Replace incoming EDNS0_OPTION_NOMDEVICEID and EDNS0_OPTION_NOMCPEID options.

src/auth.c

@@ -824,7 +824,7 @@ size_t answer_auth(struct dns_header *header, char *limit, size_t qlen, time_t n
 
   /* Advertise our packet size limit in our reply */
   if (have_pseudoheader)
-    return add_pseudoheader(header,  ansp - (unsigned char *)header, (unsigned char *)limit, daemon->edns_pktsz, 0, NULL, 0, do_bit);
+    return add_pseudoheader(header,  ansp - (unsigned char *)header, (unsigned char *)limit, daemon->edns_pktsz, 0, NULL, 0, do_bit, 0);
 
   return ansp - (unsigned char *)header;
 }

src/dnsmasq.h

@@ -1523,7 +1523,7 @@ int expand_workspace(unsigned char ***wkspc, int *szp, int new);
 unsigned char *find_pseudoheader(struct dns_header *header, size_t plen,
 				   size_t *len, unsigned char **p, int *is_sign, int *is_last);
 size_t add_pseudoheader(struct dns_header *header, size_t plen, unsigned char *limit, 
-			unsigned short udp_sz, int optno, unsigned char *opt, size_t optlen, int set_do);
+			unsigned short udp_sz, int optno, unsigned char *opt, size_t optlen, int set_do, int replace);
 size_t add_do_bit(struct dns_header *header, size_t plen, unsigned char *limit);
 size_t add_edns0_config(struct dns_header *header, size_t plen, unsigned char *limit, 
 			union mysockaddr *source, time_t now, int *check_subnet);

src/edns0.c

@@ -96,7 +96,7 @@ unsigned char *find_pseudoheader(struct dns_header *header, size_t plen, size_t
 }
  
 size_t add_pseudoheader(struct dns_header *header, size_t plen, unsigned char *limit, 
-			unsigned short udp_sz, int optno, unsigned char *opt, size_t optlen, int set_do)
+			unsigned short udp_sz, int optno, unsigned char *opt, size_t optlen, int set_do, int replace)
 { 
   unsigned char *lenp, *datap, *p, *udp_len, *buff = NULL;
   int rdlen = 0, is_sign, is_last;
@@ -120,7 +120,7 @@ size_t add_pseudoheader(struct dns_header *header, size_t plen, unsigned char *l
 
       if (set_do)
 	{
-	  p -=2;
+	  p -= 2;
 	  flags |= 0x8000;
 	  PUTSHORT(flags, p);
 	}
@@ -136,13 +136,36 @@ size_t add_pseudoheader(struct dns_header *header, size_t plen, unsigned char *l
 	return plen;
       	  
       /* check if option already there */
-      for (i = 0; i + 4 < rdlen; i += len + 4)
+      for (i = 0; i + 4 < rdlen;)
 	{
 	  GETSHORT(code, p);
 	  GETSHORT(len, p);
+	  
+	  /* malformed option, delete the whole OPT RR and start again. */
+	  if (i + len > rdlen)
+	    {
+	      rdlen = 0;
+	      islast = 0;
+	      break;
+	    }
+	  
 	  if (code == optno)
+	    {
+	      if (!replace)
 		return plen;
+
+	      /* delete option if we're to replace it. */
+	      p -= 4;
+	      rdlen -= len + 4;
+	      memcpy(p, p+len+4, rdlen - i);
+	      PUTSHORT(rdlen, lenp);
+	      lenp -= 2;
+	    }
+	  else
+	    {
 	      p += len;
+	      i += len + 4;
+	    }
 	}
 
       /* If we're going to extend the RR, it has to be the last RR in the packet */
@@ -203,7 +226,7 @@ size_t add_pseudoheader(struct dns_header *header, size_t plen, unsigned char *l
 
 size_t add_do_bit(struct dns_header *header, size_t plen, unsigned char *limit)
 {
-  return add_pseudoheader(header, plen, (unsigned char *)limit, PACKETSZ, 0, NULL, 0, 1);
+  return add_pseudoheader(header, plen, (unsigned char *)limit, PACKETSZ, 0, NULL, 0, 1, 0);
 }
 
 static unsigned char char64(unsigned char c)
@@ -235,7 +258,7 @@ static size_t add_dns_client(struct dns_header *header, size_t plen, unsigned ch
 	  encoder(mac+3, encode+4);
 	  encode[8] = 0;
 	}
-      plen = add_pseudoheader(header, plen, limit, PACKETSZ, EDNS0_OPTION_NOMDEVICEID, (unsigned char *)encode, strlen(encode), 0); 
+      plen = add_pseudoheader(header, plen, limit, PACKETSZ, EDNS0_OPTION_NOMDEVICEID, (unsigned char *)encode, strlen(encode), 0, 1); 
     }
 
   return plen; 
@@ -248,7 +271,7 @@ static size_t add_mac(struct dns_header *header, size_t plen, unsigned char *lim
   unsigned char mac[DHCP_CHADDR_MAX];
 
   if ((maclen = find_mac(l3, mac, 1, now)) != 0)
-    plen = add_pseudoheader(header, plen, limit, PACKETSZ, EDNS0_OPTION_MAC, mac, maclen, 0); 
+    plen = add_pseudoheader(header, plen, limit, PACKETSZ, EDNS0_OPTION_MAC, mac, maclen, 0, 0); 
     
   return plen; 
 }
@@ -337,7 +360,7 @@ static size_t add_source_addr(struct dns_header *header, size_t plen, unsigned c
   struct subnet_opt opt;
   
   len = calc_subnet_opt(&opt, source);
-  return add_pseudoheader(header, plen, (unsigned char *)limit, PACKETSZ, EDNS0_OPTION_CLIENT_SUBNET, (unsigned char *)&opt, len, 0);
+  return add_pseudoheader(header, plen, (unsigned char *)limit, PACKETSZ, EDNS0_OPTION_CLIENT_SUBNET, (unsigned char *)&opt, len, 0, 0);
 }
 
 int check_source(struct dns_header *header, size_t plen, unsigned char *pseudoheader, union mysockaddr *peer)
@@ -391,7 +414,7 @@ size_t add_edns0_config(struct dns_header *header, size_t plen, unsigned char *l
 
   if (daemon->dns_client_id)
     plen = add_pseudoheader(header, plen, limit, PACKETSZ, EDNS0_OPTION_NOMCPEID, 
-			    (unsigned char *)daemon->dns_client_id, strlen(daemon->dns_client_id), 0);
+			    (unsigned char *)daemon->dns_client_id, strlen(daemon->dns_client_id), 0, 1);
   
   if (option_bool(OPT_CLIENT_SUBNET))
     {

src/option.c

@@ -2171,7 +2171,7 @@ static int one_opt(int option, char *arg, char *errstr, char *gen_err, int comma
 	daemon->dns_client_id = opt_string_alloc(arg);
       break;
 
-    case LOPT_ADD_MAC:
+    case LOPT_ADD_MAC: /* --add-mac */
       if (!arg)
 	set_option_bool(OPT_ADD_MAC);
       else

src/rfc1035.c

@@ -1847,7 +1847,7 @@ size_t answer_request(struct dns_header *header, char *limit, size_t qlen,
   
   /* Advertise our packet size limit in our reply */
   if (have_pseudoheader)
-    len = add_pseudoheader(header, len, (unsigned char *)limit, daemon->edns_pktsz, 0, NULL, 0, do_bit);
+    len = add_pseudoheader(header, len, (unsigned char *)limit, daemon->edns_pktsz, 0, NULL, 0, do_bit, 0);
   
   if (ad_reqd && sec_data)
     header->hb4 |= HB4_AD;