diff options
Diffstat (limited to 'test/vfycksum.pl')
| -rwxr-xr-x | test/vfycksum.pl | 294 |
1 files changed, 294 insertions, 0 deletions
diff --git a/test/vfycksum.pl b/test/vfycksum.pl new file mode 100755 index 0000000..b3a20be --- /dev/null +++ b/test/vfycksum.pl @@ -0,0 +1,294 @@ + +# +# validate the IPv4 header checksum. +# $bytes[] is an array of 16bit values, with $cnt elements in the array. +# +sub dump { + print "\n"; + for ($i = 0; $i < $#bytes; $i++) { + printf "%04x ", $bytes[$i]; + } + print "\n"; +} + +sub dosum { + local($seed) = $_[0]; + local($start) = $_[1]; + local($max) = $_[2]; + local($idx) = $start; + local($lsum) = $seed; + + for ($idx = $start, $lsum = $seed; $idx < $max; $idx++) { + $lsum += $bytes[$idx]; + } + $lsum = ($lsum & 0xffff) + ($lsum >> 16); + $lsum = ~$lsum & 0xffff; + return $lsum; +} + +sub ipv4check { + local($base) = $_[0]; + $hl = $bytes[$base] / 256; + return if (($hl >> 4) != 4); # IPv4 ? + $hl &= 0xf; + $hl <<= 1; # get the header length in 16bit words + + $hs = &dosum(0, $base, $base + $hl); + $osum = $bytes[$base + 5]; + + if ($hs != 0) { + $bytes[$base + 5] = 0; + $hs2 = &dosum(0, $base, $base + $hl); + $bytes[$base + 5] = $osum; + printf " IP: ($hl,%x) %x != %x", $hs, $osum, $hs2; + } else { + print " IP($base): ok "; + } + + # + # Recognise TCP & UDP and calculate checksums for each of these. + # + if (($bytes[$base + 4] & 0xff) == 6) { + &tcpcheck($base); + } + + if (($bytes[$base + 4] & 0xff) == 17) { + &udpcheck($base); + } + + if (($bytes[$base + 4] & 0xff) == 1) { + &icmpcheck($base); + } + if ($base == 0) { + print "\n"; + } +} + +sub tcpcheck { + local($base) = $_[0]; + local($hl) = $bytes[$base] / 256; + return if (($hl >> 4) != 4); + return if ($bytes[$base + 3] & 0x1fff); + $hl &= 0xf; + $hl <<= 1; + + local($hs2); + local($hs) = 6; # TCP + local($len) = $bytes[$base + 1] - ($hl << 1); + $hs += $len; + $hs += $bytes[$base + 6]; # source address + $hs += $bytes[$base + 7]; + $hs += $bytes[$base + 8]; # destination address + $hs += $bytes[$base + 9]; + local($tcpsum) = $hs; + + local($thl) = $bytes[$base + $hl + 6] >> 8; + $thl &= 0xf0; + $thl >>= 2; + + $x = $bytes[$base + 1]; + $y = ($cnt - $base) * 2; + $z = 0; + if ($bytes[$base + 1] > ($cnt - $base) * 2) { + print "[cnt=$cnt base=$base]"; + $x = $bytes[$base + 1]; + $y = ($cnt - $base) * 2; + $z = 1; + } elsif (($cnt - $base) * 2 < $hl + 20) { + $x = ($cnt - $base) * 2; + $y = $hl + 20; + $z = 2; + } elsif (($cnt - $base) * 2 < $hl + $thl) { + $x = ($cnt - $base) * 2; + $y = $hl + $thl; + $z = 3; + } elsif ($len < $thl) { + $x = ($cnt - $base) * 2; + $y = $len; + $z = 4; + } + + if ($z) { + print " TCP: missing data($x $y $z) $hl"; +# &dump(); + return; + } + + local($tcpat) = $base + $hl; + $hs = &dosum($tcpsum, $tcpat, $cnt); + if ($hs != 0) { + local($osum) = $bytes[$tcpat + 8]; + $bytes[$base + $hl + 8] = 0; + $hs2 = &dosum($tcpsum, $tcpat, $cnt); + $bytes[$tcpat + 8] = $osum; + printf " TCP: (%x) %x != %x", $hs, $osum, $hs2; + } else { + print " TCP: ok ($x $y)"; + } +} + +sub udpcheck { + local($base) = $_[0]; + local($hl) = $bytes[0] / 256; + return if (($hl >> 4) != 4); + return if ($bytes[3] & 0x1fff); + $hl &= 0xf; + $hl <<= 1; + + local($hs2); + local($hs) = 17; # UDP + local($len) = $bytes[$base + 1] - ($hl << 1); + $hs += $len; + $hs += $bytes[$base + 6]; # source address + $hs += $bytes[$base + 7]; + $hs += $bytes[$base + 8]; # destination address + $hs += $bytes[$base + 9]; + local($udpsum) = $hs; + + if ($bytes[$base + 1] > ($cnt - $base) * 2) { + print " UDP: missing data(1)"; + return; + } elsif ($bytes[$base + 1] < ($hl << 1) + 8) { + print " UDP: missing data(2)"; + return; + } elsif (($cnt - $base) * 2 < ($hl << 1) + 8) { + print " UDP: missing data(3)"; + return; + } + + local($udpat) = $base + $hl; + $hs = &dosum($udpsum, $udpat, $cnt); + local($osum) = $bytes[$udpat + 3]; + + # + # It is valid for UDP packets to have a 0 checksum field. + # If it is 0, then display what it would otherwise be. + # + if ($osum == 0) { + printf " UDP: => %x", $hs; + } elsif ($hs != 0) { + $bytes[$udpat + 3] = 0; + $hs2 = &dosum($udpsum, $udpat, $cnt); + $bytes[$udpat + 3] = $osum; + printf " UDP: (%x) %x != %x", $hs, $osum, $hs2; + } else { + print " UDP: ok"; + } +} + +sub icmpcheck { + local($base) = $_[0]; + local($hl) = $bytes[$base + 0] / 256; + return if (($hl >> 4) != 4); + return if ($bytes[3] & 0x1fff); + $hl &= 0xf; + $hl <<= 1; + + local($hs); + local($hs2); + + local($len) = $bytes[$base + 1] - ($hl << 1); + + if ($bytes[$base + 1] > ($cnt - $base) * 2) { + print " ICMP: missing data(1)"; + return; + } elsif ($bytes[$base + 1] < ($hl << 1) + 8) { + print " ICMP: missing data(2)"; + return; + } elsif (($cnt - $base) * 2 < ($hl << 1) + 8) { + print " ICMP: missing data(3)"; + return; + } + + local($osum) = $bytes[$base + $hl + 1]; + $bytes[$base + $hl + 1] = 0; + $hs2 = &dosum(0, $base + $hl, $cnt); + $bytes[$base + $hl + 1] = $osum; + + if ($osum != $hs2) { + printf " ICMP: (%x) %x != %x", $hs, $osum, $hs2; + } else { + print " ICMP: ok"; + } + if ($base == 0) { + $type = $bytes[$hl] >> 8; + if ($type == 3 || $type == 4 || $type == 5 || + $type == 11 || $type == 12) { + &ipv4check($hl + 4); + } + } +} + +while ($#ARGV >= 0) { + open(I, "$ARGV[0]") || die $!; + print "--- $ARGV[0] ---\n"; + $multi = 0; + while (<I>) { + chop; + s/#.*//g; + + # + # If the first non-comment, non-empty line of input starts + # with a '[', then allow the input to be a multi-line hex + # string, otherwise it has to be all on one line. + # + if (/^\[/) { + $multi=1; + s/^\[[^]]*\]//g; + + } + s/^ *//g; + if (length == 0) { + next if ($cnt == 0); + &ipv4check(0); + $cnt = 0; + $multi = 0; + next; + } + + # + # look for 16 bits, represented with leading 0's as required, + # in hex. + # + s/\t/ /g; + while (/^[0-9a-fA-F][0-9a-fA-F] [0-9a-fA-F][0-9a-fA-F] .*/) { + s/^([0-9a-fA-F][0-9a-fA-F]) ([0-9a-fA-F][0-9a-fA-F]) (.*)/$1$2 $3/; + } + while (/.* [0-9a-fA-F][0-9a-fA-F] [0-9a-fA-F][0-9a-fA-F] .*/) { +$b=$_; + s/(.*?) ([0-9a-fA-F][0-9a-fA-F]) ([0-9a-fA-F][0-9a-fA-F]) (.*)/$1 $2$3 $4/g; + } + if (/.* [0-9a-fA-F][0-9a-fA-F] [0-9a-fA-F][0-9a-fA-F]/) { +$b=$_; + s/(.*?) ([0-9a-fA-F][0-9a-fA-F]) ([0-9a-fA-F][0-9a-fA-F])/$1 $2$3/g; + } + while (/^[0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F].*/) { + $x = $_; + $x =~ s/([0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F]).*/$1/; + $x =~ s/ *//g; + $y = hex $x; + s/[0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F] *(.*)/$1/; + $bytes[$cnt] = $y; +#print "bytes[$cnt] = $x\n"; + $cnt++; + } + + # + # Pick up stragler bytes. + # + if (/^[0-9a-fA-F][0-9a-fA-F]/) { + $y = hex $_; + $bytes[$cnt++] = $y * 256; + } + if ($multi == 0 && $cnt > 0) { + &ipv4check(0); + $cnt = 0; + } + } + + if ($cnt > 0) { + &ipv4check(0); + } + close(I); + shift(@ARGV); +} |
