Isolate extension WebView profiles and follow host proxy settings

internal/webview/proxy/server.go

@@ -0,0 +1,341 @@
+// Package proxy provides the host-owned WebView forward proxy. Browser engines
+// always use this endpoint; Gopeed decides the upstream route for each request.
+package proxy
+
+import (
+	"bufio"
+	"context"
+	"crypto/tls"
+	"encoding/base64"
+	"errors"
+	"fmt"
+	"io"
+	"log"
+	"net"
+	"net/http"
+	"net/url"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/armon/go-socks5"
+	xproxy "golang.org/x/net/proxy"
+)
+
+type Selector func(*http.Request) (*url.URL, error)
+
+type Server struct {
+	listener      net.Listener
+	socksListener net.Listener
+	server        *http.Server
+	transport     *http.Transport
+	selectProxy   Selector
+	mu            sync.Mutex
+	connections   map[io.Closer]struct{}
+	closed        bool
+}
+
+func New(selectProxy Selector) (*Server, error) {
+	if selectProxy == nil {
+		selectProxy = func(*http.Request) (*url.URL, error) { return nil, nil }
+	}
+	listener, err := net.Listen("tcp4", "127.0.0.1:0")
+	if err != nil {
+		return nil, err
+	}
+	s := &Server{listener: listener, selectProxy: selectProxy, connections: make(map[io.Closer]struct{})}
+	s.transport = &http.Transport{Proxy: selectProxy, DisableKeepAlives: true, TLSHandshakeTimeout: 15 * time.Second, ResponseHeaderTimeout: 30 * time.Second}
+	s.server = &http.Server{Handler: s, ReadHeaderTimeout: 15 * time.Second}
+	s.socksListener, err = net.Listen("tcp4", "127.0.0.1:0")
+	if err != nil {
+		listener.Close()
+		return nil, err
+	}
+	socks, err := socks5.New(&socks5.Config{Logger: log.New(io.Discard, "", 0), Resolver: unresolvedDNS{}, Dial: func(ctx context.Context, network, address string) (net.Conn, error) {
+		_, port, _ := net.SplitHostPort(address)
+		scheme := "https"
+		if port == "80" {
+			scheme = "http"
+		}
+		request := &http.Request{URL: &url.URL{Scheme: scheme, Host: address}, Header: make(http.Header)}
+		upstream, err := selectProxy(request)
+		if err != nil {
+			return nil, err
+		}
+		timed, cancel := context.WithTimeout(ctx, 30*time.Second)
+		defer cancel()
+		conn, err := dialTunnel(timed, address, upstream)
+		if err != nil {
+			return nil, err
+		}
+		return s.track(conn)
+	}})
+	if err != nil {
+		listener.Close()
+		s.socksListener.Close()
+		return nil, err
+	}
+	go s.server.Serve(listener)
+	go socks.Serve(&trackedListener{Listener: s.socksListener, server: s})
+	return s, nil
+}
+
+func (s *Server) URL() string { return "http://" + s.listener.Addr().String() }
+
+func (s *Server) SOCKSURL() string { return "socks5://" + s.socksListener.Addr().String() }
+
+func (s *Server) Close() error {
+	s.mu.Lock()
+	s.closed = true
+	connections := make([]io.Closer, 0, len(s.connections))
+	for c := range s.connections {
+		connections = append(connections, c)
+	}
+	s.mu.Unlock()
+	for _, c := range connections {
+		c.Close()
+	}
+	s.socksListener.Close()
+	s.transport.CloseIdleConnections()
+	return s.server.Close()
+}
+
+func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	if r.Method == http.MethodConnect {
+		s.connect(w, r)
+		return
+	}
+	if !r.URL.IsAbs() || (r.URL.Scheme != "http" && r.URL.Scheme != "https") {
+		http.Error(w, "absolute HTTP URL required", http.StatusBadRequest)
+		return
+	}
+	out := r.Clone(r.Context())
+	out.RequestURI = ""
+	upgrade := out.Header.Get("Upgrade")
+	stripHopHeaders(out.Header)
+	if upgrade != "" {
+		out.Header.Set("Connection", "Upgrade")
+		out.Header.Set("Upgrade", upgrade)
+	}
+	resp, err := s.transport.RoundTrip(out)
+	if err != nil {
+		http.Error(w, "upstream request failed", http.StatusBadGateway)
+		return
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode == http.StatusSwitchingProtocols {
+		remote, ok := resp.Body.(io.ReadWriteCloser)
+		if !ok {
+			http.Error(w, "invalid upstream upgrade", 502)
+			return
+		}
+		client, buffer, err := w.(http.Hijacker).Hijack()
+		if err != nil {
+			return
+		}
+		defer client.Close()
+		resp.Body = nil
+		if err := resp.Write(buffer); err != nil {
+			return
+		}
+		if err := buffer.Flush(); err != nil {
+			return
+		}
+		s.bridge(client, buffer, remote)
+		return
+	}
+	stripHopHeaders(resp.Header)
+	for k, v := range resp.Header {
+		w.Header()[k] = v
+	}
+	w.WriteHeader(resp.StatusCode)
+	io.Copy(w, resp.Body)
+}
+
+func stripHopHeaders(h http.Header) {
+	for _, key := range strings.Split(h.Get("Connection"), ",") {
+		h.Del(strings.TrimSpace(key))
+	}
+	for _, key := range []string{"Connection", "Proxy-Connection", "Proxy-Authorization", "Proxy-Authenticate", "Keep-Alive", "TE", "Trailer", "Transfer-Encoding", "Upgrade"} {
+		h.Del(key)
+	}
+}
+
+func (s *Server) connect(w http.ResponseWriter, r *http.Request) {
+	if _, _, err := net.SplitHostPort(r.Host); err != nil {
+		http.Error(w, "invalid tunnel destination", 400)
+		return
+	}
+	target := r.Clone(r.Context())
+	target.URL = &url.URL{Scheme: "https", Host: r.Host}
+	upstream, err := s.selectProxy(target)
+	if err != nil {
+		http.Error(w, "proxy selection failed", 502)
+		return
+	}
+	ctx, cancel := context.WithTimeout(r.Context(), 30*time.Second)
+	defer cancel()
+	remote, err := dialTunnel(ctx, r.Host, upstream)
+	if err != nil {
+		http.Error(w, "upstream connection failed", 502)
+		return
+	}
+	defer remote.Close()
+	client, buffer, err := w.(http.Hijacker).Hijack()
+	if err != nil {
+		return
+	}
+	defer client.Close()
+	if _, err := buffer.WriteString("HTTP/1.1 200 Connection Established\r\n\r\n"); err != nil {
+		return
+	}
+	if err := buffer.Flush(); err != nil {
+		return
+	}
+	s.bridge(client, buffer, remote)
+}
+
+func (s *Server) bridge(client net.Conn, buffer *bufio.ReadWriter, remote io.ReadWriteCloser) {
+	s.mu.Lock()
+	if s.closed {
+		s.mu.Unlock()
+		return
+	}
+	s.connections[client] = struct{}{}
+	s.connections[remote] = struct{}{}
+	s.mu.Unlock()
+	defer func() { s.mu.Lock(); delete(s.connections, client); delete(s.connections, remote); s.mu.Unlock() }()
+
+	done := make(chan struct{})
+	go func() { io.Copy(remote, buffer); remote.Close(); close(done) }()
+	io.Copy(client, remote)
+	client.Close()
+	<-done
+}
+
+type bufferedConn struct {
+	net.Conn
+	reader *bufio.Reader
+}
+
+func (c *bufferedConn) Read(p []byte) (int, error) { return c.reader.Read(p) }
+
+func dialTunnel(ctx context.Context, target string, upstream *url.URL) (net.Conn, error) {
+	dialer := &net.Dialer{}
+	if upstream == nil {
+		return dialer.DialContext(ctx, "tcp", target)
+	}
+	if upstream.Scheme == "socks5" || upstream.Scheme == "socks5h" {
+		u := *upstream
+		u.Scheme = "socks5"
+		d, err := xproxy.FromURL(&u, dialer)
+		if err != nil {
+			return nil, err
+		}
+		return d.(xproxy.ContextDialer).DialContext(ctx, "tcp", target)
+	}
+	if upstream.Scheme != "http" && upstream.Scheme != "https" {
+		return nil, errors.New("unsupported proxy scheme")
+	}
+	host := upstream.Host
+	if upstream.Port() == "" {
+		port := "80"
+		if upstream.Scheme == "https" {
+			port = "443"
+		}
+		host = net.JoinHostPort(upstream.Hostname(), port)
+	}
+	conn, err := dialer.DialContext(ctx, "tcp", host)
+	if err != nil {
+		return nil, err
+	}
+	ok := false
+	defer func() {
+		if !ok {
+			conn.Close()
+		}
+	}()
+	if deadline, exists := ctx.Deadline(); exists {
+		conn.SetDeadline(deadline)
+	}
+	if upstream.Scheme == "https" {
+		secure := tls.Client(conn, &tls.Config{ServerName: upstream.Hostname(), MinVersion: tls.VersionTLS12})
+		if err := secure.HandshakeContext(ctx); err != nil {
+			return nil, err
+		}
+		conn = secure
+	}
+	request := &http.Request{Method: http.MethodConnect, URL: &url.URL{Opaque: target}, Host: target, Header: make(http.Header)}
+	if upstream.User != nil {
+		password, _ := upstream.User.Password()
+		request.Header.Set("Proxy-Authorization", "Basic "+base64.StdEncoding.EncodeToString([]byte(upstream.User.Username()+":"+password)))
+	}
+	if err := request.Write(conn); err != nil {
+		return nil, err
+	}
+	reader := bufio.NewReader(conn)
+	response, err := http.ReadResponse(reader, request)
+	if err != nil {
+		return nil, err
+	}
+	if response.StatusCode != 200 {
+		response.Body.Close()
+		return nil, fmt.Errorf("upstream CONNECT status %d", response.StatusCode)
+	}
+	conn.SetDeadline(time.Time{})
+	ok = true
+	return &bufferedConn{Conn: conn, reader: reader}, nil
+}
+
+// Leave hostname resolution to the selected upstream (SOCKS remote DNS / CONNECT).
+type unresolvedDNS struct{}
+
+func (unresolvedDNS) Resolve(ctx context.Context, name string) (context.Context, net.IP, error) {
+	return ctx, nil, nil
+}
+
+type trackedListener struct {
+	net.Listener
+	server *Server
+}
+
+func (l *trackedListener) Accept() (net.Conn, error) {
+	c, err := l.Listener.Accept()
+	if err != nil {
+		return nil, err
+	}
+	return l.server.track(c)
+}
+
+type trackedConn struct {
+	net.Conn
+	server *Server
+}
+
+func (c *trackedConn) Close() error {
+	err := c.Conn.Close()
+	c.server.mu.Lock()
+	delete(c.server.connections, c)
+	c.server.mu.Unlock()
+	return err
+}
+func (s *Server) track(c net.Conn) (net.Conn, error) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if s.closed {
+		c.Close()
+		return nil, net.ErrClosed
+	}
+	tracked := &trackedConn{Conn: c, server: s}
+	s.connections[tracked] = struct{}{}
+	return tracked, nil
+}
+
+func (c *trackedConn) CloseWrite() error  { return closeWrite(c.Conn) }
+func (c *bufferedConn) CloseWrite() error { return closeWrite(c.Conn) }
+func closeWrite(c net.Conn) error {
+	if writer, ok := c.(interface{ CloseWrite() error }); ok {
+		return writer.CloseWrite()
+	}
+	return c.Close()
+}