curl/lib/vtls
Aritra Basu e78b1b3ecc
HTTP/3: add proxy CONNECT and MASQUE CONNECT-UDP support (ngtcp2 QUIC)
This patch adds two major proxy capabilities to curl (ngtcp2 QUIC):
- HTTP/3 Proxy CONNECT: Tunnel HTTP/1.1 or HTTP/2 traffic through an
  HTTPS proxy that speaks HTTP/3 (QUIC) using the standard CONNECT
  method over an HTTP/3 connection.
- MASQUE CONNECT-UDP: Tunnel HTTP/3 (QUIC) traffic through an HTTP
  proxy (speaking HTTP/1.1, HTTP/2, or HTTP/3) using the extended
  CONNECT method with the CONNECT-UDP protocol (RFC9297 & RFC9298).

Public API additions:
- `CURLPROXY_HTTPS3`: new proxy type constant for HTTP/3 proxy
- `--proxy-http3`: new CLI flag to negotiate HTTP/3 with HTTPS proxy

The implementation adds two new filters:
- `H3-PROXY` - enables negotiating HTTP/3 (QUIC) to the proxy and
  running CONNECT/CONNECT-UDP through that proxy transport.
- `CAPSULE` - dedicated filter inserted between QUIC transport and
  HTTP-PROXY to handle datagram capsule encapsulation/decapsulation.

Here is how the curl filter chaining looks in different scenarios:
- HTTP/3 Proxy CONNECT (tunneling TCP protocols over QUIC proxy):
  conn -> HTTP/1.1 or HTTP/2  -> SSL -> HTTP-PROXY ->
                                 H3-PROXY -> HAPPY-EYEBALLS -> UDP
- MASQUE CONNECT-UDP (tunneling QUIC over any proxy):
  conn -> HTTP/3 -> CAPSULE -> HTTP-PROXY -> H3-PROXY ->
                               HAPPY-EYEBALLS -> UDP
  conn -> HTTP/3 -> CAPSULE -> HTTP-PROXY -> H1-PROXY or H2-PROXY ->
                               SSL -> HAPPY-EYEBALLS -> TCP

- Both features currently require the ngtcp2 QUIC backend.
- Both features are experimental (disabled by default). Enable with
  `--enable-proxy-http3`(autotools) or `-DUSE_PROXY_HTTP3=ON`(CMake).

Tests:
- tests/unit/unit3400.c: Unit tests for capsule protocol encode/decode
- tests/http/test_60_h3_proxy.py: Comprehensive pytest integration suite
- tests/http/testenv/h2o.py: Managing h2o instances with HTTP/1.1, HTTP/2,
  and HTTP/3 (QUIC) listeners, proxy.connect and proxy.connect-udp enabled.

References:
  RFC 9297 - HTTP Datagrams and the Capsule Protocol
  RFC 9298 - Proxying UDP in HTTP
  RFC 9000 §16 — Variable-Length Integer Encoding

Signed-off-by: Aritra Basu <aritrbas+gh@cisco.com>

Closes #21153
2026-05-27 08:49:53 +02:00
..
apple.c tidy-up: use curlx_safefree() 2026-05-21 01:31:03 +02:00
apple.h lib: use lib source directory as base include path 2026-02-23 16:00:42 +01:00
cipher_suite.c lib: use lib source directory as base include path 2026-02-23 16:00:42 +01:00
cipher_suite.h lib: use lib source directory as base include path 2026-02-23 16:00:42 +01:00
gtls.c GnuTLS: require 3.7.2 for earlydata 2026-05-26 13:41:21 +02:00
gtls.h gtls: fix some typos 2026-05-05 08:46:26 +02:00
hostcheck.c lib: use lib source directory as base include path 2026-02-23 16:00:42 +01:00
hostcheck.h lib: use lib source directory as base include path 2026-02-23 16:00:42 +01:00
keylog.c rustls: fix memory leak on repeated SSLKEYLOGFILE fails 2026-04-23 22:58:39 +02:00
keylog.h vtls: log when key logging is enabled. 2026-04-23 08:13:59 +02:00
mbedtls.c tidy-up: miscellaneous 2026-05-20 00:50:43 +02:00
mbedtls.h lib: use lib source directory as base include path 2026-02-23 16:00:42 +01:00
openssl.c HTTP/3: add proxy CONNECT and MASQUE CONNECT-UDP support (ngtcp2 QUIC) 2026-05-27 08:49:53 +02:00
openssl.h tidy-up: miscellaneous 2026-05-20 00:50:43 +02:00
rustls.c tls: fix incomplete mTLS config in conn reuse and session cache 2026-05-20 00:02:33 +02:00
rustls.h lib: use lib source directory as base include path 2026-02-23 16:00:42 +01:00
schannel.c schannel: error on TLS 1.3-only with cipher list 2026-05-22 11:22:15 -04:00
schannel.h lib: use lib source directory as base include path 2026-02-23 16:00:42 +01:00
schannel_int.h windows: update MS SDK versions in comments 2026-05-15 03:41:33 +02:00
schannel_verify.c schannel: fix revoke_best_effort setting for proxy 2026-05-20 13:51:35 -04:00
vtls.c HTTP/3: add proxy CONNECT and MASQUE CONNECT-UDP support (ngtcp2 QUIC) 2026-05-27 08:49:53 +02:00
vtls.h tidy-up: miscellaneous 2026-05-20 00:50:43 +02:00
vtls_int.h HTTP/3: add proxy CONNECT and MASQUE CONNECT-UDP support (ngtcp2 QUIC) 2026-05-27 08:49:53 +02:00
vtls_scache.c tls: fix incomplete mTLS config in conn reuse and session cache 2026-05-20 00:02:33 +02:00
vtls_scache.h tidy-up: miscellaneous 2026-05-20 00:50:43 +02:00
vtls_spack.c tidy-up: rename more CURLcode variables to result 2026-05-19 16:55:45 +02:00
vtls_spack.h lib: use lib source directory as base include path 2026-02-23 16:00:42 +01:00
wolfssl.c tidy-up: miscellaneous 2026-05-20 00:50:43 +02:00
wolfssl.h wolfssl: fix -Wmissing-prototypes 2026-04-21 10:09:58 +02:00
x509asn1.c x509asn1: fix DH public key parameter extraction 2026-05-16 01:06:56 +02:00
x509asn1.h x509asn1: fixed and adapted for ASN1tostr unit testing 2026-03-20 13:03:40 +01:00