Avoid panic if printer is off or unreachable for some reason.

Closes #16
Closes #17
Closes #15

packages/ipp/messages.go

@@ -115,6 +115,7 @@ const (
 	SuccessfulOkIgnoredOrSubstitutedAttributes statusCode = 0x0001
 	SuccessfulOkConflictingAttributes          statusCode = 0x0002
 	ClientErrorBadRequest                      statusCode = 0x0400
+	ServerErrorServiceUnavailable              statusCode = 0x0502
 )
 
 type versionNumber uint16

packages/ipp/request.go

@@ -65,6 +65,7 @@ func (r *Request) RequestID() uint32 {
 	return r.header.requestID
 }
 
+// Operation returns the operation is of the request.
 func (r *Request) Operation() OperationID {
 	return r.header.operationID
 }

packages/ipp/response.go

@@ -52,6 +52,10 @@ func (r Response) String() string {
 	return r.header.String() + "\n" + r.a.String()
 }
 
+func (r Response) Header() ippResponseHeader {
+	return r.header
+}
+
 // Marshal converts the response object to a wire formatted byte stream.
 func (r *Response) Marshal() []byte {
 	a := make([]byte, 0, 20)

proxy/handlegetjobattributes.go

@@ -2,14 +2,13 @@ package main
 
 import (
 	"bytes"
-	"fmt"
 	"ippserver/packages/ipp"
 	"net/http"
 
 	log "github.com/sirupsen/logrus"
 )
 
-func handleGetJobAttributes(r *ipp.Request, requestID uint32) *ipp.Response {
+func handleGetJobAttributes(r *ipp.Request, requestID uint32) (*ipp.Response, error) {
 
 	request := ipp.NewRequest(ipp.GetJobAttributes, requestID)
 	request.AddOperatonAttribute(ipp.NewCharSetValue("attributes-charset", "utf-8"))
@@ -26,7 +25,7 @@ func handleGetJobAttributes(r *ipp.Request, requestID uint32) *ipp.Response {
 
 	downStreamResponse, err := http.Post("http://"+"brn30055cb5e3ae.local:631/ipp/print", "application/ipp", b)
 	if err != nil {
-		fmt.Print(err)
+		return nil, err
 	}
 
 	rb := ipp.NewResponse(0, 0)
@@ -42,5 +41,5 @@ func handleGetJobAttributes(r *ipp.Request, requestID uint32) *ipp.Response {
 	response.AddJobAttribute(rb.GetAttribute("job-state"))
 	response.AddJobAttribute(rb.GetAttribute("job-state-reasons"))
 
-	return response
+	return response, nil
 }

proxy/handlegetjobs.go

@@ -2,14 +2,13 @@ package main
 
 import (
 	"bytes"
-	"fmt"
 	"ippserver/packages/ipp"
 	"net/http"
 
 	log "github.com/sirupsen/logrus"
 )
 
-func handleGetJobs(r *ipp.Request, requestID uint32) *ipp.Response {
+func handleGetJobs(r *ipp.Request, requestID uint32) (*ipp.Response, error) {
 
 	request := ipp.NewRequest(ipp.GetJobs, requestID)
 	request.AddOperatonAttribute(ipp.NewCharSetValue("attributes-charset", "utf-8"))
@@ -25,7 +24,7 @@ func handleGetJobs(r *ipp.Request, requestID uint32) *ipp.Response {
 
 	downStreamResponse, err := http.Post("http://"+"brn30055cb5e3ae.local:631/ipp/print", "application/ipp", b)
 	if err != nil {
-		fmt.Print(err)
+		return nil, err
 	}
 
 	//log.Printf("response HTTP status: %v %v", downStreamResponse.StatusCode, downStreamResponse.Status)
@@ -43,5 +42,5 @@ func handleGetJobs(r *ipp.Request, requestID uint32) *ipp.Response {
 	response.AddJobAttribute(rb.GetAttribute("job-state"))
 	response.AddJobAttribute(rb.GetAttribute("job-state-reasons"))
 
-	return response
+	return response, nil
 }

proxy/handleprintjob.go

@@ -2,7 +2,6 @@ package main
 
 import (
 	"bytes"
-	"fmt"
 	"io"
 	"ippserver/packages/ipp"
 	"net/http"
@@ -14,7 +13,7 @@ import (
 
 const printerURI = "brn30055cb5e3ae.local:631/ipp/print"
 
-func handlePrintJob(r *ipp.Request, byteStream io.Reader, requestID uint32) *ipp.Response {
+func handlePrintJob(r *ipp.Request, byteStream io.Reader, requestID uint32) (*ipp.Response, error) {
 
 	// This request is what will be sent to the real printer
 	request := ipp.NewRequest(ipp.PrintJob, requestID)
@@ -38,7 +37,7 @@ func handlePrintJob(r *ipp.Request, byteStream io.Reader, requestID uint32) *ipp
 	mr := io.MultiReader(b, byteStream)
 	downStreamResponse, err := http.Post("http://"+"brn30055cb5e3ae.local:631/ipp/print", "application/ipp", mr)
 	if err != nil {
-		fmt.Print(err)
+		return nil, err
 	}
 
 	rb := ipp.NewResponse(0, 0)
@@ -64,5 +63,5 @@ func handlePrintJob(r *ipp.Request, byteStream io.Reader, requestID uint32) *ipp
 	response.AddJobAttribute(rb.GetAttribute("job-state"))
 	response.AddJobAttribute(rb.GetAttribute("job-state-reasons"))
 
-	return response
+	return response, nil
 }

proxy/main.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"context"
+	"flag"
 	"ippserver/packages/ipp"
 	"ippserver/packages/mdnsserver"
 	"net/http"
@@ -10,6 +11,15 @@ import (
 	log "github.com/sirupsen/logrus"
 )
 
+var (
+	loglevel string
+	location string
+)
+
+func init() {
+	flag.StringVar(&loglevel, "loglevel", "info", "The wanted loglevel error/info/debug")
+}
+
 func main() {
 	customFormatter := new(log.TextFormatter)
 	customFormatter.TimestampFormat = "2006-01-02 15:04:05"
@@ -39,29 +49,32 @@ func handle(w http.ResponseWriter, r *http.Request) {
 	mut.Unlock()
 	if r.Method != http.MethodPost {
 		http.Error(w, "Unsupported method", http.StatusMethodNotAllowed)
-
 	}
 
 	request := ipp.NewRequest(0, 0)
 	request.UnMarshal(r.Body)
-	log.Infof("Upstream Request: \n%v\n", request)
+	log.Infof("Upstream Request: id: %v op: %v", request.RequestID(), request.Operation())
 	var response *ipp.Response
+	var err error
 	switch request.Operation() {
 	case ipp.GetPrinterAttributes:
 		response = handleGetPrinterAttributes(request)
 	case ipp.PrintJob:
-		response = handlePrintJob(request, r.Body, requestID)
+		response, err = handlePrintJob(request, r.Body, requestID)
 	case ipp.GetJobs:
-		response = handleGetJobs(request, requestID)
+		response, err = handleGetJobs(request, requestID)
 	case ipp.ValidateJob:
 		response = handleValidateJob(request)
 	case ipp.GetJobAttributes:
-		response = handleGetJobAttributes(request, requestID)
+		response, err = handleGetJobAttributes(request, requestID)
 	default:
 		response = ipp.NewResponse(ipp.ClientErrorBadRequest, request.RequestID())
 	}
-
+	if err != nil {
-	log.Infof("Upstream Response:\n%v\n", response)
+		log.Errorf("Failed to handle request: %v", err.Error())
+		response = ipp.NewResponse(ipp.ServerErrorServiceUnavailable, request.RequestID())
+	}
+	log.Infof("Upstream Response: %v", response.Header())
 	data := response.Marshal()
 	w.Write(data)
 }