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gcoap.c
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/*
* Copyright (c) 2015-2020 Ken Bannister. All rights reserved.
* 2019 Freie Universität Berlin
*
* This file is subject to the terms and conditions of the GNU Lesser
* General Public License v2.1. See the file LICENSE in the top level
* directory for more details.
*/
/**
* @ingroup net_gcoap
* @{
*
* @file
* @brief GNRC's implementation of CoAP protocol
*
* Runs a thread (_pid) to manage request/response messaging.
*
* @author Ken Bannister <[email protected]>
* @author Hauke Petersen <[email protected]>
*/
#include <errno.h>
#include <stdint.h>
#include <stdatomic.h>
#include <string.h>
#include "assert.h"
#include "net/coap.h"
#include "net/gcoap.h"
#include "net/gcoap/forward_proxy.h"
#include "net/nanocoap/cache.h"
#include "net/sock/async/event.h"
#include "net/sock/util.h"
#include "mutex.h"
#include "random.h"
#include "thread.h"
#include "ztimer.h"
#if IS_USED(MODULE_GCOAP_DTLS)
#include "net/sock/dtls.h"
#include "net/credman.h"
#include "net/dsm.h"
#endif
#define ENABLE_DEBUG 0
#include "debug.h"
/* Sentinel value indicating that no immediate response is required */
#define NO_IMMEDIATE_REPLY (-1)
/* End of the range to pick a random timeout */
#define TIMEOUT_RANGE_END ((uint32_t)CONFIG_COAP_ACK_TIMEOUT_MS * CONFIG_COAP_RANDOM_FACTOR_1000 / 1000)
/* Internal functions */
static void *_event_loop(void *arg);
static void _on_sock_udp_evt(sock_udp_t *sock, sock_async_flags_t type, void *arg);
static void _process_coap_pdu(gcoap_socket_t *sock, sock_udp_ep_t *remote, sock_udp_aux_tx_t *aux,
uint8_t *buf, size_t len, bool truncated);
static int _tl_init_coap_socket(gcoap_socket_t *sock, gcoap_socket_type_t type);
static ssize_t _tl_send(gcoap_socket_t *sock, const void *data, size_t len,
const sock_udp_ep_t *remote, sock_udp_aux_tx_t *aux);
static ssize_t _tl_authenticate(gcoap_socket_t *sock, const sock_udp_ep_t *remote,
uint32_t timeout);
static ssize_t _well_known_core_handler(coap_pkt_t* pdu, uint8_t *buf, size_t len,
coap_request_ctx_t *ctx);
static void _cease_retransmission(gcoap_request_memo_t *memo);
static size_t _handle_req(gcoap_socket_t *sock, coap_pkt_t *pdu, uint8_t *buf,
size_t len, sock_udp_ep_t *remote);
static void _expire_request(gcoap_request_memo_t *memo);
static gcoap_request_memo_t* _find_req_memo_by_mid(const sock_udp_ep_t *remote,
uint16_t mid);
static gcoap_request_memo_t* _find_req_memo_by_token(const sock_udp_ep_t *remote,
const uint8_t *token, size_t tkl);
static gcoap_request_memo_t* _find_req_memo_by_pdu_token(const coap_pkt_t *src_pdu,
const sock_udp_ep_t *remote);
static int _find_resource(gcoap_socket_type_t tl_type,
coap_pkt_t *pdu,
const coap_resource_t **resource_ptr,
gcoap_listener_t **listener_ptr);
static int _find_observer(sock_udp_ep_t **observer, sock_udp_ep_t *remote);
static int _find_obs_memo(gcoap_observe_memo_t **memo, sock_udp_ep_t *remote,
coap_pkt_t *pdu);
static void _find_obs_memo_resource(gcoap_observe_memo_t **memo,
const coap_resource_t *resource);
static void _check_and_expire_obs_memo_last_mid(sock_udp_ep_t *remote,
uint16_t last_notify_mid);
static nanocoap_cache_entry_t *_cache_lookup_memo(gcoap_request_memo_t *cache_key);
static void _cache_process(gcoap_request_memo_t *memo,
coap_pkt_t *pdu);
static ssize_t _cache_build_response(nanocoap_cache_entry_t *ce, coap_pkt_t *pdu,
uint8_t *buf, size_t len);
static void _receive_from_cache_cb(void *arg);
static int _request_matcher_default(gcoap_listener_t *listener,
const coap_resource_t **resource,
coap_pkt_t *pdu);
#if IS_USED(MODULE_GCOAP_DTLS)
static void _on_sock_dtls_evt(sock_dtls_t *sock, sock_async_flags_t type, void *arg);
static void _dtls_free_up_session(void *arg);
#endif
/* Internal variables */
const coap_resource_t _default_resources[] = {
{ "/.well-known/core", COAP_GET, _well_known_core_handler, NULL },
};
static gcoap_listener_t _default_listener = {
&_default_resources[0],
ARRAY_SIZE(_default_resources),
GCOAP_SOCKET_TYPE_UNDEF,
NULL,
NULL,
_request_matcher_default
};
/* Container for the state of gcoap itself */
typedef struct {
mutex_t lock; /* Shares state attributes safely */
gcoap_listener_t *listeners; /* List of registered listeners */
gcoap_request_memo_t open_reqs[CONFIG_GCOAP_REQ_WAITING_MAX];
/* Storage for open requests; if first
byte of an entry is zero, the entry
is available */
atomic_uint next_message_id; /* Next message ID to use */
sock_udp_ep_t observers[CONFIG_GCOAP_OBS_CLIENTS_MAX];
/* Observe clients; allows reuse for
observe memos */
gcoap_observe_memo_t observe_memos[CONFIG_GCOAP_OBS_REGISTRATIONS_MAX];
/* Observed resource registrations */
uint8_t resend_bufs[CONFIG_GCOAP_RESEND_BUFS_MAX][CONFIG_GCOAP_PDU_BUF_SIZE];
/* Buffers for PDU for request resends;
if first byte of an entry is zero,
the entry is available */
} gcoap_state_t;
static gcoap_state_t _coap_state = {
.listeners = &_default_listener,
};
static kernel_pid_t _pid = KERNEL_PID_UNDEF;
static char _msg_stack[GCOAP_STACK_SIZE];
static event_queue_t _queue;
static uint8_t _listen_buf[CONFIG_GCOAP_PDU_BUF_SIZE];
static sock_udp_t _sock_udp;
static event_callback_t _receive_from_cache;
#if IS_USED(MODULE_GCOAP_DTLS)
/* DTLS variables and definitions */
#define SOCK_DTLS_CLIENT_TAG (2)
static sock_udp_t _sock_dtls_base;
static sock_dtls_t _sock_dtls;
static kernel_pid_t _auth_waiting_thread;
static event_timeout_t _dtls_session_free_up_tmout;
static event_callback_t _dtls_session_free_up_tmout_cb;
#endif
/* Event loop for gcoap _pid thread. */
static void *_event_loop(void *arg)
{
(void)arg;
sock_udp_ep_t local;
memset(&local, 0, sizeof(sock_udp_ep_t));
/* FIXME: Once the problems with IPv4/IPv6 dual stack use in RIOT are fixed, adapt these lines
* (and e.g. use AF_UNSPEC) */
#ifdef SOCK_HAS_IPV4
local.family = AF_INET;
#endif
#ifdef SOCK_HAS_IPV6
local.family = AF_INET6;
#endif
local.netif = SOCK_ADDR_ANY_NETIF;
local.port = CONFIG_GCOAP_PORT;
int res = sock_udp_create(&_sock_udp, &local, NULL, 0);
if (res < 0) {
DEBUG("gcoap: cannot create sock: %d\n", res);
return 0;
}
event_queue_init(&_queue);
sock_udp_event_init(&_sock_udp, &_queue, _on_sock_udp_evt, NULL);
if (IS_USED(MODULE_GCOAP_DTLS)) {
#if IS_USED(MODULE_GCOAP_DTLS)
local.port = CONFIG_GCOAPS_PORT;
if (sock_udp_create(&_sock_dtls_base, &local, NULL, 0)) {
DEBUG("gcoap: error creating DTLS transport sock\n");
return 0;
}
if (sock_dtls_create(&_sock_dtls, &_sock_dtls_base,
CREDMAN_TAG_EMPTY,
SOCK_DTLS_1_2, SOCK_DTLS_SERVER) < 0) {
DEBUG("gcoap: error creating DTLS sock\n");
sock_udp_close(&_sock_dtls_base);
return 0;
}
sock_dtls_event_init(&_sock_dtls, &_queue, _on_sock_dtls_evt,
NULL);
#endif
}
event_loop(&_queue);
return 0;
}
#if IS_USED(MODULE_GCOAP_DTLS)
/* Handles DTLS socket events from the event queue */
static void _on_sock_dtls_evt(sock_dtls_t *sock, sock_async_flags_t type, void *arg) {
(void)arg;
gcoap_socket_t socket = { .type = GCOAP_SOCKET_TYPE_DTLS, .socket.dtls = sock};
if (type & SOCK_ASYNC_CONN_RECV) {
ssize_t res = sock_dtls_recv(sock, &socket.ctx_dtls_session,
_listen_buf, sizeof(_listen_buf),
CONFIG_GCOAP_DTLS_HANDSHAKE_TIMEOUT_MSEC);
if (res != -SOCK_DTLS_HANDSHAKE) {
DEBUG("gcoap: could not establish DTLS session: %" PRIdSIZE "\n", res);
sock_dtls_session_destroy(sock, &socket.ctx_dtls_session);
return;
}
dsm_state_t prev_state = dsm_store(sock, &socket.ctx_dtls_session,
SESSION_STATE_ESTABLISHED, false);
/* If session is already stored and the state was SESSION_STATE_HANDSHAKE
before, the handshake has been initiated internally by a gcoap client request
and another thread is waiting for the handshake. Send message to the
waiting thread to inform about established session */
if (prev_state == SESSION_STATE_HANDSHAKE) {
msg_t msg = { .type = DTLS_EVENT_CONNECTED };
msg_send(&msg, _auth_waiting_thread);
} else if (prev_state == NO_SPACE) {
/* No space in session management. Should not happen. If it occurs,
we lost track of sessions */
DEBUG("gcoap: no space in session management. We lost track of sessions!");
sock_dtls_session_destroy(sock, &socket.ctx_dtls_session);
}
/* If not enough session slots left: set timeout to free up session */
uint8_t minimum_free = CONFIG_GCOAP_DTLS_MINIMUM_AVAILABLE_SESSIONS;
if (dsm_get_num_available_slots() < minimum_free)
{
uint32_t timeout = CONFIG_GCOAP_DTLS_MINIMUM_AVAILABLE_SESSIONS_TIMEOUT_MSEC;
event_callback_init(&_dtls_session_free_up_tmout_cb,
_dtls_free_up_session, NULL);
event_timeout_ztimer_init(&_dtls_session_free_up_tmout, ZTIMER_MSEC, &_queue,
&_dtls_session_free_up_tmout_cb.super);
event_timeout_set(&_dtls_session_free_up_tmout, timeout);
}
}
if (type & SOCK_ASYNC_CONN_FIN) {
if (sock_dtls_get_event_session(sock, &socket.ctx_dtls_session)) {
/* Session is already destroyed, only remove it from dsm */
dsm_remove(sock, &socket.ctx_dtls_session);
} else {
puts("gcoap: A session was closed, but the corresponding session " \
"could not be retrieved from the socket!");
return;
}
sock_udp_ep_t ep;
sock_dtls_session_get_udp_ep(&socket.ctx_dtls_session, &ep);
/* Remove all memos of the concerned session. TODO: oberservable memos! */
for (int i = 0; i < CONFIG_GCOAP_REQ_WAITING_MAX; i++) {
if (_coap_state.open_reqs[i].state == GCOAP_MEMO_UNUSED) {
continue;
}
gcoap_request_memo_t *memo = &_coap_state.open_reqs[i];
if (sock_udp_ep_equal(&memo->remote_ep, &ep)) {
_expire_request(memo);
event_timeout_clear(&memo->resp_evt_tmout);
}
}
}
if (type & SOCK_ASYNC_MSG_RECV) {
ssize_t res = sock_dtls_recv(sock, &socket.ctx_dtls_session, _listen_buf,
sizeof(_listen_buf), 0);
if (res <= 0) {
DEBUG("gcoap: DTLS recv failure: %" PRIdSIZE "\n", res);
return;
}
sock_udp_ep_t ep;
sock_dtls_session_get_udp_ep(&socket.ctx_dtls_session, &ep);
/* Truncated DTLS messages would already have gotten lost at verification */
_process_coap_pdu(&socket, &ep, NULL, _listen_buf, res, false);
}
}
/* Timeout function to free up a session when too many session slots are occupied */
static void _dtls_free_up_session(void *arg) {
(void)arg;
sock_dtls_session_t session;
uint8_t minimum_free = CONFIG_GCOAP_DTLS_MINIMUM_AVAILABLE_SESSIONS;
if (dsm_get_num_available_slots() < minimum_free) {
if (dsm_get_least_recently_used_session(&_sock_dtls, &session) != -1) {
/* free up session */
dsm_remove(&_sock_dtls, &session);
sock_dtls_session_destroy(&_sock_dtls, &session);
}
}
}
#endif /* MODULE_GCOAP_DTLS */
/* Handles UDP socket events from the event queue. */
static void _on_sock_udp_evt(sock_udp_t *sock, sock_async_flags_t type, void *arg)
{
(void)arg;
sock_udp_ep_t remote;
if (type & SOCK_ASYNC_MSG_RECV) {
void *stackbuf;
void *buf_ctx = NULL;
bool truncated = false;
size_t cursor = 0;
sock_udp_aux_rx_t aux_in = {
.flags = SOCK_AUX_GET_LOCAL,
};
/* The zero-copy _buf API is not used to its full potential here -- we
* still copy out data in what is a manual version of sock_udp_recv,
* but this gives the direly needed overflow information.
*
* A version that actually doesn't copy would vastly change the way
* gcoap passes the buffer to be read from and written into to the
* handler. Also, given that neither nanocoap nor the handler expects
* to gather scattered data, it'd need to rely on the data coming in a
* single slice (but that may be a realistic assumption).
*/
while (true) {
ssize_t res = sock_udp_recv_buf_aux(sock, &stackbuf, &buf_ctx, 0, &remote, &aux_in);
if (res < 0) {
DEBUG("gcoap: udp recv failure: %" PRIdSIZE "\n", res);
return;
}
if (res == 0) {
break;
}
if (cursor + res > sizeof(_listen_buf)) {
res = sizeof(_listen_buf) - cursor;
truncated = true;
}
memcpy(&_listen_buf[cursor], stackbuf, res);
cursor += res;
}
/* make sure we reply with the same address that the request was
* destined for -- except in the multicast case */
sock_udp_aux_tx_t *aux_out_ptr;
sock_udp_aux_tx_t aux_out = {
.flags = SOCK_AUX_SET_LOCAL,
.local = aux_in.local,
};
if (sock_udp_ep_is_multicast(&aux_in.local)) {
/* This eventually gets passed to sock_udp_send_aux, where NULL
* simply does not set any flags */
aux_out_ptr = NULL;
} else {
aux_out_ptr = &aux_out;
}
gcoap_socket_t socket = {
.type = GCOAP_SOCKET_TYPE_UDP,
.socket.udp = sock,
};
_process_coap_pdu(&socket, &remote, aux_out_ptr, _listen_buf, cursor, truncated);
}
}
/* Processes and evaluates the coap pdu */
static void _process_coap_pdu(gcoap_socket_t *sock, sock_udp_ep_t *remote, sock_udp_aux_tx_t *aux,
uint8_t *buf, size_t len, bool truncated)
{
coap_pkt_t pdu;
gcoap_request_memo_t *memo = NULL;
/* Code paths that necessitate a response on the message layer can set a
* response type here (COAP_TYPE_RST or COAP_TYPE_ACK). If set, at the end
* of the function there will be
* * that value will be put in the code field,
* * token length cleared,
* * code set to EMPTY, and
* * the message is returned with the rest of its header intact.
*/
int8_t messagelayer_emptyresponse_type = NO_IMMEDIATE_REPLY;
ssize_t res = coap_parse(&pdu, buf, len);
if (res < 0) {
DEBUG("gcoap: parse failure: %" PRIdSIZE "\n", res);
/* If a response, can't clear memo, but it will timeout later.
*
* There are *some* error cases in which we could continue (eg. all
* sorts of "packet ends mid-options" in truncated cases, and maybe
* also when the maximum option count is exceeded to at least respond
* with Bad Request), but these would likely require incompatible
* changes to nanocoap.
*/
return;
}
if (coap_get_type(&pdu) == COAP_TYPE_RST) {
DEBUG("gcoap: received RST, expiring potentially existing memo\n");
memo = _find_req_memo_by_mid(remote, pdu.hdr->id);
if (memo) {
event_timeout_clear(&memo->resp_evt_tmout);
_expire_request(memo);
}
/* check if this RST is due to the client not being interested
* in receiving observe notifications anymore. */
_check_and_expire_obs_memo_last_mid(remote, coap_get_id(&pdu));
}
/* validate class and type for incoming */
unsigned code_class = coap_get_code_class(&pdu);
switch (code_class) {
/* incoming request or empty */
case COAP_CLASS_REQ:
if (coap_get_code_raw(&pdu) == COAP_CODE_EMPTY) {
/* ping request */
if (coap_get_type(&pdu) == COAP_TYPE_CON) {
messagelayer_emptyresponse_type = COAP_TYPE_RST;
DEBUG("gcoap: Answering empty CON request with RST\n");
} else if (coap_get_type(&pdu) == COAP_TYPE_ACK) {
memo = _find_req_memo_by_mid(remote, pdu.hdr->id);
if ((memo != NULL) && (memo->send_limit != GCOAP_SEND_LIMIT_NON)) {
DEBUG("gcoap: empty ACK processed, stopping retransmissions\n");
_cease_retransmission(memo);
} else {
DEBUG("gcoap: empty ACK matches no known CON, ignoring\n");
}
} else {
DEBUG("gcoap: Ignoring empty non-CON request\n");
}
}
/* normal request */
else if (coap_get_type(&pdu) == COAP_TYPE_NON
|| coap_get_type(&pdu) == COAP_TYPE_CON) {
size_t pdu_len;
if (truncated) {
/* TBD: Set a Size1 */
pdu_len = gcoap_response(&pdu, _listen_buf, sizeof(_listen_buf),
COAP_CODE_REQUEST_ENTITY_TOO_LARGE);
} else {
pdu_len = _handle_req(sock, &pdu, _listen_buf,
sizeof(_listen_buf), remote);
}
if (pdu_len > 0) {
ssize_t bytes = _tl_send(sock, _listen_buf, pdu_len, remote, aux);
if (bytes <= 0) {
DEBUG("gcoap: send response failed: %" PRIdSIZE "\n", bytes);
}
}
}
else {
DEBUG("gcoap: illegal request type: %u\n", coap_get_type(&pdu));
}
break;
/* incoming response */
case COAP_CLASS_SUCCESS:
case COAP_CLASS_CLIENT_FAILURE:
case COAP_CLASS_SERVER_FAILURE:
memo = _find_req_memo_by_pdu_token(&pdu, remote);
if (memo) {
switch (coap_get_type(&pdu)) {
case COAP_TYPE_CON:
messagelayer_emptyresponse_type = COAP_TYPE_ACK;
DEBUG("gcoap: Answering CON response with ACK\n");
/* fall through */
case COAP_TYPE_NON:
case COAP_TYPE_ACK:
if (memo->resp_evt_tmout.queue) {
event_timeout_clear(&memo->resp_evt_tmout);
}
memo->state = truncated ? GCOAP_MEMO_RESP_TRUNC : GCOAP_MEMO_RESP;
if (IS_USED(MODULE_NANOCOAP_CACHE)) {
nanocoap_cache_entry_t *ce = NULL;
if ((pdu.hdr->code == COAP_CODE_VALID) &&
(ce = _cache_lookup_memo(memo))) {
/* update max_age from response and send cached response */
uint32_t max_age = 60;
coap_opt_get_uint(&pdu, COAP_OPT_MAX_AGE, &max_age);
ce->max_age = ztimer_now(ZTIMER_SEC) + max_age;
/* copy all options and possible payload from the cached response
* to the new response */
assert((uint8_t *)pdu.hdr == &_listen_buf[0]);
if (_cache_build_response(ce, &pdu, _listen_buf,
sizeof(_listen_buf)) < 0) {
memo->state = GCOAP_MEMO_ERR;
}
if (ce->truncated) {
memo->state = GCOAP_MEMO_RESP_TRUNC;
}
}
/* TODO: resend request if VALID but no cache entry? */
else if ((pdu.hdr->code != COAP_CODE_VALID)) {
_cache_process(memo, &pdu);
}
}
bool observe_notification = coap_has_observe(&pdu);
if (memo->resp_handler) {
memo->resp_handler(memo, &pdu, remote);
}
if (memo->send_limit >= 0) { /* if confirmable */
*memo->msg.data.pdu_buf = 0; /* clear resend PDU buffer */
}
/* The memo must be kept if the response is an observe notification.
* Non-2.xx notifications indicate that the associated observe entry
* was removed on the server side. Then also free the memo here. */
if (!observe_notification || (code_class != COAP_CLASS_SUCCESS)) {
/* setting the state to unused frees (drops) the memo entry */
memo->state = GCOAP_MEMO_UNUSED;
}
break;
default:
DEBUG("gcoap: illegal response type: %u\n", coap_get_type(&pdu));
break;
}
}
else {
DEBUG("gcoap: msg not found for ID: %u\n", coap_get_id(&pdu));
if (coap_get_type(&pdu) == COAP_TYPE_CON) {
/* we might run into this if an ACK to a sender got lost
* see https://datatracker.ietf.org/doc/html/rfc7252#section-5.3.2 */
messagelayer_emptyresponse_type = COAP_TYPE_RST;
DEBUG("gcoap: Answering unknown CON response with RST to "
"shut up sender\n");
} else {
/* if the response was a (NON) observe notification and there is no
* matching request, the server must be informed that this node is
* no longer interested in this notification. */
if (coap_has_observe(&pdu)) {
messagelayer_emptyresponse_type = COAP_TYPE_RST;
}
}
}
break;
default:
DEBUG("gcoap: illegal code class: %u\n", coap_get_code_class(&pdu));
}
if (messagelayer_emptyresponse_type != NO_IMMEDIATE_REPLY) {
coap_hdr_set_type(pdu.hdr, (uint8_t)messagelayer_emptyresponse_type);
coap_hdr_set_code(pdu.hdr, COAP_CODE_EMPTY);
/* Set the token length to 0, preserving the CoAP version as it was and
* the empty message type that was just set.
*
* FIXME: Introduce an internal function to set or truncate the token
* */
pdu.hdr->ver_t_tkl &= 0xf0;
ssize_t bytes = _tl_send(sock, buf, sizeof(coap_hdr_t), remote, aux);
if (bytes <= 0) {
DEBUG("gcoap: empty response failed: %" PRIdSIZE "\n", bytes);
}
}
}
/* Handles response timeout for a request; resend confirmable if needed. */
static void _on_resp_timeout(void *arg) {
gcoap_request_memo_t *memo = (gcoap_request_memo_t *)arg;
/* no retries remaining */
if ((memo->send_limit == GCOAP_SEND_LIMIT_NON) || (memo->send_limit == 0)) {
_expire_request(memo);
}
/* reduce retries remaining, double timeout and resend */
else {
memo->send_limit--;
#ifdef CONFIG_GCOAP_NO_RETRANS_BACKOFF
unsigned i = 0;
#else
unsigned i = CONFIG_COAP_MAX_RETRANSMIT - memo->send_limit;
#endif
uint32_t timeout = (uint32_t)CONFIG_COAP_ACK_TIMEOUT_MS << i;
#if CONFIG_COAP_RANDOM_FACTOR_1000 > 1000
uint32_t end = (uint32_t)TIMEOUT_RANGE_END << i;
timeout = random_uint32_range(timeout, end);
#endif
event_timeout_set(&memo->resp_evt_tmout, timeout);
if (memo->state == GCOAP_MEMO_WAIT) {
/* See _cease_retransmission: Still going through the timeouts and
* rescheduling, but not actually sending any more */
return;
}
ssize_t bytes = _tl_send(&memo->socket, memo->msg.data.pdu_buf,
memo->msg.data.pdu_len, &memo->remote_ep, NULL);
if (bytes <= 0) {
DEBUG("gcoap: sock resend failed: %" PRIdSIZE "\n", bytes);
_expire_request(memo);
}
}
}
/* Change the retransmission of the memo such that no requests are sent any more.
*
* This is used in response to an empty ACK.
*
* The current implementation does not touch the timers, but merely sets the
* memo's state to GCOAP_MEMO_WAIT. This approach needs less complex code at
* the cost of the remaining `send_limit` timers firing and some memory not
* being freed until the actual response arrives.
*
* An alternative implementation would stop the timeouts, and either free the
* whole memo if it has no response handler, or calculate the remaining timeout
* from `send_limit` to set a final timeout then. In that case, it might also
* free the gcoap_resend_t data and move it back into hdr_buf (along with a
* change in the discriminator for that). (That's not an option with the
* current design because the discriminator is the send_limit field, which is
* still used to count down).
*
* @param[inout] memo The memo indicating the pending request
*
* @pre The @p memo is GCOAP_MEMO_RETRANSMIT or GCOAP_MEMO_WAIT, and its
* send_limit is not GCOAP_SEND_LIMIT_NON.
*/
static void _cease_retransmission(gcoap_request_memo_t *memo) {
memo->state = GCOAP_MEMO_WAIT;
/* there is also no response handler to wait for => expire memo */
if (memo->resp_handler == NULL) {
event_timeout_clear(&memo->resp_evt_tmout);
_expire_request(memo);
}
}
/*
* Main request handler: generates response PDU in the provided buffer.
*
* Caller must finish the PDU and send it.
*
* return length of response pdu, or < 0 if can't handle
*/
static size_t _handle_req(gcoap_socket_t *sock, coap_pkt_t *pdu, uint8_t *buf,
size_t len, sock_udp_ep_t *remote)
{
const coap_resource_t *resource = NULL;
gcoap_listener_t *listener = NULL;
sock_udp_ep_t *observer = NULL;
gcoap_observe_memo_t *memo = NULL;
gcoap_observe_memo_t *resource_memo = NULL;
switch (_find_resource(sock->type, pdu, &resource, &listener)) {
case GCOAP_RESOURCE_WRONG_METHOD:
return gcoap_response(pdu, buf, len, COAP_CODE_METHOD_NOT_ALLOWED);
case GCOAP_RESOURCE_NO_PATH:
return gcoap_response(pdu, buf, len, COAP_CODE_PATH_NOT_FOUND);
case GCOAP_RESOURCE_FOUND:
/* find observe registration for resource */
_find_obs_memo_resource(&resource_memo, resource);
break;
case GCOAP_RESOURCE_ERROR:
default:
return gcoap_response(pdu, buf, len, COAP_CODE_INTERNAL_SERVER_ERROR);
break;
}
if (coap_get_observe(pdu) == COAP_OBS_REGISTER) {
/* lookup remote+token */
int empty_slot = _find_obs_memo(&memo, remote, pdu);
/* validate re-registration request */
if (resource_memo != NULL) {
if (memo != NULL) {
if (memo != resource_memo) {
/* reject token already used for a different resource */
memo = NULL;
coap_clear_observe(pdu);
DEBUG("gcoap: can't change resource for token\n");
}
/* otherwise OK to re-register resource with the same token */
}
else if ((sock->type == resource_memo->socket.type) &&
sock_udp_ep_equal(remote, resource_memo->observer)) {
/* accept new token for resource */
memo = resource_memo;
}
}
/* initialize new registration request */
if ((memo == NULL) && coap_has_observe(pdu)) {
/* verify resource not already registered (for another endpoint) */
if ((empty_slot >= 0) && (resource_memo == NULL)) {
int obs_slot = _find_observer(&observer, remote);
/* cache new observer */
if (observer == NULL) {
if (obs_slot >= 0) {
observer = &_coap_state.observers[obs_slot];
memcpy(observer, remote, sizeof(sock_udp_ep_t));
} else {
DEBUG("gcoap: can't register observer\n");
}
}
if (observer != NULL) {
memo = &_coap_state.observe_memos[empty_slot];
memo->observer = observer;
}
}
if (memo == NULL) {
coap_clear_observe(pdu);
DEBUG("gcoap: can't register observe memo\n");
}
}
/* finish registration */
if (memo != NULL) {
/* resource may be assigned here if it is not already registered */
memo->resource = resource;
memo->token_len = coap_get_token_len(pdu);
memo->socket = *sock;
if (memo->token_len) {
memcpy(&memo->token[0], coap_get_token(pdu), memo->token_len);
}
DEBUG("gcoap: Registered observer for: %s\n", memo->resource->path);
}
} else if (coap_get_observe(pdu) == COAP_OBS_DEREGISTER) {
_find_obs_memo(&memo, remote, pdu);
/* clear memo, and clear observer if no other memos */
if (memo != NULL) {
DEBUG("gcoap: Deregistering observer for: %s\n", memo->resource->path);
memo->observer = NULL;
memo = NULL;
_find_obs_memo(&memo, remote, NULL);
if (memo == NULL) {
_find_observer(&observer, remote);
if (observer != NULL) {
observer->family = AF_UNSPEC;
}
}
}
coap_clear_observe(pdu);
} else if (coap_has_observe(pdu)) {
/* bogus request; don't respond */
DEBUG("gcoap: Observe value unexpected: %" PRIu32 "\n", coap_get_observe(pdu));
return -1;
}
ssize_t pdu_len;
coap_request_ctx_t ctx = {
.resource = resource,
.tl_type = (uint32_t)sock->type,
.remote = remote,
};
pdu_len = resource->handler(pdu, buf, len, &ctx);
if (pdu_len < 0) {
pdu_len = gcoap_response(pdu, buf, len,
COAP_CODE_INTERNAL_SERVER_ERROR);
}
return pdu_len;
}
static int _request_matcher_default(gcoap_listener_t *listener,
const coap_resource_t **resource,
coap_pkt_t *pdu)
{
uint8_t uri[CONFIG_NANOCOAP_URI_MAX];
int ret = GCOAP_RESOURCE_NO_PATH;
if (coap_get_uri_path(pdu, uri) <= 0) {
/* The Uri-Path options are longer than
* CONFIG_NANOCOAP_URI_MAX, and thus do not match anything
* that could be found by this handler. */
return GCOAP_RESOURCE_NO_PATH;
}
coap_method_flags_t method_flag = coap_method2flag(
coap_get_code_detail(pdu));
for (size_t i = 0; i < listener->resources_len; i++) {
*resource = &listener->resources[i];
int res = coap_match_path(*resource, uri);
/* URI mismatch */
if (res != 0) {
continue;
}
/* potential match, check for method */
if (! ((*resource)->methods & method_flag)) {
/* record wrong method error for next iteration, in case
* another resource with the same URI and correct method
* exists */
ret = GCOAP_RESOURCE_WRONG_METHOD;
continue;
}
else {
return GCOAP_RESOURCE_FOUND;
}
}
return ret;
}
/*
* Searches listener registrations for the resource matching the path in a PDU.
*
* param[in] tl_type -- transport the request for the resource came over.
* param[in] pdu -- the PDU to check the resource for
* param[out] resource_ptr -- found resource
* param[out] listener_ptr -- listener for found resource
* return `GCOAP_RESOURCE_FOUND` if the resource was found,
* `GCOAP_RESOURCE_WRONG_METHOD` if a resource was found but the method
* code didn't match and `GCOAP_RESOURCE_NO_PATH` if no matching
* resource was found.
*/
static int _find_resource(gcoap_socket_type_t tl_type,
coap_pkt_t *pdu,
const coap_resource_t **resource_ptr,
gcoap_listener_t **listener_ptr)
{
int ret = GCOAP_RESOURCE_NO_PATH;
/* Find path for CoAP msg among listener resources and execute callback. */
gcoap_listener_t *listener = _coap_state.listeners;
while (listener) {
const coap_resource_t *resource;
int res;
/* only makes sense to check if non-UDP transports are supported,
* so check if module is used first. */
if (IS_USED(MODULE_GCOAP_DTLS) &&
(listener->tl_type != GCOAP_SOCKET_TYPE_UNDEF) &&
!(listener->tl_type & tl_type)) {
listener = listener->next;
continue;
}
res = listener->request_matcher(listener, &resource, pdu);
/* check next resource on mismatch */
if (res == GCOAP_RESOURCE_NO_PATH) {
listener = listener->next;
continue;
}
/* found a resource, but methods do not match */
else if (res == GCOAP_RESOURCE_WRONG_METHOD) {
ret = GCOAP_RESOURCE_WRONG_METHOD;
listener = listener->next;
continue;
}
/* found a suitable resource */
else if (res == GCOAP_RESOURCE_FOUND) {
*resource_ptr = resource;
*listener_ptr = listener;
return GCOAP_RESOURCE_FOUND;
}
/* res is probably GCOAP_RESOURCE_ERROR or some other
* unhandled error */
else {
return GCOAP_RESOURCE_ERROR;
}
}
return ret;
}
/*
* Finds the memo for an outstanding request within the _coap_state.open_reqs
* array. Matches on remote endpoint and token.
*
* remote[in] Remote endpoint to match
* token[in] Token to match
* tkl[in] Length of the token in bytes
*
* return Registered request memo, or NULL if not found
*/
static gcoap_request_memo_t* _find_req_memo_by_token(const sock_udp_ep_t *remote,
const uint8_t *token, size_t tkl)
{
/* no need to initialize struct; we only care about buffer contents below */
coap_pkt_t memo_pdu_data;
coap_pkt_t *memo_pdu = &memo_pdu_data;
for (int i = 0; i < CONFIG_GCOAP_REQ_WAITING_MAX; i++) {
if (_coap_state.open_reqs[i].state == GCOAP_MEMO_UNUSED) {
continue;
}
gcoap_request_memo_t *memo = &_coap_state.open_reqs[i];
memo_pdu->hdr = gcoap_request_memo_get_hdr(memo);
if (coap_get_token_len(memo_pdu) == tkl) {
if ((memcmp(token, coap_get_token(memo_pdu), tkl) == 0)
&& (sock_udp_ep_equal(&memo->remote_ep, remote)
/* Multicast addresses are not considered in matching responses */
|| sock_udp_ep_is_multicast(&memo->remote_ep)
)) {
return memo;
}
}
}
return NULL;
}
/*
* Utility wrapper for _find_req_memo_by_token(), using the pdu token.
* Finds the memo for an outstanding request within the _coap_state.open_reqs
* array. Matches on remote endpoint and token of the pdu.
*
* src_pdu[in] PDU which holds the token for matching
* remote[in] Remote endpoint to match
*
* return Registered request memo, or NULL if not found
*/
static gcoap_request_memo_t* _find_req_memo_by_pdu_token(
const coap_pkt_t *src_pdu,
const sock_udp_ep_t *remote)
{
unsigned tkl = coap_get_token_len(src_pdu);
uint8_t *token = coap_get_token(src_pdu);
return _find_req_memo_by_token(remote, token, tkl);
}
/*
* Finds the memo for an outstanding request within the _coap_state.open_reqs
* array. Matches on remote endpoint and message ID.
*
* remote[in] Remote endpoint to match
* mid[in] Message ID to match
*
* return Registered request memo, or NULL if not found
*/
static gcoap_request_memo_t* _find_req_memo_by_mid(const sock_udp_ep_t *remote, uint16_t mid)
{
for (int i = 0; i < CONFIG_GCOAP_REQ_WAITING_MAX; i++) {
if (_coap_state.open_reqs[i].state == GCOAP_MEMO_UNUSED) {
continue;
}
gcoap_request_memo_t *memo = &_coap_state.open_reqs[i];
if ((mid == gcoap_request_memo_get_hdr(memo)->id) &&
sock_udp_ep_equal(&memo->remote_ep, remote)) {
return memo;
}
}
return NULL;
}
/* Calls handler callback on receipt of a timeout message. */
static void _expire_request(gcoap_request_memo_t *memo)
{
DEBUG("coap: received timeout message\n");
if ((memo->state == GCOAP_MEMO_RETRANSMIT) || (memo->state == GCOAP_MEMO_WAIT)) {
memo->state = GCOAP_MEMO_TIMEOUT;
/* Pass response to handler */
if (memo->resp_handler) {
coap_pkt_t req;
req.hdr = gcoap_request_memo_get_hdr(memo);
memo->resp_handler(memo, &req, NULL);
}
if (memo->send_limit != GCOAP_SEND_LIMIT_NON) {
*memo->msg.data.pdu_buf = 0; /* clear resend buffer */
}
memo->state = GCOAP_MEMO_UNUSED;
}
else {
/* Response already handled; timeout must have fired while response */
/* was in queue. */
}
}
/*
* Handler for /.well-known/core. Lists registered handlers, except for
* /.well-known/core itself.
*/
static ssize_t _well_known_core_handler(coap_pkt_t* pdu, uint8_t *buf, size_t len,
coap_request_ctx_t *ctx)
{
(void)ctx;
gcoap_resp_init(pdu, buf, len, COAP_CODE_CONTENT);
coap_opt_add_format(pdu, COAP_FORMAT_LINK);
ssize_t plen = coap_opt_finish(pdu, COAP_OPT_FINISH_PAYLOAD);
plen += gcoap_get_resource_list(pdu->payload, (size_t)pdu->payload_len,
COAP_FORMAT_LINK,
(gcoap_socket_type_t)coap_request_ctx_get_tl_type(ctx));