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Systemd/src/libsystemd-network/lldp-neighbor.c
Lennart Poettering 34437b4f9c sd-lldp: rework sd-lldp API 
This reworks the sd-lldp substantially, simplifying things on one hand, and
extending the logic a bit on the other.

Specifically:

- Besides the sd_lldp object only one other object is maintained now,
  sd_lldp_neighbor. It's used both as storage for literal LLDP packets, and for
  maintainging info about peers in the database. Separation between packet, TLV
  and chassis data is not maintained anymore. This should be a major
  simplification.

- The sd-lldp API has been extended so that a couple of per-neighbor fields may
  be queried directly, without iterating through the object. Other fields that
  may appear multiple times, OTOH have to be iterated through.

- The maximum number of entries in the neighbor database is now configurable
  during runtime.

- The generation of callbacks from sd_lldp objects is more restricted:
  callbacks are only invoked when actual data changed.

- The TTL information is now hooked with a timer event, so that removals from
  the neighbor database due to TTLs now result in a callback event.

- Querying LLDP neighbor database will now return a strictly ordered array, to
  guarantee stability.

- A "capabilities" mask may now be configured, that selects what type of LLDP
  neighbor data is collected. This may be used to restrict collection of LLDP
  info about routers instead of all neighbors. This is now exposed via
  networkd's LLDP= setting.

- sd-lldp's API to serialize the collected data to text files has been removed.
  Instead, there's now an API to extract the raw binary data from LLDP neighbor
  objects, as well as one to convert this raw binary data back to an LLDP
  neighbor object. networkd will save this raw binary data to /run now, and the
  client side can simply parse the information.

- support for parsing the more exotic TLVs has been removed, since we are not
  using that. Instead there are now APIs to extract the raw data from TLVs.
  Given how easy it is to parse the TLVs clients should do so now directly
  instead of relying on our APIs for that.

- A lot of the APIs that parse out LLDP strings have been simplified so that
  they actually return strings, instead of char arrays with a length. To deal
  with possibly dangerous characters the strings are escaped if needed.

- APIs to extract and format the chassis and port IDs as strings has been
  added.

- lldp.h has been simplified a lot. The enums are anonymous now, since they
  were never used as enums, but simply as constants. Most definitions we don't
  actually use ourselves have eben removed.
2016-02-21 20:40:56 +01:00

793 lines
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/***
This file is part of systemd.
Copyright 2016 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include "alloc-util.h"
#include "escape.h"
#include "ether-addr-util.h"
#include "hexdecoct.h"
#include "in-addr-util.h"
#include "lldp-internal.h"
#include "lldp-neighbor.h"
#include "lldp.h"
#include "unaligned.h"
static void lldp_neighbor_id_hash_func(const void *p, struct siphash *state) {
const LLDPNeighborID *id = p;
siphash24_compress(id->chassis_id, id->chassis_id_size, state);
siphash24_compress(&id->chassis_id_size, sizeof(id->chassis_id_size), state);
siphash24_compress(id->port_id, id->port_id_size, state);
siphash24_compress(&id->port_id_size, sizeof(id->port_id_size), state);
}
static int lldp_neighbor_id_compare_func(const void *a, const void *b) {
const LLDPNeighborID *x = a, *y = b;
int r;
r = memcmp(x->chassis_id, y->chassis_id, MIN(x->chassis_id_size, y->chassis_id_size));
if (r != 0)
return r;
if (x->chassis_id_size < y->chassis_id_size)
return -1;
if (x->chassis_id_size > y->chassis_id_size)
return 1;
r = memcmp(x->port_id, y->port_id, MIN(x->port_id_size, y->port_id_size));
if (r != 0)
return r;
if (x->port_id_size < y->port_id_size)
return -1;
if (x->port_id_size > y->port_id_size)
return 1;
return 0;
}
const struct hash_ops lldp_neighbor_id_hash_ops = {
.hash = lldp_neighbor_id_hash_func,
.compare = lldp_neighbor_id_compare_func
};
int lldp_neighbor_prioq_compare_func(const void *a, const void *b) {
const sd_lldp_neighbor *x = a, *y = b;
if (x->until < y->until)
return -1;
if (x->until > y->until)
return 1;
return 0;
}
_public_ sd_lldp_neighbor *sd_lldp_neighbor_ref(sd_lldp_neighbor *n) {
if (!n)
return NULL;
assert(n->n_ref > 0 || n->lldp);
n->n_ref++;
return n;
}
static void lldp_neighbor_free(sd_lldp_neighbor *n) {
assert(n);
free(n->id.port_id);
free(n->id.chassis_id);
free(n->port_description);
free(n->system_name);
free(n->system_description);
free(n->chassis_id_as_string);
free(n->port_id_as_string);
free(n);
}
_public_ sd_lldp_neighbor *sd_lldp_neighbor_unref(sd_lldp_neighbor *n) {
/* Drops one reference from the neighbor. Note that the object is not freed unless it is already unlinked from
* the sd_lldp object. */
if (!n)
return NULL;
assert(n->n_ref > 0);
n->n_ref--;
if (n->n_ref <= 0 && !n->lldp)
lldp_neighbor_free(n);
return NULL;
}
sd_lldp_neighbor *lldp_neighbor_unlink(sd_lldp_neighbor *n) {
/* Removes the neighbor object from the LLDP object, and frees it if it also has no other reference. */
if (!n)
return NULL;
if (!n->lldp)
return NULL;
assert_se(hashmap_remove(n->lldp->neighbor_by_id, &n->id) == n);
assert_se(prioq_remove(n->lldp->neighbor_by_expiry, n, &n->prioq_idx) >= 0);
n->lldp = NULL;
if (n->n_ref <= 0)
lldp_neighbor_free(n);
return NULL;
}
sd_lldp_neighbor *lldp_neighbor_new(size_t raw_size) {
sd_lldp_neighbor *n;
n = malloc0(ALIGN(sizeof(sd_lldp_neighbor)) + raw_size);
if (!n)
return NULL;
n->raw_size = raw_size;
n->n_ref = 1;
return n;
}
static int parse_string(char **s, const void *q, size_t n) {
const char *p = q;
char *k;
assert(s);
assert(p || n == 0);
if (*s) {
log_lldp("Found duplicate string, ignoring field.");
return 0;
}
/* Strip trailing NULs, just to be nice */
while (n > 0 && p[n-1] == 0)
n--;
if (n <= 0) /* Ignore empty strings */
return 0;
/* Look for inner NULs */
if (memchr(p, 0, n)) {
log_lldp("Found inner NUL in string, ignoring field.");
return 0;
}
/* Let's escape weird chars, for security reasons */
k = cescape_length(p, n);
if (!k)
return -ENOMEM;
free(*s);
*s = k;
return 1;
}
int lldp_neighbor_parse(sd_lldp_neighbor *n) {
struct ether_header h;
const uint8_t *p;
size_t left;
int r;
assert(n);
if (n->raw_size < sizeof(struct ether_header)) {
log_lldp("Recieved truncated packet, ignoring.");
return -EBADMSG;
}
memcpy(&h, LLDP_NEIGHBOR_RAW(n), sizeof(h));
if (h.ether_type != htobe16(ETHERTYPE_LLDP)) {
log_lldp("Received packet with wrong type, ignoring.");
return -EBADMSG;
}
if (h.ether_dhost[0] != 0x01 ||
h.ether_dhost[1] != 0x80 ||
h.ether_dhost[2] != 0xc2 ||
h.ether_dhost[3] != 0x00 ||
h.ether_dhost[4] != 0x00 ||
!IN_SET(h.ether_dhost[5], 0x00, 0x03, 0x0e)) {
log_lldp("Received packet with wrong destination address, ignoring.");
return -EBADMSG;
}
memcpy(&n->source_address, h.ether_shost, sizeof(struct ether_addr));
memcpy(&n->destination_address, h.ether_dhost, sizeof(struct ether_addr));
p = (const uint8_t*) LLDP_NEIGHBOR_RAW(n) + sizeof(struct ether_header);
left = n->raw_size - sizeof(struct ether_header);
for (;;) {
uint8_t type;
uint16_t length;
if (left < 2) {
log_lldp("TLV lacks header, ignoring.");
return -EBADMSG;
}
type = p[0] >> 1;
length = p[1] + (((uint16_t) (p[0] & 1)) << 8);
p += 2, left -= 2;
if (left < length) {
log_lldp("TLV truncated, ignoring datagram.");
return -EBADMSG;
}
switch (type) {
case LLDP_TYPE_END:
if (length != 0) {
log_lldp("End marker TLV not zero-sized, ignoring datagram.");
return -EBADMSG;
}
if (left != 0) {
log_lldp("Trailing garbage in datagram, ignoring datagram.");
return -EBADMSG;
}
goto end_marker;
case LLDP_TYPE_CHASSIS_ID:
if (length < 2 || length > 256) { /* includes the chassis subtype, hence one extra byte */
log_lldp("Chassis ID field size out of range, ignoring datagram.");
return -EBADMSG;
}
if (n->id.chassis_id) {
log_lldp("Duplicate chassis ID field, ignoring datagram.");
return -EBADMSG;
}
n->id.chassis_id = memdup(p, length);
if (!n->id.chassis_id)
return -ENOMEM;
n->id.chassis_id_size = length;
break;
case LLDP_TYPE_PORT_ID:
if (length < 2 || length > 256) { /* includes the port subtype, hence one extra byte */
log_lldp("Port ID field size out of range, ignoring datagram.");
return -EBADMSG;
}
if (n->id.port_id) {
log_lldp("Duplicate port ID field, ignoring datagram.");
return -EBADMSG;
}
n->id.port_id = memdup(p, length);
if (!n->id.port_id)
return -ENOMEM;
n->id.port_id_size = length;
break;
case LLDP_TYPE_TTL:
if (length != 2) {
log_lldp("TTL field has wrong size, ignoring datagram.");
return -EBADMSG;
}
if (n->has_ttl) {
log_lldp("Duplicate TTL field, ignoring datagram.");
return -EBADMSG;
}
n->ttl = unaligned_read_be16(p);
n->has_ttl = true;
break;
case LLDP_TYPE_PORT_DESCRIPTION:
r = parse_string(&n->port_description, p, length);
if (r < 0)
return r;
break;
case LLDP_TYPE_SYSTEM_NAME:
r = parse_string(&n->system_name, p, length);
if (r < 0)
return r;
break;
case LLDP_TYPE_SYSTEM_DESCRIPTION:
r = parse_string(&n->system_description, p, length);
if (r < 0)
return r;
break;
case LLDP_TYPE_SYSTEM_CAPABILITIES:
if (length != 4)
log_lldp("System capabilities field has wrong size, ignoring.");
else {
n->system_capabilities = unaligned_read_be16(p);
n->enabled_capabilities = unaligned_read_be16(p + 2);
n->has_capabilities = true;
}
break;
case LLDP_TYPE_PRIVATE:
if (length < 4)
log_lldp("Found private TLV that is too short, ignoring.");
break;
}
p += length, left -= length;
}
end_marker:
if (!n->id.chassis_id || !n->id.port_id || !n->has_ttl) {
log_lldp("One or more mandatory TLV missing in datagram. Ignoring.");
return -EBADMSG;
}
n->rindex = sizeof(struct ether_header);
return 0;
}
void lldp_neighbor_start_ttl(sd_lldp_neighbor *n) {
assert(n);
if (n->ttl > 0)
n->until = usec_add(now(clock_boottime_or_monotonic()), n->ttl * USEC_PER_SEC);
else
n->until = 0;
if (n->lldp)
prioq_reshuffle(n->lldp->neighbor_by_expiry, n, &n->prioq_idx);
}
bool lldp_neighbor_equal(const sd_lldp_neighbor *a, const sd_lldp_neighbor *b) {
if (a == b)
return true;
if (!a || !b)
return false;
if (a->raw_size != b->raw_size)
return false;
return memcmp(LLDP_NEIGHBOR_RAW(a), LLDP_NEIGHBOR_RAW(b), a->raw_size) == 0;
}
_public_ int sd_lldp_neighbor_get_source_address(sd_lldp_neighbor *n, struct ether_addr* address) {
assert_return(n, -EINVAL);
assert_return(address, -EINVAL);
*address = n->source_address;
return 0;
}
_public_ int sd_lldp_neighbor_get_destination_address(sd_lldp_neighbor *n, struct ether_addr* address) {
assert_return(n, -EINVAL);
assert_return(address, -EINVAL);
*address = n->destination_address;
return 0;
}
_public_ int sd_lldp_neighbor_get_raw(sd_lldp_neighbor *n, const void **ret, size_t *size) {
assert_return(n, -EINVAL);
assert_return(ret, -EINVAL);
assert_return(size, -EINVAL);
*ret = LLDP_NEIGHBOR_RAW(n);
*size = n->raw_size;
return 0;
}
_public_ int sd_lldp_neighbor_get_chassis_id(sd_lldp_neighbor *n, uint8_t *type, const void **ret, size_t *size) {
assert_return(n, -EINVAL);
assert_return(type, -EINVAL);
assert_return(ret, -EINVAL);
assert_return(size, -EINVAL);
assert(n->id.chassis_id_size > 0);
*type = *(uint8_t*) n->id.chassis_id;
*ret = (uint8_t*) n->id.chassis_id + 1;
*size = n->id.chassis_id_size - 1;
return 0;
}
static int format_mac_address(const void *data, size_t sz, char **ret) {
struct ether_addr a;
char *k;
assert(data || sz <= 0);
if (sz != 7)
return 0;
memcpy(&a, (uint8_t*) data + 1, sizeof(a));
k = new(char, ETHER_ADDR_TO_STRING_MAX);
if (!k)
return -ENOMEM;
*ret = ether_addr_to_string(&a, k);
return 1;
}
static int format_network_address(const void *data, size_t sz, char **ret) {
union in_addr_union a;
int family;
if (sz == 6 && ((uint8_t*) data)[1] == 1) {
memcpy(&a.in, (uint8_t*) data + 2, sizeof(a.in));
family = AF_INET;
} else if (sz == 18 && ((uint8_t*) data)[1] == 2) {
memcpy(&a.in6, (uint8_t*) data + 2, sizeof(a.in6));
family = AF_INET6;
} else
return 0;
return in_addr_to_string(family, &a, ret);
}
_public_ int sd_lldp_neighbor_get_chassis_id_as_string(sd_lldp_neighbor *n, const char **ret) {
char *k;
int r;
assert_return(n, -EINVAL);
assert_return(ret, -EINVAL);
if (n->chassis_id_as_string) {
*ret = n->chassis_id_as_string;
return 0;
}
assert(n->id.chassis_id_size > 0);
switch (*(uint8_t*) n->id.chassis_id) {
case LLDP_CHASSIS_SUBTYPE_CHASSIS_COMPONENT:
case LLDP_CHASSIS_SUBTYPE_INTERFACE_ALIAS:
case LLDP_CHASSIS_SUBTYPE_PORT_COMPONENT:
case LLDP_CHASSIS_SUBTYPE_INTERFACE_NAME:
case LLDP_CHASSIS_SUBTYPE_LOCALLY_ASSIGNED:
k = cescape_length((char*) n->id.chassis_id + 1, n->id.chassis_id_size - 1);
if (!k)
return -ENOMEM;
goto done;
case LLDP_CHASSIS_SUBTYPE_MAC_ADDRESS:
r = format_mac_address(n->id.chassis_id, n->id.chassis_id_size, &k);
if (r < 0)
return r;
if (r > 0)
goto done;
break;
case LLDP_CHASSIS_SUBTYPE_NETWORK_ADDRESS:
r = format_network_address(n->id.chassis_id, n->id.chassis_id_size, &k);
if (r < 0)
return r;
if (r > 0)
goto done;
break;
}
/* Generic fallback */
k = hexmem(n->id.chassis_id, n->id.chassis_id_size);
if (!k)
return -ENOMEM;
done:
*ret = n->chassis_id_as_string = k;
return 0;
}
_public_ int sd_lldp_neighbor_get_port_id(sd_lldp_neighbor *n, uint8_t *type, const void **ret, size_t *size) {
assert_return(n, -EINVAL);
assert_return(type, -EINVAL);
assert_return(ret, -EINVAL);
assert_return(size, -EINVAL);
assert(n->id.port_id_size > 0);
*type = *(uint8_t*) n->id.port_id;
*ret = (uint8_t*) n->id.port_id + 1;
*size = n->id.port_id_size - 1;
return 0;
}
_public_ int sd_lldp_neighbor_get_port_id_as_string(sd_lldp_neighbor *n, const char **ret) {
char *k;
int r;
assert_return(n, -EINVAL);
assert_return(ret, -EINVAL);
if (n->port_id_as_string) {
*ret = n->port_id_as_string;
return 0;
}
assert(n->id.port_id_size > 0);
switch (*(uint8_t*) n->id.port_id) {
case LLDP_PORT_SUBTYPE_INTERFACE_ALIAS:
case LLDP_PORT_SUBTYPE_PORT_COMPONENT:
case LLDP_PORT_SUBTYPE_INTERFACE_NAME:
case LLDP_PORT_SUBTYPE_LOCALLY_ASSIGNED:
k = cescape_length((char*) n->id.port_id + 1, n->id.port_id_size - 1);
if (!k)
return -ENOMEM;
goto done;
case LLDP_PORT_SUBTYPE_MAC_ADDRESS:
r = format_mac_address(n->id.port_id, n->id.port_id_size, &k);
if (r < 0)
return r;
if (r > 0)
goto done;
break;
case LLDP_PORT_SUBTYPE_NETWORK_ADDRESS:
r = format_network_address(n->id.port_id, n->id.port_id_size, &k);
if (r < 0)
return r;
if (r > 0)
goto done;
break;
}
/* Generic fallback */
k = hexmem(n->id.port_id, n->id.port_id_size);
if (!k)
return -ENOMEM;
done:
*ret = n->port_id_as_string = k;
return 0;
}
_public_ int sd_lldp_neighbor_get_ttl(sd_lldp_neighbor *n, uint16_t *ret) {
assert_return(n, -EINVAL);
assert_return(ret, -EINVAL);
*ret = n->ttl;
return 0;
}
_public_ int sd_lldp_neighbor_get_system_name(sd_lldp_neighbor *n, const char **ret) {
assert_return(n, -EINVAL);
assert_return(ret, -EINVAL);
if (!n->system_name)
return -ENODATA;
*ret = n->system_name;
return 0;
}
_public_ int sd_lldp_neighbor_get_system_description(sd_lldp_neighbor *n, const char **ret) {
assert_return(n, -EINVAL);
assert_return(ret, -EINVAL);
if (!n->system_description)
return -ENODATA;
*ret = n->system_description;
return 0;
}
_public_ int sd_lldp_neighbor_get_port_description(sd_lldp_neighbor *n, const char **ret) {
assert_return(n, -EINVAL);
assert_return(ret, -EINVAL);
if (!n->port_description)
return -ENODATA;
*ret = n->port_description;
return 0;
}
_public_ int sd_lldp_neighbor_get_system_capabilities(sd_lldp_neighbor *n, uint16_t *ret) {
assert_return(n, -EINVAL);
assert_return(ret, -EINVAL);
if (!n->has_capabilities)
return -ENODATA;
*ret = n->system_capabilities;
return 0;
}
_public_ int sd_lldp_neighbor_get_enabled_capabilities(sd_lldp_neighbor *n, uint16_t *ret) {
assert_return(n, -EINVAL);
assert_return(ret, -EINVAL);
if (!n->has_capabilities)
return -ENODATA;
*ret = n->enabled_capabilities;
return 0;
}
int sd_lldp_neighbor_from_raw(sd_lldp_neighbor **ret, const void *raw, size_t raw_size) {
_cleanup_(sd_lldp_neighbor_unrefp) sd_lldp_neighbor *n = NULL;
int r;
assert_return(ret, -EINVAL);
assert_return(raw || raw_size <= 0, -EINVAL);
n = lldp_neighbor_new(raw_size);
if (!n)
return -ENOMEM;
memcpy(LLDP_NEIGHBOR_RAW(n), raw, raw_size);
r = lldp_neighbor_parse(n);
if (r < 0)
return r;
*ret = n;
n = 0;
return r;
}
_public_ int sd_lldp_neighbor_tlv_rewind(sd_lldp_neighbor *n) {
assert_return(n, -EINVAL);
assert(n->raw_size >= sizeof(struct ether_header));
n->rindex = sizeof(struct ether_header);
return 0;
}
_public_ int sd_lldp_neighbor_tlv_next(sd_lldp_neighbor *n) {
size_t length;
assert_return(n, -EINVAL);
if (n->rindex == n->raw_size) /* EOF */
return -ESPIPE;
if (n->rindex + 2 > n->raw_size) /* Truncated message */
return -EBADMSG;
length = LLDP_NEIGHBOR_LENGTH(n);
if (n->rindex + 2 + length > n->raw_size)
return -EBADMSG;
n->rindex += 2 + length;
return n->rindex < n->raw_size;
}
_public_ int sd_lldp_neighbor_tlv_get_type(sd_lldp_neighbor *n, uint8_t *type) {
assert_return(n, -EINVAL);
assert_return(type, -EINVAL);
if (n->rindex == n->raw_size) /* EOF */
return -ESPIPE;
if (n->rindex + 2 > n->raw_size)
return -EBADMSG;
*type = LLDP_NEIGHBOR_TYPE(n);
return 0;
}
_public_ int sd_lldp_neighbor_tlv_is_type(sd_lldp_neighbor *n, uint8_t type) {
uint8_t k;
int r;
assert_return(n, -EINVAL);
r = sd_lldp_neighbor_tlv_get_type(n, &k);
if (r < 0)
return r;
return type == k;
}
_public_ int sd_lldp_neighbor_tlv_get_oui(sd_lldp_neighbor *n, uint8_t oui[3], uint8_t *subtype) {
const uint8_t *d;
size_t length;
int r;
assert_return(n, -EINVAL);
assert_return(oui, -EINVAL);
assert_return(subtype, -EINVAL);
r = sd_lldp_neighbor_tlv_is_type(n, LLDP_TYPE_PRIVATE);
if (r < 0)
return r;
if (r == 0)
return -ENXIO;
length = LLDP_NEIGHBOR_LENGTH(n);
if (length < 4)
return -EBADMSG;
if (n->rindex + 2 + length > n->raw_size)
return -EBADMSG;
d = LLDP_NEIGHBOR_DATA(n);
memcpy(oui, d, 3);
*subtype = d[3];
return 0;
}
_public_ int sd_lldp_neighbor_tlv_is_oui(sd_lldp_neighbor *n, const uint8_t oui[3], uint8_t subtype) {
uint8_t k[3], st;
int r;
r = sd_lldp_neighbor_tlv_get_oui(n, k, &st);
if (r == -ENXIO)
return 0;
if (r < 0)
return r;
return memcmp(k, oui, 3) == 0 && st == subtype;
}
_public_ int sd_lldp_neighbor_tlv_get_raw(sd_lldp_neighbor *n, const void **ret, size_t *size) {
size_t length;
assert_return(n, -EINVAL);
assert_return(ret, -EINVAL);
assert_return(size, -EINVAL);
/* Note that this returns the full TLV, including the TLV header */
if (n->rindex + 2 > n->raw_size)
return -EBADMSG;
length = LLDP_NEIGHBOR_LENGTH(n);
if (n->rindex + 2 + length > n->raw_size)
return -EBADMSG;
*ret = (uint8_t*) LLDP_NEIGHBOR_RAW(n) + n->rindex;
*size = length + 2;
return 0;
}
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