Add Optional Parameter and Capability handling.

Optional Parameters is defined in RFC4271 and Capability advertisement in
RFC3392. For now, we only hande them upon receiving an OPEN message.

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

diff --git a/bgp.c b/bgp.c
index 6a868fa..d7701be 100644 (file)
--- a/bgp.c
+++ b/bgp.c
@@ -902,6 +902,11 @@ static int bgp_handle_input(struct bgp_peer *peer)
            struct bgp_data_open data;
            int hold;
            int i;
+           off_t param_offset, capability_offset;
+           struct bgp_opt_param *param;
+           uint8_t capabilities_len;
+           char *capabilities = NULL;
+           struct bgp_capability *capability;
 
            for (i = 0; i < sizeof(p->header.marker); i++)
            {
@@ -964,10 +969,70 @@ static int bgp_handle_input(struct bgp_peer *peer)
            if (peer->keepalive * 3 > peer->hold)
                peer->keepalive = peer->hold / 3;
 
+           /* check for optional parameters */
+           /* 2 is for the size of type + len (both uint8_t) */
+           for (param_offset = 0;
+                   param_offset < data.opt_len;
+                   param_offset += 2 + param->len)
+           {
+               param = (struct bgp_opt_param *)(&data.opt_params + param_offset);
+
+               /* sensible check */
+               if (data.opt_len - param_offset < 2
+                       || param->len > data.opt_len - param_offset - 2) {
+                   LOG(1, 0, 0, "Malformed Optional Parameter list from BGP peer %s\n",
+                       peer->name);
+
+                   bgp_send_notification(peer, BGP_ERR_OPEN, BGP_ERR_UNSPEC);
+                   return 0;
+               }
+
+               /* we know only one parameter type */
+               if (param->type != BGP_CAPABILITY_PARAM_TYPE) {
+                   LOG(1, 0, 0, "Unsupported Optional Parameter type %d from BGP peer %s\n",
+                       param->type, peer->name);
+
+                   bgp_send_notification(peer, BGP_ERR_OPEN, BGP_ERR_OPN_UNSUP_PARAM);
+                   return 0;
+               }
+
+               capabilities_len = param->len;
+               capabilities = (char *)&param->value;
+           }
+
+           /* look for BGP multiprotocol capability */
+           if (capabilities)
+           {
+               for (capability_offset = 0;
+                       capability_offset < capabilities_len;
+                       capability_offset += 2 + capability->len)
+               {
+                   capability = (struct bgp_capability *)(capabilities + capability_offset);
+
+                   /* sensible check */
+                   if (capabilities_len - capability_offset < 2
+                           || capability->len > capabilities_len - capability_offset - 2) {
+                       LOG(1, 0, 0, "Malformed Capabilities list from BGP peer %s\n",
+                           peer->name);
+
+                       bgp_send_notification(peer, BGP_ERR_OPEN, BGP_ERR_UNSPEC);
+                       return 0;
+                   }
+
+                   /* we only know one capability code */
+                   if (capability->code != XXX) {
+                       LOG(4, 0, 0, "Unsupported Capability code %d from BGP peer %s\n",
+                           capability->code, peer->name);
+
+                       /* TODO: send _which_ capability is unsupported */
+                       bgp_send_notification(peer, BGP_ERR_OPEN, BGP_ERR_OPN_UNSUP_CAP);
+                       /* we don't terminate, still; we just jump to the next one */
+                   }
+               }
+           }
+
            /* next transition requires an exchange of keepalives */
            bgp_send_keepalive(peer);
-
-           /* FIXME: may need to check for optional params */
        }
 
        break;

diff --git a/bgp.h b/bgp.h
index 0a2e59c..beb68f9 100644 (file)
--- a/bgp.h
+++ b/bgp.h
@@ -43,6 +43,21 @@ struct bgp_data_open {
     char opt_params[sizeof(((struct bgp_packet *)0)->data) - BGP_DATA_OPEN_SIZE]; /* variable */
 } __attribute__ ((packed));
 
+struct bgp_opt_param {
+    uint8_t type;
+    uint8_t len;
+#define BGP_MAX_OPT_PARAM_SIZE 256
+    char value[BGP_MAX_OPT_PARAM_SIZE];
+} __attribute__ ((packed));
+
+#define BGP_CAPABILITY_PARAM_TYPE 2
+struct bgp_capability {
+    uint8_t code;
+    uint8_t len;
+#define BGP_MAX_CAPABILITY_SIZE 256
+    char value[BGP_MAX_CAPABILITY_SIZE];
+} __attribute__ ((packed));
+
 struct bgp_ip_prefix {
     uint8_t len;
     uint32_t prefix; /* variable */
@@ -101,6 +116,7 @@ struct bgp_data_notification {
 } __attribute__ ((packed));
 
 /* bgp_data_notification.error_code, .error_subcode */
+#define BGP_ERR_UNSPEC                 0
 #define BGP_ERR_HEADER                 1
 #  define BGP_ERR_HDR_NOT_SYNC           1
 #  define BGP_ERR_HDR_BAD_LEN            2
@@ -112,6 +128,7 @@ struct bgp_data_notification {
 #  define BGP_ERR_OPN_UNSUP_PARAM        4
 #  define BGP_ERR_OPN_AUTH_FAILURE       5
 #  define BGP_ERR_OPN_HOLD_TIME                  6
+#  define BGP_ERR_OPN_UNSUP_CAP                  7
 #define BGP_ERR_UPDATE                 3
 #  define BGP_ERR_UPD_BAD_ATTR_LIST      1
 #  define BGP_ERR_UPD_UNKN_WK_ATTR       2