[PATCH] set TCP listener options on inherited sockets

[Eric Wong <e@80x24.org>]

systemd users may not set the correct TCP socket options for
us, so be sure to set TCP_NODELAY, SO_KEEPALIVE, and use
a sufficiently large listen backlog to avoid hurting performance
for users who bind sockets outside of cmogstored.
---
 bind_listen.c | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/bind_listen.c b/bind_listen.c
index 5535b92..c705576 100644
--- a/bind_listen.c
+++ b/bind_listen.c
@@ -15,15 +15,17 @@
  *   http://labs.apnic.net/blabs/?p=57
  */
 
-static int set_tcp_opts(int fd)
+static int set_tcp_opts(int fd, bool inherited)
 {
 	int val;
 	socklen_t len = sizeof(int);
 	int rc;
 
-	val = 1;
-	rc = setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &val, len);
-	if (rc < 0) return rc;
+	if (!inherited) {
+		val = 1;
+		rc = setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &val, len);
+		if (rc < 0) return rc;
+	}
 
 	val = 1;
 	rc = setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE, &val, len);
@@ -40,8 +42,11 @@ int mog_bind_listen(struct addrinfo *r)
 {
 	/* see if we inherited the socket, first */
 	int fd = mog_inherit_get(r->ai_addr, r->ai_addrlen);
+	const int backlog = 1024;
 
-	if (fd >= 0)
+	if (fd >= 0 &&
+	    set_tcp_opts(fd, true) == 0 &&
+	    listen(fd, backlog) == 0)
 		return fd;
 
 	for (; r; r = r->ai_next) {
@@ -56,9 +61,9 @@ int mog_bind_listen(struct addrinfo *r)
 		 * everywhere yet (in 2012).
 		 */
 		if (mog_set_cloexec(fd, true) == 0 &&
-		    set_tcp_opts(fd) == 0 &&
+		    set_tcp_opts(fd, false) == 0 &&
 		    bind(fd, r->ai_addr, r->ai_addrlen) == 0 &&
-		    listen(fd, 1024) == 0)
+		    listen(fd, backlog) == 0)
 			break;
 
 		PRESERVE_ERRNO( mog_close(fd) );
-- 
EW