1/* 2 * Copyright (c) 2013 The TCPDUMP project 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 15 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 16 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 17 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 18 * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 20 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 21 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 22 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN 24 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 25 * POSSIBILITY OF SUCH DAMAGE. 26 */ 27 28/* \summary: ZeroMQ Message Transport Protocol (ZMTP) printer */ 29 30#ifdef HAVE_CONFIG_H 31#include <config.h> 32#endif 33 34#include "netdissect-stdinc.h" 35 36#include "netdissect.h" 37#include "extract.h" 38 39 40/* Maximum number of ZMTP/1.0 frame body bytes (without the flags) to dump in 41 * hex and ASCII under a single "-v" flag. 42 */ 43#define VBYTES 128 44 45/* 46 * Below is an excerpt from the "13/ZMTP" specification: 47 * 48 * A ZMTP message consists of 1 or more frames. 49 * 50 * A ZMTP frame consists of a length, followed by a flags field and a frame 51 * body of (length - 1) octets. Note: the length includes the flags field, so 52 * an empty frame has a length of 1. 53 * 54 * For frames with a length of 1 to 254 octets, the length SHOULD BE encoded 55 * as a single octet. The minimum valid length of a frame is 1 octet, thus a 56 * length of 0 is invalid and such frames SHOULD be discarded silently. 57 * 58 * For frames with lengths of 255 and greater, the length SHALL BE encoded as 59 * a single octet with the value 255, followed by the length encoded as a 60 * 64-bit unsigned integer in network byte order. For frames with lengths of 61 * 1 to 254 octets this encoding MAY be also used. 62 * 63 * The flags field consists of a single octet containing various control 64 * flags. Bit 0 is the least significant bit. 65 * 66 * - Bit 0 (MORE): More frames to follow. A value of 0 indicates that there 67 * are no more frames to follow. A value of 1 indicates that more frames 68 * will follow. On messages consisting of a single frame the MORE flag MUST 69 * be 0. 70 * 71 * - Bits 1-7: Reserved. Bits 1-7 are reserved for future use and SHOULD be 72 * zero. 73 */ 74 75static const u_char * 76zmtp1_print_frame(netdissect_options *ndo, const u_char *cp, const u_char *ep) 77{ 78 uint64_t body_len_declared, body_len_captured, header_len; 79 uint8_t flags; 80 81 ND_PRINT("\n\t"); 82 83 if (GET_U_1(cp) != 0xFF) { /* length/0xFF */ 84 header_len = 1; /* length */ 85 body_len_declared = GET_U_1(cp); 86 ND_PRINT(" frame flags+body (8-bit) length %" PRIu64, body_len_declared); 87 } else { 88 header_len = 1 + 8; /* 0xFF, length */ 89 ND_PRINT(" frame flags+body (64-bit) length"); 90 ND_TCHECK_LEN(cp, header_len); /* 0xFF, length */ 91 body_len_declared = GET_BE_U_8(cp + 1); 92 ND_PRINT(" %" PRIu64, body_len_declared); 93 } 94 if (body_len_declared == 0) 95 return cp + header_len; /* skip to the next frame */ 96 ND_TCHECK_LEN(cp, header_len + 1); /* ..., flags */ 97 flags = GET_U_1(cp + header_len); 98 99 body_len_captured = ep - cp - header_len; 100 if (body_len_declared > body_len_captured) 101 ND_PRINT(" (%" PRIu64 " captured)", body_len_captured); 102 ND_PRINT(", flags 0x%02x", flags); 103 104 if (ndo->ndo_vflag) { 105 uint64_t body_len_printed = ND_MIN(body_len_captured, body_len_declared); 106 107 ND_PRINT(" (%s|%s|%s|%s|%s|%s|%s|%s)", 108 flags & 0x80 ? "MBZ" : "-", 109 flags & 0x40 ? "MBZ" : "-", 110 flags & 0x20 ? "MBZ" : "-", 111 flags & 0x10 ? "MBZ" : "-", 112 flags & 0x08 ? "MBZ" : "-", 113 flags & 0x04 ? "MBZ" : "-", 114 flags & 0x02 ? "MBZ" : "-", 115 flags & 0x01 ? "MORE" : "-"); 116 117 if (ndo->ndo_vflag == 1) 118 body_len_printed = ND_MIN(VBYTES + 1, body_len_printed); 119 if (body_len_printed > 1) { 120 ND_PRINT(", first %" PRIu64 " byte(s) of body:", body_len_printed - 1); 121 hex_and_ascii_print(ndo, "\n\t ", cp + header_len + 1, body_len_printed - 1); 122 } 123 } 124 125 /* 126 * Do not advance cp by the sum of header_len and body_len_declared 127 * before each offset has successfully passed ND_TCHECK_LEN() as the 128 * sum can roll over (9 + 0xfffffffffffffff7 = 0) and cause an 129 * infinite loop. 130 */ 131 cp += header_len; 132 ND_TCHECK_LEN(cp, body_len_declared); /* Next frame within the buffer ? */ 133 return cp + body_len_declared; 134 135trunc: 136 nd_trunc_longjmp(ndo); 137} 138 139void 140zmtp1_print(netdissect_options *ndo, const u_char *cp, u_int len) 141{ 142 const u_char *ep = ND_MIN(ndo->ndo_snapend, cp + len); 143 144 ndo->ndo_protocol = "zmtp1"; 145 ND_PRINT(": ZMTP/1.0"); 146 while (cp < ep) 147 cp = zmtp1_print_frame(ndo, cp, ep); 148} 149 150/* The functions below decode a ZeroMQ datagram, supposedly stored in the "Data" 151 * field of an ODATA/RDATA [E]PGM packet. An excerpt from zmq_pgm(7) man page 152 * follows. 153 * 154 * In order for late joining consumers to be able to identify message 155 * boundaries, each PGM datagram payload starts with a 16-bit unsigned integer 156 * in network byte order specifying either the offset of the first message frame 157 * in the datagram or containing the value 0xFFFF if the datagram contains 158 * solely an intermediate part of a larger message. 159 * 160 * Note that offset specifies where the first message begins rather than the 161 * first message part. Thus, if there are trailing message parts at the 162 * beginning of the packet the offset ignores them and points to first initial 163 * message part in the packet. 164 */ 165 166static const u_char * 167zmtp1_print_intermediate_part(netdissect_options *ndo, const u_char *cp, const u_int len) 168{ 169 u_int frame_offset; 170 u_int remaining_len; 171 172 frame_offset = GET_BE_U_2(cp); 173 ND_PRINT("\n\t frame offset 0x%04x", frame_offset); 174 cp += 2; 175 remaining_len = ND_BYTES_AVAILABLE_AFTER(cp); /* without the frame length */ 176 177 if (frame_offset == 0xFFFF) 178 frame_offset = len - 2; /* always within the declared length */ 179 else if (2 + frame_offset > len) { 180 ND_PRINT(" (exceeds datagram declared length)"); 181 goto trunc; 182 } 183 184 /* offset within declared length of the datagram */ 185 if (frame_offset) { 186 ND_PRINT("\n\t frame intermediate part, %u bytes", frame_offset); 187 if (frame_offset > remaining_len) 188 ND_PRINT(" (%u captured)", remaining_len); 189 if (ndo->ndo_vflag) { 190 u_int len_printed = ND_MIN(frame_offset, remaining_len); 191 192 if (ndo->ndo_vflag == 1) 193 len_printed = ND_MIN(VBYTES, len_printed); 194 if (len_printed > 1) { 195 ND_PRINT(", first %u byte(s):", len_printed); 196 hex_and_ascii_print(ndo, "\n\t ", cp, len_printed); 197 } 198 } 199 } 200 return cp + frame_offset; 201 202trunc: 203 nd_trunc_longjmp(ndo); 204} 205 206void 207zmtp1_datagram_print(netdissect_options *ndo, const u_char *cp, const u_int len) 208{ 209 const u_char *ep = ND_MIN(ndo->ndo_snapend, cp + len); 210 211 ndo->ndo_protocol = "zmtp1"; 212 cp = zmtp1_print_intermediate_part(ndo, cp, len); 213 while (cp < ep) 214 cp = zmtp1_print_frame(ndo, cp, ep); 215} 216