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bird/proto/snmp/snmp.c
2023-11-08 13:10:13 +01:00

666 lines
18 KiB
C

/*
* BIRD -- Simple Network Management Protocol (SNMP)
*
* (c) 2022 Vojtech Vilimek <vojtech.vilimek@nic.cz>
* (c) 2022 CZ.NIC z.s.p.o.
*
* Can be freely distributed and used under the terms of the GNU GPL.
*/
/**
* Simple Network Management Protocol State Machine
*
* States with main transitions
*
*
* +-----------------+
* | SNMP_INIT | entry state after call snmp_start()
* +-----------------+
* |
* | acquiring object lock for communication socket
* V
* +-----------------+
* | SNMP_LOCKED | object lock aquired
* +-----------------+
* |
* | opening communication socket
* V
* +-----------------+
* | SNMP_OPEN | socket created, starting subagent
* +-----------------+
* |
* | BIRD receive response for Open-PDU
* V
* +-----------------+
* | SNMP_REGISTER | session was established, subagent registers MIBs
* +-----------------+
* |
* | subagent received responses for all registration requests
* V
* +-----------------+
* | SNMP_CONN | everything is set
* +-----------------+
* |
* | function snmp_shutdown() is called, BIRD sends Close-PDU
* V
* +-----------------+
* | SNMP_STOP | waiting for response
* +-----------------+
* |
* | cleaning old state information
* V
* +-----------------+
* | SNMP_DOWN | session is closed
* +-----------------+
*
*
* +-----------------+
* | SNMP_RESET | waiting to transmit response to malformed packet
* +-----------------+
* |
* | response was send, reseting the session (with socket)
* |
* \--> SNMP_LOCKED
*
*
* Erroneous transitions:
* SNMP is UP in states SNMP_CONN and also in SNMP_REGISTER because the
* session is establised and the GetNext request should be responsed
* without regard to MIB registration.
*
* When the session has been closed for some reason (socket error, receipt of
* Close-PDU) SNMP cleans the session information and message queue and goes
* back to the SNMP_LOCKED state.
*
* Reconfiguration is done in similar fashion to BGP, the reconfiguration
* request is declined, the protocols is stoped and started with new
* configuration.
*
*/
#include "nest/bird.h"
#include "nest/cli.h"
#include "nest/locks.h"
#include "lib/socket.h"
#include "lib/lists.h"
#include "snmp.h"
#include "subagent.h"
#include "snmp_utils.h"
static const char * const snmp_state[] = {
[SNMP_INIT] = "SNMP INIT",
[SNMP_LOCKED] = "SNMP LOCKED",
[SNMP_OPEN] = "SNMP CONNECTION OPENED",
[SNMP_REGISTER] = "SNMP REGISTERING MIBS",
[SNMP_CONN] = "SNMP CONNECTED",
[SNMP_STOP] = "SNMP STOPPING",
[SNMP_DOWN] = "SNMP DOWN",
};
/*
* snmp_init - preinitialize SNMP instance
* @CF - SNMP configuration generic handle
*
* Return value is generic handle pointing to preinitialized SNMP procotol
* instance.
*/
static struct proto *
snmp_init(struct proto_config *CF)
{
struct proto *P = proto_new(CF);
struct snmp_proto *p = SKIP_BACK(struct snmp_proto, p, P);
const struct snmp_config *cf = SKIP_BACK(struct snmp_config, cf, CF);
p->rl_gen = (struct tbf) TBF_DEFAULT_LOG_LIMITS;
p->local_ip = cf->local_ip;
p->remote_ip = cf->remote_ip;
p->local_port = cf->local_port;
p->remote_port = cf->remote_port;
p->bgp_local_as = cf->bgp_local_as;
p->bgp_local_id = cf->bgp_local_id;
snmp_log("changing state to INIT");
p->state = SNMP_INIT;
p->timeout = cf->timeout;
return P;
}
/*
* snmp_cleanup - free all resources allocated by SNMP protocol
* @p - SNMP protocol instance
*
* This function forcefully stops and cleans all resources and memory acqiured
* by given SNMP protocol instance, such as timers, lists, hash tables etc.
* Function snmp_cleanup() does not change the protocol state to PS_DOWN for
* practical reasons, it should be done by the caller.
*/
static inline void
snmp_cleanup(struct snmp_proto *p)
{
/* Function tm_stop() is called inside rfree() */
rfree(p->startup_timer);
p->startup_timer = NULL;
rfree(p->ping_timer);
p->ping_timer = NULL;
rfree(p->sock);
p->sock = NULL;
rfree(p->lock);
p->lock = NULL;
struct snmp_register *r, *r2;
WALK_LIST_DELSAFE(r, r2, p->register_queue)
{
rem_node(&r->n);
mb_free(r);
r = NULL;
}
struct snmp_registered_oid *ro, *ro2;
WALK_LIST_DELSAFE(ro, ro2, p->bgp_registered)
{
rem_node(&r->n);
mb_free(ro);
ro = NULL;
}
HASH_FREE(p->bgp_hash);
rfree(p->lp);
p->bgp_trie = NULL;
p->state = SNMP_DOWN;
}
/*
* snmp_down - stop the SNMP protocol and free resources
* @p - SNMP protocol instance
*
* AgentX session is destroyed by closing underlying socket and all resources
* are freed. Afterwards, the PS_DOWN protocol state is announced.
*/
void
snmp_down(struct snmp_proto *p)
{
snmp_cleanup(p);
proto_notify_state(&p->p, PS_DOWN);
}
/*
* snmp_connected - start AgentX session on established channel
* @sk - socket owned by SNMP protocol instance
*
* Starts the AgentX communication by sending an agentx-Open-PDU.
* This function is internal and shouldn't be used outside the SNMP module.
*/
void
snmp_connected(sock *sk)
{
struct snmp_proto *p = sk->data;
p->state = SNMP_OPEN;
sk->rx_hook = snmp_rx;
sk->tx_hook = NULL;
//sk->tx_hook = snmp_tx;
snmp_start_subagent(p);
// TODO ping interval <move to do_response()>
tm_set(p->ping_timer, current_time() + p->timeout S);
}
/*
* snmp_sock_disconnect - end or reset socket connection
* @p - SNMP protocol instance
*
* If the @reconnect flags is set, we close the socket and then reestablish
* the AgentX session by reentering the start procedure as from the
* snmp_start_locked() function.
* Otherwise we simply shutdown the SNMP protocol if the flag is clear.
* This function is internal and shouldn't be used outside the SNMP module.
*/
void
snmp_sock_disconnect(struct snmp_proto *p, int reconnect)
{
tm_stop(p->ping_timer);
if (!reconnect)
return snmp_down(p);
proto_notify_state(&p->p, PS_START);
rfree(p->sock);
p->sock = NULL;
snmp_log("changing state to LOCKED");
p->state = SNMP_LOCKED;
/* We try to reconnect after a short delay */
p->startup_timer->hook = snmp_startup_timeout;
tm_start(p->startup_timer, 4 S); // TODO make me configurable
}
/*
* snmp_sock_err - handle errors on socket by reopenning the socket
* @sk - socket owned by SNMP protocol instance
* @err - socket error errno
*/
static void
snmp_sock_err(sock *sk, int UNUSED err)
{
snmp_log("socket error '%s' (errno: %d)", strerror(err), err);
struct snmp_proto *p = sk->data;
snmp_sock_disconnect(p, 1);
}
/*
* snmp_start_locked - open the socket on locked address
* @lock - object lock guarding the communication mean (address, ...)
*
* This function is called when the object lock is acquired. Main goal is to set
* socket parameters and try to open configured socket. Function
* snmp_connected() handles next stage of SNMP protocol start. When the socket
* coundn't be opened, a new try is scheduled after a small delay.
*/
static void
snmp_start_locked(struct object_lock *lock)
{
struct snmp_proto *p = lock->data;
snmp_log("changing state to LOCKED");
p->state = SNMP_LOCKED;
sock *s = p->sock;
if (!p->bgp_trie)
p->bgp_trie = f_new_trie(p->lp, 0); // TODO user-data attachment size
if (!s)
{
s = sk_new(p->pool);
s->type = SK_TCP_ACTIVE;
s->saddr = p->local_ip;
s->daddr = p->remote_ip;
s->dport = p->remote_port;
s->rbsize = SNMP_RX_BUFFER_SIZE;
s->tbsize = SNMP_TX_BUFFER_SIZE;
//s->tos = IP_PREC_INTERNET_CONTROL
s->tx_hook = snmp_connected;
s->err_hook = snmp_sock_err;
p->sock = s;
s->data = p;
}
/* Try opening the socket, schedule a retry on fail */
if (sk_open(s) < 0)
tm_set(p->startup_timer, current_time() + p->timeout S);
}
/*
* snmp_reconnect - helper restarting the AgentX session on packet errors
* @tm - the startup_timer holding the SNMP protocol instance
*
* Rerun the SNMP module start procedure. Used in situations when the master
* agent returns an agentx-Response-PDU with 'Not Opened' error. We do not close
* the socket if have one.
*/
void
snmp_reconnect(timer *tm)
{
struct snmp_proto *p = tm->data;
if (p->state == SNMP_STOP ||
p->state == SNMP_DOWN)
return;
// TODO is SNMP_RESET really needed ?
if (p->state == SNMP_INIT ||
p->state == SNMP_RESET)
snmp_startup(p);
if (!p->sock)
snmp_start_locked(p->lock);
else
snmp_connected(p->sock);
}
/*
* snmp_startup - start initialized SNMP protocol
* @p - SNMP protocol to start
*
* Starting of SNMP protocols begins with address acqusition through object
* lock. Next step is handled by snmp_start_locked() function.
* This function is internal and shouldn't be used outside the SNMP
* module.
*/
void
snmp_startup(struct snmp_proto *p)
{
if (p->state == SNMP_OPEN ||
p->state == SNMP_REGISTER ||
p->state == SNMP_CONN)
{
return;
}
if (p->lock)
{
snmp_start_locked(p->lock);
return;
}
p->state = SNMP_INIT;
struct object_lock *lock;
lock = p->lock = olock_new(p->pool);
// lock->addr
// lock->port
// lock->iface
// lock->vrf
lock->type = OBJLOCK_TCP;
lock->hook = snmp_start_locked;
lock->data = p;
olock_acquire(lock);
}
/*
* snmp_startup_timeout - start the initiliazed SNMP protocol
* @tm - the startup_timer holding the SNMP protocol instance.
*
* When the timer rings, the function snmp_startup() is invoked.
* This function is internal and shoudln't be used outside the SNMP module.
* Used when we delaying the start procedure, or we want to resend
* an agentx-Open-PDU for non-responding master agent.
*/
void
snmp_startup_timeout(timer *tm)
{
snmp_startup(tm->data);
}
/*
* snmp_stop_timeout - a timeout for nonresponding master agent
* @tm - the startup_timer holding the SNMP protocol instance.
*
* We are shutting down the SNMP protocol instance and we sent the
* agentx-Close-PDU. This function forcefully closes the AgentX session and
* stops the SNMP protocol instance. Used only when we did not receive any
* agentx-Response-PDU for the sent closed packet (before timeout).
*/
static void
snmp_stop_timeout(timer *tm)
{
snmp_down(tm->data);
}
/*
* snmp_ping_timeout - send a agentx-Ping-PDU
* @tm - the ping_timer holding the SNMP protocol instance.
*
* Send an agentx-Ping-PDU and reset the timer for next ping.
*/
static void
snmp_ping_timeout(timer *tm)
{
struct snmp_proto *p = tm->data;
if (p->state == SNMP_REGISTER ||
p->state == SNMP_CONN)
{
snmp_ping(p);
tm_set(tm, current_time() + p->timeout S);
}
}
/*
* snmp_start - Initialize the SNMP protocol instance
* @P - SNMP protocol generic handle
*
* The first step in AgentX subagent startup is protocol initialition.
* We must prepare lists, find BGP peers and finally asynchornously open
* a AgentX subagent session through snmp_startup() function call.
*/
static int
snmp_start(struct proto *P)
{
struct snmp_proto *p = (void *) P;
struct snmp_config *cf = (struct snmp_config *) P->cf;
p->startup_timer = tm_new_init(p->pool, snmp_startup_timeout, p, 0, 0);
p->ping_timer = tm_new_init(p->pool, snmp_ping_timeout, p, 0, 0);
p->pool = p->p.pool;
p->lp = lp_new(p->pool);
p->bgp_trie = f_new_trie(p->lp, 0);
//p->bgp_trie = f_new_trie(lp, cf->bonds); // TODO user-data attachment size
init_list(&p->register_queue);
init_list(&p->bgp_registered);
/* We create copy of bonds to BGP protocols. */
HASH_INIT(p->bgp_hash, p->pool, 10);
struct snmp_bond *b;
WALK_LIST(b, cf->bgp_entries)
{
const struct bgp_config *bc = (struct bgp_config *) b->proto;
if (bc && !ipa_zero(bc->remote_ip))
{
struct snmp_bgp_peer *peer = \
mb_allocz(p->pool, sizeof(struct snmp_bgp_peer));
peer->config = bc;
peer->peer_ip = bc->remote_ip;
struct net_addr net;
net_fill_ip4(&net, ipa_to_ip4(peer->peer_ip), IP4_MAX_PREFIX_LENGTH);
trie_add_prefix(p->bgp_trie, &net, IP4_MAX_PREFIX_LENGTH, IP4_MAX_PREFIX_LENGTH);
HASH_INSERT(p->bgp_hash, SNMP_HASH, peer);
}
}
p->last_header = NULL;
snmp_startup(p);
return PS_START;
}
/*
* snmp_reconfigure - Test if SNMP instance is reconfigurable
* @P - SNMP protocol generic handle, current state
* @CF - SNMP protocol configuration generic handle carring new values
*
* We accept the reconfiguration if the new configuration @CF is identical with
* the currently deployed. Otherwise we deny reconfiguration because
* the implementation would be cumbersome.
*/
static int
snmp_reconfigure(struct proto *P, struct proto_config *CF)
{
struct snmp_proto *p = SKIP_BACK(struct snmp_proto, p, P);
const struct snmp_config *new = SKIP_BACK(struct snmp_config, cf, CF);
const struct snmp_config *old = SKIP_BACK(struct snmp_config, cf, p->p.cf);
struct snmp_bond *b1, *b2;
WALK_LIST(b1, new->bgp_entries)
{
WALK_LIST(b2, old->bgp_entries)
{
if (!strcmp(b1->proto->name, b2->proto->name))
goto skip;
}
return 0;
skip:;
}
return !memcmp(((byte *) old) + sizeof(struct proto_config),
((byte *) new) + sizeof(struct proto_config),
OFFSETOF(struct snmp_config, description) - sizeof(struct proto_config))
&& ! strncmp(old->description, new->description, UINT32_MAX);
}
/*
* snmp_show_proto_info - Print basic information about SNMP protocol instance
* @P - SNMP protocol generic handle
*/
static void
snmp_show_proto_info(struct proto *P)
{
struct snmp_proto *sp = (void *) P;
struct snmp_config *c = (void *) P->cf;
cli_msg(-1006, "");
cli_msg(-1006, " snmp status %s", snmp_state[sp->state]);
cli_msg(-1006, " default local as %u", sp->bgp_local_as);
cli_msg(-1006, " default local id %I4", sp->bgp_local_id);
cli_msg(-1006, "");
cli_msg(-1006, " BGP peers");
struct snmp_bond *bond;
WALK_LIST(bond, c->bgp_entries)
{
struct proto_config *cf = P->cf;
struct bgp_config *bcf = (struct bgp_config *) cf;
struct proto *p = cf->proto;
struct bgp_proto *bp = (struct bgp_proto *) cf->proto;
struct bgp_conn *conn = bp->conn;
cli_msg(-1006, " name: %s", cf->name);
cli_msg(-1006, "");
cli_msg(-1006, " loc. identifier: %I4", bp->local_id);
cli_msg(-1006, " rem. identifier: %I4", bp->remote_id);
cli_msg(-1006, " admin status: %s", (p->disabled) ? "stop" :
"start");
cli_msg(-1006, " version: 4");
cli_msg(-1006, " local ip: %I4", bcf->local_ip);
cli_msg(-1006, " remote ip: %I4", bcf->remote_ip);
cli_msg(-1006, " local port: %I4", bcf->local_port);
cli_msg(-1006, " remote port: %I4", bcf->remote_port);
/*
if (conn) {
cli_msg(-1006, " state: %u", conn->state);
cli_msg(-1006, " remote as: %u", conn->remote_caps->as4_number);
}
*/
cli_msg(-1006, " in updates: %u", bp->stats.rx_updates);
cli_msg(-1006, " out updates: %u", bp->stats.tx_updates);
cli_msg(-1006, " in total: %u", bp->stats.rx_messages);
cli_msg(-1006, " out total: %u", bp->stats.tx_messages);
cli_msg(-1006, " fsm transitions: %u",
bp->stats.fsm_established_transitions);
cli_msg(-1006, " fsm total time: -- (0)");
cli_msg(-1006, " retry interval: %u", bcf->connect_retry_time);
/*
if (conn) {
cli_msg(-1006, " hold time: %u", conn->hold_time);
cli_msg(-1006, " keep alive: %u", conn->keepalive_time );
}
*/
cli_msg(-1006, " hold configurated: %u", bcf->hold_time );
cli_msg(-1006, " keep alive config: %u", bcf->keepalive_time );
cli_msg(-1006, " min AS origin. int.: -- (0)");
cli_msg(-1006, " min route advertisement: %u", 0 );
cli_msg(-1006, " in update elapsed time: %u", 0 );
if (!conn)
cli_msg(-1006, " no default connection");
cli_msg(-1006, " outgoinin_conn state %u", bp->outgoing_conn.state + 1);
cli_msg(-1006, " incoming_conn state: %u", bp->incoming_conn.state + 1);
cli_msg(-1006, "");
}
}
/*
* snmp_postconfig - Check configuration correctness
* @CF - SNMP procotol configuration generic handle
*/
static void
snmp_postconfig(struct proto_config *CF)
{
/* Walk the BGP protocols and cache their references. */
if (((struct snmp_config *) CF)->bgp_local_as == 0)
cf_error("local as not specified");
}
/*
* snmp_shutdown - Forcefully stop the SNMP protocol instance
* @P - SNMP protocol generic handle
*
* If we have established connection, we firstly stop the subagent and then
* later cleanup the protocol. The subagent stopping consist of sending the
* agentx-Close-PDU and changing the current protocol state to PS_STOP.
* If we have no connection created, we simple do the cleanup.
* The cleanup is transition straight to PS_DOWN state with snmp_cleanup() call.
*/
static int
snmp_shutdown(struct proto *P)
{
struct snmp_proto *p = SKIP_BACK(struct snmp_proto, p, P);
tm_stop(p->ping_timer);
if (p->state == SNMP_OPEN ||
p->state == SNMP_REGISTER ||
p->state == SNMP_CONN)
{
/* We have a connection established (at leased send out Open-PDU). */
snmp_log("changing state to STOP");
p->state = SNMP_STOP;
p->startup_timer->hook = snmp_stop_timeout;
tm_set(p->startup_timer, current_time() + p->timeout S);
snmp_stop_subagent(p);
return PS_STOP;
}
else
{
/* We did not create a connection, we clean the lock and other stuff. */
snmp_cleanup(p);
return PS_DOWN;
}
}
/*
* Protocol infrastructure
*/
struct protocol proto_snmp = {
.name = "SNMP",
.template = "snmp%d",
.channel_mask = 0,
.proto_size = sizeof(struct snmp_proto),
.config_size = sizeof(struct snmp_config),
.postconfig = snmp_postconfig,
.init = snmp_init,
.start = snmp_start,
.reconfigure = snmp_reconfigure,
.shutdown = snmp_shutdown,
.show_proto_info = snmp_show_proto_info,
};
void
snmp_build(void)
{
proto_build(&proto_snmp);
}