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)

See Issue espressif#1379

components/coap/CMakeLists.txt

@@ -8,7 +8,7 @@ set(srcs
     "libcoap/src/coap_hashkey.c"
     "libcoap/src/coap_session.c"
     "libcoap/src/coap_time.c"
-    "libcoap/src/coap_debug.c"
+    "port/coap_debug.c"
     "libcoap/src/encode.c"
     "libcoap/src/mem.c"
     "libcoap/src/net.c"
@@ -18,8 +18,8 @@ set(srcs
     "libcoap/src/str.c"
     "libcoap/src/subscribe.c"
     "libcoap/src/uri.c"
-    "libcoap/src/coap_notls.c"
-    "port/coap_io.c")
+    "libcoap/src/coap_io.c"
+    "port/coap_mbedtls.c")
 
 set(COMPONENT_REQUIRES lwip)
 
@@ -28,7 +28,7 @@ idf_component_register(SRCS "${srcs}"
                     REQUIRES lwip)
 
 # Silence format truncation warning, until it is fixed upstream
-set_source_files_properties(libcoap/src/coap_debug.c PROPERTIES COMPILE_FLAGS -Wno-format-truncation)
+set_source_files_properties(port/coap_debug.c PROPERTIES COMPILE_FLAGS -Wno-format-truncation)
 
 # Needed for coap headers in public builds, also.
 #

components/coap/component.mk

@@ -4,11 +4,11 @@
 
 COMPONENT_ADD_INCLUDEDIRS := port/include port/include/coap libcoap/include libcoap/include/coap2
 
-COMPONENT_OBJS = libcoap/src/address.o libcoap/src/async.o libcoap/src/block.o libcoap/src/coap_event.o libcoap/src/coap_hashkey.o libcoap/src/coap_session.o libcoap/src/coap_time.o libcoap/src/coap_debug.o libcoap/src/encode.o libcoap/src/mem.o libcoap/src/net.o libcoap/src/option.o libcoap/src/pdu.o libcoap/src/resource.o libcoap/src/str.o libcoap/src/subscribe.o libcoap/src/uri.o libcoap/src/coap_notls.o port/coap_io.o
+COMPONENT_OBJS = libcoap/src/address.o libcoap/src/async.o libcoap/src/block.o libcoap/src/coap_event.o libcoap/src/coap_hashkey.o libcoap/src/coap_session.o libcoap/src/coap_time.o port/coap_debug.o libcoap/src/encode.o libcoap/src/mem.o libcoap/src/net.o libcoap/src/option.o libcoap/src/pdu.o libcoap/src/resource.o libcoap/src/str.o libcoap/src/subscribe.o libcoap/src/uri.o port/coap_mbedtls.o libcoap/src/coap_io.o
 
 COMPONENT_SRCDIRS := libcoap/src libcoap port
 
 COMPONENT_SUBMODULES += libcoap
 
 # Silence format truncation warning, until it is fixed upstream
-libcoap/src/coap_debug.o: CFLAGS += -Wno-format-truncation
+port/coap_debug.o: CFLAGS += -Wno-format-truncation