snmpd [13/16]: registered instances must not return below OID

[Martijn van Duren]

If a backend registers as an instance it must never return OIDs below
their registration. Add a test for this in appl_varbind_valid().

OK?

martijn@

diff --git a/application.c b/application.c
index dfa7220..6ddeb39 100644
--- a/application.c
+++ b/application.c
@@ -128,8 +128,8 @@ void appl_request_upstream_resolve(struct 
appl_request_upstream *);
 void appl_request_downstream_send(struct appl_request_downstream *);
 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 *, int, int,
-    int, const char **);
+int appl_varbind_valid(struct appl_varbind *, struct appl_varbind_internal *,
+    int, int, int, const char **);
 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 *,
@@ -1073,9 +1073,9 @@ appl_response(struct appl_backend *backend, int32_t 
requestid,
 
        vb = vblist;
        for (i = 1; vb != NULL; vb = vb->av_next, i++) {
-                if (!appl_varbind_valid(vb, origvb == NULL ?
-                   NULL : &(origvb->avi_varbind), next,
-                    error != APPL_ERROR_NOERROR, backend->ab_range, &errstr)) {
+                if (!appl_varbind_valid(vb, origvb == NULL ?  NULL : origvb,
+                   next, error != APPL_ERROR_NOERROR, backend->ab_range,
+                   &errstr)) {
                        smi_oid2string(&(vb->av_oid), oidbuf,
                            sizeof(oidbuf), 0);
                        log_warnx("%s: %"PRIu32" %s: %s",
@@ -1173,8 +1173,9 @@ appl_response(struct appl_backend *backend, int32_t 
requestid,
 }
 
 int
-appl_varbind_valid(struct appl_varbind *varbind, struct appl_varbind *request,
-    int next, int null, int range, const char **errstr)
+appl_varbind_valid(struct appl_varbind *varbind,
+    struct appl_varbind_internal *request, int next, int null, int range,
+    const char **errstr)
 {
        int cmp;
        int eomv = 0;
@@ -1259,24 +1260,32 @@ appl_varbind_valid(struct appl_varbind *varbind, struct 
appl_varbind *request,
        if (request == NULL)
                return 1;
 
-       cmp = ober_oid_cmp(&(request->av_oid), &(varbind->av_oid));
-       if (next && !eomv) {
-               if (request->av_include) {
-                       if (cmp > 0) {
-                               *errstr = "oid not incrementing";
-                               return 0;
+       cmp = ober_oid_cmp(&(request->avi_varbind.av_oid), &(varbind->av_oid));
+       if (next) {
+               if (request->avi_region->ar_instance &&
+                   ober_oid_cmp(&(request->avi_region->ar_oid),
+                   &(varbind->av_oid)) != 0) {
+                       *errstr = "oid below instance";
+                       return 0;
+               }
+               if (!eomv) {
+                       if (request->avi_varbind.av_include) {
+                               if (cmp > 0) {
+                                       *errstr = "oid not incrementing";
+                                       return 0;
+                               }
+                       } else {
+                               if (cmp >= 0) {
+                                       *errstr = "oid not incrementing";
+                                       return 0;
+                               }
                        }
-               } else {
-                       if (cmp >= 0) {
-                               *errstr = "oid not incrementing";
+                       if (range && ober_oid_cmp(&(varbind->av_oid),
+                           &(request->avi_varbind.av_oid_end)) > 0) {
+                               *errstr = "end oid not honoured";
                                return 0;
                        }
                }
-               if (range && ober_oid_cmp(&(varbind->av_oid),
-                   &(request->av_oid_end)) > 0) {
-                       *errstr = "end oid not honoured";
-                       return 0;
-               }
        } else {
                if (cmp != 0) {
                        *errstr = "oids not equal";