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 #include <sys/cdefs.h> 29 #ifndef lint 30 __RCSID("$NetBSD: print-zeromq.c,v 1.3 2017/02/05 04:05:05 spz Exp $"); 31 #endif 32 33 /* \summary: ZeroMQ Message Transport Protocol (ZMTP) printer */ 34 35 #ifdef HAVE_CONFIG_H 36 #include "config.h" 37 #endif 38 39 #include <netdissect-stdinc.h> 40 41 #include "netdissect.h" 42 #include "extract.h" 43 44 static const char tstr[] = " [|zmtp1]"; 45 46 /* Maximum number of ZMTP/1.0 frame body bytes (without the flags) to dump in 47 * hex and ASCII under a single "-v" flag. 48 */ 49 #define VBYTES 128 50 51 /* 52 * Below is an excerpt from the "13/ZMTP" specification: 53 * 54 * A ZMTP message consists of 1 or more frames. 55 * 56 * A ZMTP frame consists of a length, followed by a flags field and a frame 57 * body of (length - 1) octets. Note: the length includes the flags field, so 58 * an empty frame has a length of 1. 59 * 60 * For frames with a length of 1 to 254 octets, the length SHOULD BE encoded 61 * as a single octet. The minimum valid length of a frame is 1 octet, thus a 62 * length of 0 is invalid and such frames SHOULD be discarded silently. 63 * 64 * For frames with lengths of 255 and greater, the length SHALL BE encoded as 65 * a single octet with the value 255, followed by the length encoded as a 66 * 64-bit unsigned integer in network byte order. For frames with lengths of 67 * 1 to 254 octets this encoding MAY be also used. 68 * 69 * The flags field consists of a single octet containing various control 70 * flags. Bit 0 is the least significant bit. 71 * 72 * - Bit 0 (MORE): More frames to follow. A value of 0 indicates that there 73 * are no more frames to follow. A value of 1 indicates that more frames 74 * will follow. On messages consisting of a single frame the MORE flag MUST 75 * be 0. 76 * 77 * - Bits 1-7: Reserved. Bits 1-7 are reserved for future use and SHOULD be 78 * zero. 79 */ 80 81 static const u_char * 82 zmtp1_print_frame(netdissect_options *ndo, const u_char *cp, const u_char *ep) 83 { 84 uint64_t body_len_declared, body_len_captured, header_len; 85 uint8_t flags; 86 87 ND_PRINT((ndo, "\n\t")); 88 ND_TCHECK2(*cp, 1); /* length/0xFF */ 89 90 if (cp[0] != 0xFF) { 91 header_len = 1; /* length */ 92 body_len_declared = cp[0]; 93 ND_PRINT((ndo, " frame flags+body (8-bit) length %" PRIu64, body_len_declared)); 94 } else { 95 header_len = 1 + 8; /* 0xFF, length */ 96 ND_PRINT((ndo, " frame flags+body (64-bit) length")); 97 ND_TCHECK2(*cp, header_len); /* 0xFF, length */ 98 body_len_declared = EXTRACT_64BITS(cp + 1); 99 ND_PRINT((ndo, " %" PRIu64, body_len_declared)); 100 } 101 if (body_len_declared == 0) 102 return cp + header_len; /* skip to the next frame */ 103 ND_TCHECK2(*cp, header_len + 1); /* ..., flags */ 104 flags = cp[header_len]; 105 106 body_len_captured = ep - cp - header_len; 107 if (body_len_declared > body_len_captured) 108 ND_PRINT((ndo, " (%" PRIu64 " captured)", body_len_captured)); 109 ND_PRINT((ndo, ", flags 0x%02x", flags)); 110 111 if (ndo->ndo_vflag) { 112 uint64_t body_len_printed = min(body_len_captured, body_len_declared); 113 114 ND_PRINT((ndo, " (%s|%s|%s|%s|%s|%s|%s|%s)", 115 flags & 0x80 ? "MBZ" : "-", 116 flags & 0x40 ? "MBZ" : "-", 117 flags & 0x20 ? "MBZ" : "-", 118 flags & 0x10 ? "MBZ" : "-", 119 flags & 0x08 ? "MBZ" : "-", 120 flags & 0x04 ? "MBZ" : "-", 121 flags & 0x02 ? "MBZ" : "-", 122 flags & 0x01 ? "MORE" : "-")); 123 124 if (ndo->ndo_vflag == 1) 125 body_len_printed = min(VBYTES + 1, body_len_printed); 126 if (body_len_printed > 1) { 127 ND_PRINT((ndo, ", first %" PRIu64 " byte(s) of body:", body_len_printed - 1)); 128 hex_and_ascii_print(ndo, "\n\t ", cp + header_len + 1, body_len_printed - 1); 129 ND_PRINT((ndo, "\n")); 130 } 131 } 132 133 /* 134 * Do not advance cp by the sum of header_len and body_len_declared 135 * before each offset has successfully passed ND_TCHECK2() as the 136 * sum can roll over (9 + 0xfffffffffffffff7 = 0) and cause an 137 * infinite loop. 138 */ 139 cp += header_len; 140 ND_TCHECK2(*cp, body_len_declared); /* Next frame within the buffer ? */ 141 return cp + body_len_declared; 142 143 trunc: 144 ND_PRINT((ndo, "%s", tstr)); 145 return ep; 146 } 147 148 void 149 zmtp1_print(netdissect_options *ndo, const u_char *cp, u_int len) 150 { 151 const u_char *ep = min(ndo->ndo_snapend, cp + len); 152 153 ND_PRINT((ndo, ": ZMTP/1.0")); 154 while (cp < ep) 155 cp = zmtp1_print_frame(ndo, cp, ep); 156 } 157 158 /* The functions below decode a ZeroMQ datagram, supposedly stored in the "Data" 159 * field of an ODATA/RDATA [E]PGM packet. An excerpt from zmq_pgm(7) man page 160 * follows. 161 * 162 * In order for late joining consumers to be able to identify message 163 * boundaries, each PGM datagram payload starts with a 16-bit unsigned integer 164 * in network byte order specifying either the offset of the first message frame 165 * in the datagram or containing the value 0xFFFF if the datagram contains 166 * solely an intermediate part of a larger message. 167 * 168 * Note that offset specifies where the first message begins rather than the 169 * first message part. Thus, if there are trailing message parts at the 170 * beginning of the packet the offset ignores them and points to first initial 171 * message part in the packet. 172 */ 173 174 static const u_char * 175 zmtp1_print_intermediate_part(netdissect_options *ndo, const u_char *cp, const u_int len) 176 { 177 u_int frame_offset; 178 uint64_t remaining_len; 179 180 ND_TCHECK2(*cp, 2); 181 frame_offset = EXTRACT_16BITS(cp); 182 ND_PRINT((ndo, "\n\t frame offset 0x%04x", frame_offset)); 183 cp += 2; 184 remaining_len = ndo->ndo_snapend - cp; /* without the frame length */ 185 186 if (frame_offset == 0xFFFF) 187 frame_offset = len - 2; /* always within the declared length */ 188 else if (2 + frame_offset > len) { 189 ND_PRINT((ndo, " (exceeds datagram declared length)")); 190 goto trunc; 191 } 192 193 /* offset within declared length of the datagram */ 194 if (frame_offset) { 195 ND_PRINT((ndo, "\n\t frame intermediate part, %u bytes", frame_offset)); 196 if (frame_offset > remaining_len) 197 ND_PRINT((ndo, " (%"PRIu64" captured)", remaining_len)); 198 if (ndo->ndo_vflag) { 199 uint64_t len_printed = min(frame_offset, remaining_len); 200 201 if (ndo->ndo_vflag == 1) 202 len_printed = min(VBYTES, len_printed); 203 if (len_printed > 1) { 204 ND_PRINT((ndo, ", first %"PRIu64" byte(s):", len_printed)); 205 hex_and_ascii_print(ndo, "\n\t ", cp, len_printed); 206 ND_PRINT((ndo, "\n")); 207 } 208 } 209 } 210 return cp + frame_offset; 211 212 trunc: 213 ND_PRINT((ndo, "%s", tstr)); 214 return cp + len; 215 } 216 217 void 218 zmtp1_print_datagram(netdissect_options *ndo, const u_char *cp, const u_int len) 219 { 220 const u_char *ep = min(ndo->ndo_snapend, cp + len); 221 222 cp = zmtp1_print_intermediate_part(ndo, cp, len); 223 while (cp < ep) 224 cp = zmtp1_print_frame(ndo, cp, ep); 225 } 226