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Marcel Gebhardt
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new syslog server with tcp and tls support, added tests
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‎.travis.yml

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language: go
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go_import_path: github.com/Neo23x0/simplesyslog
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notifications:
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email: false
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slack: nextron-systems:Q1f2uRSIFH0Sf5IzT884z4YR

‎server.go

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// Simple Syslog Server that
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// supports UDP, TCP and TLS.
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//
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// Marcel Gebhardt
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// April 2018
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package simplesyslog
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import (
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"crypto/tls"
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"fmt"
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"log/syslog"
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"net"
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"os"
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"time"
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)
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// ConnectionType defines wheather to connect via UDP or TCP (or TLS)
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type ConnectionType string
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const (
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// ConnectionUDP connects via UDP
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ConnectionUDP ConnectionType = "udp"
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// ConnectionTCP connects via TCP
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ConnectionTCP ConnectionType = "tcp"
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// ConnectionTLS connects via TLS
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ConnectionTLS ConnectionType = "tls"
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)
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const (
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// DefaultHostname will be used if hostname could not be determined
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DefaultHostname string = "unknown"
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// DefaultIP will be used if ip could not be determined
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DefaultIP string = ""
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)
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// Server holds a connection to a specified address
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type Server struct {
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Hostname string // Hostname of the system
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IP string // IP of the system
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Rfc3164 bool // rfc standard for length reduction
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Rfc5424 bool // rfc standard for length reduction
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conn net.Conn // connection to the syslog server
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}
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// NewServer initializes a new server connection.
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// Examples:
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// - NewServer(ConnectionUDP, "172.0.0.1:514")
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// - NewServer(ConnectionTCP, ":514")
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// - NewServer(ConnectionTLS, "172.0.0.1:514")
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func NewServer(connectionType ConnectionType, address string) (*Server, error) {
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// Validate data
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if connectionType != ConnectionUDP && connectionType != ConnectionTCP && connectionType != ConnectionTLS {
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return nil, fmt.Errorf("unknown connection type '%s'", connectionType)
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}
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var (
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conn net.Conn
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err error
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)
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// connect via udp / tcp / tls
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if connectionType == ConnectionTLS {
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conn, err = tls.Dial(string(ConnectionTCP), address, &tls.Config{
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InsecureSkipVerify: true,
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})
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} else {
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conn, err = net.Dial(string(connectionType), address)
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}
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if err != nil {
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return nil, err
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}
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// get hostname and ip of system
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hostname, err := os.Hostname()
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if err != nil {
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hostname = DefaultHostname
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}
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ip, _, err := net.SplitHostPort(conn.LocalAddr().String())
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if err != nil {
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ip = DefaultIP
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}
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// return the server
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return &Server{
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Hostname: hostname,
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IP: ip,
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conn: conn,
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}, nil
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}
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// Send sends a syslog message with a specified priority.
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// Examples:
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// - Send("foo", syslog.LOG_LOCAL0|syslog.LOG_NOTICE)
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// - Send("bar", syslog.LOG_DAEMON|syslog.LOG_DEBUG)
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func (server *Server) Send(message string, priority syslog.Priority) error {
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timestamp := time.Now().Format("Jan _2 15:04:05")
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hostnameCombi := fmt.Sprintf("%s/%s", server.Hostname, server.IP)
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header := fmt.Sprintf("<%d>%s %s", int(priority), timestamp, hostnameCombi)
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// RFC length reduction
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if server.Rfc3164 && len(message) > 1024 {
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message = fmt.Sprintf("%s...", message[:1020])
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}
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if server.Rfc5424 && len(message) > 2048 {
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message = fmt.Sprintf("%s...", message[:2044])
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}
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// Send message
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_, err := fmt.Fprintf(server.conn, "%s %s", header, message)
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return err
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}
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// Close closes the server connection gracefully.
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func (server *Server) Close() error {
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return server.conn.Close()
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}

‎server_test.go

+173
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package simplesyslog
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import (
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"crypto/tls"
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"crypto/x509"
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"encoding/pem"
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"io/ioutil"
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"log/syslog"
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"net"
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"regexp"
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"strconv"
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"testing"
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"time"
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)
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const host = "127.0.0.1:15140"
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const tlsCRT = `-----BEGIN CERTIFICATE-----
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MIICJzCCAZACCQCPGY+4vjNV0TANBgkqhkiG9w0BAQUFADBYMQswCQYDVQQGEwJE
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RTEPMA0GA1UECAwGSGVzc2VuMRIwEAYDVQQHDAlGcmFua2Z1cnQxEjAQBgNVBAoM
21+
CUNvZGVoYXJkdDEQMA4GA1UEAwwHVGVzdGluZzAeFw0xODA0MjAwNzUwMzZaFw0x
22+
OTA0MjEwNzUwMzZaMFgxCzAJBgNVBAYTAkRFMQ8wDQYDVQQIDAZIZXNzZW4xEjAQ
23+
BgNVBAcMCUZyYW5rZnVydDESMBAGA1UECgwJQ29kZWhhcmR0MRAwDgYDVQQDDAdU
24+
ZXN0aW5nMIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDcHWCPUdd4VfxorTjk
25+
5g/97HiAdcVn2kbDEVv2aI9HdSbcC9DC209DoaX4/7+3cEf3TwE5RKu9acf8tDue
26+
W8tAWvKH4wW7hIHiipfhFisuQeLe5NgXGqY+bs+B5+A0C/rKTrGkHu8hpXjFPY2y
27+
rwyYMBPmIm44X53tzsNYzuQakQIDAQABMA0GCSqGSIb3DQEBBQUAA4GBAL5k/7HU
28+
g2+6QcrV2K+2616D0ssgFrKqyG1dTy9w2+jZPQWcVNTRXGDkfdK/JlXzfEQwI/bZ
29+
89GmxswWxoxoMi7ZMPAG2h66vMUwCFTjUGEihgX/qksnzglMTQHlgLGENfQfawy1
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G1MpWJaW2ClQGr70dTTFeFJLSOANdAEqkTOC
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-----END CERTIFICATE-----`
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const tlsKEY = `-----BEGIN RSA PRIVATE KEY-----
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MIICXgIBAAKBgQDcHWCPUdd4VfxorTjk5g/97HiAdcVn2kbDEVv2aI9HdSbcC9DC
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209DoaX4/7+3cEf3TwE5RKu9acf8tDueW8tAWvKH4wW7hIHiipfhFisuQeLe5NgX
36+
GqY+bs+B5+A0C/rKTrGkHu8hpXjFPY2yrwyYMBPmIm44X53tzsNYzuQakQIDAQAB
37+
AoGBAI8JmCIKcRcF6YysZHh6+JFuBbCU179xHOLOeRBbSiCJhMMh+ntlwNCWTyDM
38+
MW2nTVzsvkLU2TWxdABHryZtSFpJIq69euzRtEN3uFy5qJWGvlE6Tn+ps7XIbPsX
39+
rppeclgV7a2nznrh+v1hfY/hgePyhuDsH0Hh5HB+L/gdb5DxAkEA81IPoy/UZWKg
40+
wIGeGy0mWyb4rmIxJTxOQPHd+2iJaD173eY0PskWuMLHFjyVn2gqHdy88ZDe0Xh9
41+
35SjOw5J7wJBAOeVvye1hnvOdgOHpuurDwvoTy/A+hUhzuzPKyUhNwENHk1d5L8D
42+
w2n+onITuFhRUvJW+ZCn+8BcY2Q0FNUqY38CQQCs7WhhsQ+BkqvuxPAKHneBFtxs
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iyqkbQysiXkbQXtOk0viM8ZzzNSSMRPvENXBufUczhGWmUBSnRDQgsHTqd8PAkAv
44+
Wdbz75HHzrcikaH3nco9zQoj4XlAyODeWp2fweLVPDFt8DzNMZ/LFF1ypcWTiU1E
45+
b7Qnd7Fp63oHCv8XdstRAkEA5Lf2nA2rEi5WxvSIea5KUzQp6Ut1aCLjHpdU5Pk7
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4IqCgyaC9pPvCkL6rEOthAfh9nnPJp41zMk7jHz5zmRe6g==
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-----END RSA PRIVATE KEY-----`
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var tlsConfig *tls.Config
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var messageRegex = regexp.MustCompile(`<133>[A-Z][a-z]{2} (([0-9]{2})|( [0-9])) [0-9]{2}:[0-9]{2}:[0-9]{2} testing\/127\.0\.0\.1 foo bar baz`)
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func TestNewServer(t *testing.T) {
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testNewServerTCP(t, false)
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testNewServerTCP(t, true)
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testNewServerUDP(t)
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}
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func testNewServerUDP(t *testing.T) {
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t.Logf("testing udp")
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serverAddr, err := net.ResolveUDPAddr("udp", host)
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if err != nil {
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t.Fatalf("could not resolve udp addr: %s", err)
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}
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conn, err := net.ListenUDP("udp", serverAddr)
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if err != nil {
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t.Fatalf("could not listen udp: %s", err)
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}
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if err := conn.SetReadDeadline(time.Now().Add(time.Second * 5)); err != nil {
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t.Fatalf("could not set read deadline: %s", err)
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}
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defer conn.Close()
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go func() {
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/*
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* Send the message 'foo bar baz' to the syslog server
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*/
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server, err := NewServer(ConnectionUDP, host)
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if err != nil {
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t.Fatalf("could not initialize server: %s", err)
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}
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server.Hostname = "testing" // overwrite hostname for testing
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defer server.Close()
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if err := server.Send("foo bar baz", syslog.LOG_LOCAL0|syslog.LOG_NOTICE); err != nil {
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t.Fatalf("could not send message: %s", err)
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}
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}()
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buf := make([]byte, 1024)
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n, _, err := conn.ReadFrom(buf)
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if err != nil {
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t.Fatalf("could not read udp: %s", err)
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}
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b := buf[:n]
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if !messageRegex.MatchString(string(b)) {
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t.Fatalf("wrong message: %s", string(b))
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} else {
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t.Logf("correct message: '%s'", string(b))
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}
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}
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func testNewServerTCP(t *testing.T, useTLS bool) {
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t.Logf("testing tcp with tls '%s'", strconv.FormatBool(useTLS))
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var (
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listener net.Listener
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err error
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)
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if useTLS {
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listener, err = tls.Listen("tcp", host, tlsConfig)
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} else {
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listener, err = net.Listen("tcp", host)
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}
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if err != nil {
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t.Fatalf("could not listen: %s", err)
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}
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defer listener.Close()
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go func() {
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/*
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* Send the message 'foo bar baz' to the syslog server
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*/
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connectionType := ConnectionTCP
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if useTLS {
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connectionType = ConnectionTLS
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}
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server, err := NewServer(connectionType, host)
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if err != nil {
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t.Fatalf("could not initialize server: %s", err)
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}
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server.Hostname = "testing" // overwrite hostname for testing
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defer server.Close()
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if err := server.Send("foo bar baz", syslog.LOG_LOCAL0|syslog.LOG_NOTICE); err != nil {
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t.Fatalf("could not send message: %s", err)
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}
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}()
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for {
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conn, err := listener.Accept()
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if err != nil {
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t.Fatalf("could not accept connection: %s", err)
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}
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defer conn.Close()
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b, err := ioutil.ReadAll(conn)
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if err != nil {
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t.Fatalf("could not read all: %s", err)
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}
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if !messageRegex.MatchString(string(b)) {
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t.Fatalf("wrong message: %s", string(b))
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} else {
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t.Logf("correct message: '%s'", string(b))
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}
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return
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}
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}
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func init() {
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pemCert, _ := pem.Decode([]byte(tlsCRT))
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if pemCert == nil {
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panic("no test tls certificate")
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}
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pemKey, _ := pem.Decode([]byte(tlsKEY))
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if pemKey == nil {
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panic("no test tls key")
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}
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privateKey, err := x509.ParsePKCS1PrivateKey(pemKey.Bytes)
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if err != nil {
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panic("invalid test tls key")
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}
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cert := &tls.Certificate{
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Certificate: [][]byte{pemCert.Bytes},
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PrivateKey: privateKey,
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}
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tlsConfig = &tls.Config{
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Certificates: []tls.Certificate{*cert},
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MinVersion: tls.VersionTLS11,
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}
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}

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