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net: lwm2m: correct lwm2m discover operation behavior

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According to LwM2M specification 20170208-A, there are two different
discover interfaces supported by the device.
(1) Bootstrap discover (sec 5.2.7.3) (To be implemented)
(2) Device management discover interface (Sec 5.4.2)
 - object ID is required (i.e. root directory discover is not allowed)
 - attributes should be responded accordingly when implemented

This patch correct the behavior according to the spec and summarized
as follow
(1) Still support CoAP ".well-known/core" but change to report only
    first level of the URI.
(2) Respond to caller only when object ID is provided unless it's
    bootstrap discover

Fixes #4941

Signed-off-by: Robert Chou <robert.ch.chou@acer.com>
This commit is contained in:
Robert Chou 2017-11-15 09:46:13 +08:00 • committed by Anas Nashif
commit 3062e76858
1 changed files with 120 additions and 44 deletions
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164
subsys/net/lib/lwm2m/lwm2m_engine.c
View file

@ -53,7 +53,7 @@
#define ENGINE_UPDATE_INTERVAL K_MSEC(500)
#define DISCOVER_PREFACE "</.well-known/core>;ct=40"
#define WELL_KNOWN_CORE_PATH "</.well-known/core>"
/*
* TODO: to implement a way for clients to specify alternate path
@ -2261,18 +2261,31 @@ static int do_read_op(struct lwm2m_engine_obj *obj,
return ret;
}
static int do_discover_op(struct lwm2m_engine_context *context)
static int do_discover_op(struct lwm2m_engine_context *context, bool well_known)
{
static char disc_buf[24];
struct lwm2m_output_context *out = context->out;
struct lwm2m_engine_obj *obj;
struct lwm2m_engine_obj_inst *obj_inst;
int i = 0, ret;
struct lwm2m_obj_path *path = context->path;
struct lwm2m_output_context *out = context->out;
int ret;
u16_t temp_len;
bool reported = false;
/* object ID is required unless it's bootstrap discover (TODO) or it's
* a ".well-known/core" discovery
* ref: lwm2m spec 20170208-A table 11
*/
if (!well_known &&
(path->level == 0 ||
(path->level > 0 && path->obj_id == LWM2M_OBJECT_SECURITY_ID))) {
return -EPERM;
}
/* set output content-format */
ret = coap_append_option_int(out->out_cpkt,
COAP_OPTION_CONTENT_FORMAT,
LWM2M_FORMAT_APP_LINK_FORMAT);
COAP_OPTION_CONTENT_FORMAT,
LWM2M_FORMAT_APP_LINK_FORMAT);
if (ret < 0) {
SYS_LOG_ERR("Error setting response content-format: %d", ret);
return ret;
@ -2287,45 +2300,104 @@ static int do_discover_op(struct lwm2m_engine_context *context)
&temp_len);
out->offset++;
/* </.well-known/core>,**;ct=40 */
if (!net_pkt_append_all(out->out_cpkt->pkt,
strlen(DISCOVER_PREFACE), DISCOVER_PREFACE,
BUF_ALLOC_TIMEOUT)) {
return -ENOMEM;
}
SYS_SLIST_FOR_EACH_CONTAINER(&engine_obj_inst_list, obj_inst, node) {
/* TODO: support bootstrap discover
* Avoid discovery for security object (5.2.7.3)
*/
if (obj_inst->obj->obj_id == LWM2M_OBJECT_SECURITY_ID) {
continue;
}
snprintk(disc_buf, sizeof(disc_buf), ",</%u/%u>",
obj_inst->obj->obj_id, obj_inst->obj_inst_id);
/* Handle CoAP .well-known/core discover */
if (well_known) {
/* </.well-known/core> */
if (!net_pkt_append_all(out->out_cpkt->pkt,
strlen(disc_buf), disc_buf,
strlen(WELL_KNOWN_CORE_PATH),
WELL_KNOWN_CORE_PATH,
BUF_ALLOC_TIMEOUT)) {
return -ENOMEM;
}
for (i = 0; i < obj_inst->resource_count; i++) {
snprintk(disc_buf, sizeof(disc_buf),
",</%u/%u/%u>",
obj_inst->obj->obj_id,
obj_inst->obj_inst_id,
obj_inst->resources[i].res_id);
SYS_SLIST_FOR_EACH_CONTAINER(&engine_obj_list, obj, node) {
snprintk(disc_buf, sizeof(disc_buf), ",</%u>",
obj->obj_id);
if (!net_pkt_append_all(out->out_cpkt->pkt,
strlen(disc_buf), disc_buf,
BUF_ALLOC_TIMEOUT)) {
return -ENOMEM;
}
}
return 0;
}
return 0;
/* TODO: lwm2m spec 20170208-A sec 5.2.7.3 bootstrap discover on "/"
* - report object 0 (security) with ssid
* - prefixed w/ lwm2m enabler version. e.g. lwm2m="1.0"
* - returns object and object instances only
*/
SYS_SLIST_FOR_EACH_CONTAINER(&engine_obj_inst_list, obj_inst, node) {
/* TODO: support bootstrap discover
* Avoid discovery for security object (5.2.7.3)
* Skip reporting unrelated object
*/
if (obj_inst->obj->obj_id == LWM2M_OBJECT_SECURITY_ID ||
obj_inst->obj->obj_id != path->obj_id) {
continue;
}
if (path->level == 1) {
/* TODO: report object attrs (5.4.2) */
snprintk(disc_buf, sizeof(disc_buf), "%s</%u>",
reported ? "," : "",
obj_inst->obj->obj_id);
if (!net_pkt_append_all(out->out_cpkt->pkt,
strlen(disc_buf), disc_buf,
BUF_ALLOC_TIMEOUT)) {
return -ENOMEM;
}
reported = true;
}
/* skip unrelated object instance */
if (path->level > 1 &&
path->obj_inst_id != obj_inst->obj_inst_id) {
continue;
}
if (path->level == 2) {
/* TODO: report object instance attrs (5.4.2) */
snprintk(disc_buf, sizeof(disc_buf), "%s</%u/%u>",
reported ? "," : "",
obj_inst->obj->obj_id, obj_inst->obj_inst_id);
if (!net_pkt_append_all(out->out_cpkt->pkt,
strlen(disc_buf), disc_buf,
BUF_ALLOC_TIMEOUT)) {
return -ENOMEM;
}
reported = true;
}
for (int i = 0; i < obj_inst->resource_count; i++) {
/* skip unrelated resources */
if (path->level == 3 &&
path->res_id != obj_inst->resources[i].res_id) {
continue;
}
/* TODO: report resource attrs when path > 1 (5.4.2) */
snprintk(disc_buf, sizeof(disc_buf),
"%s</%u/%u/%u>",
reported ? "," : "",
obj_inst->obj->obj_id,
obj_inst->obj_inst_id,
obj_inst->resources[i].res_id);
if (!net_pkt_append_all(out->out_cpkt->pkt,
strlen(disc_buf), disc_buf,
BUF_ALLOC_TIMEOUT)) {
return -ENOMEM;
}
reported = true;
}
}
return reported ? 0 : -ENOENT;
}
int lwm2m_get_or_create_engine_obj(struct lwm2m_engine_context *context,
@ -2390,7 +2462,7 @@ static int handle_request(struct coap_packet *request,
int r;
u8_t code;
struct coap_option options[4];
struct lwm2m_engine_obj *obj;
struct lwm2m_engine_obj *obj = NULL;
u8_t token[8];
u8_t tkl = 0;
u16_t format, accept;
@ -2399,7 +2471,7 @@ static int handle_request(struct coap_packet *request,
struct lwm2m_obj_path path;
struct lwm2m_engine_context context;
int observe = -1; /* default to -1, 0 = ENABLE, 1 = DISABLE */
bool discover = false;
bool well_known = false;
struct block_context *block_ctx = NULL;
enum coap_block_size block_size;
bool last_block = false;
@ -2452,7 +2524,7 @@ static int handle_request(struct coap_packet *request,
goto error;
}
discover = true;
well_known = true;
} else {
r = coap_options_to_path(options, r, &path);
if (r < 0) {
@ -2480,12 +2552,14 @@ static int handle_request(struct coap_packet *request,
accept = LWM2M_FORMAT_OMA_TLV;
}
/* find registered obj */
obj = get_engine_obj(path.obj_id);
if (!obj) {
/* No matching object found - ignore request */
r = -ENOENT;
goto error;
if (!well_known) {
/* find registered obj */
obj = get_engine_obj(path.obj_id);
if (!obj) {
/* No matching object found - ignore request */
r = -ENOENT;
goto error;
}
}
format = select_reader(&in, format);
@ -2499,13 +2573,15 @@ static int handle_request(struct coap_packet *request,
* Leshan sends only an accept=LWM2M_FORMAT_APP_LINK_FORMAT to
* indicate a discover OP
*/
if (discover || format == LWM2M_FORMAT_APP_LINK_FORMAT ||
accept == LWM2M_FORMAT_APP_LINK_FORMAT) {
if (well_known ||
format == LWM2M_FORMAT_APP_LINK_FORMAT ||
accept == LWM2M_FORMAT_APP_LINK_FORMAT) {
context.operation = LWM2M_OP_DISCOVER;
accept = LWM2M_FORMAT_APP_LINK_FORMAT;
} else {
context.operation = LWM2M_OP_READ;
}
/* check for observe */
observe = get_option_int(in.in_cpkt, COAP_OPTION_OBSERVE);
msg->code = COAP_RESPONSE_CODE_CONTENT;
@ -2622,7 +2698,7 @@ static int handle_request(struct coap_packet *request,
break;
case LWM2M_OP_DISCOVER:
r = do_discover_op(&context);
r = do_discover_op(&context, well_known);
break;
case LWM2M_OP_WRITE: