diff options
Diffstat (limited to 'print-loopback.c')
| -rw-r--r-- | print-loopback.c | 136 |
1 files changed, 136 insertions, 0 deletions
diff --git a/print-loopback.c b/print-loopback.c new file mode 100644 index 0000000..9a74ae6 --- /dev/null +++ b/print-loopback.c @@ -0,0 +1,136 @@ +/* + * This module implements decoding of the Loopback Protocol, originally + * defined as the Configuration Testing Protocol. It is based on the following + * specification: + * http://www.mit.edu/people/jhawk/ctp.pdf + * + * Copyright (c) 2014 The TCPDUMP project + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS + * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE + * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, + * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; + * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER + * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN + * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + */ + +#define NETDISSECT_REWORKED +#ifdef HAVE_CONFIG_H +#include "config.h" +#endif + +#include <tcpdump-stdinc.h> + +#include "interface.h" +#include "extract.h" +#include "ether.h" +#include "addrtoname.h" + +static const char tstr[] = " [|loopback]"; +static const char cstr[] = " (corrupt)"; + +#define LOOPBACK_REPLY 1 +#define LOOPBACK_FWDDATA 2 + +static const struct tok fcode_str[] = { + { LOOPBACK_REPLY, "Reply" }, + { LOOPBACK_FWDDATA, "Forward Data" }, + { 0, NULL } +}; + +static void +loopback_message_print(netdissect_options *ndo, const u_char *cp, const u_int len) +{ + const u_char *ep = cp + len; + uint16_t function; + + if (len < 2) + goto corrupt; + /* function */ + ND_TCHECK2(*cp, 2); + function = EXTRACT_LE_16BITS(cp); + cp += 2; + ND_PRINT((ndo, ", %s", tok2str(fcode_str, " invalid (%u)", function))); + + switch (function) { + case LOOPBACK_REPLY: + if (len < 4) + goto corrupt; + /* receipt number */ + ND_TCHECK2(*cp, 2); + ND_PRINT((ndo, ", receipt number %u", EXTRACT_LE_16BITS(cp))); + cp += 2; + /* data */ + ND_PRINT((ndo, ", data (%u octets)", len - 4)); + ND_TCHECK2(*cp, len - 4); + break; + case LOOPBACK_FWDDATA: + if (len < 8) + goto corrupt; + /* forwarding address */ + ND_TCHECK2(*cp, ETHER_ADDR_LEN); + ND_PRINT((ndo, ", forwarding address %s", etheraddr_string(ndo, cp))); + cp += ETHER_ADDR_LEN; + /* data */ + ND_PRINT((ndo, ", data (%u octets)", len - 8)); + ND_TCHECK2(*cp, len - 8); + break; + default: + ND_TCHECK2(*cp, len - 2); + break; + } + return; + +corrupt: + ND_PRINT((ndo, "%s", cstr)); + ND_TCHECK2(*cp, ep - cp); + return; +trunc: + ND_PRINT((ndo, "%s", tstr)); +} + +void +loopback_print(netdissect_options *ndo, const u_char *cp, const u_int len) +{ + const u_char *ep = cp + len; + uint16_t skipCount; + + ND_PRINT((ndo, "Loopback")); + if (len < 2) + goto corrupt; + /* skipCount */ + ND_TCHECK2(*cp, 2); + skipCount = EXTRACT_LE_16BITS(cp); + cp += 2; + ND_PRINT((ndo, ", skipCount %u", skipCount)); + if (skipCount % 8) + ND_PRINT((ndo, " (bogus)")); + if (skipCount > len - 2) + goto corrupt; + loopback_message_print(ndo, cp + skipCount, len - 2 - skipCount); + return; + +corrupt: + ND_PRINT((ndo, "%s", cstr)); + ND_TCHECK2(*cp, ep - cp); + return; +trunc: + ND_PRINT((ndo, "%s", tstr)); +} + |
