   - `<img src='/relative_path'>` -> `<img src='/https://proxiedsite.com/relative_path'>`
+//   - This function is designed to allow the proxified page
+//     to still be browsible by routing all resource URLs through the proxy.
+func RewriteHTMLResourceURLs() proxychain.ResponseModification {
+	return func(chain *proxychain.ProxyChain) error {
+		// don't add rewriter if it's not even html
+		ct := chain.Response.Header.Get("content-type")
+		if !strings.HasPrefix(ct, "text/html") {
+			return nil
+		}
+
+		// proxyURL is the URL of the ladder: http://localhost:8080 (ladder)
+		originalURI := chain.Context.Request().URI()
+		proxyURL := fmt.Sprintf("%s://%s", originalURI.Scheme(), originalURI.Host())
+
+		// the rewriting actually happens in chain.Execute() as the client is streaming the response body back
+		rr := rewriters.NewHTMLTokenURLRewriter(chain.Request.URL, proxyURL)
+		// we just queue it up here
+		chain.AddHTMLTokenRewriter(rr)
+
+		return nil
+	}
+}

proxychain/responsemodifers/rewriters/after_dom_idle_script_injector.js

@@ -0,0 +1,27 @@
+(() => {
+    document.addEventListener('DOMContentLoaded', (event) => {
+        initIdleMutationObserver();
+    });
+    
+    function initIdleMutationObserver() {
+        let debounceTimer;
+        const debounceDelay = 500; // adjust the delay as needed
+    
+        const observer = new MutationObserver((mutations) => {
+            // Clear the previous timer and set a new one
+            clearTimeout(debounceTimer);
+            debounceTimer = setTimeout(() => {
+                execute();
+                observer.disconnect(); // Disconnect after first execution
+            }, debounceDelay);
+        });
+    
+        const config = { attributes: false, childList: true, subtree: true };
+        observer.observe(document.body, config);
+    }
+    
+    function execute() {
+        'SCRIPT_CONTENT_PARAM'
+        //console.log('DOM is now idle. Executing...');
+    }
+})();

proxychain/responsemodifers/rewriters/css_rewriter.go

@@ -0,0 +1,3 @@
+package rewriters
+
+// todo: implement

proxychain/responsemodifers/rewriters/html_rewriter.go

@@ -0,0 +1,131 @@
+package rewriters
+
+import (
+	"bytes"
+	"io"
+
+	"golang.org/x/net/html"
+)
+
+// IHTMLTokenRewriter defines an interface for modifying HTML tokens.
+type IHTMLTokenRewriter interface {
+	// ShouldModify determines whether a given HTML token requires modification.
+	ShouldModify(*html.Token) bool
+
+	// ModifyToken applies modifications to a given HTML token.
+	// It returns strings representing content to be prepended and
+	// appended to the token. If no modifications are required or if an error occurs,
+	// it returns empty strings for both 'prepend' and 'append'.
+	// Note: The original token is not modified if an error occurs.
+	ModifyToken(*html.Token) (prepend, append string)
+}
+
+// HTMLRewriter is a struct that can take multiple TokenHandlers and process all
+// HTML tokens from http.Response.Body in a single pass, making changes and returning a new io.ReadCloser
+//
+//   - HTMLRewriter reads the http.Response.Body stream,
+//     parsing each HTML token one at a time and making modifications (defined by implementations of IHTMLTokenRewriter)
+//     in a single pass of the tokenizer.
+//
+//   - When ProxyChain.Execute() is called, the response body will be read from the server
+//     and pulled through each ResponseModification which wraps the ProxyChain.Response.Body
+//     without ever buffering the entire HTTP response in memory.
+type HTMLRewriter struct {
+	tokenizer             *html.Tokenizer
+	currentToken          *html.Token
+	tokenBuffer           *bytes.Buffer
+	currentTokenProcessed bool
+	rewriters             []IHTMLTokenRewriter
+}
+
+// NewHTMLRewriter creates a new HTMLRewriter instance.
+// It processes HTML tokens from an io.ReadCloser source (typically http.Response.Body)
+// using a series of HTMLTokenRewriters. Each HTMLTokenRewriter in the 'rewriters' slice
+// applies its specific modifications to the HTML tokens.
+// The HTMLRewriter reads from the provided 'src', applies the modifications,
+// and returns the processed content as a new io.ReadCloser.
+// This new io.ReadCloser can be used to stream the modified content back to the client.
+//
+// Parameters:
+//   - src: An io.ReadCloser representing the source of the HTML content, such as http.Response.Body.
+//   - rewriters: A slice of HTMLTokenRewriters that define the modifications to be applied to the HTML tokens.
+//
+// Returns:
+//   - A pointer to an HTMLRewriter, which implements io.ReadCloser, containing the modified HTML content.
+func NewHTMLRewriter(src io.ReadCloser, rewriters []IHTMLTokenRewriter) *HTMLRewriter {
+	return &HTMLRewriter{
+		tokenizer:             html.NewTokenizer(src),
+		currentToken:          nil,
+		tokenBuffer:           new(bytes.Buffer),
+		currentTokenProcessed: false,
+		rewriters:             rewriters,
+	}
+}
+
+// Close resets the internal state of HTMLRewriter, clearing buffers and token data.
+func (r *HTMLRewriter) Close() error {
+	r.tokenBuffer.Reset()
+	r.currentToken = nil
+	r.currentTokenProcessed = false
+	return nil
+}
+
+// Read processes the HTML content, rewriting URLs and managing the state of tokens.
+func (r *HTMLRewriter) Read(p []byte) (int, error) {
+
+	if r.currentToken == nil || r.currentToken.Data == "" || r.currentTokenProcessed {
+		tokenType := r.tokenizer.Next()
+
+		// done reading html, close out reader
+		if tokenType == html.ErrorToken {
+			if r.tokenizer.Err() == io.EOF {
+				return 0, io.EOF
+			}
+			return 0, r.tokenizer.Err()
+		}
+
+		// get the next token; reset buffer
+		t := r.tokenizer.Token()
+		r.currentToken = &t
+		r.tokenBuffer.Reset()
+
+		// buffer += "<prepends> <token> <appends>"
+		// process token through all registered rewriters
+		// rewriters will modify the token, and optionally
+		// return a <prepend> or <append> string token
+		appends := make([]string, 0, len(r.rewriters))
+		for _, rewriter := range r.rewriters {
+			if !rewriter.ShouldModify(r.currentToken) {
+				continue
+			}
+			prepend, a := rewriter.ModifyToken(r.currentToken)
+			appends = append(appends, a)
+			// add <prepends> to buffer
+			r.tokenBuffer.WriteString(prepend)
+		}
+
+		// add <token> to buffer
+		if tokenType == html.TextToken {
+			// don't unescape textTokens (such as inline scripts).
+			// Token.String() by default will escape the inputs, but
+			// we don't want to modify the original source
+			r.tokenBuffer.WriteString(r.currentToken.Data)
+		} else {
+			r.tokenBuffer.WriteString(r.currentToken.String())
+		}
+
+		// add <appends> to buffer
+		for _, a := range appends {
+			r.tokenBuffer.WriteString(a)
+		}
+
+		r.currentTokenProcessed = false
+	}
+
+	n, err := r.tokenBuffer.Read(p)
+	if err == io.EOF || r.tokenBuffer.Len() == 0 {
+		r.currentTokenProcessed = true
+		err = nil // EOF in this context is expected and not an actual error
+	}
+	return n, err
+}

proxychain/responsemodifers/rewriters/html_token_url_rewriter.go

@@ -0,0 +1,263 @@
+package rewriters
+
+import (
+	_ "embed"
+	"fmt"
+	"log"
+	"net/url"
+	"regexp"
+	"strings"
+
+	"golang.org/x/net/html"
+)
+
+var rewriteAttrs map[string]map[string]bool
+var specialRewriteAttrs map[string]map[string]bool
+var schemeBlacklist map[string]bool
+
+func init() {
+	// define all tag/attributes which might contain URLs
+	// to attempt to rewrite to point to proxy instead
+	rewriteAttrs = map[string]map[string]bool{
+		"img":        {"src": true, "srcset": true, "longdesc": true, "usemap": true},
+		"a":          {"href": true},
+		"form":       {"action": true},
+		"link":       {"href": true, "manifest": true, "icon": true},
+		"script":     {"src": true},
+		"video":      {"src": true, "poster": true},
+		"audio":      {"src": true},
+		"iframe":     {"src": true, "longdesc": true},
+		"embed":      {"src": true},
+		"object":     {"data": true, "codebase": true},
+		"source":     {"src": true, "srcset": true},
+		"track":      {"src": true},
+		"area":       {"href": true},
+		"base":       {"href": true},
+		"blockquote": {"cite": true},
+		"del":        {"cite": true},
+		"ins":        {"cite": true},
+		"q":          {"cite": true},
+		"body":       {"background": true},
+		"button":     {"formaction": true},
+		"input":      {"src": true, "formaction": true},
+		"meta":       {"content": true},
+	}
+
+	// might contain URL but requires special handling
+	specialRewriteAttrs = map[string]map[string]bool{
+		"img":    {"srcset": true},
+		"source": {"srcset": true},
+		"meta":   {"content": true},
+	}
+
+	// define URIs to NOT rewrite
+	// for example: don't overwrite <img src="data:image/png;base64;iVBORw...">"
+	schemeBlacklist = map[string]bool{
+		"data":       true,
+		"tel":        true,
+		"mailto":     true,
+		"file":       true,
+		"blob":       true,
+		"javascript": true,
+		"about":      true,
+		"magnet":     true,
+		"ws":         true,
+		"wss":        true,
+		"ftp":        true,
+	}
+
+}
+
+// HTMLTokenURLRewriter implements HTMLTokenRewriter
+// it rewrites URLs within HTML resources to use a specified proxy URL.
+// <img src='/relative_path'> -> <img src='/https://proxiedsite.com/relative_path'>
+type HTMLTokenURLRewriter struct {
+	baseURL  *url.URL
+	proxyURL string // ladder URL, not proxied site URL
+}
+
+// NewHTMLTokenURLRewriter creates a new instance of HTMLResourceURLRewriter.
+// It initializes the tokenizer with the provided source and sets the proxy URL.
+func NewHTMLTokenURLRewriter(baseURL *url.URL, proxyURL string) *HTMLTokenURLRewriter {
+	return &HTMLTokenURLRewriter{
+		baseURL:  baseURL,
+		proxyURL: proxyURL,
+	}
+}
+
+func (r *HTMLTokenURLRewriter) ShouldModify(token *html.Token) bool {
+	attrLen := len(token.Attr)
+	if attrLen == 0 {
+		return false
+	}
+	if !(token.Type == html.StartTagToken || token.Type == html.SelfClosingTagToken) {
+		return false
+	}
+	return true
+}
+
+func (r *HTMLTokenURLRewriter) ModifyToken(token *html.Token) (string, string) {
+	for i := range token.Attr {
+		attr := &token.Attr[i]
+		switch {
+		// don't touch tag/attributes that don't contain URIs
+		case !rewriteAttrs[token.Data][attr.Key]:
+			continue
+		// don't touch attributes with special URIs (like data:)
+		case schemeBlacklist[strings.Split(attr.Key, ":")[0]]:
+			continue
+		// don't double-overwrite the url
+		case strings.HasPrefix(attr.Val, r.proxyURL):
+			continue
+		case strings.HasPrefix(attr.Val, "/http://"):
+			continue
+		case strings.HasPrefix(attr.Val, "/https://"):
+			continue
+		// handle special rewrites
+		case specialRewriteAttrs[token.Data][attr.Key]:
+			r.handleSpecialAttr(token, attr, r.baseURL)
+			continue
+		default:
+			// rewrite url
+			handleURLPart(attr, r.baseURL)
+		}
+	}
+	return "", ""
+}
+
+// dispatcher for ModifyURL based on URI type
+func handleURLPart(attr *html.Attribute, baseURL *url.URL) {
+	switch {
+	case strings.HasPrefix(attr.Key, "//"):
+		handleProtocolRelativePath(attr, baseURL)
+	case strings.HasPrefix(attr.Key, "/"):
+		handleRootRelativePath(attr, baseURL)
+	case strings.HasPrefix(attr.Key, "https://"):
+		handleAbsolutePath(attr, baseURL)
+	case strings.HasPrefix(attr.Key, "http://"):
+		handleAbsolutePath(attr, baseURL)
+	default:
+		handleDocumentRelativePath(attr, baseURL)
+	}
+}
+
+// Protocol-relative URLs: These start with "//" and will use the same protocol (http or https) as the current page.
+func handleProtocolRelativePath(attr *html.Attribute, baseURL *url.URL) {
+	attr.Val = strings.TrimPrefix(attr.Val, "/")
+	handleRootRelativePath(attr, baseURL)
+	log.Printf("proto rel url rewritten-> '%s'='%s'", attr.Key, attr.Val)
+}
+
+// Root-relative URLs: These are relative to the root path and start with a "/".
+func handleRootRelativePath(attr *html.Attribute, baseURL *url.URL) {
+	// doublecheck this is a valid relative URL
+	log.Printf("PROCESSING: key: %s val: %s\n", attr.Key, attr.Val)
+	_, err := url.Parse(fmt.Sprintf("http://localhost.com%s", attr.Val))
+	if err != nil {
+		log.Println(err)
+		return
+	}
+
+	//log.Printf("BASEURL patch:  %s\n", baseURL)
+
+	attr.Val = fmt.Sprintf(
+		"/%s://%s/%s",
+		baseURL.Scheme,
+		baseURL.Host,
+		strings.TrimPrefix(attr.Val, "/"),
+	)
+	attr.Val = escape(attr.Val)
+	attr.Val = fmt.Sprintf("/%s", attr.Val)
+
+	log.Printf("root rel url rewritten-> '%s'='%s'", attr.Key, attr.Val)
+}
+
+// Document-relative URLs: These are relative to the current document's path and don't start with a "/".
+func handleDocumentRelativePath(attr *html.Attribute, baseURL *url.URL) {
+	log.Printf("PROCESSING: key: %s val: %s\n", attr.Key, attr.Val)
+	attr.Val = fmt.Sprintf(
+		"%s://%s/%s%s",
+		baseURL.Scheme,
+		strings.Trim(baseURL.Host, "/"),
+		strings.Trim(baseURL.RawPath, "/"),
+		strings.Trim(attr.Val, "/"),
+	)
+	attr.Val = escape(attr.Val)
+	attr.Val = fmt.Sprintf("/%s", attr.Val)
+	log.Printf("doc rel url rewritten-> '%s'='%s'", attr.Key, attr.Val)
+}
+
+// full URIs beginning with https?://proxiedsite.com
+func handleAbsolutePath(attr *html.Attribute, baseURL *url.URL) {
+	// check if valid URL
+	log.Printf("PROCESSING: key: %s val: %s\n", attr.Key, attr.Val)
+	u, err := url.Parse(attr.Val)
+	if err != nil {
+		return
+	}
+	if !(u.Scheme == "http" || u.Scheme == "https") {
+		return
+	}
+	attr.Val = fmt.Sprintf("/%s", escape(strings.TrimPrefix(attr.Val, "/")))
+	log.Printf("abs url rewritten-> '%s'='%s'", attr.Key, attr.Val)
+}
+
+// handle edge cases for special attributes
+func (r *HTMLTokenURLRewriter) handleSpecialAttr(token *html.Token, attr *html.Attribute, baseURL *url.URL) {
+	switch {
+	// srcset attribute doesn't contain a single URL but a comma-separated list of URLs, each potentially followed by a space and a descriptor (like a width, pixel density, or other conditions).
+	case token.Data == "img" && attr.Key == "srcset":
+		handleSrcSet(attr, baseURL)
+	case token.Data == "source" && attr.Key == "srcset":
+		handleSrcSet(attr, baseURL)
+	// meta with http-equiv="refresh": The content attribute of a meta tag, when used for a refresh directive, contains a time interval followed by a URL, like content="5;url=http://example.com/".
+	case token.Data == "meta" && attr.Key == "content" && regexp.MustCompile(`^\d+;url=`).MatchString(attr.Val):
+		handleMetaRefresh(attr, baseURL)
+	default:
+		break
+	}
+}
+
+func handleMetaRefresh(attr *html.Attribute, baseURL *url.URL) {
+	sec := strings.Split(attr.Val, ";url=")[0]
+	url := strings.Split(attr.Val, ";url=")[1]
+	f := &html.Attribute{Val: url, Key: "src"}
+	handleURLPart(f, baseURL)
+	attr.Val = fmt.Sprintf("%s;url=%s", sec, url)
+}
+
+func handleSrcSet(attr *html.Attribute, baseURL *url.URL) {
+	var srcSetBuilder strings.Builder
+	srcSetItems := strings.Split(attr.Val, ",")
+
+	for i, srcItem := range srcSetItems {
+		srcParts := strings.Fields(srcItem) // Fields splits around whitespace, trimming them
+
+		if len(srcParts) == 0 {
+			continue // skip empty items
+		}
+
+		// rewrite each URL part by passing in fake attribute
+		f := &html.Attribute{Val: srcParts[0], Key: "src"}
+		handleURLPart(f, baseURL)
+		urlPart := f.Key
+
+		// First srcset item without a descriptor
+		if i == 0 && (len(srcParts) == 1 || !strings.HasSuffix(srcParts[1], "x")) {
+			srcSetBuilder.WriteString(urlPart)
+		} else {
+			srcSetBuilder.WriteString(fmt.Sprintf("%s %s", urlPart, srcParts[1]))
+		}
+
+		if i < len(srcSetItems)-1 {
+			srcSetBuilder.WriteString(",") // Add comma for all but last item
+		}
+	}
+
+	attr.Val = srcSetBuilder.String()
+	log.Printf("srcset url rewritten-> '%s'='%s'", attr.Key, attr.Val)
+}
+
+func escape(str string) string {
+	return strings.ReplaceAll(url.PathEscape(str), "%2F", "/")
+}

proxychain/responsemodifers/rewriters/script_injector_rewriter.go

@@ -0,0 +1,91 @@
+package rewriters
+
+import (
+	_ "embed"
+	"fmt"
+	"sort"
+	"strings"
+
+	"golang.org/x/net/html"
+	"golang.org/x/net/html/atom"
+)
+
+// ScriptInjectorRewriter implements HTMLTokenRewriter
+// ScriptInjectorRewriter is a struct that injects JS into the page
+// It uses an HTML tokenizer to process HTML content and injects JS at a specified location
+type ScriptInjectorRewriter struct {
+	execTime ScriptExecTime
+	script   string
+}
+
+type ScriptExecTime int
+
+const (
+	BeforeDOMContentLoaded ScriptExecTime = iota
+	AfterDOMContentLoaded
+	AfterDOMIdle
+)
+
+func (r *ScriptInjectorRewriter) ShouldModify(token *html.Token) bool {
+	// modify if token == <head>
+	return token.DataAtom == atom.Head && token.Type == html.StartTagToken
+}
+
+//go:embed after_dom_idle_script_injector.js
+var afterDomIdleScriptInjector string
+
+func (r *ScriptInjectorRewriter) ModifyToken(token *html.Token) (string, string) {
+	switch {
+	case r.execTime == BeforeDOMContentLoaded:
+		return "", fmt.Sprintf("\n<script>\n%s\n</script>\n", r.script)
+
+	case r.execTime == AfterDOMContentLoaded:
+		return "", fmt.Sprintf("\n<script>\ndocument.addEventListener('DOMContentLoaded', () => { %s });\n</script>", r.script)
+
+	case r.execTime == AfterDOMIdle:
+		s := strings.Replace(afterDomIdleScriptInjector, `'SCRIPT_CONTENT_PARAM'`, r.script, 1)
+		return "", fmt.Sprintf("\n<script>\n%s\n</script>\n", s)
+
+	default:
+		return "", ""
+	}
+}
+
+// applies parameters by string replacement of the template script
+func (r *ScriptInjectorRewriter) applyParams(params map[string]string) {
+	// Sort the keys by length in descending order
+	keys := make([]string, 0, len(params))
+	for key := range params {
+		keys = append(keys, key)
+	}
+	sort.Slice(keys, func(i, j int) bool {
+		return len(keys[i]) > len(keys[j])
+	})
+
+	for _, key := range keys {
+		r.script = strings.ReplaceAll(r.script, key, params[key])
+	}
+}
+
+// NewScriptInjectorRewriter implements a HtmlTokenRewriter
+// and injects JS into the page for execution at a particular time
+func NewScriptInjectorRewriter(script string, execTime ScriptExecTime) *ScriptInjectorRewriter {
+	return &ScriptInjectorRewriter{
+		execTime: execTime,
+		script:   script,
+	}
+}
+
+// NewScriptInjectorRewriterWith implements a HtmlTokenRewriter
+// and injects JS into the page for execution at a particular time
+// accepting arguments into the script, which will be added via a string replace
+// the params map represents the key-value pair of the params.
+// the key will be string replaced with the value
+func NewScriptInjectorRewriterWithParams(script string, execTime ScriptExecTime, params map[string]string) *ScriptInjectorRewriter {
+	rr := &ScriptInjectorRewriter{
+		execTime: execTime,
+		script:   script,
+	}
+	rr.applyParams(params)
+	return rr
+}

tests/package-lock.json

@@ -0,0 +1,91 @@
+{
+  "name": "tests",
+  "version": "1.0.0",
+  "lockfileVersion": 3,
+  "requires": true,
+  "packages": {
+    "": {
+      "name": "tests",
+      "version": "1.0.0",
+      "license": "ISC",
+      "devDependencies": {
+        "@playwright/test": "^1.40.0",
+        "@types/node": "^20.10.0"
+      }
+    },
+    "node_modules/@playwright/test": {
+      "version": "1.40.0",
+      "resolved": "https://registry.npmjs.org/@playwright/test/-/test-1.40.0.tgz",
+      "integrity": "sha512-PdW+kn4eV99iP5gxWNSDQCbhMaDVej+RXL5xr6t04nbKLCBwYtA046t7ofoczHOm8u6c+45hpDKQVZqtqwkeQg==",
+      "dev": true,
+      "dependencies": {
+        "playwright": "1.40.0"
+      },
+      "bin": {
+        "playwright": "cli.js"
+      },
+      "engines": {
+        "node": ">=16"
+      }
+    },
+    "node_modules/@types/node": {
+      "version": "20.10.0",
+      "resolved": "https://registry.npmjs.org/@types/node/-/node-20.10.0.tgz",
+      "integrity": "sha512-D0WfRmU9TQ8I9PFx9Yc+EBHw+vSpIub4IDvQivcp26PtPrdMGAq5SDcpXEo/epqa/DXotVpekHiLNTg3iaKXBQ==",
+      "dev": true,
+      "dependencies": {
+        "undici-types": "~5.26.4"
+      }
+    },
+    "node_modules/fsevents": {
+      "version": "2.3.2",
+      "resolved": "https://registry.npmjs.org/fsevents/-/fsevents-2.3.2.tgz",
+      "integrity": "sha512-xiqMQR4xAeHTuB9uWm+fFRcIOgKBMiOBP+eXiyT7jsgVCq1bkVygt00oASowB7EdtpOHaaPgKt812P9ab+DDKA==",
+      "dev": true,
+      "hasInstallScript": true,
+      "optional": true,
+      "os": [
+        "darwin"
+      ],
+      "engines": {
+        "node": "^8.16.0 || ^10.6.0 || >=11.0.0"
+      }
+    },
+    "node_modules/playwright": {
+      "version": "1.40.0",
+      "resolved": "https://registry.npmjs.org/playwright/-/playwright-1.40.0.tgz",
+      "integrity": "sha512-gyHAgQjiDf1m34Xpwzaqb76KgfzYrhK7iih+2IzcOCoZWr/8ZqmdBw+t0RU85ZmfJMgtgAiNtBQ/KS2325INXw==",
+      "dev": true,
+      "dependencies": {
+        "playwright-core": "1.40.0"
+      },
+      "bin": {
+        "playwright": "cli.js"
+      },
+      "engines": {
+        "node": ">=16"
+      },
+      "optionalDependencies": {
+        "fsevents": "2.3.2"
+      }
+    },
+    "node_modules/playwright-core": {
+      "version": "1.40.0",
+      "resolved": "https://registry.npmjs.org/playwright-core/-/playwright-core-1.40.0.tgz",
+      "integrity": "sha512-fvKewVJpGeca8t0ipM56jkVSU6Eo0RmFvQ/MaCQNDYm+sdvKkMBBWTE1FdeMqIdumRaXXjZChWHvIzCGM/tA/Q==",
+      "dev": true,
+      "bin": {
+        "playwright-core": "cli.js"
+      },
+      "engines": {
+        "node": ">=16"
+      }
+    },
+    "node_modules/undici-types": {
+      "version": "5.26.5",
+      "resolved": "https://registry.npmjs.org/undici-types/-/undici-types-5.26.5.tgz",
+      "integrity": "sha512-JlCMO+ehdEIKqlFxk6IfVoAUVmgz7cU7zD/h9XZ0qzeosSHmUJVOzSQvvYSYWXkFXC+IfLKSIffhv0sVZup6pA==",
+      "dev": true
+    }
+  }
+}

tests/package.json

@@ -0,0 +1,14 @@
+{
+  "name": "tests",
+  "version": "1.0.0",
+  "description": "",
+  "main": "index.js",
+  "scripts": {},
+  "keywords": [],
+  "author": "",
+  "license": "ISC",
+  "devDependencies": {
+    "@playwright/test": "^1.40.0",
+    "@types/node": "^20.10.0"
+  }
+}

tests/playwright.config.ts

@@ -0,0 +1,77 @@
+import { defineConfig, devices } from "@playwright/test";
+
+/**
+ * Read environment variables from file.
+ * https://github.com/motdotla/dotenv
+ */
+// require('dotenv').config();
+
+/**
+ * See https://playwright.dev/docs/test-configuration.
+ */
+export default defineConfig({
+  testDir: "./tests",
+  /* Run tests in files in parallel */
+  fullyParallel: true,
+  /* Fail the build on CI if you accidentally left test.only in the source code. */
+  forbidOnly: !!process.env.CI,
+  /* Retry on CI only */
+  retries: process.env.CI ? 2 : 0,
+  /* Opt out of parallel tests on CI. */
+  workers: process.env.CI ? 1 : undefined,
+  /* Reporter to use. See https://playwright.dev/docs/test-reporters */
+  reporter: "html",
+  /* Shared settings for all the projects below. See https://playwright.dev/docs/api/class-testoptions. */
+  use: {
+    /* Base URL to use in actions like `await page.goto('/')`. */
+    // baseURL: 'http://127.0.0.1:3000',
+
+    /* Collect trace when retrying the failed test. See https://playwright.dev/docs/trace-viewer */
+    trace: "on-first-retry",
+  },
+
+  /* Configure projects for major browsers */
+  projects: [
+    {
+      name: "chromium",
+      use: { ...devices["Desktop Chrome"] },
+    },
+    /*
+    {
+      name: 'firefox',
+      use: { ...devices['Desktop Firefox'] },
+    },
+
+    {
+      name: 'webkit',
+      use: { ...devices['Desktop Safari'] },
+    },
+    */
+
+    /* Test against mobile viewports. */
+    // {
+    //   name: 'Mobile Chrome',
+    //   use: { ...devices['Pixel 5'] },
+    // },
+    // {
+    //   name: 'Mobile Safari',
+    //   use: { ...devices['iPhone 12'] },
+    // },
+
+    /* Test against branded browsers. */
+    // {
+    //   name: 'Microsoft Edge',
+    //   use: { ...devices['Desktop Edge'], channel: 'msedge' },
+    // },
+    // {
+    //   name: 'Google Chrome',
+    //   use: { ...devices['Desktop Chrome'], channel: 'chrome' },
+    // },
+  ],
+  /* Run your local dev server before starting the tests */
+  // webServer: {
+  //   command: 'npm run start',
+  //   url: 'http://127.0.0.1:3000',
+  //   reuseExistingServer: !process.env.CI,
+  // },
+});

tests/run_test.sh

@@ -0,0 +1,2 @@
+npx playwright test
+npx playwright show-report

tests/tests/www-wellandtribune-ca.spec.ts

@@ -0,0 +1,18 @@
+import { expect, test } from "@playwright/test";
+
+const paywallText = "This article is exclusive to subscribers.";
+const articleURL =
+  "https://www.wellandtribune.ca/news/niagara-region/niagara-transit-commission-rejects-council-request-to-reduce-its-budget-increase/article_e9fb424c-8df5-58ae-a6c3-3648e2a9df66.html";
+
+const ladderURL = "http://localhost:8080";
+let domain = (new URL(articleURL)).host;
+
+test(`${domain} has paywall by default`, async ({ page }) => {
+  await page.goto(articleURL);
+  await expect(page.getByText(paywallText)).toBeVisible();
+});
+
+test(`${domain} + Ladder doesn't have paywall`, async ({ page }) => {
+  await page.goto(`${ladderURL}/${articleURL}`);
+  await expect(page.getByText(paywallText)).toBeVisible();
+});