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