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tcpdump/print-lisp.c
Guy Harris 913a9fa712 LISP: don't decrement count variables unless we know they're not zero. 
This fixes some undefined behavior warnings.
2021-11-15 16:44:46 -08:00

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/*
* Copyright (c) 2015 Ritesh Ranjan (r.ranjan789@gmail.com)
* 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.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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: - Locator/Identifier Separation Protocol (LISP) printer */
/*
* specification: RFC 6830
*
*
* The Map-Register message format is:
*
* 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
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* |Type=3 |P|S|I|R| Reserved |M| Record Count |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Nonce . . . |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | . . . Nonce |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Key ID | Authentication Data Length |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* ~ Authentication Data ~
* +-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | | Record TTL |
* | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* R | Locator Count | EID mask-len | ACT |A| Reserved |
* e +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* c | Rsvd | Map-Version Number | EID-Prefix-AFI |
* o +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* r | EID-Prefix |
* d +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | /| Priority | Weight | M Priority | M Weight |
* | L +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | o | Unused Flags |L|p|R| Loc-AFI |
* | c +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | \| Locator |
* +-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*
*
* The Map-Notify message format is:
*
* 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
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* |Type=4 |I|R| Reserved | Record Count |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Nonce . . . |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | . . . Nonce |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Key ID | Authentication Data Length |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* ~ Authentication Data ~
* +-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | | Record TTL |
* | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* R | Locator Count | EID mask-len | ACT |A| Reserved |
* e +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* c | Rsvd | Map-Version Number | EID-Prefix-AFI |
* o +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* r | EID-Prefix |
* d +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | /| Priority | Weight | M Priority | M Weight |
* | L +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | o | Unused Flags |L|p|R| Loc-AFI |
* | c +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | \| Locator |
* +-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include "netdissect-stdinc.h"
#include "netdissect.h"
#include "ip.h"
#include "ip6.h"
#include "extract.h"
#include "addrtoname.h"
#define IPv4_AFI 1
#define IPv6_AFI 2
#define TYPE_INDEX 4
#define LISP_MAP_NOTIFY_IBIT_MASK 8
#define LISP_MAP_REGISTER_IBIT_MASK 2
enum {
LISP_MAP_REQUEST = 1,
LISP_MAP_REPLY,
LISP_MAP_REGISTER,
LISP_MAP_NOTIFY,
LISP_ENCAPSULATED_CONTROL_MESSAGE = 8
};
enum {
LISP_AUTH_NONE,
LISP_AUTH_SHA1,
LISP_AUTH_SHA256
};
static const struct tok lisp_type [] = {
{ 0, "LISP-Reserved" },
{ 1, "LISP-Map-Request" },
{ 2, "LISP-Map-Reply" },
{ 3, "LISP-Map-Register" },
{ 4, "LISP-Map-Notify" },
{ 8, "LISP-Encapsulated-Contol-Message" },
{ 0, NULL }
};
/*
* P-Bit : Request for Proxy Map-Reply from the MS/MR
* S-Bit : Security Enhancement. ETR is LISP-SEC enabled. draft-ietf-lisp-sec
* I-Bit : 128 bit xTR-ID and 64 bit Site-ID present.
* xTR-ID and Site-ID help in differentiation of xTRs in multi xTR
* and multi Site deployment scenarios.
* R-Bit : Built for a Reencapsulating-Tunnel-Router. Used in Traffic
* Engineering and Service Chaining
*/
static const struct tok map_register_hdr_flag[] = {
{ 0x08000000, "P-Proxy-Map-Reply" },
{ 0x04000000, "S-LISP-SEC-Capable" },
{ 0x02000000, "I-xTR-ID-Present" },
{ 0x01000000, "R-Build-For-RTR" },
{ 0x00000100, "M-Want-Map-Notify" },
{ 0, NULL }
};
static const struct tok map_notify_hdr_flag[] = {
{ 0x08000000, "I-xTR-ID-Present" },
{ 0x04000000, "R-Build-For-RTR" },
{ 0, NULL }
};
static const struct tok auth_type[] = {
{ LISP_AUTH_NONE, "None" },
{ LISP_AUTH_SHA1, "SHA1" },
{ LISP_AUTH_SHA256, "SHA256" },
{ 0, NULL}
};
static const struct tok lisp_eid_action[] = {
{ 0, "No-Action" },
{ 1, "Natively-Forward" },
{ 2, "Send-Map-Request" },
{ 3, "Drop" },
{ 0, NULL}
};
static const struct tok lisp_loc_flag[] = {
{ 0x0004, "Local-Locator" },
{ 0x0002, "RLoc-Probed" },
{ 0x0001, "Reachable" },
{ 0, NULL }
};
typedef struct map_register_hdr {
nd_uint8_t type_and_flag;
nd_uint8_t reserved;
nd_uint8_t reserved_and_flag2;
nd_uint8_t record_count;
nd_uint64_t nonce;
nd_uint16_t key_id;
nd_uint16_t auth_data_len;
} lisp_map_register_hdr;
#define MAP_REGISTER_HDR_LEN sizeof(lisp_map_register_hdr)
typedef struct map_register_eid {
nd_uint32_t ttl;
nd_uint8_t locator_count;
nd_uint8_t eid_prefix_mask_length;
nd_uint8_t act_auth_inc_res;
nd_uint8_t reserved;
nd_uint16_t reserved_and_version;
nd_uint16_t eid_prefix_afi;
} lisp_map_register_eid;
#define MAP_REGISTER_EID_LEN sizeof(lisp_map_register_eid)
typedef struct map_register_loc {
nd_uint8_t priority;
nd_uint8_t weight;
nd_uint8_t m_priority;
nd_uint8_t m_weight;
nd_uint16_t unused_and_flag;
nd_uint16_t locator_afi;
} lisp_map_register_loc;
#define MAP_REGISTER_LOC_LEN sizeof(lisp_map_register_loc)
static uint8_t extract_lisp_type(uint8_t);
static uint8_t is_xtr_data_present(uint8_t, uint8_t);
static void lisp_hdr_flag(netdissect_options *, const lisp_map_register_hdr *);
static void action_flag(netdissect_options *, uint8_t);
static void loc_hdr_flag(netdissect_options *, uint16_t);
void
lisp_print(netdissect_options *ndo, const u_char *bp, u_int length)
{
uint8_t type_and_flag;
uint8_t type;
uint8_t mask_len;
uint8_t loc_count;
uint8_t xtr_present;
uint8_t record_count;
uint16_t key_id;
uint16_t eid_afi;
uint16_t loc_afi;
uint16_t map_version;
uint16_t packet_offset;
uint16_t auth_data_len;
uint32_t ttl;
const u_char *packet_iterator;
const u_char *loc_ip_pointer;
const lisp_map_register_hdr *lisp_hdr;
const lisp_map_register_eid *lisp_eid;
const lisp_map_register_loc *lisp_loc;
ndo->ndo_protocol = "lisp";
/* Check if enough bytes for header are available */
ND_TCHECK_LEN(bp, MAP_REGISTER_HDR_LEN);
lisp_hdr = (const lisp_map_register_hdr *) bp;
lisp_hdr_flag(ndo, lisp_hdr);
/* Supporting only MAP NOTIFY and MAP REGISTER LISP packets */
type_and_flag = GET_U_1(lisp_hdr->type_and_flag);
type = extract_lisp_type(type_and_flag);
if ((type != LISP_MAP_REGISTER) && (type != LISP_MAP_NOTIFY))
return;
/* Find if the packet contains xTR and Site-ID data */
xtr_present = is_xtr_data_present(type, type_and_flag);
/* Extract the number of EID records present */
auth_data_len = GET_BE_U_2(lisp_hdr->auth_data_len);
packet_iterator = (const u_char *)(lisp_hdr);
packet_offset = MAP_REGISTER_HDR_LEN;
record_count = GET_U_1(lisp_hdr->record_count);
if (ndo->ndo_vflag) {
key_id = GET_BE_U_2(lisp_hdr->key_id);
ND_PRINT("\n %u record(s), ", record_count);
ND_PRINT("Authentication %s,",
tok2str(auth_type, "unknown-type", key_id));
hex_print(ndo, "\n Authentication-Data: ", packet_iterator +
packet_offset, auth_data_len);
} else {
ND_PRINT(" %u record(s),", record_count);
}
packet_offset += auth_data_len;
if (record_count == 0)
goto invalid;
/* Print all the EID records */
while ((length > packet_offset) && (record_count != 0)) {
record_count--;
ND_TCHECK_LEN(packet_iterator + packet_offset,
MAP_REGISTER_EID_LEN);
ND_PRINT("\n");
lisp_eid = (const lisp_map_register_eid *)
((const u_char *)lisp_hdr + packet_offset);
packet_offset += MAP_REGISTER_EID_LEN;
mask_len = GET_U_1(lisp_eid->eid_prefix_mask_length);
eid_afi = GET_BE_U_2(lisp_eid->eid_prefix_afi);
loc_count = GET_U_1(lisp_eid->locator_count);
if (ndo->ndo_vflag) {
ttl = GET_BE_U_4(lisp_eid->ttl);
ND_PRINT(" Record TTL %u,", ttl);
action_flag(ndo, GET_U_1(lisp_eid->act_auth_inc_res));
map_version = GET_BE_U_2(lisp_eid->reserved_and_version) & 0x0FFF;
ND_PRINT(" Map Version: %u,", map_version);
}
switch (eid_afi) {
case IPv4_AFI:
ND_PRINT(" EID %s/%u,",
GET_IPADDR_STRING(packet_iterator + packet_offset),
mask_len);
packet_offset += 4;
break;
case IPv6_AFI:
ND_PRINT(" EID %s/%u,",
GET_IP6ADDR_STRING(packet_iterator + packet_offset),
mask_len);
packet_offset += 16;
break;
default:
/*
* No support for LCAF right now.
*/
return;
break;
}
ND_PRINT(" %u locator(s)", loc_count);
while (loc_count != 0) {
loc_count--;
ND_TCHECK_LEN(packet_iterator + packet_offset,
MAP_REGISTER_LOC_LEN);
lisp_loc = (const lisp_map_register_loc *) (packet_iterator + packet_offset);
loc_ip_pointer = (const u_char *) (lisp_loc + 1);
packet_offset += MAP_REGISTER_LOC_LEN;
loc_afi = GET_BE_U_2(lisp_loc->locator_afi);
if (ndo->ndo_vflag)
ND_PRINT("\n ");
switch (loc_afi) {
case IPv4_AFI:
ND_TCHECK_4(packet_iterator + packet_offset);
ND_PRINT(" LOC %s", GET_IPADDR_STRING(loc_ip_pointer));
packet_offset += 4;
break;
case IPv6_AFI:
ND_TCHECK_16(packet_iterator + packet_offset);
ND_PRINT(" LOC %s", GET_IP6ADDR_STRING(loc_ip_pointer));
packet_offset += 16;
break;
default:
break;
}
if (ndo->ndo_vflag) {
ND_PRINT("\n Priority/Weight %u/%u,"
" Multicast Priority/Weight %u/%u,",
GET_U_1(lisp_loc->priority),
GET_U_1(lisp_loc->weight),
GET_U_1(lisp_loc->m_priority),
GET_U_1(lisp_loc->m_weight));
loc_hdr_flag(ndo,
GET_BE_U_2(lisp_loc->unused_and_flag));
}
}
}
/*
* Print xTR and Site ID. Handle the fact that the packet could be invalid.
* If the xTR_ID_Present bit is not set, and we still have data to display,
* show it as hex data.
*/
if (xtr_present) {
if (!ND_TTEST_LEN(packet_iterator + packet_offset, 24))
goto invalid;
hex_print(ndo, "\n xTR-ID: ", packet_iterator + packet_offset, 16);
ND_PRINT("\n SITE-ID: %" PRIu64,
GET_BE_U_8(packet_iterator + packet_offset + 16));
} else {
/* Check if packet isn't over yet */
if (packet_iterator + packet_offset < ndo->ndo_snapend) {
hex_print(ndo, "\n Data: ", packet_iterator + packet_offset,
ND_BYTES_AVAILABLE_AFTER(packet_iterator + packet_offset));
}
}
return;
trunc:
nd_print_trunc(ndo);
return;
invalid:
nd_print_invalid(ndo);
}
static uint8_t
extract_lisp_type(uint8_t lisp_hdr_flags)
{
return (lisp_hdr_flags) >> TYPE_INDEX;
}
static uint8_t
is_xtr_data_present(uint8_t type, uint8_t lisp_hdr_flags)
{
uint8_t xtr_present = 0;
if (type == LISP_MAP_REGISTER)
xtr_present = (lisp_hdr_flags) & LISP_MAP_REGISTER_IBIT_MASK;
else if (type == LISP_MAP_NOTIFY)
xtr_present = (lisp_hdr_flags) & LISP_MAP_NOTIFY_IBIT_MASK;
return xtr_present;
}
static void lisp_hdr_flag(netdissect_options *ndo, const lisp_map_register_hdr *lisp_hdr)
{
uint8_t type = extract_lisp_type(GET_U_1(lisp_hdr->type_and_flag));
if (!ndo->ndo_vflag) {
ND_PRINT("%s,", tok2str(lisp_type, "unknown-type-%u", type));
return;
} else {
ND_PRINT("%s,", tok2str(lisp_type, "unknown-type-%u", type));
}
if (type == LISP_MAP_REGISTER) {
ND_PRINT(" flags [%s],", bittok2str(map_register_hdr_flag,
"none", GET_BE_U_4(lisp_hdr)));
} else if (type == LISP_MAP_NOTIFY) {
ND_PRINT(" flags [%s],", bittok2str(map_notify_hdr_flag,
"none", GET_BE_U_4(lisp_hdr)));
}
}
static void action_flag(netdissect_options *ndo, uint8_t act_auth_inc_res)
{
uint8_t action;
uint8_t authoritative;
authoritative = ((act_auth_inc_res >> 4) & 1);
if (authoritative)
ND_PRINT(" Authoritative,");
else
ND_PRINT(" Non-Authoritative,");
action = act_auth_inc_res >> 5;
ND_PRINT(" %s,", tok2str(lisp_eid_action, "unknown", action));
}
static void loc_hdr_flag(netdissect_options *ndo, uint16_t flag)
{
ND_PRINT(" flags [%s],", bittok2str(lisp_loc_flag, "none", flag));
}
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