Add iscsi_set_tcp_syncnt function

This patch adds support for setting TCP_SYNCNT to overwrite
the system default values. This allows indirect support
for a configurable connect timeout.

Linux uses a exponential backoff for SYN retries starting
with 1 second.

This means for a value n for TCP_SYNCNT, the connect will
effectively timeout after 2^(n+1)-1 seconds.

include/iscsi-private.h

@@ -89,6 +89,7 @@ struct iscsi_context {
 	int tcp_keepcnt;
 	int tcp_keepintvl;
 	int tcp_keepidle;
+	int tcp_syncnt;
 
 	int current_phase;
 	int next_phase;

lib/connect.c

@@ -238,6 +238,7 @@ try_again:
 	iscsi->tcp_keepidle = old_iscsi->tcp_keepidle;
 	iscsi->tcp_keepcnt = old_iscsi->tcp_keepcnt;
 	iscsi->tcp_keepintvl = old_iscsi->tcp_keepintvl;
+	iscsi->tcp_syncnt = old_iscsi->tcp_syncnt;
 
 	if (iscsi_full_connect_sync(iscsi, iscsi->portal, iscsi->lun) != 0) {
 		iscsi_destroy_context(iscsi);

lib/init.c

@@ -74,6 +74,10 @@ iscsi_create_context(const char *initiator_name)
 	iscsi->tcp_keepcnt=3;
 	iscsi->tcp_keepintvl=30;
 	iscsi->tcp_keepidle=30;
+
+	if (getenv("LIBISCSI_DEBUG") != NULL) {
+		iscsi_set_debug(iscsi,atoi(getenv("LIBISCSI_DEBUG")));
+	}
 	
 	if (getenv("LIBISCSI_TCP_USER_TIMEOUT") != NULL) {
 		iscsi_set_tcp_user_timeout(iscsi,atoi(getenv("LIBISCSI_TCP_USER_TIMEOUT")));
@@ -90,9 +94,9 @@ iscsi_create_context(const char *initiator_name)
 	if (getenv("LIBISCSI_TCP_KEEPIDLE") != NULL) {
 		iscsi_set_tcp_keepidle(iscsi,atoi(getenv("LIBISCSI_TCP_KEEPIDLE")));
 	}
-	
-	if (getenv("LIBISCSI_DEBUG") != NULL) {
-		iscsi_set_debug(iscsi,atoi(getenv("LIBISCSI_DEBUG")));
+
+	if (getenv("LIBISCSI_TCP_SYNCNT") != NULL) {
+		iscsi_set_tcp_syncnt(iscsi,atoi(getenv("LIBISCSI_TCP_SYNCNT")));
 	}
 
 	return iscsi;

lib/libiscsi.def

@@ -76,6 +76,7 @@ iscsi_set_tcp_user_timeout
 iscsi_set_tcp_keepidle
 iscsi_set_tcp_keepcnt
 iscsi_set_tcp_keepintvl
+iscsi_set_tcp_syncnt
 iscsi_startstopunit_sync
 iscsi_startstopunit_task
 iscsi_synchronizecache10_sync

lib/libiscsi.syms

@@ -74,6 +74,7 @@ iscsi_set_tcp_user_timeout
 iscsi_set_tcp_keepidle
 iscsi_set_tcp_keepcnt
 iscsi_set_tcp_keepintvl
+iscsi_set_tcp_syncnt
 iscsi_startstopunit_sync
 iscsi_startstopunit_task
 iscsi_synchronizecache10_sync

lib/socket.c

@@ -86,6 +86,34 @@ int set_tcp_user_timeout(struct iscsi_context *iscsi)
 	return 0;
 }
 
+#ifndef TCP_SYNCNT
+#define TCP_SYNCNT        7
+#endif
+
+int set_tcp_syncnt(struct iscsi_context *iscsi)
+{
+    int level, value;
+	
+	#if defined(__FreeBSD__) || defined(__sun)
+	struct protoent *buf;
+
+	if ((buf = getprotobyname("tcp")) != NULL)
+		level = buf->p_proto;
+	else
+		return -1;
+	#else
+		level = SOL_TCP;
+	#endif
+	
+	value = iscsi->tcp_syncnt;
+	if (setsockopt(iscsi->fd, level, TCP_SYNCNT, &value, sizeof(value)) != 0) {
+		iscsi_set_error(iscsi, "TCP: Failed to set tcp syn retries. Error %s(%d)", strerror(errno), errno);
+		return -1;
+	}
+	DPRINTF(iscsi,3,"TCP_SYNCNT set to %d",value);
+	return 0;
+}
+
 int
 iscsi_connect_async(struct iscsi_context *iscsi, const char *portal,
 		    iscsi_command_cb cb, void *private_data)
@@ -194,6 +222,10 @@ iscsi_connect_async(struct iscsi_context *iscsi, const char *portal,
 		set_tcp_user_timeout(iscsi);
 	}
 
+    if (iscsi->tcp_syncnt > 0) {
+		set_tcp_syncnt(iscsi);
+	}
+
 	if (connect(iscsi->fd, ai->ai_addr, socksize) != 0
 	    && errno != EINPROGRESS) {
 		iscsi_set_error(iscsi, "Connect failed with errno : "
@@ -461,7 +493,7 @@ iscsi_service(struct iscsi_context *iscsi, int revents)
 	if (iscsi->is_connected == 0 && iscsi->fd != -1 && revents&POLLOUT) {
 		int err = 0;
 		socklen_t err_size = sizeof(err);
-
+        DPRINTF(iscsi,3,"inside iscsi service is_connected=0");
 		if (getsockopt(iscsi->fd, SOL_SOCKET, SO_ERROR,
 			       &err, &err_size) != 0 || err != 0) {
 			if (err == 0) {
@@ -480,6 +512,8 @@ iscsi_service(struct iscsi_context *iscsi, int revents)
 			return -1;
 		}
 
+        DPRINTF(iscsi,2,"connection to %s established",iscsi->connected_portal);
+
 		iscsi->is_connected = 1;
 		iscsi->socket_status_cb(iscsi, SCSI_STATUS_GOOD, NULL,
 					iscsi->connect_data);
@@ -557,6 +591,12 @@ iscsi_free_iscsi_inqueue(struct iscsi_in_pdu *inqueue)
 	}
 }
 
+void iscsi_set_tcp_syncnt(struct iscsi_context *iscsi, int value)
+{
+    iscsi->tcp_syncnt=value;
+    DPRINTF(iscsi,2,"TCP_SYNCNT will be set to %d on next socket creation",value);    
+}
+
 void iscsi_set_tcp_user_timeout(struct iscsi_context *iscsi, int timeout_ms)
 {
     iscsi->tcp_user_timeout=timeout_ms;