commit b740f57488945b90d9629ea63508ec5858a6b783
Author: Tanishq Dubey <dubey@dws.rip>
Date:   Mon Jul 15 18:35:32 2024 -0400

    Basic server

diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..24cf7a4
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,3 @@
+module git.dws.rip/dwshttp
+
+go 1.22.5
diff --git a/main.go b/main.go
new file mode 100644
index 0000000..10c2caa
--- /dev/null
+++ b/main.go
@@ -0,0 +1,210 @@
+package main
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"log"
+	"net"
+	"os"
+	"strings"
+	"time"
+)
+
+type HTTPMethod string
+
+const (
+	HTTPMETHOD_GET  HTTPMethod = "GET"
+	HTTPMETHOD_POST HTTPMethod = "POST"
+)
+
+/*
+	A request-line begins with a method token, followed by a single space
+
+(SP), the request-target, another single space (SP), the protocol
+version, and ends with CRLF.
+
+		request-line   = method SP request-target SP HTTP-version CRLF
+	     HTTP-version  = HTTP-name "/" DIGIT "." DIGIT
+*/
+type RequestLine struct {
+	Method        HTTPMethod
+	RequestTarget string
+	HTTPVersion   string
+}
+
+/*
+The first line of a response message is the status-line, consisting
+of the protocol version, a space (SP), the status code, another
+space, a possibly empty textual phrase describing the status code,
+and ending with CRLF.
+
+	status-line = HTTP-version SP status-code SP reason-phrase CRLF
+*/
+type StatusLine struct {
+}
+
+/*
+All HTTP/1.1 messages consist of a start-line followed by a sequence
+of octets in a format similar to the Internet Message Format
+[RFC5322]: zero or more header fields (collectively referred to as
+the "headers" or the "header section"), an empty line indicating the
+end of the header section, and an optional message body.
+
+	HTTP-message   = start-line
+	                 *( header-field CRLF )
+	                 CRLF
+	                 [ message-body ]
+*/
+type HTTPRequest struct {
+	StartLine RequestLine
+}
+
+type HTTPResponse struct {
+	StartLine StatusLine
+}
+
+func printDiff(s1, s2 string) {
+	length := len(s1)
+	if len(s2) > length {
+		length = len(s2)
+	}
+
+	for i := 0; i < length; i++ {
+		var char1, char2 byte
+
+		if i < len(s1) {
+			char1 = s1[i]
+		} else {
+			char1 = ' ' // padding for shorter string
+		}
+
+		if i < len(s2) {
+			char2 = s2[i]
+		} else {
+			char2 = ' ' // padding for shorter string
+		}
+
+		if char1 != char2 {
+			fmt.Printf("Difference at index %d: '%c' != '%c'\n", i, char1, char2)
+		}
+	}
+}
+
+func ParseHTTPRequest(b []byte) (HTTPRequest, error) {
+	ret := HTTPRequest{}
+	rs := string(b[:])
+
+	method, rs, found := strings.Cut(rs, " ")
+	if !found {
+		return ret, errors.New("could not find method in request")
+	}
+
+	method = strings.ToUpper(strings.TrimSpace(method))
+	ret.StartLine = RequestLine{}
+	switch method {
+	case string(HTTPMETHOD_GET):
+		ret.StartLine.Method = HTTPMETHOD_GET
+	case string(HTTPMETHOD_POST):
+		ret.StartLine.Method = HTTPMETHOD_POST
+	default:
+		if method != "GET" {
+			result1 := strings.Compare("GET", method)
+			fmt.Println(result1)
+			fmt.Println(len("GET"), len(method))
+		}
+
+		return ret, fmt.Errorf("unsupported method '%s'", method)
+	}
+
+	rt, rs, found := strings.Cut(rs, " ")
+	if !found {
+		return ret, errors.New("could not find target in request")
+	}
+	ret.StartLine.RequestTarget = rt
+
+	hv, rs, found := strings.Cut(rs, "\r\n")
+	if !found {
+		return ret, errors.New("could not find http version in request")
+	}
+	if hv != "HTTP/1.0" && hv != "HTTP/1.1" {
+		return ret, fmt.Errorf("unsupported http version %s", hv)
+	}
+	ret.StartLine.HTTPVersion = hv
+	fmt.Println("rm: ", rs)
+
+	return ret, nil
+}
+
+func main() {
+	logger := log.New(os.Stdout, "DWSHTTP", log.LstdFlags)
+
+	l, err := net.Listen("tcp", ":4221")
+	if err != nil {
+		logger.Fatal(err)
+	}
+	defer l.Close()
+	logger.Print("Started server on 4221")
+
+	for {
+		conn, err := l.Accept()
+		if err != nil {
+			logger.Fatal(err)
+		}
+
+		logger.Printf("New connection: %s", conn.RemoteAddr().String())
+		go func(c net.Conn) {
+			defer c.Close()
+
+			bSize := 0
+			rSize := 256
+			buf := make([]byte, bSize)
+			tmp := make([]byte, rSize)
+			err := c.SetReadDeadline(time.Now().Add(time.Second * 5))
+			if err != nil {
+				logger.Printf("ERROR %s - (%s) %s", c.RemoteAddr().String(), "connsetup", err)
+			}
+
+			for {
+				n, err := c.Read(tmp)
+				if err != nil {
+					if err != io.EOF {
+						logger.Fatalf("ERROR %s - (%s) %s", c.RemoteAddr().String(), "unexpected error while reading", err)
+					}
+					break
+				}
+				buf = append(buf, tmp[:n]...)
+				if n > 0 {
+					if n < rSize {
+						break
+					}
+					continue
+				}
+			}
+
+			req, err := ParseHTTPRequest(buf)
+			if err != nil {
+				logger.Printf("ERROR %s - (%s) %s", c.RemoteAddr().String(), "parsing", err)
+				bw, err := c.Write([]byte("HTTP/1.1 500 Internal Server Error\r\n\r\n"))
+				if err != nil {
+					logger.Printf("ERROR %s - (Could not write err) %s", c.RemoteAddr().String(), err)
+					return
+				}
+				if bw < 1 {
+					return
+				}
+			}
+
+			logger.Printf("%s - %s - %s -> 200", req.StartLine.Method, req.StartLine.HTTPVersion, req.StartLine.RequestTarget)
+			bw, err := c.Write([]byte("HTTP/1.1 200 OK\r\n\r\n"))
+			if err != nil {
+				logger.Printf("ERROR %s - (Could not write err) %s", c.RemoteAddr().String(), err)
+				return
+			}
+			if bw < 1 {
+				return
+			}
+
+		}(conn)
+	}
+}