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tcpdump/print-bfd.c
Guy Harris a3fa8638e8 Clean up handling of different packet types. 
Only look at the header for control packets; we don't know what the
payload contains for other packet types.

This fixes some cases where we fail to check whether we have a full
header before fetching from the header - we only need to fetch from the
header for control packets, so we now only need to check that we have it
for control packets; make sure we *don't* look at the header for other
packet types.

Update the v0 code to match draft-ietf-bfd-base-01, which was the last
draft that discussed v0.
2018-07-10 01:01:32 -07:00

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/*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that: (1) source code
* distributions retain the above copyright notice and this paragraph
* in its entirety, and (2) distributions including binary code include
* the above copyright notice and this paragraph in its entirety in
* the documentation or other materials provided with the distribution.
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND
* WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT
* LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE.
*
* Original code by Hannes Gredler (hannes@gredler.at)
*/
/* \summary: Bidirectional Forwarding Detection (BFD) printer */
/*
* specification: draft-ietf-bfd-base-01 for version 0,
* RFC 5880 for version 1, and RFC 5881
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include "netdissect-stdinc.h"
#include "netdissect.h"
#include "extract.h"
#include "udp.h"
/*
* Control packet, BFDv0, draft-ietf-bfd-base-01
*
* 0 1 2 3
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* |Vers | Diag |H|D|P|F|C|A|Rsv| Detect Mult | Length |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | My Discriminator |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Your Discriminator |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Desired Min TX Interval |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Required Min RX Interval |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Required Min Echo RX Interval |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*/
/*
* Control packet, BFDv1, RFC 5880
*
* 0 1 2 3
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* |Vers | Diag |Sta|P|F|C|A|D|M| Detect Mult | Length |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | My Discriminator |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Your Discriminator |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Desired Min TX Interval |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Required Min RX Interval |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Required Min Echo RX Interval |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*/
struct bfd_header_t {
nd_uint8_t version_diag;
nd_uint8_t flags;
nd_uint8_t detect_time_multiplier;
nd_uint8_t length;
nd_uint32_t my_discriminator;
nd_uint32_t your_discriminator;
nd_uint32_t desired_min_tx_interval;
nd_uint32_t required_min_rx_interval;
nd_uint32_t required_min_echo_interval;
};
/*
* An optional Authentication Header may be present
*
* 0 1 2 3
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Auth Type | Auth Len | Authentication Data... |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*/
struct bfd_auth_header_t {
nd_uint8_t auth_type;
nd_uint8_t auth_len;
nd_uint8_t auth_data;
nd_uint8_t dummy; /* minimum 4 bytes */
};
enum auth_type {
AUTH_PASSWORD = 1,
AUTH_MD5 = 2,
AUTH_MET_MD5 = 3,
AUTH_SHA1 = 4,
AUTH_MET_SHA1 = 5
};
static const struct tok bfd_v1_authentication_values[] = {
{ AUTH_PASSWORD, "Simple Password" },
{ AUTH_MD5, "Keyed MD5" },
{ AUTH_MET_MD5, "Meticulous Keyed MD5" },
{ AUTH_SHA1, "Keyed SHA1" },
{ AUTH_MET_SHA1, "Meticulous Keyed SHA1" },
{ 0, NULL }
};
enum auth_length {
AUTH_PASSWORD_FIELD_MIN_LEN = 4, /* header + password min: 3 + 1 */
AUTH_PASSWORD_FIELD_MAX_LEN = 19, /* header + password max: 3 + 16 */
AUTH_MD5_FIELD_LEN = 24,
AUTH_MD5_HASH_LEN = 16,
AUTH_SHA1_FIELD_LEN = 28,
AUTH_SHA1_HASH_LEN = 20
};
#define BFD_EXTRACT_VERSION(x) (((x)&0xe0)>>5)
#define BFD_EXTRACT_DIAG(x) ((x)&0x1f)
static const struct tok bfd_diag_values[] = {
{ 0, "No Diagnostic" },
{ 1, "Control Detection Time Expired" },
{ 2, "Echo Function Failed" },
{ 3, "Neighbor Signaled Session Down" },
{ 4, "Forwarding Plane Reset" },
{ 5, "Path Down" },
{ 6, "Concatenated Path Down" },
{ 7, "Administratively Down" },
{ 8, "Reverse Concatenated Path Down" },
{ 0, NULL }
};
#define BFD_FLAG_AUTH 0x04
static const struct tok bfd_v0_flag_values[] = {
{ 0x80, "I Hear You" },
{ 0x40, "Demand" },
{ 0x20, "Poll" },
{ 0x10, "Final" },
{ 0x08, "Control Plane Independent" },
{ BFD_FLAG_AUTH, "Authentication Present" },
{ 0x02, "Reserved" },
{ 0x01, "Reserved" },
{ 0, NULL }
};
static const struct tok bfd_v1_flag_values[] = {
{ 0x20, "Poll" },
{ 0x10, "Final" },
{ 0x08, "Control Plane Independent" },
{ BFD_FLAG_AUTH, "Authentication Present" },
{ 0x02, "Demand" },
{ 0x01, "Multipoint" },
{ 0, NULL }
};
static const struct tok bfd_v1_state_values[] = {
{ 0, "AdminDown" },
{ 1, "Down" },
{ 2, "Init" },
{ 3, "Up" },
{ 0, NULL }
};
static int
auth_print(netdissect_options *ndo, const u_char *pptr)
{
const struct bfd_auth_header_t *bfd_auth_header;
uint8_t auth_type, auth_len;
int i;
pptr += sizeof (struct bfd_header_t);
bfd_auth_header = (const struct bfd_auth_header_t *)pptr;
ND_TCHECK_SIZE(bfd_auth_header);
auth_type = EXTRACT_U_1(bfd_auth_header->auth_type);
auth_len = EXTRACT_U_1(bfd_auth_header->auth_len);
ND_PRINT("\n\tAuthentication: %s (%u), length: %u",
tok2str(bfd_v1_authentication_values,"Unknown",auth_type),
auth_type, auth_len);
pptr += 2;
ND_PRINT("\n\t Auth Key ID: %u", EXTRACT_U_1(pptr));
switch(auth_type) {
case AUTH_PASSWORD:
/*
* Simple Password Authentication Section Format
*
* 0 1 2 3
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Auth Type | Auth Len | Auth Key ID | Password... |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | ... |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*/
if (auth_len < AUTH_PASSWORD_FIELD_MIN_LEN ||
auth_len > AUTH_PASSWORD_FIELD_MAX_LEN) {
ND_PRINT("[invalid length %u]",
auth_len);
break;
}
pptr++;
ND_PRINT(", Password: ");
/* the length is equal to the password length plus three */
if (nd_printn(ndo, pptr, auth_len - 3,
ndo->ndo_snapend))
goto trunc;
break;
case AUTH_MD5:
case AUTH_MET_MD5:
/*
* Keyed MD5 and Meticulous Keyed MD5 Authentication Section Format
*
* 0 1 2 3
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Auth Type | Auth Len | Auth Key ID | Reserved |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Sequence Number |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Auth Key/Digest... |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | ... |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*/
if (auth_len != AUTH_MD5_FIELD_LEN) {
ND_PRINT("[invalid length %u]",
auth_len);
break;
}
pptr += 2;
ND_TCHECK_4(pptr);
ND_PRINT(", Sequence Number: 0x%08x", EXTRACT_BE_U_4(pptr));
pptr += 4;
ND_TCHECK_LEN(pptr, AUTH_MD5_HASH_LEN);
ND_PRINT("\n\t Digest: ");
for(i = 0; i < AUTH_MD5_HASH_LEN; i++)
ND_PRINT("%02x", EXTRACT_U_1(pptr + i));
break;
case AUTH_SHA1:
case AUTH_MET_SHA1:
/*
* Keyed SHA1 and Meticulous Keyed SHA1 Authentication Section Format
*
* 0 1 2 3
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Auth Type | Auth Len | Auth Key ID | Reserved |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Sequence Number |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Auth Key/Hash... |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | ... |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*/
if (auth_len != AUTH_SHA1_FIELD_LEN) {
ND_PRINT("[invalid length %u]",
auth_len);
break;
}
pptr += 2;
ND_TCHECK_4(pptr);
ND_PRINT(", Sequence Number: 0x%08x", EXTRACT_BE_U_4(pptr));
pptr += 4;
ND_TCHECK_LEN(pptr, AUTH_SHA1_HASH_LEN);
ND_PRINT("\n\t Hash: ");
for(i = 0; i < AUTH_SHA1_HASH_LEN; i++)
ND_PRINT("%02x", EXTRACT_U_1(pptr + i));
break;
}
return 0;
trunc:
return 1;
}
void
bfd_print(netdissect_options *ndo, const u_char *pptr,
u_int len, u_int port)
{
ndo->ndo_protocol = "bfd";
if (port == BFD_CONTROL_PORT) {
/*
* Control packet.
*/
const struct bfd_header_t *bfd_header;
uint8_t version_diag;
uint8_t version = 0;
uint8_t flags;
bfd_header = (const struct bfd_header_t *)pptr;
ND_TCHECK_SIZE(bfd_header);
version_diag = EXTRACT_U_1(bfd_header->version_diag);
version = BFD_EXTRACT_VERSION(version_diag);
flags = EXTRACT_U_1(bfd_header->flags);
switch (version) {
/* BFDv0 */
case 0:
if (ndo->ndo_vflag < 1)
{
ND_PRINT("BFDv0, Control, Flags: [%s], length: %u",
bittok2str(bfd_v0_flag_values, "none", flags),
len);
return;
}
ND_PRINT("BFDv0, length: %u\n\tControl, Flags: [%s], Diagnostic: %s (0x%02x)",
len,
bittok2str(bfd_v0_flag_values, "none", flags),
tok2str(bfd_diag_values,"unknown",BFD_EXTRACT_DIAG(version_diag)),
BFD_EXTRACT_DIAG(version_diag));
ND_PRINT("\n\tDetection Timer Multiplier: %u (%u ms Detection time), BFD Length: %u",
EXTRACT_U_1(bfd_header->detect_time_multiplier),
EXTRACT_U_1(bfd_header->detect_time_multiplier) * EXTRACT_BE_U_4(bfd_header->desired_min_tx_interval)/1000,
EXTRACT_U_1(bfd_header->length));
ND_PRINT("\n\tMy Discriminator: 0x%08x", EXTRACT_BE_U_4(bfd_header->my_discriminator));
ND_PRINT(", Your Discriminator: 0x%08x", EXTRACT_BE_U_4(bfd_header->your_discriminator));
ND_PRINT("\n\t Desired min Tx Interval: %4u ms", EXTRACT_BE_U_4(bfd_header->desired_min_tx_interval)/1000);
ND_PRINT("\n\t Required min Rx Interval: %4u ms", EXTRACT_BE_U_4(bfd_header->required_min_rx_interval)/1000);
ND_PRINT("\n\t Required min Echo Interval: %4u ms", EXTRACT_BE_U_4(bfd_header->required_min_echo_interval)/1000);
if (flags & BFD_FLAG_AUTH) {
if (auth_print(ndo, pptr))
goto trunc;
}
break;
/* BFDv1 */
case 1:
if (ndo->ndo_vflag < 1)
{
ND_PRINT("BFDv1, Control, State %s, Flags: [%s], length: %u",
tok2str(bfd_v1_state_values, "unknown (%u)", (flags & 0xc0) >> 6),
bittok2str(bfd_v1_flag_values, "none", flags & 0x3f),
len);
return;
}
ND_PRINT("BFDv1, length: %u\n\tControl, State %s, Flags: [%s], Diagnostic: %s (0x%02x)",
len,
tok2str(bfd_v1_state_values, "unknown (%u)", (flags & 0xc0) >> 6),
bittok2str(bfd_v1_flag_values, "none", flags & 0x3f),
tok2str(bfd_diag_values,"unknown",BFD_EXTRACT_DIAG(version_diag)),
BFD_EXTRACT_DIAG(version_diag));
ND_PRINT("\n\tDetection Timer Multiplier: %u (%u ms Detection time), BFD Length: %u",
EXTRACT_U_1(bfd_header->detect_time_multiplier),
EXTRACT_U_1(bfd_header->detect_time_multiplier) * EXTRACT_BE_U_4(bfd_header->desired_min_tx_interval)/1000,
EXTRACT_U_1(bfd_header->length));
ND_PRINT("\n\tMy Discriminator: 0x%08x", EXTRACT_BE_U_4(bfd_header->my_discriminator));
ND_PRINT(", Your Discriminator: 0x%08x", EXTRACT_BE_U_4(bfd_header->your_discriminator));
ND_PRINT("\n\t Desired min Tx Interval: %4u ms", EXTRACT_BE_U_4(bfd_header->desired_min_tx_interval)/1000);
ND_PRINT("\n\t Required min Rx Interval: %4u ms", EXTRACT_BE_U_4(bfd_header->required_min_rx_interval)/1000);
ND_PRINT("\n\t Required min Echo Interval: %4u ms", EXTRACT_BE_U_4(bfd_header->required_min_echo_interval)/1000);
if (flags & BFD_FLAG_AUTH) {
if (auth_print(ndo, pptr))
goto trunc;
}
break;
default:
ND_PRINT("BFDv%u, Control, length: %u",
version,
len);
if (ndo->ndo_vflag >= 1) {
if(!print_unknown_data(ndo, pptr,"\n\t",len))
return;
}
break;
}
} else if (port == BFD_ECHO_PORT) {
/*
* Echo packet.
*/
ND_PRINT("BFD, Echo, length: %u",
len);
if (ndo->ndo_vflag >= 1) {
if(!print_unknown_data(ndo, pptr,"\n\t",len))
return;
}
} else {
/*
* Unknown packet type.
*/
ND_PRINT("BFD, unknown (%u), length: %u",
port,
len);
if (ndo->ndo_vflag >= 1) {
if(!print_unknown_data(ndo, pptr,"\n\t",len))
return;
}
}
return;
trunc:
nd_print_trunc(ndo);
}
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