feat: add examples for coap client, update readme

Signed-off-by: 1998-felix <[email protected]>

README.md

@@ -122,7 +122,7 @@ mProxy is used to proxy requests to a backend server. For the example setup, we
    - mProxy server for `HTTP protocol without TLS` on port `8086` with prefix path `/messages`
    - mProxy server for `HTTP protocol with TLS` on port `8087` with prefix path `/messages`
    - mProxy server for `HTTP protocol with mTLS` on port `8088` with prefix path `/messages`
-   - mProxy server for `COAP protocol without DTLS` on port `5682` 
+   - mProxy server for `COAP protocol without DTLS` on port `5682`
    - mProxy server for `COAP protocol with DTLS` on port `5684`
 
 ### Example testing of mProxy
@@ -193,6 +193,23 @@ Bash scripts available in `examples/client/http` directory help to test the mPro
   examples/client/http/with_mtls.sh
   ```
 
+### Test mProxy server for CoAP protocols
+
+Bash scripts available in `example/client/coap` directory help to test the mProxy servers running for CoAP protocols.
+This scripts can be used after changing the `MPROXY_COAP_WITHOUT_DTLS_TARGET` and `MPROXY_COAP_WITH_DTLS_TARGET` to a public coap server such as `coap://coap.me:5683`
+
+- Script to test mProxy server running at 5682 for CoAP without DTLS
+
+  ```bash
+    examples/client/coap/without_dtls.sh
+  ```
+
+- Script to test mProxy server running at 5684 for CoAP with DTLS
+
+  ```bash
+    examples/client/coap/without_dtls.sh
+  ```
+
 ## Configuration
 
 The service is configured using the environment variables presented in the following table. Note that any unset variables will be replaced with their default values.
@@ -248,6 +265,14 @@ The service is configured using the environment variables presented in the follo
 | MPROXY_HTTP_WITH_MTLS_CLIENT_CA_FILE               | HTTP with mTLS client CA file path                                                                                                    | ssl/certs/ca.crt             |
 | MPROXY_HTTP_WITH_MTLS_CERT_VERIFICATION_METHODS    | HTTP with mTLS certificate verification methods, if no value or unset then mProxy server will not do client validation                | ocsp                         |
 | MPROXY_HTTP_WITH_MTLS_OCSP_RESPONDER_URL           | HTTP with mTLS OCSP responder URL, it is used if OCSP responder URL is not available in client certificate AIA                        | <http://localhost:8080/ocsp> |
+| MPROXY_COAP_WITHOUT_DTLS_ADDRESS                   | CoAP without DTLS inbound (IN) connection listening address                                                                           | localhost:5682               |
+| MPROXY_COAP_WITH_DTLS_TARGET                       | CoAP without DTLS outbound (OUT) connection                                                                                           | localhost:5683               |
+| MPROXY_COAP_WITH_DTLS_ADDRESS                      | CoAP with DTLS inbound (IN) connection listening address                                                                              | localhost:5684               |
+| MPROXY_COAP_WITH_DTLS_TARGET                       | CoAP with DTLS outbound (OUT) connection                                                                                              | localhost:5683               |
+| MPROXY_COAP_WITH_DTLS_CERT_FILE                    | CoAP with DTLS certificate file                                                                                                       | ssl/certs/server.crt         |
+| MPROXY_COAP_WITH_DTLS_KEY_FILE                     | CoAP with DTLS key file                                                                                                               | ssl/certs/server.key         |
+| MPROXY_COAP_WITH_DTLS_SERVER_CA_FILE               | CoAP with DTLS server CA file                                                                                                         | ssl/certs/ca.crt             |
+| MPROXY_COAP_WITH_DTLS_CLIENT_CA_FILE               | CoAP with DTLS client CA file                                                                                                         | ssl/certs/ca.crt             |
 
 ## mProxy Configuration Environment Variables
 

examples/client/coap/with_dtls.sh

@@ -0,0 +1,25 @@
+#!/bin/bash
+protocol=coaps
+host=localhost
+port=5684
+path="test"
+content=0x32
+message="{\"message\": \"Hello mProxy\"}"
+auth="TOKEN"
+cafile=ssl/certs/ca.crt
+certfile=ssl/certs/client.crt
+keyfile=ssl/certs/client.key
+
+echo "Posting message to ${protocol}://${host}:${port}/${path} with dtls ..."
+coap-client -m post coap://${host}:${port}/${path} -e "${message}" -O 12,${content} -O 15,auth=${auth} \
+    -c $certfile -k $keyfile -C $cafile
+
+echo "Getting message from ${protocol}://${host}:${port}/${path} with dtls ..."
+coap-client -m get coap://${host}:${port}/${path} -O 6,0x00 -O 15,auth=${auth} -c $certfile -k $keyfile -C $cafile
+
+echo "Posting message to ${protocol}://${host}:${port}/${path} with dtls and invalid client certificate..."
+coap-client -m post coap://${host}:${port}/${path} -e "${message}" -O 12,${content} -O 15,auth=${auth} \
+    -c ssl/certs/client_unknown.crt -k ssl/certs/client_unknown.key -C $cafile
+
+echo "Getting message from ${protocol}://${host}:${port}/${path} with dtls and invalid client certificate..."
+coap-client -m get coap://${host}:${port}/${path} -O 6,0x00 -O 15,auth=${auth} -c ssl/certs/client_unknown.crt -k ssl/certs/client_unknown.key -C $cafile

examples/client/coap/without_dtls.sh

@@ -0,0 +1,14 @@
+#!/bin/bash
+protocol=coap
+host=localhost
+port=5682
+path="test"
+content=0x32
+message="{\"message\": \"Hello mProxy\"}"
+auth="TOKEN"
+
+echo "Posting message to ${protocol}://${host}:${port}/${path} without tls ..."
+coap-client -m post coap://${host}:${port}/${path} -e "${message}" -O 12,${content} -O 15,auth=${auth}
+
+echo "Getting message from ${protocol}://${host}:${port}/${path} without tls ..."
+coap-client -m get coap://${host}:${port}/${path} -O 6,0x00 -O 15,auth=${auth} -

pkg/coap/coap.go

@@ -22,6 +22,11 @@ import (
 	"github.com/plgd-dev/go-coap/v3/udp"
 )
 
+var (
+	errUnsupportedConfig = errors.New("unsupported CoAP configuration")
+	errUnsupportedMethod = errors.New("unsupported CoAP method")
+)
+
 type Proxy struct {
 	config  mproxy.Config
 	session session.Handler
@@ -47,15 +52,19 @@ func sendErrorMessage(cc mux.Conn, token []byte, err error, code codes.Code) err
 }
 
 func (p *Proxy) postUpstream(cc mux.Conn, req *mux.Message, token []byte) error {
-	format, err := req.ContentFormat()
-	if err != nil {
-		return err
-	}
 	path, err := req.Options().Path()
 	if err != nil {
 		return err
 	}
 
+	format := message.TextPlain
+	if req.HasOption(message.ContentFormat) {
+		format, err = req.ContentFormat()
+		if err != nil {
+			return err
+		}
+	}
+
 	targetConn, err := udp.Dial(p.config.Target)
 	if err != nil {
 		return err
@@ -92,7 +101,7 @@ func (p *Proxy) observeUpstream(ctx context.Context, cc mux.Conn, opts []message
 	targetConn, err := udp.Dial(p.config.Target)
 	if err != nil {
 		if err := sendErrorMessage(cc, token, err, codes.BadGateway); err != nil {
-			p.logger.Error("cannot send error response: %v", err)
+			p.logger.Error(fmt.Sprintf("cannot send error response: %v", err))
 		}
 	}
 	defer targetConn.Close()
@@ -112,14 +121,14 @@ func (p *Proxy) observeUpstream(ctx context.Context, cc mux.Conn, opts []message
 	}, opts...)
 	if err != nil {
 		if err := sendErrorMessage(cc, token, err, codes.BadGateway); err != nil {
-			p.logger.Error("cannot send error response: %v", err)
+			p.logger.Error(fmt.Sprintf("cannot send error response: %v", err))
 		}
 	}
 
 	select {
 	case <-doneObserving:
 		if err := obs.Cancel(ctx); err != nil {
-			p.logger.Error("failed to cancel observation: %v", err)
+			p.logger.Error(fmt.Sprintf("failed to cancel observation:%v", err))
 		}
 	case <-ctx.Done():
 		return
@@ -168,6 +177,10 @@ func (p *Proxy) handler(w mux.ResponseWriter, r *mux.Message) {
 			return
 		}
 		p.handlePost(ctx, w.Conn(), body, r.Token(), path, r)
+	default:
+		if err := sendErrorMessage(w.Conn(), r.Token(), errUnsupportedMethod, codes.MethodNotAllowed); err != nil {
+			p.logger.Error(err.Error())
+		}
 	}
 }
 
@@ -273,6 +286,6 @@ func (p *Proxy) Listen(ctx context.Context) error {
 		}
 		return nil
 	default:
-		return errors.New("unsupported CoAP configuration")
+		return errUnsupportedConfig
 	}
 }