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package proxy
import (
"bytes"
"context"
"crypto/tls"
"crypto/x509"
"errors"
"fmt"
"io"
"net"
"net/http"
"time"
"golang.org/x/net/http2"
"github.com/shiv/internal/events"
internalhttp "github.com/shiv/internal/http"
"github.com/shiv/internal/logger"
)
const (
h2UpstreamDialTimeout = 10 * time.Second
h2UpstreamHeaderTimeout = 30 * time.Second
// h2StreamRequestTimeout is a per-stream deadline, not a connection-level
// timeout. Using a context timeout per stream instead of a client-level
// Timeout means a single slow stream cannot kill the entire H2 connection.
h2StreamRequestTimeout = 60 * time.Second
// h2MaxConcurrentStreams matches the HTTP/2 spec default (RFC 7540 §6.5.2).
h2MaxConcurrentStreams = 250
)
func (p *Proxy) handleConnectH2(browserTLS *tls.Conn, connectReq *http.Request, bareHost string) {
defer recoverPanic("handleConnectH2 " + bareHost)
// Use the port-aware host from the original CONNECT request for upstream
// dialling so non-443 HTTPS ports are preserved.
upstreamHost := connectReq.Host
upstreamTransport := &http.Transport{
DialTLSContext: func(ctx context.Context, network, addr string) (net.Conn, error) {
conn, err := (&net.Dialer{Timeout: h2UpstreamDialTimeout}).DialContext(ctx, "tcp", addr)
if err != nil {
return nil, fmt.Errorf("mitm/h2: dial %s: %w", addr, err)
}
tlsConn := tls.Client(conn, &tls.Config{
ServerName: bareHost,
InsecureSkipVerify: true, //nolint:gosec
NextProtos: []string{"h2", "http/1.1"},
VerifyPeerCertificate: func(rawCerts [][]byte, _ [][]*x509.Certificate) error {
if len(rawCerts) == 0 {
return nil
}
cert, err := x509.ParseCertificate(rawCerts[0])
if err != nil {
return nil
}
now := time.Now()
if now.After(cert.NotAfter) {
logger.Info("mitm/h2: EXPIRED cert for %s (expired %s, issuer: %s)",
bareHost, cert.NotAfter.Format("2006-01-02"), cert.Issuer.CommonName)
} else if now.Before(cert.NotBefore) {
logger.Info("mitm/h2: NOT YET VALID cert for %s (valid from %s, issuer: %s)",
bareHost, cert.NotBefore.Format("2006-01-02"), cert.Issuer.CommonName)
}
if err := cert.VerifyHostname(bareHost); err != nil {
logger.Info("mitm/h2: hostname mismatch for %s: %v (CN: %s, SANs: %v)",
bareHost, err, cert.Subject.CommonName, cert.DNSNames)
}
return nil
},
})
if err := tlsConn.Handshake(); err != nil {
conn.Close()
return nil, fmt.Errorf("mitm/h2: upstream TLS handshake for %s: %w", addr, err)
}
return tlsConn, nil
},
ResponseHeaderTimeout: h2UpstreamHeaderTimeout,
}
if err := http2.ConfigureTransport(upstreamTransport); err != nil {
logger.Error("mitm/h2: configure upstream transport: %v", err)
}
defer upstreamTransport.CloseIdleConnections()
// No client-level Timeout — that would kill the entire H2 connection on
// any slow stream. Per-stream timeouts are applied via request contexts.
upstreamClient := &http.Client{
Transport: upstreamTransport,
CheckRedirect: func(req *http.Request, via []*http.Request) error {
return http.ErrUseLastResponse
},
}
streamHandler := http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
defer recoverPanic("h2 stream " + bareHost)
req.URL.Scheme = "https"
req.URL.Host = upstreamHost
reqBody, err := io.ReadAll(io.LimitReader(req.Body, maxBodySize))
if err != nil {
logger.Error("mitm/h2: read request body for %s: %v", bareHost, err)
http.Error(w, "bad request", http.StatusBadRequest)
return
}
req.Body.Close()
start := time.Now()
result := p.bus.EmitRequest(events.RequestEvent{Request: req, Body: reqBody})
if result.Drop {
// Stream is dropped by intercept rules; the H2 connection stays alive.
http.Error(w, "request dropped", http.StatusForbidden)
return
}
interceptedReq, reqBody := result.Request, result.Body
streamCtx, cancel := context.WithTimeout(req.Context(), h2StreamRequestTimeout)
defer cancel()
outReq, err := http.NewRequestWithContext(streamCtx, interceptedReq.Method, interceptedReq.URL.String(), bytes.NewReader(reqBody))
if err != nil {
logger.Error("mitm/h2: build upstream request for %s: %v", bareHost, err)
http.Error(w, "internal error", http.StatusInternalServerError)
return
}
outReq.Header = interceptedReq.Header.Clone()
outReq.Host = internalhttp.NormalizeHost(bareHost, true)
// Strip H2-illegal headers before forwarding.
outReq.Header.Del("Transfer-Encoding")
internalhttp.StripRequestCacheHeaders(outReq.Header)
resp, err := upstreamClient.Do(outReq)
if err != nil {
// context.Canceled means the browser cancelled the stream (RST_STREAM)
// or we hit our per-stream deadline. This is normal browser behaviour
// (prefetch, autocomplete, navigation away) — log at Debug, not Error.
if errors.Is(err, context.Canceled) || errors.Is(err, context.DeadlineExceeded) {
logger.Debug("mitm/h2: stream cancelled/timed out for %s: %v", bareHost, err)
} else {
logger.Error("mitm/h2: upstream request for %s: %v", bareHost, err)
}
http.Error(w, "bad gateway", http.StatusBadGateway)
return
}
var respBuf bytes.Buffer
reader := io.TeeReader(io.LimitReader(resp.Body, maxBodySize), &respBuf)
// Strip Transfer-Encoding — illegal in HTTP/2 responses (RFC 7540 §8.1.2.2).
// Strip caching headers so the browser always fetches fresh content.
resp.Header.Del("Transfer-Encoding")
internalhttp.StripResponseCacheHeaders(resp.Header)
for k, vals := range resp.Header {
for _, v := range vals {
w.Header().Add(k, v)
}
}
w.WriteHeader(resp.StatusCode)
if _, err := io.Copy(w, reader); err != nil {
logger.Debug("mitm/h2: write response to browser for %s: %v", bareHost, err)
// Drain whatever remains into respBuf so the log body is as complete
// as possible even if the browser disconnected mid-stream.
_, _ = io.Copy(&respBuf, resp.Body)
}
respBody := respBuf.Bytes()
resp.Body.Close()
if len(respBody) >= int(maxBodySize) {
logger.Debug("mitm/h2: response body truncated at %d bytes for %s %s",
maxBodySize, interceptedReq.Method, interceptedReq.URL)
}
elapsed := time.Since(start).Milliseconds()
logger.Info("%s %s %d %db %dms (h2)", interceptedReq.Method, interceptedReq.URL, resp.StatusCode, len(respBody), elapsed)
logBody := internalhttp.Decompress(resp.Header, respBody)
if internalhttp.IsBinary(resp.Header) {
logBody = nil
}
p.bus.EmitResponse(events.ResponseEvent{
Timestamp: start,
Host: connectReq.Host,
Proto: "HTTP/2",
Method: interceptedReq.Method,
URL: interceptedReq.URL.String(),
ReqHeaders: interceptedReq.Header,
ReqBody: reqBody,
StatusCode: resp.StatusCode,
RespHeaders: resp.Header,
RespBody: logBody,
DurationMs: elapsed,
TLS: true,
})
})
h2srv := &http2.Server{
MaxConcurrentStreams: h2MaxConcurrentStreams,
}
// ServeConn blocks until the browser closes the underlying TLS connection.
// It handles all stream multiplexing internally. No idle timer is needed —
// the connection lifetime is naturally tied to browserTLS.
h2srv.ServeConn(browserTLS, &http2.ServeConnOpts{
Handler: streamHandler,
})
}
|
