esp-idf/examples/protocols/coap_client/README.md

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| Supported Targets | ESP32 | ESP32-C3 | ESP32-S2 | ESP32-S3 |
| ----------------- | ----- | -------- | -------- | -------- |
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# CoAP client example
(See the README.md file in the upper level 'examples' directory for more information about examples.)
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
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This CoAP client example is very simplified adaptation of one of the
[libcoap](https://github.com/obgm/libcoap) examples.
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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
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CoAP client example will connect your ESP32 device to a CoAP server, send off a GET request and
fetch the response data from CoAP server. The client can be extended to PUT / POST / DELETE requests,
as well as supporting the Observer extensions [RFC7641](https://tools.ietf.org/html/rfc7641).
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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
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If the URI is prefixed with coaps:// instead of coap://, then the CoAP client will attempt to use
the DTLS protocol using the defined Pre-Shared Keys(PSK) or Public Key Infrastructure (PKI) which the
CoAP server needs to know about.
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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
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If the URI is prefixed with coap+tcp://, then the CoAP will try to use TCP for the communication.
NOTE: coaps+tcp:// is 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.
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
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The protocol is designed for machine-to-machine (M2M) applications such as smart energy and
building automation.
Please refer to [RFC7252](https://www.rfc-editor.org/rfc/pdfrfc/rfc7252.txt.pdf) for more details.
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## How to use example
### Configure the project
```
idf.py menuconfig
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```
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
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Example Connection Configuration --->
* Set WiFi SSID under Example Configuration
* Set WiFi Password under Example Configuration
Example CoAP Client Configuration --->
* Set CoAP Target Uri
* If PSK, Set CoAP Preshared Key to use in connection to the server
* If PSK, Set CoAP PSK Client identity (username)
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
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Component config --->
CoAP Configuration --->
* Set encryption method definition, PSK (default) or PKI
* Enable CoAP debugging if required
High resolution timer (esp_timer) --->
* Hardware timer to use for esp_timer - change if required (FRC2 for QEMU)
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### Build and Flash
Build the project and flash it to the board, then run monitor tool to view serial output:
```
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
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idf.py build
idf.py -p PORT flash monitor
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```
(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
Prerequisite: we startup a CoAP server on coap server example,
or use the default of coap://californium.eclipseprojects.io.
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and you could receive data from CoAP server if succeed,
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such as the following log:
```
...
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 (2582) event: sta ip: 192.168.3.89, mask: 255.255.255.0, gw: 192.168.3.1
I (2582) CoAP_client: Connected to AP
I (2582) CoAP_client: DNS lookup succeeded. IP=35.185.40.182
Received:
****************************************************************
CoAP RFC 7252 Cf 3.0.0-SNAPSHOT
****************************************************************
This server is using the Eclipse Californium (Cf) CoAP framework
published under EPL+EDL: http://www.eclipse.org/californium/
(c) 2014-2020 Institute for Pervasive Computing, ETH Zurich and others
****************************************************************
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...
```
## libcoap Documentation
This can be found at [libcoap Documentation](https://libcoap.net/documentation.html).
The current API is 4.3.0.
## libcoap Specific Issues
These can be raised at [libcoap Issues](https://github.com/obgm/libcoap/issues).
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## Troubleshooting
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
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* Please make sure Target Url includes valid `host`, optional `port`,
optional `path`, and begins with `coap://`, `coaps://` or `coap+tcp://`
for a coap server that supports TCP
(not all do including coap+tcp://californium.eclipseprojects.io).
* CoAP logging can be enabled by running 'idf.py menuconfig -> Component config -> CoAP Configuration' and setting appropriate log level