X-Git-Url: https://vcs.fsf.org/?p=exim.git;a=blobdiff_plain;f=src%2Fsrc%2Fdns.c;h=fc0ffb2baa59e2b1e09582b2c24943da5cd0d82a;hp=27ab2d2a237984469a17f990392734c03d2a980c;hb=4fab92fbc2b63bac2d89c1dae69fa1845cb640b7;hpb=94431adbd61d7706fe6df3a19bcae043fec950bf

diff --git a/src/src/dns.c b/src/src/dns.c
index 27ab2d2a2..fc0ffb2ba 100644
--- a/src/src/dns.c
+++ b/src/src/dns.c
@@ -2,7 +2,7 @@
 *     Exim - an Internet mail transport agent    *
 *************************************************/
 
-/* Copyright (c) University of Cambridge 1995 - 2015 */
+/* Copyright (c) University of Cambridge 1995 - 2016 */
 /* See the file NOTICE for conditions of use and distribution. */
 
 /* Functions for interfacing with the DNS. */
@@ -305,6 +305,15 @@ else
 
 
 
+/* Increment the aptr in dnss, checking against dnsa length.
+Return: TRUE for a bad result
+*/
+static BOOL
+dnss_inc_aptr(const dns_answer * dnsa, dns_scan * dnss, unsigned delta)
+{
+return (dnss->aptr += delta) >= dnsa->answer + dnsa->answerlen;
+}
+
 /*************************************************
 *       Get next DNS record from answer block    *
 *************************************************/
@@ -323,15 +332,24 @@ Returns:    next dns record, or NULL when no more
 */
 
 dns_record *
-dns_next_rr(dns_answer *dnsa, dns_scan *dnss, int reset)
+dns_next_rr(const dns_answer *dnsa, dns_scan *dnss, int reset)
 {
-HEADER *h = (HEADER *)dnsa->answer;
+const HEADER * h = (const 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_aptr(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_aptr(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_aptr(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. */
@@ -379,51 +414,66 @@ 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 += 2;                      /* 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 */
-dnss->aptr += dnss->srr.size;         /* Advance to next RR */
+TRACE trace = "R-name";
+if (dnss_inc_aptr(dnsa, dnss, namelen)) goto null_return;
+
+GETSHORT(dnss->srr.type, dnss->aptr);		/* Record type */
+TRACE trace = "R-class";
+if (dnss_inc_aptr(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;
 }
 
 
-/* Extract the AUTHORITY information from the answer. If the
-answer isn't authoritive (AA not set), we do not extract anything.
+/* Extract the AUTHORITY information from the answer. If the answer isn't
+authoritive (AA not set), we do not extract anything.
+
+The AUTHORITIVE section contains NS records if the name in question was found,
+it contains a SOA record otherwise. (This is just from experience and some
+tests, is there some spec?)
 
-The AUTHORITIVE section contains NS records if
-the name in question was found, it contains a SOA record
-otherwise. (This is just from experience and some tests, is there
-some spec?)
+Scan the whole AUTHORITY section, since it may contain other records
+(e.g. NSEC3) too.
 
-We've cycle through the AUTHORITY section, since it may contain
-other records (e.g. NSEC3) too.  */
+Return: name for the authority, in an allocated string, or NULL if none found */
 
 static const uschar *
 dns_extract_auth_name(const dns_answer * dnsa)	/* FIXME: const dns_answer */
 {
 dns_scan dnss;
 dns_record * rr;
-HEADER * h = (HEADER *) dnsa->answer;
+const HEADER * h = (const HEADER *) dnsa->answer;
 
-if (!h->nscount || !h->aa) return NULL;
-for (rr = dns_next_rr((dns_answer*) dnsa, &dnss, RESET_AUTHORITY);
-     rr;
-     rr = dns_next_rr((dns_answer*) dnsa, &dnss, RESET_NEXT))
-  if (rr->type == (h->ancount ? T_NS : T_SOA)) return rr->name;
+if (h->nscount && h->aa)
+  for (rr = dns_next_rr(dnsa, &dnss, RESET_AUTHORITY);
+       rr; rr = dns_next_rr(dnsa, &dnss, RESET_NEXT))
+    if (rr->type == (h->ancount ? T_NS : T_SOA))
+      return string_copy(rr->name);
 return NULL;
 }
 
@@ -450,7 +500,7 @@ DEBUG(D_dns)
   debug_printf("DNSSEC support disabled at build-time; dns_is_secure() false\n");
 return FALSE;
 #else
-HEADER * h = (HEADER *) dnsa->answer;
+const HEADER * h = (const HEADER *) dnsa->answer;
 const uschar * auth_name;
 const uschar * trusted;
 
@@ -483,8 +533,10 @@ return TRUE;
 static void
 dns_set_insecure(dns_answer * dnsa)
 {
+#ifndef DISABLE_DNSSEC
 HEADER * h = (HEADER *)dnsa->answer;
-h->ad = 0;
+h->aa = h->ad = 0;
+#endif
 }
 
 /************************************************
@@ -496,7 +548,11 @@ h->ad = 0;
 BOOL
 dns_is_aa(const dns_answer *dnsa)
 {
-return ((HEADER*)dnsa->answer)->aa;
+#ifdef DISABLE_DNSSEC
+return FALSE;
+#else
+return ((const HEADER*)dnsa->answer)->aa;
+#endif
 }
 
 
@@ -558,7 +614,7 @@ 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;
@@ -607,9 +663,8 @@ 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);
-previous = tree_search(tree_dns_fails, node_name);
-if (previous != NULL)
+  (unsigned long) resp->options);
+if ((previous = tree_search(tree_dns_fails, node_name)))
   {
   DEBUG(D_dns) debug_printf("DNS lookup of %.255s-%s: using cached value %s\n",
     name, dns_text_type(type),
@@ -620,7 +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;
@@ -714,48 +769,48 @@ if (dnsa->answerlen > MAXPACKET)
 if (dnsa->answerlen < 0) switch (h_errno)
   {
   case HOST_NOT_FOUND:
-  DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) gave HOST_NOT_FOUND\n"
-    "returning DNS_NOMATCH\n", name, dns_text_type(type));
-  return dns_return(name, type, DNS_NOMATCH);
+    DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) gave HOST_NOT_FOUND\n"
+      "returning DNS_NOMATCH\n", name, dns_text_type(type));
+    return dns_return(name, type, DNS_NOMATCH);
 
   case TRY_AGAIN:
-  DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) gave TRY_AGAIN\n",
-    name, dns_text_type(type));
+    DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) gave TRY_AGAIN\n",
+      name, dns_text_type(type));
 
-  /* Cut this out for various test programs */
+    /* Cut this out for various test programs */
 #ifndef STAND_ALONE
-  save_domain = deliver_domain;
-  deliver_domain = string_copy(name);  /* set $domain */
-  rc = match_isinlist(name, (const uschar **)&dns_again_means_nonexist, 0, NULL, NULL,
-    MCL_DOMAIN, TRUE, NULL);
-  deliver_domain = save_domain;
-  if (rc != OK)
-    {
-    DEBUG(D_dns) debug_printf("returning DNS_AGAIN\n");
-    return dns_return(name, type, DNS_AGAIN);
-    }
-  DEBUG(D_dns) debug_printf("%s is in dns_again_means_nonexist: returning "
-    "DNS_NOMATCH\n", name);
-  return dns_return(name, type, DNS_NOMATCH);
+    save_domain = deliver_domain;
+    deliver_domain = string_copy(name);  /* set $domain */
+    rc = match_isinlist(name, (const uschar **)&dns_again_means_nonexist, 0, NULL, NULL,
+      MCL_DOMAIN, TRUE, NULL);
+    deliver_domain = save_domain;
+    if (rc != OK)
+      {
+      DEBUG(D_dns) debug_printf("returning DNS_AGAIN\n");
+      return dns_return(name, type, DNS_AGAIN);
+      }
+    DEBUG(D_dns) debug_printf("%s is in dns_again_means_nonexist: returning "
+      "DNS_NOMATCH\n", name);
+    return dns_return(name, type, DNS_NOMATCH);
 
 #else   /* For stand-alone tests */
-  return dns_return(name, type, DNS_AGAIN);
+    return dns_return(name, type, DNS_AGAIN);
 #endif
 
   case NO_RECOVERY:
-  DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) gave NO_RECOVERY\n"
-    "returning DNS_FAIL\n", name, dns_text_type(type));
-  return dns_return(name, type, DNS_FAIL);
+    DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) gave NO_RECOVERY\n"
+      "returning DNS_FAIL\n", name, dns_text_type(type));
+    return dns_return(name, type, DNS_FAIL);
 
   case NO_DATA:
-  DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) gave NO_DATA\n"
-    "returning DNS_NODATA\n", name, dns_text_type(type));
-  return dns_return(name, type, DNS_NODATA);
+    DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) gave NO_DATA\n"
+      "returning DNS_NODATA\n", name, dns_text_type(type));
+    return dns_return(name, type, DNS_NODATA);
 
   default:
-  DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) gave unknown DNS error %d\n"
-    "returning DNS_FAIL\n", name, dns_text_type(type), h_errno);
-  return dns_return(name, type, DNS_FAIL);
+    DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) gave unknown DNS error %d\n"
+      "returning DNS_FAIL\n", name, dns_text_type(type), h_errno);
+    return dns_return(name, type, DNS_FAIL);
   }
 
 DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) succeeded\n",
@@ -813,14 +868,15 @@ 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;
 
   /* DNS lookup failures get passed straight back. */
 
-  if ((rc = dns_basic_lookup(dnsa, name, type)) != DNS_SUCCEED) return rc;
+  if ((rc = dns_basic_lookup(dnsa, name, type)) != DNS_SUCCEED)
+    return rc;
 
   /* We should have either records of the required type, or a CNAME record,
   or both. We need to know whether both exist for getting the fully qualified
@@ -830,28 +886,26 @@ for (i = 0; i < 10; i++)
 
   cname_rr.data = type_rr.data = NULL;
   for (rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS);
-       rr;
-       rr = dns_next_rr(dnsa, &dnss, RESET_NEXT))
-    {
+       rr; rr = dns_next_rr(dnsa, &dnss, RESET_NEXT))
     if (rr->type == type)
       {
       if (type_rr.data == NULL) type_rr = *rr;
       if (cname_rr.data != NULL) break;
       }
-    else if (rr->type == T_CNAME) cname_rr = *rr;
-    }
+    else if (rr->type == T_CNAME)
+      cname_rr = *rr;
 
   /* For the first time round this loop, if a CNAME was found, take the fully
   qualified name from it; otherwise from the first data record, if present. */
 
-  if (i == 0 && fully_qualified_name != NULL)
+  if (i == 0 && fully_qualified_name)
     {
-    uschar * rr_name = cname_rr.data ? cname_rr.name
-      : type_rr.data ? type_rr.name : NULL;
+    uschar * rr_name = cname_rr.data
+      ? cname_rr.name : type_rr.data ? type_rr.name : NULL;
     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
@@ -863,7 +917,7 @@ 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);
@@ -875,10 +929,13 @@ 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;
-  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;
+  if (!cname_rr.data)
+    return DNS_FAIL;
+
+  data = store_get(256);
+  if ((datalen = dn_expand(dnsa->answer, dnsa->answer + dnsa->answerlen,
+    cname_rr.data, (DN_EXPAND_ARG4_TYPE)data, 256)) < 0)
+    return DNS_FAIL;
   name = data;
 
   if (!dns_is_secure(dnsa))
@@ -1025,7 +1082,7 @@ switch (type)
       success and packet length return values.) For added safety we only reset
       the packet length if the packet header looks plausible. */
 
-      HEADER *h = (HEADER *)dnsa->answer;
+      const HEADER * h = (const HEADER *)dnsa->answer;
       if (h->qr == 1 && h->opcode == QUERY && h->tc == 0
 	  && (h->rcode == NOERROR || h->rcode == NXDOMAIN)
 	  && ntohs(h->qdcount) == 1 && ntohs(h->ancount) == 0
@@ -1033,8 +1090,7 @@ switch (type)
 	    dnsa->answerlen = MAXPACKET;
 
       for (rr = dns_next_rr(dnsa, &dnss, RESET_AUTHORITY);
-	   rr;
-	   rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
+	   rr; rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
 	  )
 	if (rr->type != T_SOA) continue;
 	else if (strcmpic(rr->name, US"") == 0 ||
@@ -1069,13 +1125,11 @@ switch (type)
       might make stricter assertions than its parent domain. */
 
       for (rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS);
-	   rr;
-	   rr = dns_next_rr(dnsa, &dnss, RESET_NEXT))
+	   rr; rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)) if (rr->type == T_SRV)
 	{
-	if (rr->type != T_SRV) continue;
+	const uschar * p = rr->data;
 
 	/* Extract the numerical SRV fields (p is incremented) */
-	p = rr->data;
 	GETSHORT(priority, p);
 	GETSHORT(weight, p);	weight = weight; /* compiler quietening */
 	GETSHORT(port, p);
@@ -1112,8 +1166,7 @@ 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
@@ -1145,8 +1198,11 @@ 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;
     }
   }