address the remote address, in text form
port the remote port
timeout a timeout (zero for indefinite timeout)
+ fastopen TRUE iff TCP_FASTOPEN can be used
Returns: 0 on success; -1 on failure, with errno set
*/
int
-ip_connect(int sock, int af, const uschar *address, int port, int timeout)
+ip_connect(int sock, int af, const uschar *address, int port, int timeout,
+ BOOL fastopen)
{
struct sockaddr_in s_in4;
struct sockaddr *s_ptr;
callout_address = string_sprintf("[%s]:%d", address, port);
sigalrm_seen = FALSE;
if (timeout > 0) alarm(timeout);
-rc = connect(sock, s_ptr, s_len);
+
+#if defined(TCP_FASTOPEN) && defined(MSG_FASTOPEN)
+/* TCP Fast Open, if the system has a cookie from a previous call to
+this peer, can send data in the SYN packet. The peer can send data
+before it gets our ACK of its SYN,ACK - the latter is useful for
+the SMTP banner. Is there any usage where the former might be?
+We might extend the ip_connect() args for data if so. For now,
+connect in FASTOPEN mode but with zero data.
+*/
+
+if (fastopen)
+ {
+ if ( (rc = sendto(sock, NULL, 0, MSG_FASTOPEN, s_ptr, s_len)) < 0
+ && errno == EOPNOTSUPP
+ )
+ {
+ DEBUG(D_transport)
+ debug_printf("Tried TCP Fast Open but apparently not enabled by sysctl\n");
+ rc = connect(sock, s_ptr, s_len);
+ }
+ }
+else
+#endif
+ rc = connect(sock, s_ptr, s_len);
+
save_errno = errno;
alarm(0);
/* Try to connect to the server - test each IP till one works */
-for (h = &shost; h != NULL; h = h->next)
+for (h = &shost; h; h = h->next)
{
fd = Ustrchr(h->address, ':') != 0
? fd6 < 0 ? (fd6 = ip_socket(type, af = AF_INET6)) : fd6
}
for(port = portlo; port <= porthi; port++)
- if (ip_connect(fd, af, h->address, port, timeout) == 0)
+ if (ip_connect(fd, af, h->address, port, timeout, type == SOCK_STREAM) == 0)
{
if (fd != fd6) close(fd6);
if (fd != fd4) close(fd4);