X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/aa7751be078fe9a20efa2cf2a8856fadb98f4178..806c3df997132e99f4abade6d00be18930695408:/src/src/dns.c

diff --git a/src/src/dns.c b/src/src/dns.c
index a239bec30..17152d9a6 100644
--- a/src/src/dns.c
+++ b/src/src/dns.c
@@ -305,6 +305,15 @@ else
 
 
 
+/* Increment the aptr in dnss, checking against dnsa length.
+Return: TRUE for a bad result
+*/
+static BOOL
+dnss_inc(dns_answer * dnsa, dns_scan * dnss, unsigned delta)
+{
+return (dnss->aptr += delta) >= dnsa->answer + dnsa->answerlen;
+}
+
 /*************************************************
 *       Get next DNS record from answer block    *
 *************************************************/
@@ -328,10 +337,19 @@ dns_next_rr(dns_answer *dnsa, dns_scan *dnss, int reset)
 HEADER *h = (HEADER *)dnsa->answer;
 int namelen;
 
+char * trace = NULL;
+#ifdef rr_trace
+# define TRACE DEBUG(D_dns)
+#else
+trace = trace;
+# define TRACE if (FALSE)
+#endif
+
 /* Reset the saved data when requested to, and skip to the first required RR */
 
 if (reset != RESET_NEXT)
   {
+  TRACE debug_printf("%s: reset\n", __FUNCTION__);
   dnss->rrcount = ntohs(h->qdcount);
   dnss->aptr = dnsa->answer + sizeof(HEADER);
 
@@ -339,10 +357,13 @@ if (reset != RESET_NEXT)
 
   while (dnss->rrcount-- > 0)
     {
+    TRACE trace = "Q-namelen";
     namelen = dn_expand(dnsa->answer, dnsa->answer + dnsa->answerlen,
-      dnss->aptr, (DN_EXPAND_ARG4_TYPE) &(dnss->srr.name), DNS_MAXNAME);
-    if (namelen < 0) { dnss->rrcount = 0; return NULL; }
-    dnss->aptr += namelen + 4;    /* skip name & type & class */
+      dnss->aptr, (DN_EXPAND_ARG4_TYPE) &dnss->srr.name, DNS_MAXNAME);
+    if (namelen < 0) goto null_return;
+    /* skip name & type & class */
+    TRACE trace = "Q-skip";
+    if (dnss_inc(dnsa, dnss, namelen+4)) goto null_return;
     }
 
   /* Get the number of answer records. */
@@ -353,23 +374,37 @@ if (reset != RESET_NEXT)
   the NS records (i.e. authority section) if wanting to look at the additional
   records. */
 
-  if (reset == RESET_ADDITIONAL) dnss->rrcount += ntohs(h->nscount);
+  if (reset == RESET_ADDITIONAL)
+    {
+    TRACE debug_printf("%s: additional\n", __FUNCTION__);
+    dnss->rrcount += ntohs(h->nscount);
+    }
 
   if (reset == RESET_AUTHORITY || reset == RESET_ADDITIONAL)
     {
+    TRACE if (reset == RESET_AUTHORITY)
+      debug_printf("%s: authority\n", __FUNCTION__);
     while (dnss->rrcount-- > 0)
       {
+      TRACE trace = "A-namelen";
       namelen = dn_expand(dnsa->answer, dnsa->answer + dnsa->answerlen,
-        dnss->aptr, (DN_EXPAND_ARG4_TYPE) &(dnss->srr.name), DNS_MAXNAME);
-      if (namelen < 0) { dnss->rrcount = 0; return NULL; }
-      dnss->aptr += namelen + 8;            /* skip name, type, class & TTL */
+        dnss->aptr, (DN_EXPAND_ARG4_TYPE) &dnss->srr.name, DNS_MAXNAME);
+      if (namelen < 0) goto null_return;
+      /* skip name, type, class & TTL */
+      TRACE trace = "A-hdr";
+      if (dnss_inc(dnsa, dnss, namelen+8)) goto null_return;
       GETSHORT(dnss->srr.size, dnss->aptr); /* size of data portion */
-      dnss->aptr += dnss->srr.size;         /* skip over it */
+      /* skip over it */
+      TRACE trace = "A-skip";
+      if (dnss_inc(dnsa, dnss, dnss->srr.size)) goto null_return;
       }
-    dnss->rrcount = (reset == RESET_AUTHORITY)
+    dnss->rrcount = reset == RESET_AUTHORITY
       ? ntohs(h->nscount) : ntohs(h->arcount);
     }
+  TRACE debug_printf("%s: %d RRs to read\n", __FUNCTION__, dnss->rrcount);
   }
+else
+  TRACE debug_printf("%s: next (%d left)\n", __FUNCTION__, dnss->rrcount);
 
 /* The variable dnss->aptr is now pointing at the next RR, and dnss->rrcount
 contains the number of RR records left. */
@@ -379,24 +414,39 @@ if (dnss->rrcount-- <= 0) return NULL;
 /* If expanding the RR domain name fails, behave as if no more records
 (something safe). */
 
+TRACE trace = "R-namelen";
 namelen = dn_expand(dnsa->answer, dnsa->answer + dnsa->answerlen, dnss->aptr,
-  (DN_EXPAND_ARG4_TYPE) &(dnss->srr.name), DNS_MAXNAME);
-if (namelen < 0) { dnss->rrcount = 0; return NULL; }
+  (DN_EXPAND_ARG4_TYPE) &dnss->srr.name, DNS_MAXNAME);
+if (namelen < 0) goto null_return;
 
 /* Move the pointer past the name and fill in the rest of the data structure
 from the following bytes. */
 
-dnss->aptr += namelen;
-GETSHORT(dnss->srr.type, dnss->aptr); /* Record type */
-dnss->aptr += 6;                      /* Don't want class or TTL */
-GETSHORT(dnss->srr.size, dnss->aptr); /* Size of data portion */
-dnss->srr.data = dnss->aptr;          /* The record's data follows */
-dnss->aptr += dnss->srr.size;         /* Advance to next RR */
+TRACE trace = "R-name";
+if (dnss_inc(dnsa, dnss, namelen)) goto null_return;
+
+GETSHORT(dnss->srr.type, dnss->aptr);		/* Record type */
+TRACE trace = "R-class";
+if (dnss_inc(dnsa, dnss, 2)) goto null_return;	/* Don't want class */
+GETLONG(dnss->srr.ttl, dnss->aptr);		/* TTL */
+GETSHORT(dnss->srr.size, dnss->aptr);		/* Size of data portion */
+dnss->srr.data = dnss->aptr;			/* The record's data follows */
+
+/* Unchecked increment ok here since no further access on this iteration;
+will be checked on next at "R-name". */
+
+dnss->aptr += dnss->srr.size;			/* Advance to next RR */
 
 /* Return a pointer to the dns_record structure within the dns_answer. This is
 for convenience so that the scans can use nice-looking for loops. */
 
-return &(dnss->srr);
+return &dnss->srr;
+
+null_return:
+  TRACE debug_printf("%s: terminate (%d RRs left). Last op: %s\n",
+    __FUNCTION__, dnss->rrcount, trace);
+  dnss->rrcount = 0;
+  return NULL;
 }
 
 
@@ -467,7 +517,7 @@ if (  !h->aa
    || !*trusted
    || !(auth_name = dns_extract_auth_name(dnsa))
    || OK != match_isinlist(auth_name, &trusted, 0, NULL, NULL,
-			    MCL_DOMAIN, TRUE, NULL) 
+			    MCL_DOMAIN, TRUE, NULL)
    )
   return FALSE;
 
@@ -482,8 +532,10 @@ return TRUE;
 static void
 dns_set_insecure(dns_answer * dnsa)
 {
+#ifndef DISABLE_DNSSEC
 HEADER * h = (HEADER *)dnsa->answer;
 h->ad = 0;
+#endif
 }
 
 /************************************************
@@ -495,7 +547,11 @@ h->ad = 0;
 BOOL
 dns_is_aa(const dns_answer *dnsa)
 {
+#ifdef DISABLE_DNSSEC
+return FALSE;
+#else
 return ((HEADER*)dnsa->answer)->aa;
+#endif
 }
 
 
@@ -557,7 +613,7 @@ dns_return(const uschar * name, int type, int rc)
 res_state resp = os_get_dns_resolver_res();
 tree_node *node = store_get_perm(sizeof(tree_node) + 290);
 sprintf(CS node->name, "%.255s-%s-%lx", name, dns_text_type(type),
-  resp->options);
+  (unsigned long) resp->options);
 node->data.val = rc;
 (void)tree_insertnode(&tree_dns_fails, node);
 return rc;
@@ -606,7 +662,7 @@ have many addresses in the same domain. We rely on the resolver and name server
 caching for successful lookups. */
 
 sprintf(CS node_name, "%.255s-%s-%lx", name, dns_text_type(type),
-  resp->options);
+  (unsigned long) resp->options);
 previous = tree_search(tree_dns_fails, node_name);
 if (previous != NULL)
   {
@@ -619,7 +675,7 @@ if (previous != NULL)
   return previous->data.val;
   }
 
-#ifdef EXPERIMENTAL_INTERNATIONAL
+#ifdef SUPPORT_I18N
 /* Convert all names to a-label form before doing lookup */
   {
   uschar * alabel;
@@ -812,7 +868,7 @@ BOOL secure_so_far = TRUE;
 
 for (i = 0; i < 10; i++)
   {
-  uschar data[256];
+  uschar * data;
   dns_record *rr, cname_rr, type_rr;
   dns_scan dnss;
   int datalen, rc;
@@ -850,7 +906,7 @@ for (i = 0; i < 10; i++)
     if (  rr_name
        && Ustrcmp(rr_name, *fully_qualified_name) != 0
        && rr_name[0] != '*'
-#ifdef EXPERIMENTAL_INTERNATIONAL
+#ifdef SUPPORT_I18N
        && (  !string_is_utf8(*fully_qualified_name)
 	  || Ustrcmp(rr_name,
 	       string_domain_utf8_to_alabel(*fully_qualified_name, NULL)) != 0
@@ -862,7 +918,7 @@ for (i = 0; i < 10; i++)
 
   /* If any data records of the correct type were found, we are done. */
 
-  if (type_rr.data != NULL)
+  if (type_rr.data)
     {
     if (!secure_so_far)	/* mark insecure if any element of CNAME chain was */
       dns_set_insecure(dnsa);
@@ -874,10 +930,14 @@ for (i = 0; i < 10; i++)
   have had a failure from dns_lookup). However code against the possibility of
   its not existing. */
 
-  if (cname_rr.data == NULL) return DNS_FAIL;
+  if (!cname_rr.data)
+    return DNS_FAIL;
+
+  data = store_get(256);
   datalen = dn_expand(dnsa->answer, dnsa->answer + dnsa->answerlen,
-    cname_rr.data, (DN_EXPAND_ARG4_TYPE)data, sizeof(data));
-  if (datalen < 0) return DNS_FAIL;
+    cname_rr.data, (DN_EXPAND_ARG4_TYPE)data, 256);
+  if (datalen < 0)
+    return DNS_FAIL;
   name = data;
 
   if (!dns_is_secure(dnsa))
@@ -1111,8 +1171,7 @@ return DNS_FAIL;
 *          Get address(es) from DNS record       *
 *************************************************/
 
-/* The record type is either T_A for an IPv4 address or T_AAAA (or T_A6 when
-supported) for an IPv6 address.
+/* The record type is either T_A for an IPv4 address or T_AAAA for an IPv6 address.
 
 Argument:
   dnsa       the DNS answer block
@@ -1144,8 +1203,11 @@ else
   {
   if (rr->data + 16 <= dnsa_lim)
     {
+    struct in6_addr in6;
+    int i;
+    for (i = 0; i < 16; i++) in6.s6_addr[i] = rr->data[i];
     yield = store_get(sizeof(dns_address) + 50);
-    inet_ntop(AF_INET6, US rr->data, CS yield->address, 50);
+    inet_ntop(AF_INET6, &in6, CS yield->address, 50);
     yield->next = NULL;
     }
   }