216 lines
7.4 KiB
C
216 lines
7.4 KiB
C
/*
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* This file implements decoding of ZeroMQ network protocol(s).
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*
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*
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* Copyright (c) 2013 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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static const char tstr[] = " [|zmtp1]";
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/* Maximum number of ZMTP/1.0 frame body bytes (without the flags) to dump in
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* hex and ASCII under a single "-v" flag.
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*/
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#define VBYTES 128
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/*
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* Below is an excerpt from the "13/ZMTP" specification:
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*
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* A ZMTP message consists of 1 or more frames.
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*
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* A ZMTP frame consists of a length, followed by a flags field and a frame
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* body of (length - 1) octets. Note: the length includes the flags field, so
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* an empty frame has a length of 1.
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*
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* For frames with a length of 1 to 254 octets, the length SHOULD BE encoded
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* as a single octet. The minimum valid length of a frame is 1 octet, thus a
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* length of 0 is invalid and such frames SHOULD be discarded silently.
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*
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* For frames with lengths of 255 and greater, the length SHALL BE encoded as
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* a single octet with the value 255, followed by the length encoded as a
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* 64-bit unsigned integer in network byte order. For frames with lengths of
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* 1 to 254 octets this encoding MAY be also used.
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*
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* The flags field consists of a single octet containing various control
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* flags. Bit 0 is the least significant bit.
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*
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* - Bit 0 (MORE): More frames to follow. A value of 0 indicates that there
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* are no more frames to follow. A value of 1 indicates that more frames
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* will follow. On messages consisting of a single frame the MORE flag MUST
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* be 0.
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*
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* - Bits 1-7: Reserved. Bits 1-7 are reserved for future use and SHOULD be
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* zero.
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*/
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static const u_char *
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zmtp1_print_frame(netdissect_options *ndo, const u_char *cp, const u_char *ep) {
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uint64_t body_len_declared, body_len_captured, header_len;
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uint8_t flags;
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ND_PRINT((ndo, "\n\t"));
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ND_TCHECK2(*cp, 1); /* length/0xFF */
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if (cp[0] != 0xFF) {
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header_len = 1; /* length */
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body_len_declared = cp[0];
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if (body_len_declared == 0)
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return cp + header_len; /* skip to next frame */
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ND_PRINT((ndo, " frame flags+body (8-bit) length %u", cp[0]));
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ND_TCHECK2(*cp, header_len + 1); /* length, flags */
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flags = cp[1];
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} else {
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header_len = 1 + 8; /* 0xFF, length */
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ND_PRINT((ndo, " frame flags+body (64-bit) length"));
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ND_TCHECK2(*cp, header_len); /* 0xFF, length */
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body_len_declared = EXTRACT_64BITS(cp + 1);
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if (body_len_declared == 0)
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return cp + header_len; /* skip to next frame */
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ND_PRINT((ndo, " %" PRIu64, body_len_declared));
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ND_TCHECK2(*cp, header_len + 1); /* 0xFF, length, flags */
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flags = cp[9];
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}
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body_len_captured = ep - cp - header_len;
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if (body_len_declared > body_len_captured)
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ND_PRINT((ndo, " (%" PRIu64 " captured)", body_len_captured));
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ND_PRINT((ndo, ", flags 0x%02x", flags));
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if (ndo->ndo_vflag) {
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uint64_t body_len_printed = min(body_len_captured, body_len_declared);
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ND_PRINT((ndo, " (%s|%s|%s|%s|%s|%s|%s|%s)",
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flags & 0x80 ? "MBZ" : "-",
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flags & 0x40 ? "MBZ" : "-",
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flags & 0x20 ? "MBZ" : "-",
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flags & 0x10 ? "MBZ" : "-",
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flags & 0x08 ? "MBZ" : "-",
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flags & 0x04 ? "MBZ" : "-",
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flags & 0x02 ? "MBZ" : "-",
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flags & 0x01 ? "MORE" : "-"));
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if (ndo->ndo_vflag == 1)
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body_len_printed = min(VBYTES + 1, body_len_printed);
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if (body_len_printed > 1) {
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ND_PRINT((ndo, ", first %" PRIu64 " byte(s) of body:", body_len_printed - 1));
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hex_and_ascii_print(ndo, "\n\t ", cp + header_len + 1, body_len_printed - 1);
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ND_PRINT((ndo, "\n"));
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}
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}
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ND_TCHECK2(*cp, header_len + body_len_declared); /* Next frame within the buffer ? */
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return cp + header_len + body_len_declared;
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trunc:
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ND_PRINT((ndo, "%s", tstr));
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return ep;
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}
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void
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zmtp1_print(netdissect_options *ndo, const u_char *cp, u_int len) {
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const u_char *ep = min(ndo->ndo_snapend, cp + len);
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ND_PRINT((ndo, ": ZMTP/1.0"));
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while (cp < ep)
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cp = zmtp1_print_frame(ndo, cp, ep);
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}
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/* The functions below decode a ZeroMQ datagram, supposedly stored in the "Data"
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* field of an ODATA/RDATA [E]PGM packet. An excerpt from zmq_pgm(7) man page
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* follows.
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*
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* In order for late joining consumers to be able to identify message
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* boundaries, each PGM datagram payload starts with a 16-bit unsigned integer
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* in network byte order specifying either the offset of the first message frame
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* in the datagram or containing the value 0xFFFF if the datagram contains
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* solely an intermediate part of a larger message.
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*
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* Note that offset specifies where the first message begins rather than the
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* first message part. Thus, if there are trailing message parts at the
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* beginning of the packet the offset ignores them and points to first initial
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* message part in the packet.
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*/
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static const u_char *
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zmtp1_print_intermediate_part(netdissect_options *ndo, const u_char *cp, const u_int len) {
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u_int frame_offset;
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uint64_t remaining_len;
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ND_TCHECK2(*cp, 2);
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frame_offset = EXTRACT_16BITS(cp);
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ND_PRINT((ndo, "\n\t frame offset 0x%04x", frame_offset));
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cp += 2;
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remaining_len = ndo->ndo_snapend - cp; /* without the frame length */
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if (frame_offset == 0xFFFF)
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frame_offset = len - 2; /* always within the declared length */
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else if (2 + frame_offset > len) {
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ND_PRINT((ndo, " (exceeds datagram declared length)"));
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goto trunc;
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}
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/* offset within declared length of the datagram */
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if (frame_offset) {
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ND_PRINT((ndo, "\n\t frame intermediate part, %u bytes", frame_offset));
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if (frame_offset > remaining_len)
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ND_PRINT((ndo, " (%"PRIu64" captured)", remaining_len));
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if (ndo->ndo_vflag) {
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uint64_t len_printed = min(frame_offset, remaining_len);
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if (ndo->ndo_vflag == 1)
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len_printed = min(VBYTES, len_printed);
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if (len_printed > 1) {
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ND_PRINT((ndo, ", first %"PRIu64" byte(s):", len_printed));
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hex_and_ascii_print(ndo, "\n\t ", cp, len_printed);
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ND_PRINT((ndo, "\n"));
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}
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}
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}
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return cp + frame_offset;
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trunc:
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ND_PRINT((ndo, "%s", tstr));
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return cp + len;
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}
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void
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zmtp1_print_datagram(netdissect_options *ndo, const u_char *cp, const u_int len) {
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const u_char *ep = min(ndo->ndo_snapend, cp + len);
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cp = zmtp1_print_intermediate_part(ndo, cp, len);
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while (cp < ep)
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cp = zmtp1_print_frame(ndo, cp, ep);
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}
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