From 93a44d4c4c6c73248481e486a33347eb2a6b725f Mon Sep 17 00:00:00 2001
From: Tatsuhiro Tsujikawa <tatsuhiro.t@gmail.com>
Date: Tue, 17 Aug 2021 21:48:11 +0900
Subject: [PATCH] nghttpx: Send stateless reset

---
 src/shrpx_quic_connection_handler.cc | 52 ++++++++++++++++++++++++++++
 src/shrpx_quic_connection_handler.h  |  3 ++
 2 files changed, 55 insertions(+)

diff --git a/src/shrpx_quic_connection_handler.cc b/src/shrpx_quic_connection_handler.cc
index 3d6d97ed..7fc1965a 100644
--- a/src/shrpx_quic_connection_handler.cc
+++ b/src/shrpx_quic_connection_handler.cc
@@ -92,6 +92,8 @@ int QUICConnectionHandler::handle_packet(const UpstreamAddr *faddr,
                                remote_addr, local_addr);
       return 0;
     default:
+      // TODO Must be rate limited
+      send_stateless_reset(faddr, dcid, dcidlen, remote_addr, local_addr);
       return 0;
     }
 
@@ -217,6 +219,56 @@ int QUICConnectionHandler::send_version_negotiation(
                           0);
 }
 
+int QUICConnectionHandler::send_stateless_reset(const UpstreamAddr *faddr,
+                                                const uint8_t *dcid,
+                                                size_t dcidlen,
+                                                const Address &remote_addr,
+                                                const Address &local_addr) {
+  int rv;
+  std::array<uint8_t, NGTCP2_STATELESS_RESET_TOKENLEN> token;
+  ngtcp2_cid cid;
+
+  ngtcp2_cid_init(&cid, dcid, dcidlen);
+
+  auto config = get_config();
+  auto &quicconf = config->quic;
+  auto &stateless_resetconf = quicconf.stateless_reset;
+
+  rv = generate_quic_stateless_reset_token(token.data(), &cid,
+                                           stateless_resetconf.secret.data(),
+                                           stateless_resetconf.secret.size());
+  if (rv != 0) {
+    return -1;
+  }
+
+  std::array<uint8_t, NGTCP2_MIN_STATELESS_RESET_RANDLEN> rand_bytes;
+
+  if (RAND_bytes(rand_bytes.data(), rand_bytes.size()) != 1) {
+    return -1;
+  }
+
+  std::array<uint8_t, 1280> buf;
+
+  auto nwrite =
+      ngtcp2_pkt_write_stateless_reset(buf.data(), buf.size(), token.data(),
+                                       rand_bytes.data(), rand_bytes.size());
+  if (nwrite < 0) {
+    LOG(ERROR) << "ngtcp2_pkt_write_stateless_reset: "
+               << ngtcp2_strerror(nwrite);
+    return -1;
+  }
+
+  if (LOG_ENABLED(INFO)) {
+    LOG(INFO) << "Send stateless_reset to remote="
+              << util::to_numeric_addr(&remote_addr)
+              << " dcid=" << util::format_hex(dcid, dcidlen);
+  }
+
+  return quic_send_packet(faddr, &remote_addr.su.sa, remote_addr.len,
+                          &local_addr.su.sa, local_addr.len, buf.data(), nwrite,
+                          0);
+}
+
 void QUICConnectionHandler::add_connection_id(const ngtcp2_cid *cid,
                                               ClientHandler *handler) {
   auto key = make_cid_key(cid);
diff --git a/src/shrpx_quic_connection_handler.h b/src/shrpx_quic_connection_handler.h
index 38b2f217..d4941ffe 100644
--- a/src/shrpx_quic_connection_handler.h
+++ b/src/shrpx_quic_connection_handler.h
@@ -55,6 +55,9 @@ public:
                                const uint8_t *scid, size_t scidlen,
                                const Address &remote_addr,
                                const Address &local_addr);
+  int send_stateless_reset(const UpstreamAddr *faddr, const uint8_t *dcid,
+                           size_t dcidlen, const Address &remote_addr,
+                           const Address &local_addr);
   ClientHandler *handle_new_connection(const UpstreamAddr *faddr,
                                        const Address &remote_addr,
                                        const Address &local_addr,