From 429eb6b33945a070c7614afa3ce512704ece9d10 Mon Sep 17 00:00:00 2001
From: Sebastian Frank <sebastian@webmakers.de>
Date: Fri, 9 Apr 2021 17:30:22 +0200
Subject: [PATCH] udp client with buffer

---
 .air.toml  |  2 +-
 .gitignore |  1 +
 main.go    | 63 ++++++++++++++++++++++++++++++++++++++++++++++++++----
 3 files changed, 61 insertions(+), 5 deletions(-)

diff --git a/.air.toml b/.air.toml
index ff56bb1..1986aed 100644
--- a/.air.toml
+++ b/.air.toml
@@ -4,4 +4,4 @@ cmd = "go build -o ./tmp/main ."
 # Binary file yields from `cmd`.
 bin = "tmp/main"
 # Customize binary.
-full_bin = "./tmp/main -socket=./log.socket"
\ No newline at end of file
+full_bin = "./tmp/main -socket=./log.socket -udpAddr=localhost:4040"
\ No newline at end of file
diff --git a/.gitignore b/.gitignore
index bfb8067..f497205 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,3 @@
 tmp/
 devlogforward
+log.socket
diff --git a/main.go b/main.go
index 62c1fb5..98bb30c 100644
--- a/main.go
+++ b/main.go
@@ -1,25 +1,68 @@
 package main
 
 import (
+	"encoding/json"
 	"flag"
-	"fmt"
+	"log"
+	"net"
 	"os"
 	"text/template"
+	"time"
 
 	"gopkg.in/mcuadros/go-syslog.v2"
 )
 
+func udpConnect(addr string) (conn *net.UDPConn) {
+	if addr != "" {
+		uaddr, err := net.ResolveUDPAddr("udp4", addr)
+		if err != nil {
+			log.Printf("error resolving udp address: %s (%s)\n", addr, err)
+		}
+		if uaddr != nil {
+			conn, err = net.DialUDP("udp4", nil, uaddr)
+			if err != nil {
+				log.Printf("error connecting to udp address: %s (%s)", addr, err)
+			} else {
+				log.Printf("udp client initialized")
+			}
+		}
+	}
+
+	return
+}
+
 func main() {
 	socketFile := flag.String("socket", "/dev/log", "socket file")
 	stdoutTpl := flag.String("stdoutTpl", "[{{.timestamp}}] {{.content}}", "stdout line template, variables are: timestamp, content, facility, hostname, priority, severity, tag")
+	udpAddr := flag.String("udpAddr", "", "udp address, format is host:port")
+	udpTpl := flag.String("udpTpl", "{{ json . }}", "udp line template, see stdoutTpl for variables")
 
 	flag.Parse()
 
-	stdoutTemplate := template.Must(template.New("stdout").Parse(*stdoutTpl + "\n"))
+	fMap := template.FuncMap{
+		"json": func(i interface{}) string {
+			b, _ := json.Marshal(i)
+			return string(b)
+		},
+	}
 
-	channel := make(syslog.LogPartsChannel)
+	stdoutTemplate := template.Must(template.New("stdout").Funcs(fMap).Parse(*stdoutTpl + "\n"))
+	udpTemplate := template.Must(template.New("udp").Funcs(fMap).Parse(*udpTpl + "\n"))
+
+	udpConnection := udpConnect(*udpAddr)
+	go func() {
+		for range time.Tick(time.Second * 60) {
+			if udpConnection == nil {
+				udpConnection = udpConnect(*udpAddr)
+			}
+		}
+	}()
+
+	channel := make(syslog.LogPartsChannel, 1000)
 	handler := syslog.NewChannelHandler(channel)
 
+	udpChannel := make(syslog.LogPartsChannel, 1000)
+
 	server := syslog.NewServer()
 	// server.SetFormat(syslog.RFC5424)
 	server.SetFormat(syslog.Automatic)
@@ -41,9 +84,21 @@ func main() {
 	go func(channel syslog.LogPartsChannel) {
 		for logParts := range channel {
 			stdoutTemplate.Execute(os.Stdout, logParts)
-			fmt.Println(logParts)
+			udpChannel <- logParts
+			// fmt.Println(logParts)
 		}
 	}(channel)
 
+	go func(channel syslog.LogPartsChannel) {
+		for logParts := range channel {
+			if udpConnection != nil {
+				err := udpTemplate.Execute(udpConnection, logParts)
+				if err != nil {
+					log.Printf("error executing udp template: %s", err)
+				}
+			}
+		}
+	}(udpChannel)
+
 	server.Wait()
 }