| /* |
| * 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); |
| } |
| |