Add support for http proxy (#68)

* Add support for http proxy

* add test case for http proxy

---------

Co-authored-by: octeep <github@bandersnatch.anonaddy.com>
Co-authored-by: pufferfish <74378430+pufferffish@users.noreply.github.com>

http.go

@@ -0,0 +1,156 @@
+package wireproxy
+
+import (
+	"bufio"
+	"bytes"
+	"encoding/base64"
+	"fmt"
+	"io"
+	"log"
+	"net"
+	"net/http"
+	"strings"
+)
+
+const proxyAuthHeaderKey = "Proxy-Authorization"
+
+type HTTPServer struct {
+	config *HTTPConfig
+
+	auth CredentialValidator
+	dial func(network, address string) (net.Conn, error)
+
+	authRequired bool
+}
+
+func (s *HTTPServer) authenticate(req *http.Request) (int, error) {
+	if !s.authRequired {
+		return 0, nil
+	}
+
+	auth := req.Header.Get(proxyAuthHeaderKey)
+	if auth != "" {
+		enc := strings.TrimPrefix(auth, "Basic ")
+		str, err := base64.StdEncoding.DecodeString(enc)
+		if err != nil {
+			return http.StatusNotAcceptable, fmt.Errorf("decode username and password failed: %w", err)
+		}
+		pairs := bytes.SplitN(str, []byte(":"), 2)
+		if len(pairs) != 2 {
+			return http.StatusLengthRequired, fmt.Errorf("username and password format invalid")
+		}
+		if s.auth.Valid(string(pairs[0]), string(pairs[1])) {
+			return 0, nil
+		}
+		return http.StatusUnauthorized, fmt.Errorf("username and password not matching")
+	}
+
+	return http.StatusProxyAuthRequired, fmt.Errorf(http.StatusText(http.StatusProxyAuthRequired))
+}
+
+func (s *HTTPServer) handleConn(req *http.Request, conn net.Conn) (peer net.Conn, err error) {
+	addr := req.Host
+	if !strings.Contains(addr, ":") {
+		port := "443"
+		addr = net.JoinHostPort(addr, port)
+	}
+
+	peer, err = s.dial("tcp", addr)
+	if err != nil {
+		return peer, fmt.Errorf("tun tcp dial failed: %w", err)
+	}
+
+	_, err = conn.Write([]byte("HTTP/1.1 200 Connection established\r\n\r\n"))
+	if err != nil {
+		peer.Close()
+		peer = nil
+	}
+
+	return
+}
+
+func (s *HTTPServer) handle(req *http.Request) (peer net.Conn, err error) {
+	addr := req.Host
+	if !strings.Contains(addr, ":") {
+		port := "80"
+		addr = net.JoinHostPort(addr, port)
+	}
+
+	peer, err = s.dial("tcp", addr)
+	if err != nil {
+		return peer, fmt.Errorf("tun tcp dial failed: %w", err)
+	}
+
+	err = req.Write(peer)
+	if err != nil {
+		peer.Close()
+		peer = nil
+		return peer, fmt.Errorf("conn write failed: %w", err)
+	}
+
+	return
+}
+
+func (s *HTTPServer) serve(conn net.Conn) error {
+	defer conn.Close()
+
+	var rd io.Reader = bufio.NewReader(conn)
+	req, err := http.ReadRequest(rd.(*bufio.Reader))
+	if err != nil {
+		return fmt.Errorf("read request failed: %w", err)
+	}
+
+	code, err := s.authenticate(req)
+	if err != nil {
+		_ = responseWith(req, code).Write(conn)
+		return err
+	}
+
+	var peer net.Conn
+	switch req.Method {
+	case http.MethodConnect:
+		peer, err = s.handleConn(req, conn)
+	case http.MethodGet:
+		peer, err = s.handle(req)
+	default:
+		_ = responseWith(req, http.StatusMethodNotAllowed).Write(conn)
+		return fmt.Errorf("unsupported protocol: %s", req.Method)
+	}
+	if err != nil {
+		return fmt.Errorf("dial proxy failed: %w", err)
+	}
+	if peer == nil {
+		return fmt.Errorf("dial proxy failed: peer nil")
+	}
+	defer peer.Close()
+
+	go func() {
+		defer peer.Close()
+		defer conn.Close()
+		_, _ = io.Copy(conn, peer)
+	}()
+	_, err = io.Copy(peer, conn)
+
+	return err
+}
+
+// ListenAndServe is used to create a listener and serve on it
+func (s *HTTPServer) ListenAndServe(network, addr string) error {
+	server, err := net.Listen("tcp", s.config.BindAddress)
+	if err != nil {
+		return fmt.Errorf("listen tcp failed: %w", err)
+	}
+
+	for {
+		conn, err := server.Accept()
+		if err != nil {
+			return fmt.Errorf("accept request failed: %w", err)
+		}
+		go func(conn net.Conn) {
+			err = s.serve(conn)
+			if err != nil {
+				log.Println(err)
+			}
+		}(conn)
+	}
+}