net: coap: Use 64bit timestamps

Use 64bit timestamps from k_uptime_get() so they don't
roll over during the expected device lifetime.

Fixes #60826

Signed-off-by: Seppo Takalo <[email protected]>

Author: SeppoTakalo

include/zephyr/net/coap.h

@@ -269,7 +269,7 @@ typedef int (*coap_reply_t)(const struct coap_packet *response,
  */
 struct coap_pending {
 	struct sockaddr addr;
-	uint32_t t0;
+	int64_t t0;
 	uint32_t timeout;
 	uint16_t id;
 	uint8_t *data;

samples/net/sockets/coap_server/src/coap-server.c

@@ -954,8 +954,8 @@ static int large_create_post(struct coap_resource *resource,
 static void schedule_next_retransmission(void)
 {
 	struct coap_pending *pending;
-	int32_t remaining;
-	uint32_t now = k_uptime_get_32();
+	int64_t remaining;
+	int64_t now = k_uptime_get();
 
 	/* Get the first pending retransmission to expire after cycling. */
 	pending = coap_pending_next_to_expire(pendings, NUM_PENDINGS);

subsys/net/lib/coap/coap.c

@@ -1287,7 +1287,7 @@ int coap_pending_init(struct coap_pending *pending,
 
 	pending->data = request->data;
 	pending->len = request->offset;
-	pending->t0 = k_uptime_get_32();
+	pending->t0 = k_uptime_get();
 	pending->retries = retries;
 
 	return 0;
@@ -1382,7 +1382,7 @@ struct coap_pending *coap_pending_next_to_expire(
 {
 	struct coap_pending *p, *found = NULL;
 	size_t i;
-	uint32_t expiry, min_expiry;
+	int64_t expiry, min_expiry = INT64_MAX;
 
 	for (i = 0, p = pendings; i < len; i++, p++) {
 		if (!p->timeout) {
@@ -1391,7 +1391,7 @@ struct coap_pending *coap_pending_next_to_expire(
 
 		expiry = p->t0 + p->timeout;
 
-		if (!found || (int32_t)(expiry - min_expiry) < 0) {
+		if (expiry < min_expiry) {
 			min_expiry = expiry;
 			found = p;
 		}

subsys/net/lib/lwm2m/lwm2m_engine.c

@@ -368,7 +368,6 @@ static int64_t retransmit_request(struct lwm2m_ctx *client_ctx, const int64_t ti
 			continue;
 		}
 
-		/* TODO: will roll over in 47 days */
 		remaining = p->t0 + p->timeout;
 		if (remaining < timestamp) {
 			msg = find_msg(p, NULL);