Support TCP Fast Openfast-open

New function gnutls_transport_set_fastopen() with example usage
in gnutls-cli (enabled with new --fastopen option).

1 files changed, 70 insertions, 10 deletions

diff --git a/lib/system.c b/lib/system.c
index 5c9bc6e68f..e08510d283 100644
--- a/lib/system.c
+++ b/lib/system.c
@@ -31,6 +31,11 @@
 #include <sys/types.h>
 #include <c-ctype.h>
 
+/* Get TCP_FASTOPEN */
+#ifdef HAVE_NETINET_TCP_H
+#include <netinet/tcp.h>
+#endif
+
 #ifdef _WIN32
 # include <windows.h>
 # include <wincrypt.h>
@@ -111,10 +116,9 @@ int system_errno(gnutls_transport_ptr_t ptr)
 	return errno;
 }
 
-#ifdef MSG_NOSIGNAL
-ssize_t
-system_writev_nosignal(gnutls_transport_ptr_t ptr, const giovec_t * iovec,
-	      int iovec_cnt)
+static ssize_t
+_system_writev(gnutls_transport_ptr_t ptr, const giovec_t * iovec,
+	      int iovec_cnt, int flags)
 {
 	struct msghdr hdr;
 
@@ -122,21 +126,77 @@ system_writev_nosignal(gnutls_transport_ptr_t ptr, const giovec_t * iovec,
 	hdr.msg_iov = (struct iovec *)iovec;
 	hdr.msg_iovlen = iovec_cnt;
 
-	return sendmsg(GNUTLS_POINTER_TO_INT(ptr), &hdr, MSG_NOSIGNAL);
+	return sendmsg(GNUTLS_POINTER_TO_INT(ptr), &hdr, flags);
 }
-#endif
 
-ssize_t
-system_writev(gnutls_transport_ptr_t ptr, const giovec_t * iovec,
-	      int iovec_cnt)
+static ssize_t
+_system_writev_tfo(gnutls_session_t session, const giovec_t * iovec,
+	      int iovec_cnt, int flags)
 {
+	int fd = GNUTLS_POINTER_TO_INT(session->internals.transport_send_ptr);
+	int ret, on = 1;
+
 	struct msghdr hdr;
 
+	if (setsockopt(fd, IPPROTO_TCP, TCP_FASTOPEN, &on, sizeof(on)) == -1)
+		_gnutls_debug_log("Failed to set socket option FASTOPEN\n");
+
 	memset(&hdr, 0, sizeof(hdr));
+	hdr.msg_name = session->internals.connect_addr;
+	hdr.msg_namelen = session->internals.connect_addrlen;
 	hdr.msg_iov = (struct iovec *)iovec;
 	hdr.msg_iovlen = iovec_cnt;
 
-	return sendmsg(GNUTLS_POINTER_TO_INT(ptr), &hdr, 0);
+	ret = sendmsg(fd, &hdr, flags | MSG_FASTOPEN);
+
+	if (ret < 0) {
+		if (errno == EINPROGRESS) {
+			errno = EAGAIN; // GnuTLS does not handle EINPROGRESS
+		} else if (errno == EOPNOTSUPP) {
+			// fallback from fastopen, e.g. when fastopen is disabled in system
+			_gnutls_debug_log("Fallback from TCP Fast Open... TFO is not enabled at system level\n");
+			ret = connect(fd, session->internals.connect_addr, session->internals.connect_addrlen);
+			if (errno == ENOTCONN || errno == EINPROGRESS)
+				errno = EAGAIN;
+		}
+	}
+
+	/* This function has to be called just once, connect info not needed any more */
+	gnutls_free(session->internals.connect_addr);
+	session->internals.connect_addr = NULL;
+	session->internals.connect_addrlen = 0;
+
+	return ret;
+}
+
+#ifdef MSG_NOSIGNAL
+ssize_t
+system_writev_nosignal(gnutls_transport_ptr_t ptr, const giovec_t * iovec,
+	      int iovec_cnt)
+{
+	return _system_writev(ptr, iovec, iovec_cnt, MSG_NOSIGNAL);
+}
+
+ssize_t
+system_writev_nosignal_tfo(gnutls_session_t session, const giovec_t * iovec,
+	      int iovec_cnt)
+{
+	return _system_writev_tfo(session, iovec, iovec_cnt, MSG_NOSIGNAL);
+}
+#endif
+
+ssize_t
+system_writev(gnutls_transport_ptr_t ptr, const giovec_t * iovec,
+	      int iovec_cnt)
+{
+	return _system_writev(ptr, iovec, iovec_cnt, 0);
+}
+
+ssize_t
+system_writev_tfo(gnutls_session_t session, const giovec_t * iovec,
+	      int iovec_cnt)
+{
+	return _system_writev_tfo(session, iovec, iovec_cnt, 0);
 }
 #endif