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1 | #!/usr/bin/perl |
2 | # Simple tunnel for userv-ipif tunnels. |
3 | # |
4 | # usage: |
5 | # udptunnel |
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6 | # [ -l[<local-command/arg>] ... . ] |
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7 | # <public-local-host/addr>,<public-local-port> |
8 | # <public-remote-host/addr>,<public-remote-port> |
9 | # <private-local-addr>,<private-remote-addr>,<mtu>,<proto> |
10 | # <keepalive>,<timeout> |
11 | # <extra-local-nets> <extra-remote-nets> |
12 | # [ <remote-command> [<remote-args> ...] ] |
13 | # |
14 | # <local-public-port> may be number or `print' or `silent' |
15 | # |
16 | # <remote-public-port> may number or `command', in which case |
17 | # <remote-command> must be specified and should run udptunnel at the |
18 | # remote end; it will be invoked as |
19 | # <remote-command> <public-remote-host/addr>,print |
20 | # <public-local-addr>,<public-local-port> |
21 | # <private-remote-addr>,<private-local-addr>,<mtu>,<proto> |
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22 | # <keepalive>,<timeout> |
23 | # <extra-remote-nets> <extra-local-nets> |
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24 | # |
25 | # udptunnel will userv ipif locally, as |
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26 | # userv root ipif <private-local-addr>,<private-remote-addr>,<mtu>,<proto> |
27 | # <extra-local-nets> |
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28 | # or, if -lc was given, userv root ipif is replaced with the argument(s) to |
29 | # successive -lc options. |
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30 | |
31 | use Socket; |
32 | use POSIX; |
33 | use Fcntl; |
34 | |
35 | $progname= $0; $progname =~ s,.*/,,; |
36 | $|=1; |
37 | |
38 | chomp($hostname= `uname -n`); |
39 | $? and die "$progname: cannot get hostname (uname failed with code $?)\n"; |
40 | |
41 | sub quit ($) { die "$progname - $hostname: fatal error: $_[0]\n"; } |
42 | sub debug ($) { print "$progname - $hostname: debug: $_[0]\n"; } |
43 | sub fail ($) { quit("unexpected system call failure: $_[0]: $!\n"); } |
44 | sub warning ($) { warn "$progname - $hostname: $_[0]\n"; } |
45 | |
46 | sub eat_addr_port ($) { |
47 | my ($x) = @_; |
48 | @ARGV or quit("<host/addr>,<port> missing"); |
49 | $_= shift(@ARGV); |
50 | $_ =~ m/^([^,]+)\,(\d+|$x)$/ or quit("$_: <host/addr>,<port> bad syntax"); |
51 | return ($1,$2); |
52 | } |
53 | sub conv_host_addr ($) { |
54 | my ($s,$r) = @_; |
55 | defined($r= inet_aton($s)) or quit("$s: cannot convert to address"); |
56 | return $r; |
57 | } |
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58 | sub conv_port_number ($) { |
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59 | my ($s,$r) = @_; |
60 | if ($s =~ m/\d/) { |
61 | $r= $s+0; |
62 | $r>0 && $r<65536 or quit("$s: port out of range"); |
63 | } else { |
64 | $r= 0; |
65 | } |
66 | return $r; |
67 | } |
68 | sub show_addr_port ($) { |
69 | my ($s,@s) = @_; |
70 | @s= unpack_sockaddr_in($s); |
71 | return inet_ntoa($s[1]).','.$s[0]; |
72 | } |
73 | |
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74 | @lcmd= (); |
75 | |
76 | while ($ARGV[0] =~ m/^-/) { |
77 | $_= shift @ARGV; |
78 | last if $_ eq '--'; |
79 | if (s/^-l//) { |
80 | push @lcmd,$_ if length; |
81 | while (@ARGV && ($_= shift @ARGV) ne '-') { push @lcmd, $_; } |
82 | } else { |
83 | quit("unknown option \`$_'"); |
84 | } |
85 | } |
86 | |
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87 | ($las,$lps)= eat_addr_port('print|silent'); |
88 | $la= conv_host_addr($las); |
89 | $lp= conv_port_number($lps); |
90 | $ls= pack_sockaddr_in $lp,$la; |
91 | |
92 | ($ras,$rps)= eat_addr_port('command'); |
93 | $rp= conv_port_number($rps); |
94 | $ra= $rps eq 'command' ? '' : conv_host_addr($ras); |
95 | |
96 | $_= shift @ARGV; |
97 | m/^([.0-9]+),([.0-9]+),(\d+),(slip|cslip)$/ |
98 | or quit("lvaddr,rvaddr,mtu,proto missing or bad syntax or proto not [c]slip"); |
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99 | ($lva,$rva,$mtu,$proto) = ($1,$2,$3,$4); |
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100 | |
101 | $_= shift @ARGV; |
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102 | m/^(\d+),(\d+)$/ or quit("keepalive,timeout missing or bad syntax"); |
103 | ($keepalive,$timeout)= ($1,$2); |
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104 | $keepalive && ($timeout > $keepalive*2) or quit("timeout must be < 2*keepalive") |
105 | if $timeout; |
106 | |
107 | $lepn= shift @ARGV; |
108 | $repn= shift @ARGV; |
109 | |
110 | alarm($timeout); |
111 | |
112 | defined($udp= getprotobyname('udp')) or fail("getprotobyname udp"); |
113 | |
114 | socket(L,PF_INET,SOCK_DGRAM,$udp) or fail("socket"); |
115 | bind(L,$ls) or quit("bind failed: $!"); |
116 | defined($ls= getsockname(L)) or fail("getsockname"); |
117 | $lsp= show_addr_port($ls); |
118 | |
119 | if ($rps eq 'command') { |
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120 | quit("when using ,command for remote, must supply command") unless @ARGV; |
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121 | @rcmd= (@ARGV, "$ras,print", "$lsp", "$rva,$lva,$mtu,$proto", |
122 | "$keepalive,$timeout", $repn, $lepn); |
123 | debug("remote command @rcmd"); |
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124 | defined($c= open C,"-|") or fail("fork for remote"); |
125 | if (!$c) { |
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126 | exec @rcmd; die "$progname: error: failed to execute $rcmd[0]: $!\n"; |
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127 | } |
128 | $_= <C>; |
129 | if (!length) { |
130 | close C; |
131 | quit($? ? "remote command failed (code $?)" : "no details received from remote"); |
132 | } |
133 | chomp; |
134 | m/^([.0-9]+)\,(\d+)$/ or quit("invalid details from remote end ($_)"); |
135 | ($ras,$rps) = ($1,$2); |
136 | $ra= conv_host_addr($ras); |
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137 | $rp= conv_port_number($rps); |
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138 | defined($c2= fork) or fail("fork for cat"); |
139 | if (!$c2) { |
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140 | open(STDIN,"<&C") or fail("redirect remote pipe to stdin"); |
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141 | close C; |
142 | exec "cat"; fail("execute cat"); |
143 | } |
144 | } else { |
145 | quit("when not using ,command for remote, must not supply command") if @ARGV; |
146 | } |
147 | |
148 | $rs= pack_sockaddr_in $rp,$ra; |
149 | $rsp= show_addr_port($rs); |
150 | |
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151 | if ($lps eq 'print') { print($lsp,"\n") or quit("write port to stdout: $!"); } |
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152 | |
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153 | @lcmd= qw(userv root ipif) unless @lcmd; |
154 | |
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155 | debug("using remote $rsp local $lsp"); |
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156 | push @lcmd, ("$lva,$rva,$mtu,$proto",$lepn); |
157 | debug("local command @lcmd"); |
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158 | |
159 | pipe(UR,UW) or fail("up pipe"); |
160 | pipe(DR,DW) or fail("down pipe"); |
161 | |
162 | defined($c3= fork) or fail("fork for ipif"); |
163 | if (!$c3) { |
164 | close UR; close DW; |
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165 | open(STDIN,"<&DR") or fail("reopen stdin for packets"); |
166 | open(STDOUT,">&UW") or fail("reopen stdout for packets"); |
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167 | exec @lcmd; |
168 | quit("cannot execute $lcmd[0]: $!"); |
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169 | } |
170 | close UW; |
171 | close DR; |
172 | |
173 | $upyet= 0; |
174 | $downyet= 0; |
175 | |
176 | $wantreadfds=''; |
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177 | vec($wantreadfds,fileno(UR),1)= 1; |
178 | vec($wantreadfds,fileno(L),1)= 1; |
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179 | |
180 | sub nonblock ($) { |
181 | my ($fh,$fl) = @_; |
182 | ($fl= fcntl($fh,F_GETFL,0)) or fail("nonblock F_GETFL"); |
183 | $fl |= O_NONBLOCK; |
184 | fcntl($fh, F_SETFL, $fl) or fail("nonblock F_SETFL"); |
185 | } |
186 | |
187 | nonblock('UR'); |
188 | nonblock('L'); |
189 | |
190 | $upbuf= ''; |
191 | |
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192 | sub now () { my ($v); defined($v= time) or fail("get time"); return $v; } |
193 | if ($keepalive) { $nextsendka= now(); } |
194 | |
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195 | for (;;) { |
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196 | if ($keepalive) { |
197 | $now= now(); |
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198 | $thistimeout= $nextsendka-$now; |
199 | if ($thistimeout < 0) { |
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200 | defined(send L,"\300",0,$rs) |
201 | or warning("transmit keepalive error: $!"); |
202 | $nextsendka= $now+$keepalive; |
198680ad |
203 | $thistimeout= $keepalive; |
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204 | } |
205 | } else { |
198680ad |
206 | $thistimeout= undef; |
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207 | } |
198680ad |
208 | select($readfds=$wantreadfds,'','',$thistimeout); |
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209 | for (;;) { |
210 | if (!defined($r= sysread(UR,$upbuf,$mtu*2+3,length($upbuf)))) { |
211 | $! == EAGAIN || warning("tunnel endpoint read error: $!"); |
212 | last; |
213 | } |
214 | if (!$r) { |
215 | quit "tunnel endpoint closed by system"; |
216 | } |
217 | while (($p= index($upbuf,"\300")) >= 0) { |
198680ad |
218 | if (!defined(send L,substr($upbuf,0,$p+1),0,$rs)) { |
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219 | warning("transmit error: $!"); |
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220 | } else { |
221 | if (!$upyet) { |
222 | $upyet= 1; |
223 | debug($downyet ? "tunnel open at this end" : "transmitting"); |
224 | } |
225 | if ($keepalive) { $nextsendka= now()+$keepalive; } |
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226 | } |
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227 | $upbuf= substr($upbuf,$p+1); |
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228 | } |
229 | } |
230 | while (defined($rs_from= recv L,$downbuf,$mtu*2+3,0)) { |
231 | $rsp_from= show_addr_port($rs_from); |
232 | if ($rsp_from ne $rsp) { |
233 | warning("got packet from incorrect peer $rsp_from"); |
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234 | next; |
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235 | } |
236 | if (!defined($r= syswrite(DW,$downbuf,length $downbuf))) { |
237 | warning("tunnel endpoint write error: $!"); |
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238 | } elsif ($r != length $downbuf) { |
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239 | warning("tunnel endpoint wrong write length"); |
240 | } else { |
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241 | if (!$downyet) { |
242 | $downyet= 1; |
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243 | debug($upyet ? "tunnel open at this end" : "receiving"); |
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244 | } |
245 | alarm($timeout) if $timeout; |
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246 | } |
247 | } |
248 | $! == EAGAIN || warning("receive error: $!"); |
249 | } |