feat: support http/https proxy for IMAP via HTTP CONNECT tunnel

Extend IMAP_PROXY_URL to accept http:// and https:// schemes in addition to the existing socks5:// support. HTTP CONNECT tunneling is used for both new schemes, with TLS to the proxy for https://. Proxy auth via user:pass@ in the URL is supported for all schemes. Refactors dialTLSViaSOCKS5 into a generic dialTLSViaProxy dispatcher. Fixes #9 Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
update agent instruction
2026-04-28 10:56:57 +07:00 · 2026-04-28 09:58:47 +07:00
3 changed files with 323 additions and 31 deletions
@@ -3,16 +3,19 @@
 ## 1. Coding Principles

 ### 1.1 Simplicity First
+
 - No out-of-scope features.
 - No abstractions for single-use code.
 - If 50 lines work instead of 200, write 50.

 ### 1.2 Surgical Changes
+
 - Only change lines directly related to the request.
 - Never refactor adjacent code unless asked.
 - Remove orphaned imports/variables/functions your changes created.

 ### 1.3 Goal-Driven Execution
+
 - Define success criteria before coding.
 - Verify each step before moving to the next.

@@ -83,10 +86,9 @@ All work starts from a Gitea issue. Two phases, each with a dedicated role:

 ## 5. Gitea Tools

- If git remote contains `git.thuanle.me`, ALWAYS use Gitea MCP tools.
+- Alway use Gitea MCP tools in this project.
 - Scope: read PR/issue, list comments, post replies, create/edit PRs, reviews.
 - Use `tea` CLI only as fallback when MCP is unavailable.
- Do not use `gh` for Gitea repositories.
 - Local CLI tools (`git`, `go`, `rg`) are fine for local validation.

 ---
@@ -1,13 +1,16 @@
 package mail

 import (
+	"bufio"
 	"context"
 	"crypto/tls"
+	"encoding/base64"
 	"encoding/json"
 	"fmt"
 	"io"
 	"log/slog"
 	"net"
+	"net/http"
 	"net/url"
 	"strings"
 	"time"
@@ -59,6 +62,10 @@ func (d timeoutContextDialer) DialContext(ctx context.Context, network, address

 var socks5DialerFactory = proxy.SOCKS5

+var proxyTLSConfigForTest = func(host string) *tls.Config {
+	return &tls.Config{ServerName: host}
+}
+
 // NewIMAPWatcher creates a new IMAP watcher.
 func NewIMAPWatcher(cfg *config.Config, db *gorm.DB) *IMAPWatcher {
 	var externalRules []rules.Rule
@@ -73,7 +80,7 @@ func NewIMAPWatcher(cfg *config.Config, db *gorm.DB) *IMAPWatcher {
 		cfg:              cfg,
 		db:               db,
 		dialIMAP:         imapclient.DialTLS,
-		dialIMAPViaProxy: dialTLSViaSOCKS5,
+		dialIMAPViaProxy: dialTLSViaProxy,
 		rules:            rules.NewPipeline(externalRules),
 	}
 }
@@ -193,34 +200,20 @@ func (w *IMAPWatcher) connectAndWatch(ctx context.Context) error {
 	}
 }

-func dialTLSViaSOCKS5(addr, proxyURL string, options *imapclient.Options) (*imapclient.Client, error) {
+func dialTLSViaProxy(addr, proxyURL string, options *imapclient.Options) (*imapclient.Client, error) {
 	u, err := url.Parse(proxyURL)
 	if err != nil {
 		return nil, fmt.Errorf("parse proxy url: %w", err)
 	}
-	if u.Scheme != "socks5" {
-		return nil, fmt.Errorf("unsupported proxy scheme: %s", u.Scheme)
-	}
-
-	var auth *proxy.Auth
-	if u.User != nil {
-		pw, _ := u.User.Password()
-		auth = &proxy.Auth{User: u.User.Username(), Password: pw}
-	}
-
-	dialer, err := socks5DialerFactory("tcp", u.Host, auth, timeoutContextDialer{timeout: imapDialTimeout})
-	if err != nil {
-		return nil, fmt.Errorf("create socks5 dialer: %w", err)
-	}
-
-	dialCtx, dialCancel := context.WithTimeout(context.Background(), imapDialTimeout)
-	defer dialCancel()

 	var conn net.Conn
-	if cd, ok := dialer.(proxy.ContextDialer); ok {
-		conn, err = cd.DialContext(dialCtx, "tcp", addr)
-	} else {
-		conn, err = dialer.Dial("tcp", addr)
+	switch u.Scheme {
+	case "socks5":
+		conn, err = dialViaSOCKS5(u, addr)
+	case "http", "https":
+		conn, err = dialViaCONNECT(u, addr)
+	default:
+		return nil, fmt.Errorf("unsupported proxy scheme: %s", u.Scheme)
 	}
 	if err != nil {
 		return nil, fmt.Errorf("proxy dial: %w", err)
@@ -243,6 +236,96 @@ func dialTLSViaSOCKS5(addr, proxyURL string, options *imapclient.Options) (*imap
 	return imapclient.New(tlsConn, options), nil
 }

+func dialViaSOCKS5(u *url.URL, targetAddr string) (net.Conn, error) {
+	var auth *proxy.Auth
+	if u.User != nil {
+		pw, _ := u.User.Password()
+		auth = &proxy.Auth{User: u.User.Username(), Password: pw}
+	}
+
+	dialer, err := socks5DialerFactory("tcp", u.Host, auth, timeoutContextDialer{timeout: imapDialTimeout})
+	if err != nil {
+		return nil, fmt.Errorf("create socks5 dialer: %w", err)
+	}
+
+	dialCtx, dialCancel := context.WithTimeout(context.Background(), imapDialTimeout)
+	defer dialCancel()
+
+	if cd, ok := dialer.(proxy.ContextDialer); ok {
+		return cd.DialContext(dialCtx, "tcp", targetAddr)
+	}
+	return dialer.Dial("tcp", targetAddr)
+}
+
+// proxyConn wraps a net.Conn, draining buffered data from a bufio.Reader
+// before delegating reads to the underlying connection.
+type proxyConn struct {
+	net.Conn
+	reader io.Reader
+}
+
+func (c *proxyConn) Read(b []byte) (int, error) {
+	return c.reader.Read(b)
+}
+
+// dialToProxy is the function used to establish a TCP connection to the proxy.
+var dialToProxy = func(ctx context.Context, network, addr string) (net.Conn, error) {
+	return (&net.Dialer{Timeout: imapDialTimeout}).DialContext(ctx, network, addr)
+}
+
+func dialViaCONNECT(u *url.URL, targetAddr string) (net.Conn, error) {
+	ctx, cancel := context.WithTimeout(context.Background(), imapDialTimeout)
+	defer cancel()
+
+	conn, err := dialToProxy(ctx, "tcp", u.Host)
+	if err != nil {
+		return nil, fmt.Errorf("dial proxy %s: %w", u.Host, err)
+	}
+
+	if u.Scheme == "https" {
+		tlsConn := tls.Client(conn, proxyTLSConfigForTest(u.Hostname()))
+		if err := tlsConn.HandshakeContext(ctx); err != nil {
+			_ = tlsConn.Close()
+			return nil, fmt.Errorf("tls handshake to proxy: %w", err)
+		}
+		conn = tlsConn
+	}
+
+	_ = conn.SetDeadline(time.Now().Add(imapDialTimeout))
+
+	connectReq := fmt.Sprintf("CONNECT %s HTTP/1.1\r\nHost: %s\r\n", targetAddr, targetAddr)
+	if u.User != nil {
+		username := u.User.Username()
+		password, _ := u.User.Password()
+		creds := base64.StdEncoding.EncodeToString([]byte(username + ":" + password))
+		connectReq += fmt.Sprintf("Proxy-Authorization: Basic %s\r\n", creds)
+	}
+	connectReq += "\r\n"
+
+	if _, err := fmt.Fprint(conn, connectReq); err != nil {
+		_ = conn.Close()
+		return nil, fmt.Errorf("send connect: %w", err)
+	}
+
+	br := bufio.NewReader(conn)
+	resp, err := http.ReadResponse(br, nil)
+	if err != nil {
+		_ = conn.Close()
+		return nil, fmt.Errorf("read connect response: %w", err)
+	}
+	if resp.StatusCode != http.StatusOK {
+		_ = conn.Close()
+		return nil, fmt.Errorf("proxy connect failed: %s", resp.Status)
+	}
+
+	_ = conn.SetDeadline(time.Time{})
+
+	if br.Buffered() > 0 {
+		return &proxyConn{Conn: conn, reader: io.MultiReader(br, conn)}, nil
+	}
+	return conn, nil
+}
+
 // fetchUnseen searches for UNSEEN messages and processes each one.
 func (w *IMAPWatcher) fetchUnseen(c *imapclient.Client) error {
 	criteria := &imap.SearchCriteria{
@@ -1,10 +1,20 @@
 package mail

 import (
+	"bufio"
 	"context"
+	"crypto/ecdsa"
+	"crypto/elliptic"
+	"crypto/rand"
+	"crypto/tls"
+	"crypto/x509"
+	"encoding/base64"
 	"errors"
+	"fmt"
 	"io"
+	"math/big"
 	"net"
+	"net/http"
 	"strings"
 	"testing"
 	"time"
@@ -73,13 +83,22 @@ func TestConnectAndWatch_UsesProxyDial_WhenProxySet(t *testing.T) {
 	}
 }

-func TestDialTLSViaSOCKS5_RejectsNonSocks5Scheme(t *testing.T) {
-	_, err := dialTLSViaSOCKS5("imap.example.com:993", "http://proxy:8080", nil)
+func TestDialTLSViaProxy_RejectsUnsupportedScheme(t *testing.T) {
+	_, err := dialTLSViaProxy("imap.example.com:993", "ftp://proxy:21", nil)
 	if err == nil || !strings.Contains(err.Error(), "unsupported proxy scheme") {
 		t.Fatalf("expected unsupported scheme error, got %v", err)
 	}
 }

+func TestDialTLSViaProxy_RejectsMalformedURL(t *testing.T) {
+	_, err := dialTLSViaProxy("imap.example.com:993", "://bad", nil)
+	if err == nil {
+		t.Fatal("expected error for malformed URL")
+	}
+}
+
+// --- SOCKS5 path ---
+
 type fakeContextDialer struct{}

 func (fakeContextDialer) Dial(network, address string) (net.Conn, error) {
@@ -93,7 +112,7 @@ func (fakeContextDialer) DialContext(ctx context.Context, network, address strin
 	return nil, errors.New("used dialcontext")
 }

-func TestDialTLSViaSOCKS5_UsesDialContextWithTimeout(t *testing.T) {
+func TestDialTLSViaProxy_SOCKS5_UsesDialContextWithTimeout(t *testing.T) {
 	orig := socks5DialerFactory
 	t.Cleanup(func() { socks5DialerFactory = orig })

@@ -104,7 +123,7 @@ func TestDialTLSViaSOCKS5_UsesDialContextWithTimeout(t *testing.T) {
 		return fakeContextDialer{}, nil
 	}

-	_, err := dialTLSViaSOCKS5("imap.example.com:993", "socks5://127.0.0.1:1080", nil)
+	_, err := dialTLSViaProxy("imap.example.com:993", "socks5://127.0.0.1:1080", nil)
 	if err == nil || !strings.Contains(err.Error(), "proxy dial: used dialcontext") {
 		t.Fatalf("expected DialContext path, got %v", err)
 	}
@@ -143,7 +162,7 @@ func (d contextConnDialer) DialContext(ctx context.Context, network, address str
 	return d.conn, nil
 }

-func TestDialTLSViaSOCKS5_SetsDeadlineForTLSHandshake(t *testing.T) {
+func TestDialTLSViaProxy_SOCKS5_SetsDeadlineForTLSHandshake(t *testing.T) {
 	orig := socks5DialerFactory
 	t.Cleanup(func() { socks5DialerFactory = orig })

@@ -152,7 +171,7 @@ func TestDialTLSViaSOCKS5_SetsDeadlineForTLSHandshake(t *testing.T) {
 		return contextConnDialer{conn: conn}, nil
 	}

-	_, err := dialTLSViaSOCKS5("imap.example.com:993", "socks5://127.0.0.1:1080", nil)
+	_, err := dialTLSViaProxy("imap.example.com:993", "socks5://127.0.0.1:1080", nil)
 	if err == nil || !strings.Contains(err.Error(), "tls handshake") {
 		t.Fatalf("expected tls handshake error, got %v", err)
 	}
@@ -160,3 +179,191 @@ func TestDialTLSViaSOCKS5_SetsDeadlineForTLSHandshake(t *testing.T) {
 		t.Fatal("expected TLS handshake deadline to be set")
 	}
 }
+
+// --- HTTP CONNECT path ---
+
+func startFakeProxy(t *testing.T, handler func(host string) bool) (addr string, cleanup func()) {
+	t.Helper()
+	ln, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatalf("listen: %v", err)
+	}
+	done := make(chan struct{})
+	go func() {
+		defer close(done)
+		for {
+			conn, err := ln.Accept()
+			if err != nil {
+				return
+			}
+			go func(c net.Conn) {
+				defer c.Close()
+				br := bufio.NewReader(c)
+				req, err := http.ReadRequest(br)
+				if err != nil {
+					return
+				}
+				if handler(req.URL.Host) {
+					fmt.Fprintf(c, "HTTP/1.1 200 OK\r\n\r\n")
+				} else {
+					fmt.Fprintf(c, "HTTP/1.1 403 Forbidden\r\n\r\n")
+				}
+			}(conn)
+		}
+	}()
+	return ln.Addr().String(), func() {
+		ln.Close()
+		<-done
+	}
+}
+
+func TestDialTLSViaProxy_HTTPConnect_ReachesTLSHandshake(t *testing.T) {
+	addr, cleanup := startFakeProxy(t, func(host string) bool { return true })
+	defer cleanup()
+
+	_, err := dialTLSViaProxy("imap.example.com:993", fmt.Sprintf("http://%s", addr), nil)
+	if err == nil || !strings.Contains(err.Error(), "tls handshake") {
+		t.Fatalf("expected tls handshake error (CONNECT succeeded), got %v", err)
+	}
+}
+
+func TestDialTLSViaProxy_HTTPConnect_RejectsOnProxyFailure(t *testing.T) {
+	addr, cleanup := startFakeProxy(t, func(host string) bool { return false })
+	defer cleanup()
+
+	_, err := dialTLSViaProxy("imap.example.com:993", fmt.Sprintf("http://%s", addr), nil)
+	if err == nil || !strings.Contains(err.Error(), "proxy connect failed") {
+		t.Fatalf("expected proxy connect failed error, got %v", err)
+	}
+}
+
+func TestDialTLSViaProxy_HTTPConnect_SendsProxyAuth(t *testing.T) {
+	var gotAuth string
+	ln, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatalf("listen: %v", err)
+	}
+	go func() {
+		defer ln.Close()
+		conn, err := ln.Accept()
+		if err != nil {
+			return
+		}
+		defer conn.Close()
+		br := bufio.NewReader(conn)
+		req, err := http.ReadRequest(br)
+		if err != nil {
+			return
+		}
+		gotAuth = req.Header.Get("Proxy-Authorization")
+		fmt.Fprintf(conn, "HTTP/1.1 200 OK\r\n\r\n")
+	}()
+
+	_, _ = dialTLSViaProxy("imap.example.com:993",
+		fmt.Sprintf("http://testuser:testpass@%s", ln.Addr().String()), nil)
+
+	expected := "Basic " + base64.StdEncoding.EncodeToString([]byte("testuser:testpass"))
+	if gotAuth != expected {
+		t.Fatalf("expected auth %q, got %q", expected, gotAuth)
+	}
+}
+
+func TestDialTLSViaProxy_HTTPConnect_DialError(t *testing.T) {
+	origDial := dialToProxy
+	t.Cleanup(func() { dialToProxy = origDial })
+
+	dialToProxy = func(ctx context.Context, network, addr string) (net.Conn, error) {
+		return nil, errors.New("dial refused")
+	}
+
+	_, err := dialTLSViaProxy("imap.example.com:993", "http://127.0.0.1:1", nil)
+	if err == nil || !strings.Contains(err.Error(), "dial proxy") {
+		t.Fatalf("expected dial proxy error, got %v", err)
+	}
+}
+
+// --- HTTPS CONNECT path ---
+
+func generateTestCert(t *testing.T) tls.Certificate {
+	t.Helper()
+	key, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
+	if err != nil {
+		t.Fatalf("generate key: %v", err)
+	}
+	tmpl := &x509.Certificate{
+		SerialNumber: big.NewInt(1),
+		NotBefore:    time.Now(),
+		NotAfter:     time.Now().Add(time.Hour),
+		KeyUsage:     x509.KeyUsageDigitalSignature,
+		DNSNames:     []string{"127.0.0.1"},
+		IPAddresses:  []net.IP{net.ParseIP("127.0.0.1")},
+	}
+	certDER, err := x509.CreateCertificate(rand.Reader, tmpl, tmpl, &key.PublicKey, key)
+	if err != nil {
+		t.Fatalf("create cert: %v", err)
+	}
+	cert, err := x509.ParseCertificate(certDER)
+	if err != nil {
+		t.Fatalf("parse cert: %v", err)
+	}
+	return tls.Certificate{
+		Certificate: [][]byte{certDER},
+		PrivateKey:  key,
+		Leaf:        cert,
+	}
+}
+
+func TestDialTLSViaProxy_HTTPSConnect_ReachesTLSHandshake(t *testing.T) {
+	cert := generateTestCert(t)
+
+	ln, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatalf("listen: %v", err)
+	}
+	tlsLn := tls.NewListener(ln, &tls.Config{
+		Certificates: []tls.Certificate{cert},
+	})
+	done := make(chan struct{})
+	go func() {
+		defer close(done)
+		for {
+			conn, err := tlsLn.Accept()
+			if err != nil {
+				return
+			}
+			go func(c net.Conn) {
+				defer c.Close()
+				br := bufio.NewReader(c)
+				req, err := http.ReadRequest(br)
+				if err != nil {
+					return
+				}
+				if req.URL.Host != "" {
+					fmt.Fprintf(c, "HTTP/1.1 200 OK\r\n\r\n")
+				}
+			}(conn)
+		}
+	}()
+	defer func() {
+		tlsLn.Close()
+		<-done
+	}()
+
+	// Override dialToProxy to return raw TCP, but inject InsecureSkipVerify
+	// so the TLS handshake to proxy succeeds with the test cert.
+	origDial := dialToProxy
+	t.Cleanup(func() { dialToProxy = origDial })
+
+	origProxyTLS := proxyTLSConfigForTest
+	t.Cleanup(func() { proxyTLSConfigForTest = origProxyTLS })
+
+	proxyTLSConfigForTest = func(host string) *tls.Config {
+		return &tls.Config{ServerName: host, InsecureSkipVerify: true}
+	}
+
+	_, err = dialTLSViaProxy("imap.example.com:993",
+		fmt.Sprintf("https://%s", ln.Addr().String()), nil)
+	if err == nil || !strings.Contains(err.Error(), "tls handshake") {
+		t.Fatalf("expected tls handshake error (HTTPS CONNECT succeeded), got %v", err)
+	}
+}