X-Git-Url: http://git.jankratochvil.net/?a=blobdiff_plain;f=netdnsspoof;h=af67626c8cbb22c332fef8f615fce509edbd8d46;hb=172e36acd9a868fb687b61ec5a6f870b195c1c7d;hp=fec77418ef463913436fa4330c5ca622966a275f;hpb=35a0ffb072701b56c7c1818ff826338a74cf868c;p=netdnsspoof.git diff --git a/netdnsspoof b/netdnsspoof index fec7741..af67626 100755 --- a/netdnsspoof +++ b/netdnsspoof @@ -1,6 +1,7 @@ #! /usr/bin/perl # -# $Id$ +# $Id$ + use strict; use warnings; @@ -10,6 +11,8 @@ require Net::DNS::Packet; use Fcntl; use Carp qw(cluck confess); use Socket; +use Socket::MsgHdr; +require "linux/in.ph"; my $V=1; @@ -42,6 +45,15 @@ my $sock_udp_priv=IO::Socket::INET->new( ) or die "socket(): $!"; ###fcntl($sock_udp,F_SETFL,O_NONBLOCK) or die "fnctl(sock_udp,F_SETFL,O_NONBLOCK)"; +my $ip_pktinfo_got=setsockopt $sock_udp,IPPROTO_IP(),IP_PKTINFO(),pack("i",1); +# FIXME: Why Linux kernel 2.6.9-1.678_FC3 returns 1 instead of 0? +confess 'setsockopt(sock_udp,IPPROTO_IP,IP_PKTINFO,&1)='.$ip_pktinfo_got + if !defined $ip_pktinfo_got || 0>$ip_pktinfo_got; +my $ip_pktinfo_val=getsockopt $sock_udp,IPPROTO_IP(),IP_PKTINFO(); +confess 'getsockopt(sock_udp,IPPROTO_IP,IP_PKTINFO)!=1' + if 1!=unpack("i",$ip_pktinfo_val); + + sub id_next() { our $id; @@ -53,11 +65,13 @@ sub id_next() my %sent; -sub got_query($$) +sub got_query($$$) { -my($msg,$from_addr)=@_; +my($msg,$from_addr,$pktinfo_data)=@_; my $query=Net::DNS::Packet->new(\$msg); + # FIXME: It really occured on hoteltest. + do { warn "Failed to parse DNS packet query: ".unpack("H*",$msg); return; } if !$query; my $query_id_orig=$query->header()->id(); my $query_id=id_next(); $query->header()->id($query_id); @@ -66,6 +80,7 @@ my($msg,$from_addr)=@_; $sent{$query_id}={ "msg"=>$msg, "from_addr"=>$from_addr, + "pktinfo_data"=>$pktinfo_data, "query"=>$query, }; warn "registered pending query id $query_id..." if $D; @@ -110,7 +125,16 @@ my($query_from_addr,$query)=@_; $spoof->header()->id($query->header()->id()); my $msg_spoof=$spoof->data(); warn "sending spoof reply..." if $D; - send $sock_udp,$msg_spoof,0,$query_from_addr or cluck "send(): $!"; + return $msg_spoof; + if ($V) { + my($query_from_addr_port,$query_from_addr_host)=sockaddr_in($query_from_addr); + my $query_from_addr_name=inet_ntoa $query_from_addr_host; + print localtime()." spoof:" + ." from=$query_from_addr_name:$query_from_addr_port" + ." qname=".$question->qname() + ." ip=".$opt_spoof_ip + ."\n"; + } } sub got_forward_reply($) @@ -120,26 +144,33 @@ my($msg)=@_; warn "parsing reply from our forwarded DNS..." if $D; my $reply=Net::DNS::Packet->new(\$msg); my $reply_id=$reply->header()->id(); - my($query_msg,$query_from_addr,$query); + my($query_msg,$query_from_addr,$query_pktinfo_data,$query); if (my $hash=$sent{$reply_id}) { delete $sent{$reply_id}; - $query_msg =$hash->{"msg"}; - $query_from_addr=$hash->{"from_addr"}; - $query =$hash->{"query"}; + $query_msg =$hash->{"msg"}; + $query_from_addr =$hash->{"from_addr"}; + $query_pktinfo_data=$hash->{"pktinfo_data"}; + $query =$hash->{"query"}; warn "deleted pending record with id $reply_id." if $D; } else { warn "Got DNS reply for unknown packet id $reply_id"; return; } + my $reply_back; if (check_spoofable($reply,$query)) { - reply_spoof $query_from_addr,$query; - return; + $reply_back=reply_spoof $query_from_addr,$query or return; + } + else { + $reply->header()->id($query->header()->id()); + $reply_back=$reply->data(); + warn "passing reply back to the original query host..." if $D; } - $reply->header()->id($query->header()->id()); - my $reply_back=$reply->data(); - warn "parsing reply back to the original query host..." if $D; - send $sock_udp,$reply_back,0,$query_from_addr or cluck "send(): $!"; + my $msghdr=Socket::MsgHdr->new(); + $msghdr->buf($reply_back); + $msghdr->name($query_from_addr); + $msghdr->cmsghdr(IPPROTO_IP(),IP_PKTINFO(),$query_pktinfo_data); + sendmsg $sock_udp,$msghdr or cluck "sendmsg(): $!"; } $V and print localtime()." START\n"; @@ -152,27 +183,39 @@ for (;;) { warn "got from select." if $D; die "Invalid select(2): ".Dumper($got) if !defined $got || $got<0; - for my $sock ($sock_udp,$sock_udp_priv) { + if (vec($rfds,fileno($sock_udp_priv),1)) {{ my $msg; - defined(my $from_addr=recv $sock,$msg,0x1000,0) or do { cluck "recv(): $!"; next; }; - warn "got packet." if $D; + defined(my $from_addr=recv $sock_udp_priv,$msg,0x10000,0) or do { cluck "recv(sock_udp_priv): $!"; next; }; + warn "got packet from forwarding DNS..." if $D; my($from_addr_port,$from_addr_host)=sockaddr_in($from_addr); - if ($from_addr_host eq $forward_host && $from_addr_port eq $opt_forward_port) { - warn "packet returned from forwarding DNS..." if $D; - if ($sock eq $sock_udp) { - warn "packet returned from forwarding DNS forbidden from the main listening socket"; - next; - } - got_forward_reply $msg; + if ($from_addr_host ne $forward_host || $from_addr_port ne $opt_forward_port) { + warn "original query forbidden from the private forwarding socket"; + next; } - else { - warn "original query..." if $D; - if ($sock eq $sock_udp_priv) { - warn "original query forbidden from the private forwarding socket"; - next; - } - got_query $msg,$from_addr; + got_forward_reply $msg; + }} + if (vec($rfds,fileno($sock_udp),1)) {{ + # "namelen"=>0x10 to prevent: Bad arg length for Socket::unpack_sockaddr_in, length is 4096, should be 16 at /usr/lib/perl5/5.8.5/i386-linux-thread-multi/Socket.pm line 370. + my $msghdr=Socket::MsgHdr->new("buflen"=>0x10000,"namelen"=>0x10,"controllen"=>0x1000); + defined(recvmsg($sock_udp,$msghdr,0)) or do { cluck "recvmsg(sock_udp): $!"; next; }; + warn "got packet as original query..." if $D; + my $msg=$msghdr->buf(); + my $pktinfo_data; + my @cmsg=$msghdr->cmsghdr(); + while (my($level,$type,$data)=splice(@cmsg,0,3)) { + do { warn "unknown cmsg level $level"; next; } if $level!=IPPROTO_IP(); + do { warn "unknown cmsg level $type"; next; } if $type !=IP_PKTINFO(); + $pktinfo_data=$data; } - } + do { warn "IP_PKTINFO not found for a packet"; next; } if !defined $pktinfo_data; + my $from_addr=$msghdr->name(); + my($from_addr_port,$from_addr_host)=sockaddr_in($from_addr); + + if ($from_addr_host eq $forward_host && $from_addr_port eq $opt_forward_port) { + warn "packet returned from forwarding DNS forbidden from the main listening socket"; + next; + } + got_query $msg,$from_addr,$pktinfo_data; + }} }