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net: lwm2m: Implement bootstrap discovery

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Bootstrap discovery was not implemented properly in the LwM2M engine.

Although, there were some indications in the source code that it is
implemented, it was not done according to spec (and actually broken).

Given that Bootstrap Discovery procedure differs a lot from the regular
Device Management Discovery (different permissions, different
information returned), it's easier to implement it as a separate
function (`bootstrap_discovery()`) instead of making the existing
`do_discovery_op()` function even more complicated.

Signed-off-by: Robert Lubos <robert.lubos@nordicsemi.no>
This commit is contained in:
Robert Lubos 2020-11-25 17:12:08 +01:00 • committed by Carles Cufí
commit 1c9fb5488b
1 changed files with 150 additions and 0 deletions
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150
subsys/net/lib/lwm2m/lwm2m_engine.c
View file

@ -3390,6 +3390,149 @@ static int bootstrap_delete(struct lwm2m_message *msg)
return ret;
}
static inline int bs_discover_fill_enabler(struct lwm2m_message *msg)
{
char buf[sizeof("lwm2m='" LWM2M_PROTOCOL_VERSION "'")];
snprintk(buf, sizeof(buf), "lwm2m=\"%s\"", LWM2M_PROTOCOL_VERSION);
return buf_append(CPKT_BUF_WRITE(msg->out.out_cpkt), buf, strlen(buf));
}
static inline int bs_discover_fill_object(struct lwm2m_engine_obj *obj,
struct lwm2m_message *msg)
{
char buf[sizeof(",</xxxxx>")];
snprintk(buf, sizeof(buf), ",</%u>", obj->obj_id);
return buf_append(CPKT_BUF_WRITE(msg->out.out_cpkt), buf, strlen(buf));
}
static int bs_discover_fill_instance(struct lwm2m_engine_obj_inst *obj_inst,
struct lwm2m_message *msg)
{
char buf[sizeof(",</xxxxx/xxxxx>")];
bool bootstrap_inst;
uint16_t server_id;
int ret;
snprintk(buf, sizeof(buf), ",</%u/%u>", obj_inst->obj->obj_id,
obj_inst->obj_inst_id);
ret = buf_append(CPKT_BUF_WRITE(msg->out.out_cpkt), buf, strlen(buf));
if (ret < 0) {
return ret;
}
/* Security and Server instnaces shall report Short Server ID associated
* with them (but only if not bootstrap instance).
*/
if (obj_inst->obj->obj_id == LWM2M_OBJECT_SECURITY_ID) {
snprintk(buf, sizeof(buf), "0/%d/1", obj_inst->obj_inst_id);
ret = lwm2m_engine_get_bool(buf, &bootstrap_inst);
if (ret < 0) {
return ret;
}
if (!bootstrap_inst) {
snprintk(buf, sizeof(buf), "0/%d/10",
obj_inst->obj_inst_id);
ret = lwm2m_engine_get_u16(buf, &server_id);
if (ret < 0) {
return ret;
}
snprintk(buf, sizeof(buf), ";ssid=%d", server_id);
ret = buf_append(CPKT_BUF_WRITE(msg->out.out_cpkt),
buf, strlen(buf));
if (ret < 0) {
return ret;
}
}
}
if (obj_inst->obj->obj_id == LWM2M_OBJECT_SERVER_ID) {
snprintk(buf, sizeof(buf), "1/%d/0", obj_inst->obj_inst_id);
ret = lwm2m_engine_get_u16(buf, &server_id);
if (ret < 0) {
return ret;
}
snprintk(buf, sizeof(buf), ";ssid=%d", server_id);
ret = buf_append(CPKT_BUF_WRITE(msg->out.out_cpkt),
buf, strlen(buf));
if (ret < 0) {
return ret;
}
}
return 0;
}
static int bootstrap_discover(struct lwm2m_message *msg)
{
struct lwm2m_engine_obj *obj;
struct lwm2m_engine_obj_inst *obj_inst;
int ret;
bool reported = false;
/* set output content-format */
ret = coap_append_option_int(msg->out.out_cpkt,
COAP_OPTION_CONTENT_FORMAT,
LWM2M_FORMAT_APP_LINK_FORMAT);
if (ret < 0) {
LOG_ERR("Error setting response content-format: %d", ret);
return ret;
}
ret = coap_packet_append_payload_marker(msg->out.out_cpkt);
if (ret < 0) {
return ret;
}
/*
* lwm2m spec 20170208-A sec 5.2.7.3 bootstrap discover on "/"
* - prefixed w/ lwm2m enabler version. e.g. lwm2m="1.0"
* - returns object and object instances only
*/
ret = bs_discover_fill_enabler(msg);
if (ret < 0) {
return ret;
}
SYS_SLIST_FOR_EACH_CONTAINER(&engine_obj_list, obj, node) {
if (msg->path.level > 0 && msg->path.obj_id != obj->obj_id) {
continue;
}
/* Only report </OBJ_ID> when no instance available */
if (obj->instance_count == 0U) {
ret = bs_discover_fill_object(obj, msg);
if (ret < 0) {
return ret;
}
reported = true;
continue;
}
SYS_SLIST_FOR_EACH_CONTAINER(&engine_obj_inst_list,
obj_inst, node) {
if (obj_inst->obj->obj_id != obj->obj_id) {
continue;
}
ret = bs_discover_fill_instance(obj_inst, msg);
if (ret < 0) {
return ret;
}
reported = true;
}
}
return reported ? 0 : -ENOENT;
}
#endif
static int handle_request(struct coap_packet *request,
@ -3449,6 +3592,7 @@ static int handle_request(struct coap_packet *request,
switch (code & COAP_REQUEST_MASK) {
#if defined(CONFIG_LWM2M_RD_CLIENT_SUPPORT_BOOTSTRAP)
case COAP_METHOD_DELETE:
case COAP_METHOD_GET:
if (msg->ctx->bootstrap_mode) {
break;
}
@ -3705,6 +3849,12 @@ static int handle_request(struct coap_packet *request,
break;
case LWM2M_OP_DISCOVER:
#if defined(CONFIG_LWM2M_RD_CLIENT_SUPPORT_BOOTSTRAP)
if (msg->ctx->bootstrap_mode) {
r = bootstrap_discover(msg);
break;
}
#endif
r = do_discover_op(msg, well_known);
break;