/*
- * This file implements decoding of ZeroMQ network protocol(s).
- *
- *
* Copyright (c) 2013 The TCPDUMP project
* All rights reserved.
*
* POSSIBILITY OF SUCH DAMAGE.
*/
-#ifdef HAVE_CONFIG_H
-#include "config.h"
-#endif
+/* \summary: ZeroMQ Message Transport Protocol (ZMTP) printer */
+/* specification: https://rfc.zeromq.org/spec/13/ */
-#include <tcpdump-stdinc.h>
+#include <config.h>
-#include <stdio.h>
+#include "netdissect-stdinc.h"
-#include "interface.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
+static const struct tok flags_bm[] = {
+ { 0x01, "MORE" },
+ { 0x02, "R1" },
+ { 0x04, "R2" },
+ { 0x08, "R3" },
+ { 0x10, "R4" },
+ { 0x20, "R5" },
+ { 0x40, "R6" },
+ { 0x80, "R7" },
+ { 0, NULL }
+};
+
/*
* Below is an excerpt from the "13/ZMTP" specification:
*
*/
static const u_char *
-zmtp1_print_frame(const u_char *cp, const u_char *ep) {
- u_int64_t body_len_declared, body_len_captured, header_len;
- u_int8_t flags;
+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;
- printf("\n\t");
- TCHECK2(*cp, 1); /* length/0xFF */
+ ND_PRINT("\n\t");
- if (cp[0] != 0xFF) {
+ if (GET_U_1(cp) != 0xFF) { /* length/0xFF */
header_len = 1; /* length */
- body_len_declared = cp[0];
- if (body_len_declared == 0)
- return cp + header_len; /* skip to next frame */
- printf(" frame flags+body (8-bit) length %"PRIu8"", cp[0]);
- TCHECK2(*cp, header_len + 1); /* length, flags */
- flags = cp[1];
+ 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 */
- printf(" frame flags+body (64-bit) length");
- TCHECK2(*cp, header_len); /* 0xFF, length */
- body_len_declared = EXTRACT_64BITS(cp + 1);
- if (body_len_declared == 0)
- return cp + header_len; /* skip to next frame */
- printf(" %"PRIu64"", body_len_declared);
- TCHECK2(*cp, header_len + 1); /* 0xFF, length, flags */
- flags = cp[9];
+ 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)
- printf(" (%"PRIu64" captured)", body_len_captured);
- printf(", flags 0x%02"PRIx8"", flags);
-
- if (vflag) {
- u_int64_t body_len_printed = MIN(body_len_captured, body_len_declared);
-
- printf(" (%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 (vflag == 1)
- body_len_printed = MIN(VBYTES + 1, body_len_printed);
+ 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)", bittok2str(flags_bm, "none", flags));
+ if (ndo->ndo_vflag == 1)
+ body_len_printed = ND_MIN(VBYTES + 1, body_len_printed);
if (body_len_printed > 1) {
- printf(", first %"PRIu64" byte(s) of body:", body_len_printed - 1);
- hex_and_ascii_print("\n\t ", cp + header_len + 1, body_len_printed - 1);
- printf("\n");
+ 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);
}
}
- TCHECK2(*cp, header_len + body_len_declared); /* Next frame within the buffer ? */
- return cp + header_len + body_len_declared;
+ /*
+ * 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:
- printf(" [|zmtp1]");
- return ep;
+ nd_trunc_longjmp(ndo);
}
void
-zmtp1_print(const u_char *cp, u_int len) {
- const u_char *ep = MIN(snapend, cp + len);
+zmtp1_print(netdissect_options *ndo, const u_char *cp, u_int len)
+{
+ const u_char *ep = ND_MIN(ndo->ndo_snapend, cp + len);
- printf(": ZMTP/1.0");
+ ndo->ndo_protocol = "zmtp1";
+ ND_PRINT(": ZMTP/1.0");
while (cp < ep)
- cp = zmtp1_print_frame(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);
+}
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