1 /* 2 * This file implements decoding of ZeroMQ network protocol(s). 3 * 4 * 5 * Copyright (c) 2013 The TCPDUMP project 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 18 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 19 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 20 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 21 * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 23 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 24 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 25 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN 27 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 28 * POSSIBILITY OF SUCH DAMAGE. 29 */ 30 31 #ifdef HAVE_CONFIG_H 32 #include "config.h" 33 #endif 34 35 #include <tcpdump-stdinc.h> 36 37 #include <stdio.h> 38 39 #include "interface.h" 40 #include "extract.h" 41 42 /* Maximum number of ZMTP/1.0 frame body bytes (without the flags) to dump in 43 * hex and ASCII under a single "-v" flag. 44 */ 45 #define VBYTES 128 46 47 /* 48 * Below is an excerpt from the "13/ZMTP" specification: 49 * 50 * A ZMTP message consists of 1 or more frames. 51 * 52 * A ZMTP frame consists of a length, followed by a flags field and a frame 53 * body of (length - 1) octets. Note: the length includes the flags field, so 54 * an empty frame has a length of 1. 55 * 56 * For frames with a length of 1 to 254 octets, the length SHOULD BE encoded 57 * as a single octet. The minimum valid length of a frame is 1 octet, thus a 58 * length of 0 is invalid and such frames SHOULD be discarded silently. 59 * 60 * For frames with lengths of 255 and greater, the length SHALL BE encoded as 61 * a single octet with the value 255, followed by the length encoded as a 62 * 64-bit unsigned integer in network byte order. For frames with lengths of 63 * 1 to 254 octets this encoding MAY be also used. 64 * 65 * The flags field consists of a single octet containing various control 66 * flags. Bit 0 is the least significant bit. 67 * 68 * - Bit 0 (MORE): More frames to follow. A value of 0 indicates that there 69 * are no more frames to follow. A value of 1 indicates that more frames 70 * will follow. On messages consisting of a single frame the MORE flag MUST 71 * be 0. 72 * 73 * - Bits 1-7: Reserved. Bits 1-7 are reserved for future use and SHOULD be 74 * zero. 75 */ 76 77 static const u_char * 78 zmtp1_print_frame(const u_char *cp, const u_char *ep) { 79 u_int64_t body_len_declared, body_len_captured, header_len; 80 u_int8_t flags; 81 82 printf("\n\t"); 83 TCHECK2(*cp, 1); /* length/0xFF */ 84 85 if (cp[0] != 0xFF) { 86 header_len = 1; /* length */ 87 body_len_declared = cp[0]; 88 if (body_len_declared == 0) 89 return cp + header_len; /* skip to next frame */ 90 printf(" frame flags+body (8-bit) length %u", cp[0]); 91 TCHECK2(*cp, header_len + 1); /* length, flags */ 92 flags = cp[1]; 93 } else { 94 header_len = 1 + 8; /* 0xFF, length */ 95 printf(" frame flags+body (64-bit) length"); 96 TCHECK2(*cp, header_len); /* 0xFF, length */ 97 body_len_declared = EXTRACT_64BITS(cp + 1); 98 if (body_len_declared == 0) 99 return cp + header_len; /* skip to next frame */ 100 printf(" %" PRIu64, body_len_declared); 101 TCHECK2(*cp, header_len + 1); /* 0xFF, length, flags */ 102 flags = cp[9]; 103 } 104 105 body_len_captured = ep - cp - header_len; 106 if (body_len_declared > body_len_captured) 107 printf(" (%" PRIu64 " captured)", body_len_captured); 108 printf(", flags 0x%02x", flags); 109 110 if (vflag) { 111 u_int64_t body_len_printed = MIN(body_len_captured, body_len_declared); 112 113 printf(" (%s|%s|%s|%s|%s|%s|%s|%s)", 114 flags & 0x80 ? "MBZ" : "-", 115 flags & 0x40 ? "MBZ" : "-", 116 flags & 0x20 ? "MBZ" : "-", 117 flags & 0x10 ? "MBZ" : "-", 118 flags & 0x08 ? "MBZ" : "-", 119 flags & 0x04 ? "MBZ" : "-", 120 flags & 0x02 ? "MBZ" : "-", 121 flags & 0x01 ? "MORE" : "-"); 122 123 if (vflag == 1) 124 body_len_printed = MIN(VBYTES + 1, body_len_printed); 125 if (body_len_printed > 1) { 126 printf(", first %" PRIu64 " byte(s) of body:", body_len_printed - 1); 127 hex_and_ascii_print("\n\t ", cp + header_len + 1, body_len_printed - 1); 128 printf("\n"); 129 } 130 } 131 132 TCHECK2(*cp, header_len + body_len_declared); /* Next frame within the buffer ? */ 133 return cp + header_len + body_len_declared; 134 135 trunc: 136 printf(" [|zmtp1]"); 137 return ep; 138 } 139 140 void 141 zmtp1_print(const u_char *cp, u_int len) { 142 const u_char *ep = MIN(snapend, cp + len); 143 144 printf(": ZMTP/1.0"); 145 while (cp < ep) 146 cp = zmtp1_print_frame(cp, ep); 147 } 148 149 /* The functions below decode a ZeroMQ datagram, supposedly stored in the "Data" 150 * field of an ODATA/RDATA [E]PGM packet. An excerpt from zmq_pgm(7) man page 151 * follows. 152 * 153 * In order for late joining consumers to be able to identify message 154 * boundaries, each PGM datagram payload starts with a 16-bit unsigned integer 155 * in network byte order specifying either the offset of the first message frame 156 * in the datagram or containing the value 0xFFFF if the datagram contains 157 * solely an intermediate part of a larger message. 158 * 159 * Note that offset specifies where the first message begins rather than the 160 * first message part. Thus, if there are trailing message parts at the 161 * beginning of the packet the offset ignores them and points to first initial 162 * message part in the packet. 163 */ 164 165 static const u_char * 166 zmtp1_print_intermediate_part(const u_char *cp, const u_int len) { 167 u_int frame_offset; 168 u_int64_t remaining_len; 169 170 TCHECK2(*cp, 2); 171 frame_offset = EXTRACT_16BITS(cp); 172 printf("\n\t frame offset 0x%04x", frame_offset); 173 cp += 2; 174 remaining_len = snapend - cp; /* without the frame length */ 175 176 if (frame_offset == 0xFFFF) 177 frame_offset = len - 2; /* always within the declared length */ 178 else if (2 + frame_offset > len) { 179 printf(" (exceeds datagram declared length)"); 180 goto trunc; 181 } 182 183 /* offset within declared length of the datagram */ 184 if (frame_offset) { 185 printf("\n\t frame intermediate part, %u bytes", frame_offset); 186 if (frame_offset > remaining_len) 187 printf(" (%"PRIu64" captured)", remaining_len); 188 if (vflag) { 189 u_int64_t len_printed = MIN(frame_offset, remaining_len); 190 191 if (vflag == 1) 192 len_printed = MIN(VBYTES, len_printed); 193 if (len_printed > 1) { 194 printf(", first %"PRIu64" byte(s):", len_printed); 195 hex_and_ascii_print("\n\t ", cp, len_printed); 196 printf("\n"); 197 } 198 } 199 } 200 return cp + frame_offset; 201 202 trunc: 203 printf(" [|zmtp1]"); 204 return cp + len; 205 } 206 207 void 208 zmtp1_print_datagram(const u_char *cp, const u_int len) { 209 const u_char *ep = MIN(snapend, cp + len); 210 211 cp = zmtp1_print_intermediate_part(cp, len); 212 while (cp < ep) 213 cp = zmtp1_print_frame(cp, ep); 214 } 215
