Add an option to set source address for a BGP session.

When adding a BGP neighbour, one can set "update-source" (quagga syntax) to the
source IP address that will be used for that session.

Signed-off-by: Benjamin Cama <benoar@dolka.fr>

diff --git a/bgp.c b/bgp.c
index 6a868fa..4b7f949 100644 (file)
--- a/bgp.c
+++ b/bgp.c
@@ -95,7 +95,7 @@ int bgp_setup(int as)
 
 /* start connection with a peer */
 int bgp_start(struct bgp_peer *peer, char *name, int as, int keepalive,
-    int hold, int enable)
+    int hold, struct in_addr update_source, int enable)
 {
     struct hostent *h;
     int ibgp;
@@ -124,6 +124,7 @@ int bgp_start(struct bgp_peer *peer, char *name, int as, int keepalive,
     }
 
     memcpy(&peer->addr, h->h_addr, sizeof(peer->addr));
+    peer->source_addr = update_source.s_addr;
     peer->as = as > 0 ? as : our_as;
     ibgp = peer->as == our_as;
 
@@ -696,6 +697,7 @@ static int bgp_connect(struct bgp_peer *peer)
 {
     static int bgp_port = 0;
     struct sockaddr_in addr;
+    struct sockaddr_in source_addr;
     struct epoll_event ev;
 
     if (!bgp_port)
@@ -727,6 +729,19 @@ static int bgp_connect(struct bgp_peer *peer)
     /* set to non-blocking */
     fcntl(peer->sock, F_SETFL, fcntl(peer->sock, F_GETFL, 0) | O_NONBLOCK);
 
+    /* set source address */
+    memset(&source_addr, 0, sizeof(source_addr));
+    source_addr.sin_family = AF_INET;
+    source_addr.sin_addr.s_addr = peer->source_addr; /* defaults to INADDR_ANY */
+    if (bind(peer->sock, (struct sockaddr *) &source_addr, sizeof(source_addr)) < 0)
+    {
+       LOG(1, 0, 0, "Can't set source address to %s: %s\n",
+           inet_ntoa(source_addr.sin_addr), strerror(errno));
+
+       bgp_set_retry(peer);
+       return 0;
+    }
+
     /* try connect */
     memset(&addr, 0, sizeof(addr));
     addr.sin_family = AF_INET;

diff --git a/bgp.h b/bgp.h
index 0a2e59c..1dbee29 100644 (file)
--- a/bgp.h
+++ b/bgp.h
@@ -152,6 +152,7 @@ struct bgp_buf {
 struct bgp_peer {
     char name[32];                     /* peer name */
     in_addr_t addr;                    /* peer address */
+    in_addr_t source_addr;             /* our source address */
     int as;                            /* AS number */
     int sock;
     enum bgp_state state;              /* FSM state */
@@ -188,7 +189,7 @@ extern int bgp_configured;
 /* actions */
 int bgp_setup(int as);
 int bgp_start(struct bgp_peer *peer, char *name, int as, int keepalive,
-    int hold, int enable);
+    int hold, struct in_addr update_source, int enable);
 
 void bgp_stop(struct bgp_peer *peer);
 void bgp_halt(struct bgp_peer *peer);

diff --git a/cli.c b/cli.c
index e182e8b..8377339 100644 (file)
--- a/cli.c
+++ b/cli.c
@@ -1038,6 +1038,11 @@ static int cmd_show_run(struct cli_def *cli, char *command, char **argv, int arg
                                h = BGP_HOLD_TIME;
 
                        cli_print(cli, " neighbour %s timers %d %d", config->neighbour[i].name, k, h);
+
+                       if (config->neighbour[i].update_source.s_addr != INADDR_ANY)
+                               cli_print(cli, " neighbour %s update-source %s",
+                                               config->neighbour[i].name,
+                                               inet_ntoa(config->neighbour[i].update_source));
                }
        }
 #endif
@@ -2064,6 +2069,7 @@ static int cmd_router_bgp_neighbour(struct cli_def *cli, char *command, char **a
                        return cli_arg_help(cli, 0,
                                "remote-as", "Set remote autonomous system number",
                                "timers",    "Set timers",
+                               "update-source",    "Set source address to use for the BGP session",
                                NULL);
 
                default:
@@ -2082,6 +2088,9 @@ static int cmd_router_bgp_neighbour(struct cli_def *cli, char *command, char **a
                                        return cli_arg_help(cli, 1, NULL);
                        }
 
+                       if (MATCH("update-source", argv[1]))
+                               return cli_arg_help(cli, argc > 3, "A.B.C.D", "Source IP address", NULL);
+
                        return CLI_OK;
                }
        }
@@ -2118,12 +2127,33 @@ static int cmd_router_bgp_neighbour(struct cli_def *cli, char *command, char **a
                        snprintf(config->neighbour[i].name, sizeof(config->neighbour[i].name), "%s", argv[0]);
                        config->neighbour[i].keepalive = -1;
                        config->neighbour[i].hold = -1;
+                       config->neighbour[i].update_source.s_addr = INADDR_ANY;
                }
 
                config->neighbour[i].as = as;
                return CLI_OK;
        }
 
+       if (MATCH("update-source", argv[1]))
+       {
+               struct in_addr addr;
+
+               if (!config->neighbour[i].name[0])
+               {
+                       cli_error(cli, "Specify remote-as first");
+                       return CLI_OK;
+               }
+
+               if (!inet_aton(argv[2], &addr))
+               {
+                       cli_error(cli, "Cannot parse IP \"%s\"", argv[2]);
+                       return CLI_OK;
+               }
+
+               config->neighbour[i].update_source = addr;
+               return CLI_OK;
+       }
+
        if (argc != 4 || !MATCH("timers", argv[1]))
        {
                cli_error(cli, "Invalid arguments");

diff --git a/l2tpns.c b/l2tpns.c
index 19289b0..7f94d24 100644 (file)
--- a/l2tpns.c
+++ b/l2tpns.c
@@ -3564,7 +3564,8 @@ static void mainloop(void)
                if (config->neighbour[i].name[0])
                        bgp_start(&bgp_peers[i], config->neighbour[i].name,
                                config->neighbour[i].as, config->neighbour[i].keepalive,
-                               config->neighbour[i].hold, 0); /* 0 = routing disabled */
+                               config->neighbour[i].hold, config->neighbour[i].update_source,
+                               0); /* 0 = routing disabled */
        }
 #endif /* BGP */
 

diff --git a/l2tpns.h b/l2tpns.h
index 6849be9..032c237 100644 (file)
--- a/l2tpns.h
+++ b/l2tpns.h
@@ -723,6 +723,7 @@ typedef struct
                uint16_t as;
                int keepalive;
                int hold;
+               struct in_addr update_source;
        } neighbour[BGP_NUM_PEERS];
 #endif
 } configt;