Fix handling of compressed data

respond/collector.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"compress/flate"
 	"encoding/json"
+	"io/ioutil"
 	"log"
 	"net"
 	"reflect"
@@ -117,11 +118,27 @@ func (coll *Collector) parse(response *Response) (err error) {
 	reader := flate.NewReader(bytes.NewReader(response.Raw))
 	defer reader.Close()
 
-	decoder := json.NewDecoder(reader)
+	decompressed, err := ioutil.ReadAll(reader)
-	if err = decoder.Decode(data); err == nil {
+	if err != nil {
-		coll.onReceive(response.Address, data)
+		return
 	}
 
+	// Remove useless wrapper element that only exists in compressed data.
+	// Who introduced this !?
+	if bytes.HasPrefix(decompressed, []byte(`{"neighbours":`)) ||
+		bytes.HasPrefix(decompressed, []byte(`{"statistics":`)) {
+		decompressed = decompressed[14 : len(decompressed)-1]
+	} else if bytes.HasPrefix(decompressed, []byte(`{"nodeinfo":`)) {
+		decompressed = decompressed[12 : len(decompressed)-1]
+	}
+
+	err = json.Unmarshal(decompressed, data)
+	if err != nil {
+		return
+	}
+
+	coll.onReceive(response.Address, data)
+
 	return
 }
 

respond/collector_test.go

@@ -0,0 +1,42 @@
+package respond
+
+import (
+	"io/ioutil"
+	"net"
+	"reflect"
+	"testing"
+
+	"github.com/FreifunkBremen/respond-collector/data"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestParse(t *testing.T) {
+	assert := assert.New(t)
+	var decompressed *data.NodeInfo
+
+	// callback function
+	onReceive := func(addr net.UDPAddr, msg interface{}) {
+		switch msg := msg.(type) {
+		case *data.NodeInfo:
+			decompressed = msg
+		default:
+			t.Error("unexpected message:", msg)
+		}
+	}
+
+	collector := &Collector{
+		msgType:   reflect.TypeOf(data.NodeInfo{}),
+		onReceive: onReceive,
+	}
+
+	// read testdata
+	compressed, err := ioutil.ReadFile("testdata/nodeinfo.flated")
+	assert.Nil(err)
+
+	collector.parse(&Response{
+		Raw: compressed,
+	})
+
+	assert.NotNil(decompressed)
+	assert.Equal("f81a67a5e9c1", decompressed.NodeId)
+}