Merge branch '33-tcp-keepalive-should-be-applied-to-connection-so-that-dead-connections-can-be-properly-reaped' into 'develop'

apply tcp keepalive to serving sockets

Closes #33

See merge request open-source/flexnbd-c!33

debian/changelog

@@ -1,3 +1,9 @@
+flexnbd (0.1.8) UNRELEASED; urgency=medium
+
+  * Set TCP keepalive on sockets so broken connections are reaped (#33, !33)
+
+ -- James Carter <james.carter@bytemark.co.uk>  Wed, 10 Jan 2018 13:57:10 +0000
+
 flexnbd (0.1.7) stable; urgency=medium
 
   * Return bytes_left in migration statistics.

src/common/sockutil.c

@@ -68,6 +68,37 @@ int sock_set_reuseaddr( int fd, int optval )
 	return setsockopt( fd, SOL_SOCKET, SO_REUSEADDR, &optval, sizeof(optval) );
 }
 
+int sock_set_keepalive_params( int fd, int time, int intvl, int probes)
+{
+	if (sock_set_keepalive(fd, 1) ||
+		sock_set_tcp_keepidle(fd, time) ||
+		sock_set_tcp_keepintvl(fd, intvl) ||
+		sock_set_tcp_keepcnt(fd, probes)) {
+		return -1;
+	}
+	return 0;
+}
+
+int sock_set_keepalive( int fd, int optval )
+{
+	return setsockopt( fd, SOL_SOCKET, SO_KEEPALIVE, &optval, sizeof(optval) );
+}
+
+int sock_set_tcp_keepidle( int fd, int optval )
+{
+	return setsockopt( fd, IPPROTO_TCP, TCP_KEEPIDLE, &optval, sizeof(optval) );
+}
+
+int sock_set_tcp_keepintvl( int fd, int optval )
+{
+	return setsockopt( fd, IPPROTO_TCP, TCP_KEEPINTVL, &optval, sizeof(optval) );
+}
+
+int sock_set_tcp_keepcnt( int fd, int optval )
+{
+	return setsockopt( fd, IPPROTO_TCP, TCP_KEEPCNT, &optval, sizeof(optval) );
+}
+
 /* Set the tcp_nodelay option */
 int sock_set_tcp_nodelay( int fd, int optval )
 {

src/common/sockutil.h

@@ -14,9 +14,24 @@ size_t sockaddr_size(const struct sockaddr* sa);
  */
 const char* sockaddr_address_string(const struct sockaddr* sa, char* dest, size_t len);
 
+/* Configure TCP keepalive on a socket */
+int sock_set_keepalive_params( int fd, int time, int intvl, int probes);
+
+/* Set the SOL_KEEPALIVE otion */
+int sock_set_keepalive(int fd, int optval);
+
 /* Set the SOL_REUSEADDR otion */
 int sock_set_reuseaddr(int fd, int optval);
 
+/* Set the tcp_keepidle option */
+int sock_set_tcp_keepidle(int fd, int optval);
+
+/* Set the tcp_keepintvl option */
+int sock_set_tcp_keepintvl(int fd, int optval);
+
+/* Set the tcp_keepcnt option */
+int sock_set_tcp_keepcnt(int fd, int optval);
+
 /* Set the tcp_nodelay option */
 int sock_set_tcp_nodelay(int fd, int optval);
 

src/server/serve.c

@@ -422,6 +422,9 @@ void accept_nbd_client(
 	int slot;
 	char s_client_address[64] = {0};
 
+	FATAL_IF_NEGATIVE( sock_set_keepalive_params( client_fd, CLIENT_KEEPALIVE_TIME, CLIENT_KEEPALIVE_INTVL, CLIENT_KEEPALIVE_PROBES),
+		"Error setting keepalive parameters on client socket fd %d", client_fd );
+
 
 	if ( !server_should_accept_client( params, client_address, s_client_address, 64 ) ) {
 		FATAL_IF_NEGATIVE( close( client_fd ),

src/server/serve.h

@@ -21,6 +21,9 @@ struct client_tbl_entry {
 
 
 #define MAX_NBD_CLIENTS 16
+#define CLIENT_KEEPALIVE_TIME 30
+#define CLIENT_KEEPALIVE_INTVL 10
+#define CLIENT_KEEPALIVE_PROBES 3
 struct server {
 	/* The flexnbd wrapper this server is attached to */
 	struct flexnbd * flexnbd;