snmpd [14/16]: Validate the returned error code

[Martijn van Duren]

Certain error codes are only intended for certain request-types. Add an
appl_error_valid() function to test for this.

OK?

martijn@

diff --git a/application.c b/application.c
index 6ddeb39..53e793d 100644
--- a/application.c
+++ b/application.c
@@ -130,6 +130,7 @@ void appl_request_downstream_timeout(int, short, void *);
 void appl_request_upstream_reply(struct appl_request_upstream *);
 int appl_varbind_valid(struct appl_varbind *, struct appl_varbind_internal *,
     int, int, int, const char **);
+int appl_error_valid(enum appl_error, enum snmp_pdutype);
 int appl_varbind_backend(struct appl_varbind_internal *);
 void appl_varbind_error(struct appl_varbind_internal *, enum appl_error);
 void appl_report(struct snmp_message *, int32_t, struct ber_oid *,
@@ -1069,6 +1070,11 @@ appl_response(struct appl_backend *backend, int32_t 
requestid,
                next = pdutype == SNMP_C_GETNEXTREQ ||
                    pdutype == SNMP_C_GETBULKREQ;
                origvb = dreq->ard_vblist;
+               if (!appl_error_valid(error, dreq->ard_requesttype)) {
+                       log_warnx("%s: %"PRIu32" Invalid error",
+                           backend->ab_name, requestid);
+                       invalid = 1;
+               }
        }
 
        vb = vblist;
@@ -1295,6 +1301,37 @@ appl_varbind_valid(struct appl_varbind *varbind,
        return 1;
 }
 
+int
+appl_error_valid(enum appl_error error, enum snmp_pdutype type)
+{
+       switch (error) {
+       case APPL_ERROR_NOERROR:
+       case APPL_ERROR_TOOBIG:
+       case APPL_ERROR_NOSUCHNAME:
+       case APPL_ERROR_GENERR:
+               return 1;
+       case APPL_ERROR_BADVALUE:
+       case APPL_ERROR_READONLY:
+       case APPL_ERROR_NOACCESS:
+       case APPL_ERROR_WRONGTYPE:
+       case APPL_ERROR_WRONGLENGTH:
+       case APPL_ERROR_WRONGENCODING:
+       case APPL_ERROR_WRONGVALUE:
+       case APPL_ERROR_NOCREATION:
+       case APPL_ERROR_INCONSISTENTVALUE:
+       case APPL_ERROR_RESOURCEUNAVAILABLE:
+       case APPL_ERROR_COMMITFAILED:
+       case APPL_ERROR_UNDOFAILED:
+       case APPL_ERROR_NOTWRITABLE:
+       case APPL_ERROR_INCONSISTENTNAME:
+               return type == SNMP_C_SETREQ;
+       case APPL_ERROR_AUTHORIZATIONERROR:
+               return type == SNMP_C_GETREQ || type == SNMP_C_SETREQ;
+       default:
+               return 0;
+       }
+}
+
 int
 appl_varbind_backend(struct appl_varbind_internal *ivb)
 {