Fix #5 - support unprintable messages in MESSAGE from journal, add tests

.gitignore

@@ -1 +1,2 @@
 SystemdJournal2Gelf
+.idea/

SystemdJournal2Gelf.go

@@ -141,6 +141,32 @@ func (this *SystemdJournalEntry) process() {
 	this.Message = re.ReplaceAllString(this.Message, "")
 }
 
+// Custom wrapper to support unprintable chars in message
+func (this *SystemdJournalEntry) UnmarshalJSON(data []byte) error {
+	// use an alias to prevent recursion
+	type entryAlias SystemdJournalEntry
+	aux := (*entryAlias)(this)
+
+	if err := json.Unmarshal(data, &aux); err == nil {
+		return nil
+	} else if ute, ok := err.(*json.UnmarshalTypeError); ok && ute.Field == "MESSAGE" && ute.Value == "array" {
+		// Include brackets, which is why we subtract and add by one
+		len := int64(strings.Index(string(data[ute.Offset:]), `]`)) + 1
+
+		var message []byte
+		if err := json.Unmarshal(data[ute.Offset-1:ute.Offset+len], &message); err != nil {
+			return err
+		}
+
+		// only the failing field is skipped, so we can still use the rest
+		this.Message = string(message)
+
+		return nil
+	} else {
+		return err
+	}
+}
+
 func (this *SystemdJournalEntry) send() {
 	message := this.toGelf()
 
@@ -155,7 +181,7 @@ func (this *SystemdJournalEntry) send() {
 }
 
 func (this *SystemdJournalEntry) isJsonMessage() bool {
-	return len(this.Message) > 64 && this.Message[0:2] == `{"`
+	return this.Message[0:2] == `{"`
 }
 
 type pendingEntry struct {

SystemdJournal2Gelf_test.go

@@ -0,0 +1,136 @@
+package main
+
+import (
+	"encoding/json"
+	"testing"
+)
+
+func TestUnmarshalEntry(t *testing.T) {
+	entry := SystemdJournalEntry{}
+
+	err := json.Unmarshal([]byte(`{
+        "MESSAGE" : "Linux version 4.20.6-arch1-1-ARCH (builduser@heftig-32156) (gcc version 8.2.1 20181127 (GCC)) #1 SMP PREEMPT Thu Jan 31 08:22:01 UTC 2019",
+        "PRIORITY" : "5",
+        "__REALTIME_TIMESTAMP" : "1549067421724300",
+        "_TRANSPORT" : "kernel",
+        "SYSLOG_FACILITY" : "0",
+        "SYSLOG_IDENTIFIER" : "kernel",
+        "_HOSTNAME" : "machine.nl",
+        "_BOOT_ID" : "61c0e40c739f4f009c785cef13b46e17",
+		"_UID" : "99",
+		"_PID" : "1234"
+	}`), &entry)
+
+	AssertNotError(t, err)
+
+	gelf := entry.toGelf()
+	AssertEquals(t, "machine.nl", gelf.Host)
+	AssertEquals(t, "Linux version 4.20.6-arch1-1-ARCH (builduser@heftig-32156) (gcc version 8.2.1 20181127 (GCC)) #1 SMP PREEMPT Thu Jan 31 08:22:01 UTC 2019", gelf.Short)
+	AssertEquals(t, "", gelf.Full)
+	AssertEquals(t, float64(1549067421.7243001), gelf.TimeUnix)
+	AssertEquals(t, int32(5), gelf.Level)
+	AssertEquals(t, "kernel", gelf.Facility)
+
+	AssertEquals(t, 3, len(gelf.Extra))
+	AssertEquals(t, "61c0e40c739f4f009c785cef13b46e17", gelf.Extra["Boot_id"])
+	AssertEquals(t, "99", gelf.Extra["Uid"])
+	AssertEquals(t, "1234", gelf.Extra["Pid"])
+
+}
+
+func TestJsonMessageOverridesNormalProperties(t *testing.T) {
+	entry := SystemdJournalEntry{}
+
+	err := json.Unmarshal([]byte(`{
+        "_HOSTNAME" : "machine.nl",
+        "MESSAGE" : "{\"Message\":\"actually something else\",\"FullMessage\":\"additional data\"}",
+        "SYSLOG_IDENTIFIER" : "kernel"
+	}`), &entry)
+
+	AssertNotError(t, err)
+
+	gelf := entry.toGelf()
+
+	AssertEquals(t, "machine.nl", gelf.Host)
+	AssertEquals(t, "actually something else", gelf.Short)
+	AssertEquals(t, "additional data", gelf.Full)
+	AssertEquals(t, "kernel", gelf.Facility)
+	AssertEquals(t, 3, len(gelf.Extra))
+}
+
+func TestJsonMessageIncludeDataInExtra(t *testing.T) {
+	entry := SystemdJournalEntry{}
+
+	err := json.Unmarshal([]byte(`{
+        "_HOSTNAME" : "machine.nl",
+		"MESSAGE" : "{\"Message\":\"actually something else\",\"stuff\":\"things and stuff and more like that\"}",
+        "SYSLOG_IDENTIFIER" : "kernel"
+	}`), &entry)
+
+	AssertNotError(t, err)
+
+	gelf := entry.toGelf()
+
+	AssertEquals(t, "machine.nl", gelf.Host)
+	AssertEquals(t, "actually something else", gelf.Short)
+	AssertEquals(t, "kernel", gelf.Facility)
+	AssertEquals(t, 4, len(gelf.Extra))
+	AssertEquals(t, "things and stuff and more like that", gelf.Extra["stuff"])
+}
+
+func TestUnmarshalUnprintableEntry(t *testing.T) {
+	entry := SystemdJournalEntry{}
+
+	err := json.Unmarshal([]byte(`{
+        "_HOSTNAME" : "machine.nl",
+        "MESSAGE" : [ 116, 104, 105, 115, 32, 105, 115, 32, 97, 32, 98, 105, 110, 97, 114, 121, 32, 118, 97, 108, 117, 101, 32, 7 ],
+        "SYSLOG_IDENTIFIER" : "kernel"
+	}`), &entry)
+
+	AssertNotError(t, err)
+
+	gelf := entry.toGelf()
+	AssertEquals(t, "this is a binary value \a", gelf.Short)
+
+	AssertEquals(t, "kernel", gelf.Facility)
+	AssertEquals(t, "machine.nl", gelf.Host)
+
+}
+
+func AssertEquals(t *testing.T, expected, actual interface{}) {
+	if expected != actual {
+		t.Errorf("AssertEquals: %[1]T(%#[1]v) does not match %[2]T(%#[2]v))", actual, expected)
+	}
+}
+
+func AssertNotEquals(t *testing.T, expected, actual interface{}) {
+	if expected == actual {
+		t.Errorf("AssertNotEquals: %[1]T(%#[1]v) unexpectedly matches %[2]T(%#[2]v)", actual, expected)
+	}
+}
+
+func AssertError(t *testing.T, err interface{}) {
+	_, ok := err.(error)
+
+	if !ok {
+		t.Errorf("AssertError: %[1]T(%#[1]v) is not an error", err)
+	}
+}
+
+func AssertSpecificError(t *testing.T, err interface{}, specific error) {
+	_, ok := err.(error)
+
+	if !ok {
+		t.Errorf("AssertError: %[1]T(%#[1]v) is not an error", err)
+	} else if specific != nil && err != specific {
+		t.Errorf("AssertError: %[1]T(%#[1]v) is not an %[1]T(%#[1]v)", err, specific)
+	}
+}
+
+func AssertNotError(t *testing.T, err interface{}) {
+	_, ok := err.(error)
+
+	if ok {
+		t.Errorf("AssertNotError: %#[1]v is unexpectedly an error", err)
+	}
+}