File net-snmp-5.7.1-more-robust-handling-of-agentx-errors.patch of Package net-snmp

commit 2a17b37430c1852998c3588e547d7eb61c06da71
Author: Dave Shield <D.T.Shield@liverpool.ac.uk>
Date:   Tue Dec 27 21:45:38 2011 +0000

    CHANGES: agentx: PATCHES: 3445440: More robust handling of AgentX errors
    Patch provided by Bill Fenner

Index: net-snmp-5.7.1/agent/mibgroup/agentx/subagent.c
===================================================================
--- net-snmp-5.7.1.orig/agent/mibgroup/agentx/subagent.c
+++ net-snmp-5.7.1/agent/mibgroup/agentx/subagent.c
@@ -243,6 +243,24 @@ free_set_vars(netsnmp_session * ss, nets
 }
 #endif /* !NETSNMP_NO_WRITE_SUPPORT */
 
+static void
+send_agentx_error(netsnmp_session *session, netsnmp_pdu *pdu, int errstat, int errindex)
+{
+    pdu = snmp_clone_pdu(pdu);
+    pdu->command   = AGENTX_MSG_RESPONSE;
+    pdu->version   = session->version;
+    pdu->errstat   = errstat;
+    pdu->errindex  = errindex;
+    snmp_free_varbind(pdu->variables);
+    pdu->variables = NULL;
+
+    DEBUGMSGTL(("agentx/subagent", "Sending AgentX response error stat %d idx %d\n",
+             errstat, errindex));
+    if (!snmp_send(session, pdu)) {
+        snmp_free_pdu(pdu);
+    }
+}
+
 int
 handle_agentx_packet(int operation, netsnmp_session * session, int reqid,
                      netsnmp_pdu *pdu, void *magic)
@@ -327,6 +345,7 @@ handle_agentx_packet(int operation, nets
             (ns_subagent_magic *) calloc(1, sizeof(ns_subagent_magic));
         if (smagic == NULL) {
             DEBUGMSGTL(("agentx/subagent", "couldn't malloc() smagic\n"));
+            /* would like to send_agentx_error(), but it needs memory too */
             return 1;
         }
         smagic->original_command = pdu->command;
@@ -391,6 +410,7 @@ handle_agentx_packet(int operation, nets
         if (asi == NULL) {
             SNMP_FREE(smagic);
             snmp_log(LOG_WARNING, "save_set_vars() failed\n");
+            send_agentx_error(session, pdu, AGENTX_ERR_PARSE_FAILED, 0);
             return 1;
         }
         asi->mode = pdu->command = SNMP_MSG_INTERNAL_SET_RESERVE1;
@@ -404,6 +424,7 @@ handle_agentx_packet(int operation, nets
         if (asi == NULL) {
             SNMP_FREE(smagic);
             snmp_log(LOG_WARNING, "restore_set_vars() failed\n");
+            send_agentx_error(session, pdu, AGENTX_ERR_PROCESSING_ERROR, 0);
             return 1;
         }
         if (asi->mode != SNMP_MSG_INTERNAL_SET_RESERVE2) {
@@ -411,6 +432,7 @@ handle_agentx_packet(int operation, nets
             snmp_log(LOG_WARNING,
                      "dropping bad AgentX request (wrong mode %d)\n",
                      asi->mode);
+            send_agentx_error(session, pdu, AGENTX_ERR_PROCESSING_ERROR, 0);
             return 1;
         }
         asi->mode = pdu->command = SNMP_MSG_INTERNAL_SET_ACTION;
@@ -424,6 +446,7 @@ handle_agentx_packet(int operation, nets
         if (asi == NULL) {
             SNMP_FREE(smagic);
             snmp_log(LOG_WARNING, "restore_set_vars() failed\n");
+            send_agentx_error(session, pdu, AGENTX_ERR_PROCESSING_ERROR, 0);
             return 1;
         }
         if (asi->mode == SNMP_MSG_INTERNAL_SET_RESERVE1 ||