diff options
Diffstat (limited to 'print-loopback.c')
| -rw-r--r-- | print-loopback.c | 135 |
1 files changed, 135 insertions, 0 deletions
diff --git a/print-loopback.c b/print-loopback.c new file mode 100644 index 0000000..ee0caf3 --- /dev/null +++ b/print-loopback.c @@ -0,0 +1,135 @@ +/* + * 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. + */ + +/* \summary: Loopback Protocol printer */ + +/* + * originally defined as the Ethernet Configuration Testing Protocol. + * specification: https://www.mit.edu/people/jhawk/ctp.pdf + */ + +#ifdef HAVE_CONFIG_H +#include <config.h> +#endif + +#include "netdissect-stdinc.h" + +#define ND_LONGJMP_FROM_TCHECK +#include "netdissect.h" +#include "extract.h" +#include "addrtoname.h" + + +#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, u_int len) +{ + uint16_t function; + + if (len < 2) + goto invalid; + /* function */ + function = GET_LE_U_2(cp); + cp += 2; + len -= 2; + ND_PRINT(", %s", tok2str(fcode_str, " invalid (%u)", function)); + + switch (function) { + case LOOPBACK_REPLY: + if (len < 2) + goto invalid; + /* receipt number */ + ND_PRINT(", receipt number %u", GET_LE_U_2(cp)); + cp += 2; + len -= 2; + /* data */ + ND_PRINT(", data (%u octets)", len); + ND_TCHECK_LEN(cp, len); + break; + case LOOPBACK_FWDDATA: + if (len < MAC_ADDR_LEN) + goto invalid; + /* forwarding address */ + ND_PRINT(", forwarding address %s", GET_ETHERADDR_STRING(cp)); + cp += MAC_ADDR_LEN; + len -= MAC_ADDR_LEN; + /* data */ + ND_PRINT(", data (%u octets)", len); + ND_TCHECK_LEN(cp, len); + break; + default: + ND_TCHECK_LEN(cp, len); + break; + } + return; + +invalid: + nd_print_invalid(ndo); + ND_TCHECK_LEN(cp, len); +} + +void +loopback_print(netdissect_options *ndo, + const u_char *cp, u_int len) +{ + uint16_t skipCount; + + ndo->ndo_protocol = "loopback"; + ND_PRINT("Loopback"); + if (len < 2) + goto invalid; + /* skipCount */ + skipCount = GET_LE_U_2(cp); + cp += 2; + len -= 2; + ND_PRINT(", skipCount %u", skipCount); + if (skipCount % 8) + ND_PRINT(" (bogus)"); + if (skipCount > len) + goto invalid; + /* the octets to skip */ + ND_TCHECK_LEN(cp, skipCount); + cp += skipCount; + len -= skipCount; + /* the first message to decode */ + loopback_message_print(ndo, cp, len); + return; + +invalid: + nd_print_invalid(ndo); + ND_TCHECK_LEN(cp, len); +} + |