agentx: handle SNMP traps

smux_trap() signature has been changed to provide appropriate level
information to send SNMPv2 notifications. This includes the addition
of the enterprise OID to use (from which is derived the SNMP trap OID)
and the MIB registry to locate the appropriate function for variable
bindings provided by the trap.

The SMUX implementation has been updated but ignore the provided
enterprise OID. Instead, it still uses the SMUX peer OID to keep
compatibility with previous versions of Quagga. The SMUX
implementation also ignores the provided MIB registry since it uses
smux_get() function to grab the appropriate values. This is not
possible with the AgentX implementation since there is no such
function provided by NetSNMP.

3 files changed, 117 insertions, 5 deletions

diff --git a/lib/agentx.c b/lib/agentx.c
index 2358581f..be6b4320 100644
--- a/lib/agentx.c
+++ b/lib/agentx.c
@@ -122,11 +122,91 @@ smux_register_mib (const char *descr, struct variable *var,
 }
 
 int
-smux_trap (const oid *name, size_t namelen,
+smux_trap (struct variable *vp, size_t vp_len,
+	   const oid *ename, size_t enamelen,
+	   const oid *name, size_t namelen,
 	   const oid *iname, size_t inamelen,
 	   const struct trap_object *trapobj, size_t trapobjlen,
 	   u_char sptrap)
 {
+  oid objid_snmptrap[] = { 1, 3, 6, 1, 6, 3, 1, 1, 4, 1, 0 };
+  size_t objid_snmptrap_len = sizeof objid_snmptrap / sizeof (oid);
+  oid notification_oid[MAX_OID_LEN];
+  size_t notification_oid_len;
+  unsigned int i;
+
+  netsnmp_variable_list *notification_vars = NULL;
+  if (!agentx_enabled) return 0;
+
+  /* snmpTrapOID */
+  oid_copy (notification_oid, ename, enamelen);
+  notification_oid[enamelen] = sptrap;
+  notification_oid_len = enamelen + 1;
+  snmp_varlist_add_variable (&notification_vars,
+			     objid_snmptrap, objid_snmptrap_len,
+			     ASN_OBJECT_ID,
+			     (u_char *) notification_oid,
+			     notification_oid_len * sizeof(oid));
+
+  /* Provided bindings */
+  for (i = 0; i < trapobjlen; i++)
+    {
+      unsigned int j;
+      oid oid[MAX_OID_LEN];
+      size_t oid_len, onamelen;
+      u_char *val;
+      size_t val_len;
+      WriteMethod *wm = NULL;
+      struct variable cvp;
+
+      /* Make OID. */
+      if (trapobj[i].namelen > 0)
+        {
+	  /* Columnar object */
+	  onamelen = trapobj[i].namelen;
+	  oid_copy (oid, name, namelen);
+	  oid_copy (oid + namelen, trapobj[i].name, onamelen);
+	  oid_copy (oid + namelen + onamelen, iname, inamelen);
+	  oid_len = namelen + onamelen + inamelen;
+        }
+      else
+        {
+	  /* Scalar object */
+	  onamelen = trapobj[i].namelen * (-1);
+	  oid_copy (oid, name, namelen);
+	  oid_copy (oid + namelen, trapobj[i].name, onamelen);
+	  oid[onamelen + namelen] = 0;
+	  oid_len = namelen + onamelen + 1;
+        }
+
+      /* Locate the appropriate function and type in the MIB registry. */
+      for (j = 0; j < vp_len; j++)
+	{
+	  if (oid_compare (trapobj[i].name, onamelen, vp[j].name, vp[j].namelen) != 0)
+	    continue;
+	  /* We found the appropriate variable in the MIB registry. */
+	  oid_copy(cvp.name, name, namelen);
+	  oid_copy(cvp.name + namelen, vp[j].name, vp[j].namelen);
+	  cvp.namelen = namelen + vp[j].namelen;
+	  cvp.type = vp[j].type;
+	  cvp.magic = vp[j].magic;
+	  cvp.acl = vp[j].acl;
+	  cvp.findVar = vp[j].findVar;
+	  /* Grab the result. */
+	  val = cvp.findVar (&cvp, oid, &oid_len, 1, &val_len, &wm);
+	  if (!val) break;
+	  snmp_varlist_add_variable (&notification_vars,
+				     oid, oid_len,
+				     vp[j].type,
+				     val,
+				     val_len);
+	  break;
+	}
+    }
+
+
+  send_v2trap (notification_vars);
+  snmp_free_varbind (notification_vars);
   return 1;
 }
 
diff --git a/lib/smux.c b/lib/smux.c
index 38c7018e..07466400 100644
--- a/lib/smux.c
+++ b/lib/smux.c
@@ -968,8 +968,15 @@ smux_open (int sock)
   return send (sock, buf, (ptr - buf), 0);
 }
 
+/* `ename` is ignored. Instead of using the provided enterprise OID,
+   the SMUX peer is used. This keep compatibility with the previous
+   versions of Quagga.
+
+   All other fields are used as they are intended. */
 int
-smux_trap (const oid *name, size_t namelen,
+smux_trap (struct variable *vp, size_t vp_len,
+	   const oid *ename, size_t enamelen,
+	   const oid *name, size_t namelen,
 	   const oid *iname, size_t inamelen,
 	   const struct trap_object *trapobj, size_t trapobjlen,
 	   u_char sptrap)
diff --git a/lib/smux.h b/lib/smux.h
index b7d5096e..b29fdc72 100644
--- a/lib/smux.h
+++ b/lib/smux.h
@@ -75,9 +75,34 @@ extern void smux_register_mib(const char *, struct variable *,
                               size_t, int, oid [], size_t);
 extern int smux_header_generic (struct variable *, oid [], size_t *, 
                                 int, size_t *, WriteMethod **);
-extern int smux_trap (const oid *, size_t, const oid *, size_t, 
-		      const struct trap_object *, 
-                      size_t, u_char);
+
+/* For traps, three OID are provided:
+
+ 1. The enterprise OID to use (the last argument will be appended to
+    it to form the SNMP trap OID)
+
+ 2. The base OID for objects to be sent in traps.
+
+ 3. The index OID for objects to be sent in traps. This index is used
+    to designate a particular instance of a column.
+
+ The provided trap object contains the bindings to be sent with the
+ trap. The base OID will be prefixed to the provided OID and, if the
+ length is positive, the requested OID is assumed to be a columnar
+ object and the index OID will be appended.
+
+ The two first arguments are the MIB registry used to locate the trap
+ objects.
+
+ The use of the arguments may differ depending on the implementation
+ used.
+*/
+extern int smux_trap (struct variable *, size_t,
+		      const oid *, size_t,
+		      const oid *, size_t,
+		      const oid *, size_t,
+		      const struct trap_object *, size_t,
+		      u_char);
 
 extern int oid_compare (oid *, int, oid *, int);
 extern void oid2in_addr (oid [], int, struct in_addr *);