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Jon Shallow 1aaec808da Add DTLS support to libcoap using MbedTLS 
This update supports DTLS, TLS is a future TODO

components/coap/CMakeLists.txt:
components/coap/component.mk:

Add in the new files that have to be built
Replace libcoap/src/coap_notls.c with libcoap/src/coap_mbedtls.c

components/coap/libcoap:

Update the version to include the current version for supporting MbedTLS

components/coap/port/coap_debug.c:
components/coap/port/coap_mbedtls.c:
components/coap/port/include/coap/coap_dtls.h:

New port files for DTLS

components/coap/port/include/coap_config_posix.h:

Include building with MbedTLS

examples/protocols/coap_client/README.md:
examples/protocols/coap_client/main/CMakeLists.txt:
examples/protocols/coap_client/main/Kconfig.projbuild:
examples/protocols/coap_client/main/coap_client_example_main.c:
examples/protocols/coap_client/main/component.mk:

Update CoAP client to support DTLS

examples/protocols/coap_client/main/coap_ca.pem
examples/protocols/coap_client/main/coap_client.crt
examples/protocols/coap_client/main/coap_client.key

New PKI Certs for CoAP client (copied from wpa2_enterprise example)

examples/protocols/coap_server/README.md:
examples/protocols/coap_server/main/CMakeLists.txt:
examples/protocols/coap_server/main/Kconfig.projbuild:
examples/protocols/coap_server/main/coap_server_example_main.c:
examples/protocols/coap_server/main/component.mk:

Update CoAP server to support DTLS
Change "no data" to "Hello World!" to prevent confusion

examples/protocols/coap_server/main/coap_ca.pem
examples/protocols/coap_server/main/coap_server.crt
examples/protocols/coap_server/main/coap_server.key

New PKI Certs for CoAP server (copied from wpa2_enterprise example)

Closes https://github.com/espressif/esp-idf/pull/3345
Closes https://github.com/espressif/esp-idf/issues/1379
2019-08-06 10:37:40 +05:30
..
main Add DTLS support to libcoap using MbedTLS 2019-08-06 10:37:40 +05:30
CMakeLists.txt examples/protocols/coap: use common network component 2019-04-15 03:32:05 +00:00
Makefile examples/protocols/coap: use common network component 2019-04-15 03:32:05 +00:00
README.md Add DTLS support to libcoap using MbedTLS 2019-08-06 10:37:40 +05:30

README.md

CoAP server example

(See the README.md file in the upper level 'examples' directory for more information about examples.)
This CoAP server example is very simplified adaptation of one of the libcoap examples.

CoAP server example will startup a daemon task, receive requests / data from CoAP client and transmit data to CoAP client.

If the incoming request requests the use of DTLS (connecting to port 5684), then the CoAP server will try to establish a DTLS session using the previously defined Pre-Shared Key (PSK) - which must be the same as the one that the CoAP client is using, or Public Key Infrastructure (PKI) where the PKI information must match as requested.

NOTE: Client sessions trying to use coaps+tcp:// are not currently supported, even though both libcoap and MbedTLS support it.

The Constrained Application Protocol (CoAP) is a specialized web transfer protocol for use with constrained nodes and constrained networks in the Internet of Things.
The protocol is designed for machine-to-machine (M2M) applications such as smart energy and building automation.

Please refer to RFC7252 for more details.

How to use example

Configure the project

idf.py menuconfig

Example Connection Configuration --->

  • Set WiFi SSID under Example Configuration
  • Set WiFi Password under Example Configuration Example CoAP Client Configuration --->
  • Set CoAP Target Uri
  • Set encryption method definitions (None, PSK or PKI)
  • If PSK Set CoAP Preshared Key to use in connection to the server
  • If PSK Set CoAP PSK Client identity (username) Enable CoAP debugging if required Component config ---> mbedTLS ---> [] Enable mbedtls certificate expiry check TLS Key Exchange Methods ---> [] Enable pre-shared-key ciphersuites [] Enable PSK based ciphersuite modes [] Support DTLS protocol (all versions)

Build and Flash

Build the project and flash it to the board, then run monitor tool to view serial output:

idf.py build
idf.py -p PORT flash monitor

(To exit the serial monitor, type Ctrl-].)

See the Getting Started Guide for full steps to configure and use ESP-IDF to build projects.

Example Output

current CoAP server would startup a daemon task,
and the log is such as the following:

...
I (332) wifi: mode : sta (30:ae:a4:04:1b:7c)
I (1672) wifi: n:11 0, o:1 0, ap:255 255, sta:11 0, prof:1
I (1672) wifi: state: init -> auth (b0)
I (1682) wifi: state: auth -> assoc (0)
I (1692) wifi: state: assoc -> run (10)
I (1692) wifi: connected with huawei_cw, channel 11
I (1692) wifi: pm start, type: 1

I (2622) event: sta ip: 192.168.3.84, mask: 255.255.255.0, gw: 192.168.3.1
I (2622) CoAP_server: Connected to AP
...

If a CoAP client queries the /Espressif resource, CoAP server will return "Hello World!"
until a CoAP client does a PUT with different data.

libcoap Documentation

This can be found at https://libcoap.net/doc/reference/4.2.0/

Troubleshooting

  • Please make sure CoAP client fetchs or puts data under path: /Espressif or fetches /.well-known/core

  • CoAP logging can be enabled by running 'make menuconfig' and enable debugging

  • Encryption (MbedTLS) can be enabled by running 'make menuconfig' and enable debugging