102 lines
2.5 KiB
Go
102 lines
2.5 KiB
Go
package responsemodifiers
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import (
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"embed"
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"encoding/json"
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"io"
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"log"
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"regexp"
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"ladder/proxychain"
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)
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//go:embed vendor/ddg-tracker-surrogates/mapping.json
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var mappingJSON []byte
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//go:embed vendor/ddg-tracker-surrogates/surrogates/*
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var surrogateFS embed.FS
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var rules domainRules
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func init() {
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err := json.Unmarshal([]byte(mappingJSON), &rules)
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if err != nil {
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log.Printf("[ERROR]: PatchTrackerScripts: failed to deserialize ladder/proxychain/responsemodifiers/vendor/ddg-tracker-surrogates/mapping.json")
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}
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}
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// mapping.json schema
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type rule struct {
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RegexRule *regexp.Regexp `json:"regexRule"`
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Surrogate string `json:"surrogate"`
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Action string `json:"action,omitempty"`
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}
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type domainRules map[string][]rule
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func (r *rule) UnmarshalJSON(data []byte) error {
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type Tmp struct {
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RegexRule string `json:"regexRule"`
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Surrogate string `json:"surrogate"`
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Action string `json:"action,omitempty"`
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}
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var tmp Tmp
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if err := json.Unmarshal(data, &tmp); err != nil {
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return err
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}
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regex := regexp.MustCompile(tmp.RegexRule)
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r.RegexRule = regex
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r.Surrogate = tmp.Surrogate
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r.Action = tmp.Action
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return nil
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}
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// PatchTrackerScripts replaces any request to tracker scripts such as google analytics
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// with a no-op stub that mocks the API structure of the original scripts they replace.
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// Some pages depend on the existence of these structures for proper loading, so this may fix
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// some broken elements.
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// Surrogate script code borrowed from: DuckDuckGo Privacy Essentials browser extension for Firefox, Chrome. (Apache 2.0 license)
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func PatchTrackerScripts() proxychain.ResponseModification {
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return func(chain *proxychain.ProxyChain) error {
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// preflight checks
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reqURL := chain.Request.URL.String()
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isTracker := false
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//
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var surrogateScript io.ReadCloser
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for domain, domainRules := range rules {
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for _, rule := range domainRules {
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if !rule.RegexRule.MatchString(reqURL) {
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continue
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}
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// found tracker script, replacing response body with nop stub from
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// ./vendor/ddg-tracker-surrogates/surrogates/{{rule.Surrogate}}
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isTracker = true
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script, err := surrogateFS.Open("vendor/ddg-tracker-surrogates/surrogates/" + rule.Surrogate)
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if err != nil {
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panic(err)
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}
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surrogateScript = io.NopCloser(script)
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log.Printf("INFO: PatchTrackerScripts :: injecting surrogate for '%s' => 'surrogates/%s'\n", domain, rule.Surrogate)
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break
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}
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}
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if !isTracker {
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return nil
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}
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chain.Response.Body = surrogateScript
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chain.Context.Set("content-type", "text/javascript")
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return nil
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}
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}
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