Don't BIND DHCP socket if more interfaces may come along later.

Also make man page on this clearer, as it's been confusing many.

CHANGELOG

@@ -40,6 +40,22 @@ version 2.67
 	    Generalise --interface-name to cope with IPv6 addresses
 	    and multiple addresses per interface per address family.
 
+	    Fix option parsing for --dhcp-host, which was generating a
+	    spurious error when all seven possible items were
+	    included. Thanks to Zhiqiang Wang for the bug report.
+
+	    Remove restriction on prefix-length in --auth-zone. Thanks
+	    to Toke Hoiland-Jorgensen for suggesting this.
+
+	    Log when the maximum number of concurrent DNS queries is
+	    reached. Thanks to Marcelo Salhab Brogliato for the patch.
+
+	    If wildcards are used in --interface, don't assume that 
+	    there will only ever be one available interface for DHCP
+	    just because there is one at start-up. More may appear, so
+	    we can't use SO_BINDTODEVICE. Thanks to Natrio for the bug
+	    report. 
+
 		
 version 2.66
             Add the ability to act as an authoritative DNS

debian/changelog

@@ -2,7 +2,13 @@ dnsmasq (2.67-1) unstable; urgency=low
 
    * New upstream.
 
- -- Simon Kelley <simon@thekelleys.org.uk>  Mon, 20 May 2013 11:50:22 +0000
+ -- Simon Kelley <simon@thekelleys.org.uk>  Tue, 28 May 2013 14:50:22 +0000
+
+dnsmasq (2.66-3) unstable; urgency=low
+
+   * Update resolvconf script for dnscrypt-proxy integration. (closes: #709179)
+
+ -- Simon Kelley <simon@thekelleys.org.uk>  Tue, 28 May 2013 14:39:51 +0000
 
 dnsmasq (2.66-2) unstable; urgency=low
 

debian/resolvconf

@@ -1,16 +1,14 @@
-#!/bin/bash
+#!/bin/sh
 #
 # Script to update the resolver list for dnsmasq
 #
-# N.B. Resolvconf may run us even if dnsmasq is not running.
-# If dnsmasq is installed then we go ahead and update
-# the resolver list in case dnsmasq is started later.
+# N.B. Resolvconf may run us even if dnsmasq is not (yet) running.
+# If dnsmasq is installed then we go ahead and update the resolver list
+# in case dnsmasq is started later.
 #
-# Assumption: On entry, PWD contains the resolv.conf-type files
+# Assumption: On entry, PWD contains the resolv.conf-type files.
 #
-# Requires bash because it uses a non-POSIX printf extension.
-#
-# Licensed under the GNU GPL.  See /usr/share/common-licenses/GPL.
+# This file is part of the dnsmasq package.
 #
 
 set -e
@@ -18,6 +16,8 @@ set -e
 RUN_DIR="/var/run/dnsmasq"
 RSLVRLIST_FILE="${RUN_DIR}/resolv.conf"
 TMP_FILE="${RSLVRLIST_FILE}_new.$$"
+MY_RECORD_NAME="lo.dnsmasq"
+DNSCRYPT_RECORD_NAME="lo.dnscrypt"
 
 [ -x /usr/sbin/dnsmasq ] || exit 0
 [ -x /lib/resolvconf/list-records ] || exit 1
@@ -27,7 +27,7 @@ PATH=/bin:/sbin
 report_err() { echo "$0: Error: $*" >&2 ; }
 
 # Stores arguments (minus duplicates) in RSLT, separated by spaces
-# Doesn't work properly if an argument itself contain whitespace
+# Doesn't work properly if an argument itself contains whitespace
 uniquify()
 {
 	RSLT=""
@@ -45,7 +45,22 @@ if [ ! -d "$RUN_DIR" ] && ! mkdir --parents --mode=0755 "$RUN_DIR" ; then
 	exit 1
 fi
 
-RSLVCNFFILES="$(/lib/resolvconf/list-records | sed -e '/^lo.dnsmasq$/d')"
+RSLVCNFFILES=""
+for F in $(/lib/resolvconf/list-records) ; do
+	case "$F" in
+	  "$MY_RECORD_NAME")
+		# Omit
+		;;
+	  "$DNSCRYPT_RECORD_NAME")
+		# Dnscrypt, I only have eyes for you
+		RSLVCNFFILES="$DNSCRYPT_RECORD_NAME"
+		break
+		;;
+	  *)
+		RSLVCNFFILES="${RSLVCNFFILES:+$RSLVCNFFILES }$F"
+		;;
+	esac
+done
 
 NMSRVRS=""
 if [ "$RSLVCNFFILES" ] ; then
@@ -56,8 +71,8 @@ fi
 # Dnsmasq uses the mtime of $RSLVRLIST_FILE, with a resolution of one second,
 # to detect changes in the file. This means that if a resolvconf update occurs
 # within one second of the previous one then dnsmasq may fail to notice the
-# more recent change.  To work around this problem we sleep here to ensure
-# that the new mtime is different.
+# more recent change. To work around this problem we sleep one second here
+# if necessary in order to ensure that the new mtime is different.
 if [ -f "$RSLVRLIST_FILE" ] && [ "$(ls -go --time-style='+%s' "$RSLVRLIST_FILE" | { read p h s t n ; echo "$t" ; })" = "$(date +%s)" ] ; then
 	sleep 1
 fi

man/dnsmasq.8

@@ -572,13 +572,18 @@ If you use the first DNSSEC mode, validating resolvers in clients,
 this option is not required. Dnsmasq always returns all the data
 needed for a client to do validation itself. 
 .TP
-.B --auth-zone=<domain>[,<subnet>[,<subnet>.....]]
+.B --auth-zone=<domain>[,<subnet>[/<prefix length>][,<subnet>[/<prefix length>].....]]
 Define a DNS zone for which dnsmasq acts as authoritative server. Locally defined DNS records which are in the domain
-will be served, except that A and AAAA records must be in one of the
+will be served. A and AAAA records must be in one of the
 specified subnets, or in a subnet corresponding to a constructed DHCP
-range. The subnet(s) are also used to define in-addr.arpa and
-ipv6.arpa domains which are served for reverse-DNS queries. For IPv4
-subnets, the prefix length is limited to the values 8, 16 or 24.
+range. (This can be overridden with 
+.B constructor-noauth:
+) The subnet(s) are also used to define in-addr.arpa and
+ipv6.arpa domains which are served for reverse-DNS queries. If not
+specified, the prefix length defaults to 24 for IPv4 and 64 for IPv6.
+For IPv4 subnets, the prefix length should be have the value 8, 16 or 24
+unless you are familiar with RFC 2317 and have arranged the
+in-addr.arpa delegation accordingly. 
 .TP
 .B --auth-soa=<serial>[,<hostmaster>[,<refresh>[,<retry>[,<expiry>]]]]
 Specify fields in the SOA record associated with authoritative
@@ -646,7 +651,22 @@ This forms a template which describes how to create ranges, based on the address
 
 .B --dhcp-range=::1,::400,constructor:eth0
 
-will look for addresses of the form <network>::1 on eth0 and then create a range from <network>::1 to <network>::400. If the interface is assigned more than one network, then the corresponding ranges will be automatically created, and then deprecated and finally removed again as the address is deprecated and then deleted. The interface name may have a final "*" wildcard.
+will look for addresses of the form <network>::1 or <network>:400 on
+eth0 and then create a range from <network>::1 to <network>::400. If
+the interface is assigned more than one network, then the
+corresponding ranges will be automatically created, and then
+deprecated and finally removed again as the address is deprecated and
+then deleted. The interface name may have a final "*" wildcard. Note
+that just any address on eth0 will not do: the non-prefix part must be
+equal either the start or end address given in the dhcp-range. This is
+to prevent prefixes becoming perpetual if the interface 
+gains a SLAAC address for the prefix when it is advertised by dnsmasq.
+
+There is a variant of the constructor: syntax using the keyword
+.B constructor-noauth.
+See 
+.B --auth-zone
+for an explanation of this.
 
 The optional 
 .B set:<tag> 

src/auth.c

@@ -54,6 +54,7 @@ static int filter_constructed_dhcp(struct auth_zone *zone, int flag, struct all_
   if (flag & F_IPV6)
     for (context = daemon->dhcp6; context; context = context->next)
       if ((context->flags & CONTEXT_CONSTRUCTED) &&
+	  !(context->flags & CONTEXT_NOAUTH) &&
 	  is_same_net6(&(addr_u->addr.addr6), &context->start6, context->prefix))
 	return 1;
 #endif
@@ -520,10 +521,10 @@ size_t answer_auth(struct dns_header *header, char *limit, size_t qlen, time_t n
 	      in_addr_t a = ntohl(subnet->addr4.s_addr) >> 8;
 	      char *p = name;
 	      
-	      if (subnet->prefixlen == 24)
+	      if (subnet->prefixlen >= 24)
 		p += sprintf(p, "%d.", a & 0xff);
 	      a = a >> 8;
-	      if (subnet->prefixlen != 8)
+	      if (subnet->prefixlen >= 16 )
 		p += sprintf(p, "%d.", a & 0xff);
 	      a = a >> 8;
 	      p += sprintf(p, "%d.in-addr.arpa", a & 0xff);

src/dhcp-common.c

@@ -347,21 +347,27 @@ void bindtodevice(int fd)
      to that device. This is for the use case of  (eg) OpenStack, which runs a new
      dnsmasq instance for each VLAN interface it creates. Without the BINDTODEVICE, 
      individual processes don't always see the packets they should.
-     SO_BINDTODEVICE is only available Linux. */
+     SO_BINDTODEVICE is only available Linux. 
+
+     Note that if wildcards are used in --interface, or a configured interface doesn't
+     yet exist, then more interfaces may arrive later, so we can't safely assert there
+     is only one interface and proceed.
+*/
   
   struct irec *iface, *found;
-  
+  struct iname *if_tmp;
+
+  for (if_tmp = daemon->if_names; if_tmp; if_tmp = if_tmp->next)
+    if (if_tmp->name && (!if_tmp->used || strchr(if_tmp->name, '*')))
+      return;
+
   for (found = NULL, iface = daemon->interfaces; iface; iface = iface->next)
     if (iface->dhcp_ok)
       {
 	if (!found)
 	  found = iface;
 	else if (strcmp(found->name, iface->name) != 0) 
-	  {
-	    /* more than one. */
-	    found = NULL;
-	    break;
-	  }
+	  return; /* more than one. */
       }
   
   if (found)

src/dhcp6.c

@@ -538,7 +538,9 @@ static int construct_worker(struct in6_addr *local, int prefix,
 	  }
 	
       }
-    else if (addr6part(local) == addr6part(&template->start6) && wildcard_match(template->template_interface, ifrn_name))
+    else if ((addr6part(local) == addr6part(&template->start6) ||
+	      addr6part(local) == addr6part(&template->end6)) && 
+	     wildcard_match(template->template_interface, ifrn_name))
       {
 	start6 = *local;
 	setaddr6part(&start6, addr6part(&template->start6));

src/dnsmasq.c

@@ -1355,63 +1355,71 @@ static void check_dns_listeners(fd_set *set, time_t now)
 	  
 	  if (confd == -1)
 	    continue;
-
+	  
 	  if (getsockname(confd, (struct sockaddr *)&tcp_addr, &tcp_len) == -1)
 	    {
 	      close(confd);
 	      continue;
 	    }
+	  
+	  /* Make sure that the interface list is up-to-date.
+	     
+	     We do this here as we may need the results below, and
+	     the DNS code needs them for --interface-name stuff.
 
-	   if (option_bool(OPT_NOWILD))
-	    iface = listener->iface; /* May be NULL */
-	   else 
-	     {
-	       int if_index;
-	       char intr_name[IF_NAMESIZE];
+	     Multiple calls to enumerate_interfaces() per select loop are
+	     inhibited, so calls to it in the child process (which doesn't select())
+	     have no effect. This avoids two processes reading from the same
+	     netlink fd and screwing the pooch entirely.
+	  */
  
-	       /* In full wildcard mode, need to refresh interface list.
-		  This happens automagically in CLEVERBIND */
-	       if (!option_bool(OPT_CLEVERBIND))
-		 enumerate_interfaces(0);
-	       
-	       /* if we can find the arrival interface, check it's one that's allowed */
-	       if ((if_index = tcp_interface(confd, tcp_addr.sa.sa_family)) != 0 &&
-		   indextoname(listener->tcpfd, if_index, intr_name))
-		 {
-		   struct all_addr addr;
-		   addr.addr.addr4 = tcp_addr.in.sin_addr;
+	  enumerate_interfaces(0);
+	  
+	  if (option_bool(OPT_NOWILD))
+	    iface = listener->iface; /* May be NULL */
+	  else 
+	    {
+	      int if_index;
+	      char intr_name[IF_NAMESIZE];
+	      
+	      /* if we can find the arrival interface, check it's one that's allowed */
+	      if ((if_index = tcp_interface(confd, tcp_addr.sa.sa_family)) != 0 &&
+		  indextoname(listener->tcpfd, if_index, intr_name))
+		{
+		  struct all_addr addr;
+		  addr.addr.addr4 = tcp_addr.in.sin_addr;
 #ifdef HAVE_IPV6
-		   if (tcp_addr.sa.sa_family == AF_INET6)
-		     addr.addr.addr6 = tcp_addr.in6.sin6_addr;
+		  if (tcp_addr.sa.sa_family == AF_INET6)
+		    addr.addr.addr6 = tcp_addr.in6.sin6_addr;
 #endif
-		   
-		   for (iface = daemon->interfaces; iface; iface = iface->next)
-		     if (iface->index == if_index)
-		       break;
-		   
-		   if (!iface && !loopback_exception(listener->tcpfd, tcp_addr.sa.sa_family, &addr, intr_name))
-		     client_ok = 0;
-		 }
-	       
-	       if (option_bool(OPT_CLEVERBIND))
-		 iface = listener->iface; /* May be NULL */
-	       else
-		 {
-		    /* Check for allowed interfaces when binding the wildcard address:
-		       we do this by looking for an interface with the same address as 
-		       the local address of the TCP connection, then looking to see if that's
-		       an allowed interface. As a side effect, we get the netmask of the
-		      interface too, for localisation. */
-		   
-		   for (iface = daemon->interfaces; iface; iface = iface->next)
-		     if (sockaddr_isequal(&iface->addr, &tcp_addr))
-		       break;
-		   
-		   if (!iface)
-		     client_ok = 0;
-		 }
-	     }
-	  	  
+		  
+		  for (iface = daemon->interfaces; iface; iface = iface->next)
+		    if (iface->index == if_index)
+		      break;
+		  
+		  if (!iface && !loopback_exception(listener->tcpfd, tcp_addr.sa.sa_family, &addr, intr_name))
+		    client_ok = 0;
+		}
+	      
+	      if (option_bool(OPT_CLEVERBIND))
+		iface = listener->iface; /* May be NULL */
+	      else
+		{
+		  /* Check for allowed interfaces when binding the wildcard address:
+		     we do this by looking for an interface with the same address as 
+		     the local address of the TCP connection, then looking to see if that's
+		     an allowed interface. As a side effect, we get the netmask of the
+		     interface too, for localisation. */
+		  
+		  for (iface = daemon->interfaces; iface; iface = iface->next)
+		    if (sockaddr_isequal(&iface->addr, &tcp_addr))
+		      break;
+		  
+		  if (!iface)
+		    client_ok = 0;
+		}
+	    }
+	  
 	  if (!client_ok)
 	    {
 	      shutdown(confd, SHUT_RDWR);

src/dnsmasq.h

@@ -731,6 +731,7 @@ struct dhcp_context {
 #define CONTEXT_RA          8192
 #define CONTEXT_CONF_USED  16384
 #define CONTEXT_USED       32768
+#define CONTEXT_NOAUTH     65536
 
 struct ping_result {
   struct in_addr addr;

src/forward.c

@@ -1205,8 +1205,17 @@ struct frec *get_new_frec(time_t now, int *wait)
   /* none available, calculate time 'till oldest record expires */
   if (count > daemon->ftabsize)
     {
+      static time_t last_log = 0;
+      
       if (oldest && wait)
 	*wait = oldest->time + (time_t)TIMEOUT - now;
+      
+      if ((int)difftime(now, last_log) > 5)
+	{
+	  last_log = now;
+	  my_syslog(LOG_WARNING, _("Maximum number of concurrent DNS queries reached (max: %d)"), daemon->ftabsize);
+	}
+
       return NULL;
     }
   

src/network.c

@@ -438,7 +438,9 @@ int enumerate_interfaces(int reset)
   struct addrlist *addr, *tmp;
   struct interface_name *intname;
   
-  /* DO this max once per select cycle */
+  /* Do this max once per select cycle  - also inhibits netlink socket use
+   in TCP child processes. */
+  
   if (reset)
     {
       done = 0;

src/option.c

@@ -1637,8 +1637,6 @@ static int one_opt(int option, char *arg, char *errstr, char *gen_err, int comma
 	    
 	    if (inet_pton(AF_INET, arg, &subnet->addr4))
 	      {
-		if ((prefixlen & 0x07) != 0 || prefixlen > 24)
-		  ret_err(_("bad prefix"));
 		subnet->prefixlen = (prefixlen == 0) ? 24 : prefixlen;
 		subnet->is6 = 0;
 	      }
@@ -2411,6 +2409,11 @@ static int one_opt(int option, char *arg, char *errstr, char *gen_err, int comma
 		    new->template_interface = opt_string_alloc(a[leasepos] + 12);
 		    new->flags |= CONTEXT_TEMPLATE;
 		  }
+		else if (strstr(a[leasepos], "constructor-noauth:") == a[leasepos])
+		  {
+		    new->template_interface = opt_string_alloc(a[leasepos] + 19);
+		    new->flags |= CONTEXT_TEMPLATE | CONTEXT_NOAUTH;
+		  }
 		else  
 		  break;
 	      }
@@ -2510,7 +2513,7 @@ static int one_opt(int option, char *arg, char *errstr, char *gen_err, int comma
     case 'G':  /* --dhcp-host */
       {
 	int j, k = 0;
-	char *a[6] = { NULL, NULL, NULL, NULL, NULL, NULL };
+	char *a[7] = { NULL, NULL, NULL, NULL, NULL, NULL, NULL };
 	struct dhcp_config *new;
 	struct in_addr in;
 	
@@ -2522,7 +2525,7 @@ static int one_opt(int option, char *arg, char *errstr, char *gen_err, int comma
 	new->netid = NULL;
 
 	if ((a[0] = arg))
-	  for (k = 1; k < 6; k++)
+	  for (k = 1; k < 7; k++)
 	    if (!(a[k] = split(a[k-1])))
 	      break;