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-rw-r--r--print-zeromq.c215
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+/*
+ * 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);
+}