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Diffstat (limited to 'print-zeromq.c')
| -rw-r--r-- | print-zeromq.c | 215 |
1 files changed, 215 insertions, 0 deletions
diff --git a/print-zeromq.c b/print-zeromq.c new file mode 100644 index 0000000..c702046 --- /dev/null +++ b/print-zeromq.c @@ -0,0 +1,215 @@ +/* + * Copyright (c) 2013 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: ZeroMQ Message Transport Protocol (ZMTP) printer */ + +#ifdef HAVE_CONFIG_H +#include <config.h> +#endif + +#include "netdissect-stdinc.h" + +#include "netdissect.h" +#include "extract.h" + + +/* Maximum number of ZMTP/1.0 frame body bytes (without the flags) to dump in + * hex and ASCII under a single "-v" flag. + */ +#define VBYTES 128 + +/* + * Below is an excerpt from the "13/ZMTP" specification: + * + * A ZMTP message consists of 1 or more frames. + * + * A ZMTP frame consists of a length, followed by a flags field and a frame + * body of (length - 1) octets. Note: the length includes the flags field, so + * an empty frame has a length of 1. + * + * For frames with a length of 1 to 254 octets, the length SHOULD BE encoded + * as a single octet. The minimum valid length of a frame is 1 octet, thus a + * length of 0 is invalid and such frames SHOULD be discarded silently. + * + * For frames with lengths of 255 and greater, the length SHALL BE encoded as + * a single octet with the value 255, followed by the length encoded as a + * 64-bit unsigned integer in network byte order. For frames with lengths of + * 1 to 254 octets this encoding MAY be also used. + * + * The flags field consists of a single octet containing various control + * flags. Bit 0 is the least significant bit. + * + * - Bit 0 (MORE): More frames to follow. A value of 0 indicates that there + * are no more frames to follow. A value of 1 indicates that more frames + * will follow. On messages consisting of a single frame the MORE flag MUST + * be 0. + * + * - Bits 1-7: Reserved. Bits 1-7 are reserved for future use and SHOULD be + * zero. + */ + +static const u_char * +zmtp1_print_frame(netdissect_options *ndo, const u_char *cp, const u_char *ep) +{ + uint64_t body_len_declared, body_len_captured, header_len; + uint8_t flags; + + ND_PRINT("\n\t"); + + if (GET_U_1(cp) != 0xFF) { /* length/0xFF */ + header_len = 1; /* length */ + body_len_declared = GET_U_1(cp); + ND_PRINT(" frame flags+body (8-bit) length %" PRIu64, body_len_declared); + } else { + header_len = 1 + 8; /* 0xFF, length */ + ND_PRINT(" frame flags+body (64-bit) length"); + ND_TCHECK_LEN(cp, header_len); /* 0xFF, length */ + body_len_declared = GET_BE_U_8(cp + 1); + ND_PRINT(" %" PRIu64, body_len_declared); + } + if (body_len_declared == 0) + return cp + header_len; /* skip to the next frame */ + ND_TCHECK_LEN(cp, header_len + 1); /* ..., flags */ + flags = GET_U_1(cp + header_len); + + body_len_captured = ep - cp - header_len; + if (body_len_declared > body_len_captured) + ND_PRINT(" (%" PRIu64 " captured)", body_len_captured); + ND_PRINT(", flags 0x%02x", flags); + + if (ndo->ndo_vflag) { + uint64_t body_len_printed = ND_MIN(body_len_captured, body_len_declared); + + ND_PRINT(" (%s|%s|%s|%s|%s|%s|%s|%s)", + flags & 0x80 ? "MBZ" : "-", + flags & 0x40 ? "MBZ" : "-", + flags & 0x20 ? "MBZ" : "-", + flags & 0x10 ? "MBZ" : "-", + flags & 0x08 ? "MBZ" : "-", + flags & 0x04 ? "MBZ" : "-", + flags & 0x02 ? "MBZ" : "-", + flags & 0x01 ? "MORE" : "-"); + + if (ndo->ndo_vflag == 1) + body_len_printed = ND_MIN(VBYTES + 1, body_len_printed); + if (body_len_printed > 1) { + ND_PRINT(", first %" PRIu64 " byte(s) of body:", body_len_printed - 1); + hex_and_ascii_print(ndo, "\n\t ", cp + header_len + 1, body_len_printed - 1); + } + } + + /* + * Do not advance cp by the sum of header_len and body_len_declared + * before each offset has successfully passed ND_TCHECK_LEN() as the + * sum can roll over (9 + 0xfffffffffffffff7 = 0) and cause an + * infinite loop. + */ + cp += header_len; + ND_TCHECK_LEN(cp, body_len_declared); /* Next frame within the buffer ? */ + return cp + body_len_declared; + +trunc: + nd_trunc_longjmp(ndo); +} + +void +zmtp1_print(netdissect_options *ndo, const u_char *cp, u_int len) +{ + const u_char *ep = ND_MIN(ndo->ndo_snapend, cp + len); + + ndo->ndo_protocol = "zmtp1"; + ND_PRINT(": ZMTP/1.0"); + while (cp < ep) + cp = zmtp1_print_frame(ndo, cp, ep); +} + +/* The functions below decode a ZeroMQ datagram, supposedly stored in the "Data" + * field of an ODATA/RDATA [E]PGM packet. An excerpt from zmq_pgm(7) man page + * follows. + * + * In order for late joining consumers to be able to identify message + * boundaries, each PGM datagram payload starts with a 16-bit unsigned integer + * in network byte order specifying either the offset of the first message frame + * in the datagram or containing the value 0xFFFF if the datagram contains + * solely an intermediate part of a larger message. + * + * Note that offset specifies where the first message begins rather than the + * first message part. Thus, if there are trailing message parts at the + * beginning of the packet the offset ignores them and points to first initial + * message part in the packet. + */ + +static const u_char * +zmtp1_print_intermediate_part(netdissect_options *ndo, const u_char *cp, const u_int len) +{ + u_int frame_offset; + u_int remaining_len; + + frame_offset = GET_BE_U_2(cp); + ND_PRINT("\n\t frame offset 0x%04x", frame_offset); + cp += 2; + remaining_len = ND_BYTES_AVAILABLE_AFTER(cp); /* without the frame length */ + + if (frame_offset == 0xFFFF) + frame_offset = len - 2; /* always within the declared length */ + else if (2 + frame_offset > len) { + ND_PRINT(" (exceeds datagram declared length)"); + goto trunc; + } + + /* offset within declared length of the datagram */ + if (frame_offset) { + ND_PRINT("\n\t frame intermediate part, %u bytes", frame_offset); + if (frame_offset > remaining_len) + ND_PRINT(" (%u captured)", remaining_len); + if (ndo->ndo_vflag) { + u_int len_printed = ND_MIN(frame_offset, remaining_len); + + if (ndo->ndo_vflag == 1) + len_printed = ND_MIN(VBYTES, len_printed); + if (len_printed > 1) { + ND_PRINT(", first %u byte(s):", len_printed); + hex_and_ascii_print(ndo, "\n\t ", cp, len_printed); + } + } + } + return cp + frame_offset; + +trunc: + nd_trunc_longjmp(ndo); +} + +void +zmtp1_datagram_print(netdissect_options *ndo, const u_char *cp, const u_int len) +{ + const u_char *ep = ND_MIN(ndo->ndo_snapend, cp + len); + + ndo->ndo_protocol = "zmtp1"; + cp = zmtp1_print_intermediate_part(ndo, cp, len); + while (cp < ep) + cp = zmtp1_print_frame(ndo, cp, ep); +} |