/
syslog_raw.go
246 lines (211 loc) · 4.62 KB
/
syslog_raw.go
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package syslog
import (
"crypto/tls"
"crypto/x509"
"fmt"
"io"
"net"
"net/url"
"os"
"strconv"
"sync"
"time"
)
type Writer struct {
hostname string
network string
raddr string
conn serverConn
mu sync.Mutex // guards conn
tlsConf *tls.Config
inTls bool
nbConnTry int
muTry sync.Mutex
hasBeenReconnected bool
}
type serverConn interface {
writeString(string) error
close() error
}
func NewWriter(addresses ...string) (io.WriteCloser, error) {
if len(addresses) == 0 {
return nil, fmt.Errorf("One address must be given")
}
if len(addresses) > 1 {
return MultiDial(addresses...)
}
addr := addresses[0]
u, err := url.Parse(addr)
if err != nil {
return nil, err
}
if u.Scheme == "http" || u.Scheme == "https" {
return HttpDial(addr)
}
if u.Scheme == "udp" {
return Dial(addr)
}
poolSizeQuery := u.Query().Get("pool_size")
if poolSizeQuery == "" {
return Dial(addr)
}
poolSize, err := strconv.Atoi(poolSizeQuery)
if err != nil {
return nil, fmt.Errorf("pool_size must be an integer")
}
if poolSize < 1 {
return nil, fmt.Errorf("pool_size must be greater than 0")
}
return NewWriterPool(poolSize, addr)
}
func Dial(addr string) (*Writer, error) {
u, err := url.Parse(addr)
if err != nil {
return nil, err
}
inTls := false
scheme := u.Scheme
if u.Scheme == "tcp+tls" {
inTls = true
scheme = "tcp"
}
tlsConf, err := tlsConfigFromAddr(u)
if err != nil {
return nil, err
}
hostname, _ := os.Hostname()
w := &Writer{
hostname: hostname,
network: scheme,
raddr: u.Host,
tlsConf: tlsConf,
inTls: inTls,
}
err = w.connect()
if err != nil {
return nil, err
}
return w, err
}
func tlsConfigFromAddr(u *url.URL) (*tls.Config, error) {
tlsConf := &tls.Config{}
verifyParam := u.Query().Get("verify")
if verifyParam != "" {
verify, err := strconv.ParseBool(verifyParam)
if err != nil {
verify = true
}
tlsConf.InsecureSkipVerify = !verify
}
certPath := u.Query().Get("cert")
if certPath == "" {
return tlsConf, nil
}
b, err := os.ReadFile(certPath)
if err != nil {
return nil, err
}
pool := x509.NewCertPool()
pool.AppendCertsFromPEM(b)
tlsConf.RootCAs = pool
return tlsConf, nil
}
// connect makes a connection to the syslog server.
// It must be called with w.mu held.
func (w *Writer) connect() (err error) {
w.muTry.Lock()
if w.nbConnTry >= 20 {
w.muTry.Unlock()
return fmt.Errorf("20 connect tries has been already made, erroring for preferring drop instead of server locking cause a lot of goroutine")
}
w.nbConnTry += 1
w.muTry.Unlock()
if w.nbConnTry > 0 && w.hasBeenReconnected {
w.muTry.Lock()
// if last connect try we remove
if w.nbConnTry == 1 {
w.hasBeenReconnected = false
}
w.nbConnTry -= 1
w.muTry.Unlock()
return nil
}
w.mu.Lock()
defer w.mu.Unlock()
if w.conn != nil {
// ignore err from close, it makes sense to continue anyway
w.conn.close()
w.conn = nil
}
var c net.Conn
if !w.inTls {
c, err = net.DialTimeout(w.network, w.raddr, 5*time.Second)
} else {
c, err = tls.DialWithDialer(&net.Dialer{Timeout: 5 * time.Second}, w.network, w.raddr, w.tlsConf)
}
if err != nil {
w.muTry.Lock()
w.nbConnTry -= 1
w.muTry.Unlock()
return err
}
w.conn = &netConn{conn: c}
if w.hostname == "" {
w.hostname = c.LocalAddr().String()
}
w.muTry.Lock()
w.hasBeenReconnected = true
w.nbConnTry -= 1
w.muTry.Unlock()
return nil
}
func (w *Writer) writeAndRetry(s string) (int, error) {
if w.conn != nil {
if n, err := w.write(s); err == nil {
return n, err
}
}
if err := w.connect(); err != nil {
return 0, err
}
return w.write(s)
}
func (w *Writer) write(msg string) (int, error) {
err := w.conn.writeString(msg)
if err != nil {
return 0, err
}
// Note: return the length of the input, not the number of
// bytes printed by Fprintf, because this must behave like
// an io.Writer.
return len(msg), nil
}
// Write sends a log message to the syslog daemon.
func (w *Writer) Write(b []byte) (int, error) {
return w.writeAndRetry(string(b))
}
// WriteString sends a log message to the syslog daemon.
func (w *Writer) WriteString(mes string) (int, error) {
return w.writeAndRetry(mes)
}
// Close closes a connection to the syslog daemon.
func (w *Writer) Close() error {
w.mu.Lock()
defer w.mu.Unlock()
if w.conn != nil {
err := w.conn.close()
w.conn = nil
return err
}
return nil
}
type netConn struct {
conn net.Conn
}
func (n *netConn) writeString(mes string) error {
_, err := fmt.Fprint(n.conn, mes)
return err
}
func (n *netConn) close() error {
return n.conn.Close()
}