1*b636d99dSDavid van Moolenbroek /*
2*b636d99dSDavid van Moolenbroek * This file implements decoding of ZeroMQ network protocol(s).
3*b636d99dSDavid van Moolenbroek *
4*b636d99dSDavid van Moolenbroek *
5*b636d99dSDavid van Moolenbroek * Copyright (c) 2013 The TCPDUMP project
6*b636d99dSDavid van Moolenbroek * All rights reserved.
7*b636d99dSDavid van Moolenbroek *
8*b636d99dSDavid van Moolenbroek * Redistribution and use in source and binary forms, with or without
9*b636d99dSDavid van Moolenbroek * modification, are permitted provided that the following conditions
10*b636d99dSDavid van Moolenbroek * are met:
11*b636d99dSDavid van Moolenbroek * 1. Redistributions of source code must retain the above copyright
12*b636d99dSDavid van Moolenbroek * notice, this list of conditions and the following disclaimer.
13*b636d99dSDavid van Moolenbroek * 2. Redistributions in binary form must reproduce the above copyright
14*b636d99dSDavid van Moolenbroek * notice, this list of conditions and the following disclaimer in the
15*b636d99dSDavid van Moolenbroek * documentation and/or other materials provided with the distribution.
16*b636d99dSDavid van Moolenbroek *
17*b636d99dSDavid van Moolenbroek * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
18*b636d99dSDavid van Moolenbroek * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
19*b636d99dSDavid van Moolenbroek * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
20*b636d99dSDavid van Moolenbroek * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
21*b636d99dSDavid van Moolenbroek * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
22*b636d99dSDavid van Moolenbroek * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
23*b636d99dSDavid van Moolenbroek * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
24*b636d99dSDavid van Moolenbroek * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
25*b636d99dSDavid van Moolenbroek * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26*b636d99dSDavid van Moolenbroek * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
27*b636d99dSDavid van Moolenbroek * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
28*b636d99dSDavid van Moolenbroek * POSSIBILITY OF SUCH DAMAGE.
29*b636d99dSDavid van Moolenbroek */
30*b636d99dSDavid van Moolenbroek
31*b636d99dSDavid van Moolenbroek #define NETDISSECT_REWORKED
32*b636d99dSDavid van Moolenbroek #ifdef HAVE_CONFIG_H
33*b636d99dSDavid van Moolenbroek #include "config.h"
34*b636d99dSDavid van Moolenbroek #endif
35*b636d99dSDavid van Moolenbroek
36*b636d99dSDavid van Moolenbroek #include <tcpdump-stdinc.h>
37*b636d99dSDavid van Moolenbroek
38*b636d99dSDavid van Moolenbroek #include "interface.h"
39*b636d99dSDavid van Moolenbroek #include "extract.h"
40*b636d99dSDavid van Moolenbroek
41*b636d99dSDavid van Moolenbroek static const char tstr[] = " [|zmtp1]";
42*b636d99dSDavid van Moolenbroek
43*b636d99dSDavid van Moolenbroek /* Maximum number of ZMTP/1.0 frame body bytes (without the flags) to dump in
44*b636d99dSDavid van Moolenbroek * hex and ASCII under a single "-v" flag.
45*b636d99dSDavid van Moolenbroek */
46*b636d99dSDavid van Moolenbroek #define VBYTES 128
47*b636d99dSDavid van Moolenbroek
48*b636d99dSDavid van Moolenbroek /*
49*b636d99dSDavid van Moolenbroek * Below is an excerpt from the "13/ZMTP" specification:
50*b636d99dSDavid van Moolenbroek *
51*b636d99dSDavid van Moolenbroek * A ZMTP message consists of 1 or more frames.
52*b636d99dSDavid van Moolenbroek *
53*b636d99dSDavid van Moolenbroek * A ZMTP frame consists of a length, followed by a flags field and a frame
54*b636d99dSDavid van Moolenbroek * body of (length - 1) octets. Note: the length includes the flags field, so
55*b636d99dSDavid van Moolenbroek * an empty frame has a length of 1.
56*b636d99dSDavid van Moolenbroek *
57*b636d99dSDavid van Moolenbroek * For frames with a length of 1 to 254 octets, the length SHOULD BE encoded
58*b636d99dSDavid van Moolenbroek * as a single octet. The minimum valid length of a frame is 1 octet, thus a
59*b636d99dSDavid van Moolenbroek * length of 0 is invalid and such frames SHOULD be discarded silently.
60*b636d99dSDavid van Moolenbroek *
61*b636d99dSDavid van Moolenbroek * For frames with lengths of 255 and greater, the length SHALL BE encoded as
62*b636d99dSDavid van Moolenbroek * a single octet with the value 255, followed by the length encoded as a
63*b636d99dSDavid van Moolenbroek * 64-bit unsigned integer in network byte order. For frames with lengths of
64*b636d99dSDavid van Moolenbroek * 1 to 254 octets this encoding MAY be also used.
65*b636d99dSDavid van Moolenbroek *
66*b636d99dSDavid van Moolenbroek * The flags field consists of a single octet containing various control
67*b636d99dSDavid van Moolenbroek * flags. Bit 0 is the least significant bit.
68*b636d99dSDavid van Moolenbroek *
69*b636d99dSDavid van Moolenbroek * - Bit 0 (MORE): More frames to follow. A value of 0 indicates that there
70*b636d99dSDavid van Moolenbroek * are no more frames to follow. A value of 1 indicates that more frames
71*b636d99dSDavid van Moolenbroek * will follow. On messages consisting of a single frame the MORE flag MUST
72*b636d99dSDavid van Moolenbroek * be 0.
73*b636d99dSDavid van Moolenbroek *
74*b636d99dSDavid van Moolenbroek * - Bits 1-7: Reserved. Bits 1-7 are reserved for future use and SHOULD be
75*b636d99dSDavid van Moolenbroek * zero.
76*b636d99dSDavid van Moolenbroek */
77*b636d99dSDavid van Moolenbroek
78*b636d99dSDavid van Moolenbroek static const u_char *
zmtp1_print_frame(netdissect_options * ndo,const u_char * cp,const u_char * ep)79*b636d99dSDavid van Moolenbroek zmtp1_print_frame(netdissect_options *ndo, const u_char *cp, const u_char *ep)
80*b636d99dSDavid van Moolenbroek {
81*b636d99dSDavid van Moolenbroek uint64_t body_len_declared, body_len_captured, header_len;
82*b636d99dSDavid van Moolenbroek uint8_t flags;
83*b636d99dSDavid van Moolenbroek
84*b636d99dSDavid van Moolenbroek ND_PRINT((ndo, "\n\t"));
85*b636d99dSDavid van Moolenbroek ND_TCHECK2(*cp, 1); /* length/0xFF */
86*b636d99dSDavid van Moolenbroek
87*b636d99dSDavid van Moolenbroek if (cp[0] != 0xFF) {
88*b636d99dSDavid van Moolenbroek header_len = 1; /* length */
89*b636d99dSDavid van Moolenbroek body_len_declared = cp[0];
90*b636d99dSDavid van Moolenbroek if (body_len_declared == 0)
91*b636d99dSDavid van Moolenbroek return cp + header_len; /* skip to next frame */
92*b636d99dSDavid van Moolenbroek ND_PRINT((ndo, " frame flags+body (8-bit) length %u", cp[0]));
93*b636d99dSDavid van Moolenbroek ND_TCHECK2(*cp, header_len + 1); /* length, flags */
94*b636d99dSDavid van Moolenbroek flags = cp[1];
95*b636d99dSDavid van Moolenbroek } else {
96*b636d99dSDavid van Moolenbroek header_len = 1 + 8; /* 0xFF, length */
97*b636d99dSDavid van Moolenbroek ND_PRINT((ndo, " frame flags+body (64-bit) length"));
98*b636d99dSDavid van Moolenbroek ND_TCHECK2(*cp, header_len); /* 0xFF, length */
99*b636d99dSDavid van Moolenbroek body_len_declared = EXTRACT_64BITS(cp + 1);
100*b636d99dSDavid van Moolenbroek if (body_len_declared == 0)
101*b636d99dSDavid van Moolenbroek return cp + header_len; /* skip to next frame */
102*b636d99dSDavid van Moolenbroek ND_PRINT((ndo, " %" PRIu64, body_len_declared));
103*b636d99dSDavid van Moolenbroek ND_TCHECK2(*cp, header_len + 1); /* 0xFF, length, flags */
104*b636d99dSDavid van Moolenbroek flags = cp[9];
105*b636d99dSDavid van Moolenbroek }
106*b636d99dSDavid van Moolenbroek
107*b636d99dSDavid van Moolenbroek body_len_captured = ep - cp - header_len;
108*b636d99dSDavid van Moolenbroek if (body_len_declared > body_len_captured)
109*b636d99dSDavid van Moolenbroek ND_PRINT((ndo, " (%" PRIu64 " captured)", body_len_captured));
110*b636d99dSDavid van Moolenbroek ND_PRINT((ndo, ", flags 0x%02x", flags));
111*b636d99dSDavid van Moolenbroek
112*b636d99dSDavid van Moolenbroek if (ndo->ndo_vflag) {
113*b636d99dSDavid van Moolenbroek uint64_t body_len_printed = min(body_len_captured, body_len_declared);
114*b636d99dSDavid van Moolenbroek
115*b636d99dSDavid van Moolenbroek ND_PRINT((ndo, " (%s|%s|%s|%s|%s|%s|%s|%s)",
116*b636d99dSDavid van Moolenbroek flags & 0x80 ? "MBZ" : "-",
117*b636d99dSDavid van Moolenbroek flags & 0x40 ? "MBZ" : "-",
118*b636d99dSDavid van Moolenbroek flags & 0x20 ? "MBZ" : "-",
119*b636d99dSDavid van Moolenbroek flags & 0x10 ? "MBZ" : "-",
120*b636d99dSDavid van Moolenbroek flags & 0x08 ? "MBZ" : "-",
121*b636d99dSDavid van Moolenbroek flags & 0x04 ? "MBZ" : "-",
122*b636d99dSDavid van Moolenbroek flags & 0x02 ? "MBZ" : "-",
123*b636d99dSDavid van Moolenbroek flags & 0x01 ? "MORE" : "-"));
124*b636d99dSDavid van Moolenbroek
125*b636d99dSDavid van Moolenbroek if (ndo->ndo_vflag == 1)
126*b636d99dSDavid van Moolenbroek body_len_printed = min(VBYTES + 1, body_len_printed);
127*b636d99dSDavid van Moolenbroek if (body_len_printed > 1) {
128*b636d99dSDavid van Moolenbroek ND_PRINT((ndo, ", first %" PRIu64 " byte(s) of body:", body_len_printed - 1));
129*b636d99dSDavid van Moolenbroek hex_and_ascii_print(ndo, "\n\t ", cp + header_len + 1, body_len_printed - 1);
130*b636d99dSDavid van Moolenbroek ND_PRINT((ndo, "\n"));
131*b636d99dSDavid van Moolenbroek }
132*b636d99dSDavid van Moolenbroek }
133*b636d99dSDavid van Moolenbroek
134*b636d99dSDavid van Moolenbroek ND_TCHECK2(*cp, header_len + body_len_declared); /* Next frame within the buffer ? */
135*b636d99dSDavid van Moolenbroek return cp + header_len + body_len_declared;
136*b636d99dSDavid van Moolenbroek
137*b636d99dSDavid van Moolenbroek trunc:
138*b636d99dSDavid van Moolenbroek ND_PRINT((ndo, "%s", tstr));
139*b636d99dSDavid van Moolenbroek return ep;
140*b636d99dSDavid van Moolenbroek }
141*b636d99dSDavid van Moolenbroek
142*b636d99dSDavid van Moolenbroek void
zmtp1_print(netdissect_options * ndo,const u_char * cp,u_int len)143*b636d99dSDavid van Moolenbroek zmtp1_print(netdissect_options *ndo, const u_char *cp, u_int len)
144*b636d99dSDavid van Moolenbroek {
145*b636d99dSDavid van Moolenbroek const u_char *ep = min(ndo->ndo_snapend, cp + len);
146*b636d99dSDavid van Moolenbroek
147*b636d99dSDavid van Moolenbroek ND_PRINT((ndo, ": ZMTP/1.0"));
148*b636d99dSDavid van Moolenbroek while (cp < ep)
149*b636d99dSDavid van Moolenbroek cp = zmtp1_print_frame(ndo, cp, ep);
150*b636d99dSDavid van Moolenbroek }
151*b636d99dSDavid van Moolenbroek
152*b636d99dSDavid van Moolenbroek /* The functions below decode a ZeroMQ datagram, supposedly stored in the "Data"
153*b636d99dSDavid van Moolenbroek * field of an ODATA/RDATA [E]PGM packet. An excerpt from zmq_pgm(7) man page
154*b636d99dSDavid van Moolenbroek * follows.
155*b636d99dSDavid van Moolenbroek *
156*b636d99dSDavid van Moolenbroek * In order for late joining consumers to be able to identify message
157*b636d99dSDavid van Moolenbroek * boundaries, each PGM datagram payload starts with a 16-bit unsigned integer
158*b636d99dSDavid van Moolenbroek * in network byte order specifying either the offset of the first message frame
159*b636d99dSDavid van Moolenbroek * in the datagram or containing the value 0xFFFF if the datagram contains
160*b636d99dSDavid van Moolenbroek * solely an intermediate part of a larger message.
161*b636d99dSDavid van Moolenbroek *
162*b636d99dSDavid van Moolenbroek * Note that offset specifies where the first message begins rather than the
163*b636d99dSDavid van Moolenbroek * first message part. Thus, if there are trailing message parts at the
164*b636d99dSDavid van Moolenbroek * beginning of the packet the offset ignores them and points to first initial
165*b636d99dSDavid van Moolenbroek * message part in the packet.
166*b636d99dSDavid van Moolenbroek */
167*b636d99dSDavid van Moolenbroek
168*b636d99dSDavid van Moolenbroek static const u_char *
zmtp1_print_intermediate_part(netdissect_options * ndo,const u_char * cp,const u_int len)169*b636d99dSDavid van Moolenbroek zmtp1_print_intermediate_part(netdissect_options *ndo, const u_char *cp, const u_int len)
170*b636d99dSDavid van Moolenbroek {
171*b636d99dSDavid van Moolenbroek u_int frame_offset;
172*b636d99dSDavid van Moolenbroek uint64_t remaining_len;
173*b636d99dSDavid van Moolenbroek
174*b636d99dSDavid van Moolenbroek ND_TCHECK2(*cp, 2);
175*b636d99dSDavid van Moolenbroek frame_offset = EXTRACT_16BITS(cp);
176*b636d99dSDavid van Moolenbroek ND_PRINT((ndo, "\n\t frame offset 0x%04x", frame_offset));
177*b636d99dSDavid van Moolenbroek cp += 2;
178*b636d99dSDavid van Moolenbroek remaining_len = ndo->ndo_snapend - cp; /* without the frame length */
179*b636d99dSDavid van Moolenbroek
180*b636d99dSDavid van Moolenbroek if (frame_offset == 0xFFFF)
181*b636d99dSDavid van Moolenbroek frame_offset = len - 2; /* always within the declared length */
182*b636d99dSDavid van Moolenbroek else if (2 + frame_offset > len) {
183*b636d99dSDavid van Moolenbroek ND_PRINT((ndo, " (exceeds datagram declared length)"));
184*b636d99dSDavid van Moolenbroek goto trunc;
185*b636d99dSDavid van Moolenbroek }
186*b636d99dSDavid van Moolenbroek
187*b636d99dSDavid van Moolenbroek /* offset within declared length of the datagram */
188*b636d99dSDavid van Moolenbroek if (frame_offset) {
189*b636d99dSDavid van Moolenbroek ND_PRINT((ndo, "\n\t frame intermediate part, %u bytes", frame_offset));
190*b636d99dSDavid van Moolenbroek if (frame_offset > remaining_len)
191*b636d99dSDavid van Moolenbroek ND_PRINT((ndo, " (%"PRIu64" captured)", remaining_len));
192*b636d99dSDavid van Moolenbroek if (ndo->ndo_vflag) {
193*b636d99dSDavid van Moolenbroek uint64_t len_printed = min(frame_offset, remaining_len);
194*b636d99dSDavid van Moolenbroek
195*b636d99dSDavid van Moolenbroek if (ndo->ndo_vflag == 1)
196*b636d99dSDavid van Moolenbroek len_printed = min(VBYTES, len_printed);
197*b636d99dSDavid van Moolenbroek if (len_printed > 1) {
198*b636d99dSDavid van Moolenbroek ND_PRINT((ndo, ", first %"PRIu64" byte(s):", len_printed));
199*b636d99dSDavid van Moolenbroek hex_and_ascii_print(ndo, "\n\t ", cp, len_printed);
200*b636d99dSDavid van Moolenbroek ND_PRINT((ndo, "\n"));
201*b636d99dSDavid van Moolenbroek }
202*b636d99dSDavid van Moolenbroek }
203*b636d99dSDavid van Moolenbroek }
204*b636d99dSDavid van Moolenbroek return cp + frame_offset;
205*b636d99dSDavid van Moolenbroek
206*b636d99dSDavid van Moolenbroek trunc:
207*b636d99dSDavid van Moolenbroek ND_PRINT((ndo, "%s", tstr));
208*b636d99dSDavid van Moolenbroek return cp + len;
209*b636d99dSDavid van Moolenbroek }
210*b636d99dSDavid van Moolenbroek
211*b636d99dSDavid van Moolenbroek void
zmtp1_print_datagram(netdissect_options * ndo,const u_char * cp,const u_int len)212*b636d99dSDavid van Moolenbroek zmtp1_print_datagram(netdissect_options *ndo, const u_char *cp, const u_int len)
213*b636d99dSDavid van Moolenbroek {
214*b636d99dSDavid van Moolenbroek const u_char *ep = min(ndo->ndo_snapend, cp + len);
215*b636d99dSDavid van Moolenbroek
216*b636d99dSDavid van Moolenbroek cp = zmtp1_print_intermediate_part(ndo, cp, len);
217*b636d99dSDavid van Moolenbroek while (cp < ep)
218*b636d99dSDavid van Moolenbroek cp = zmtp1_print_frame(ndo, cp, ep);
219*b636d99dSDavid van Moolenbroek }
220