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package srslog
import (
"crypto/tls"
"strings"
"sync"
)
// A Writer is a connection to a syslog server.
type Writer struct {
priority Priority
tag string
hostname string
network string
raddr string
tlsConfig *tls.Config
framer Framer
formatter Formatter
//non-nil if custom dialer set, used in getDialer
customDial DialFunc
mu sync.RWMutex // guards conn
conn serverConn
}
// getConn provides access to the internal conn, protected by a mutex. The
// conn is threadsafe, so it can be used while unlocked, but we want to avoid
// race conditions on grabbing a reference to it.
func (w *Writer) getConn() serverConn {
w.mu.RLock()
conn := w.conn
w.mu.RUnlock()
return conn
}
// setConn updates the internal conn, protected by a mutex.
func (w *Writer) setConn(c serverConn) {
w.mu.Lock()
w.conn = c
w.mu.Unlock()
}
// connect makes a connection to the syslog server.
func (w *Writer) connect() (serverConn, error) {
conn := w.getConn()
if conn != nil {
// ignore err from close, it makes sense to continue anyway
conn.close()
w.setConn(nil)
}
var hostname string
var err error
dialer := w.getDialer()
conn, hostname, err = dialer.Call()
if err == nil {
w.setConn(conn)
w.hostname = hostname
return conn, nil
} else {
return nil, err
}
}
// SetFormatter changes the formatter function for subsequent messages.
func (w *Writer) SetFormatter(f Formatter) {
w.formatter = f
}
// SetFramer changes the framer function for subsequent messages.
func (w *Writer) SetFramer(f Framer) {
w.framer = f
}
// SetHostname changes the hostname for syslog messages if needed.
func (w *Writer) SetHostname(hostname string) {
w.hostname = hostname
}
// Write sends a log message to the syslog daemon using the default priority
// passed into `srslog.New` or the `srslog.Dial*` functions.
func (w *Writer) Write(b []byte) (int, error) {
return w.writeAndRetry(w.priority, string(b))
}
// WriteWithPriority sends a log message with a custom priority.
func (w *Writer) WriteWithPriority(p Priority, b []byte) (int, error) {
return w.writeAndRetryWithPriority(p, string(b))
}
// Close closes a connection to the syslog daemon.
func (w *Writer) Close() error {
conn := w.getConn()
if conn != nil {
err := conn.close()
w.setConn(nil)
return err
}
return nil
}
// Emerg logs a message with severity LOG_EMERG; this overrides the default
// priority passed to `srslog.New` and the `srslog.Dial*` functions.
func (w *Writer) Emerg(m string) (err error) {
_, err = w.writeAndRetry(LOG_EMERG, m)
return err
}
// Alert logs a message with severity LOG_ALERT; this overrides the default
// priority passed to `srslog.New` and the `srslog.Dial*` functions.
func (w *Writer) Alert(m string) (err error) {
_, err = w.writeAndRetry(LOG_ALERT, m)
return err
}
// Crit logs a message with severity LOG_CRIT; this overrides the default
// priority passed to `srslog.New` and the `srslog.Dial*` functions.
func (w *Writer) Crit(m string) (err error) {
_, err = w.writeAndRetry(LOG_CRIT, m)
return err
}
// Err logs a message with severity LOG_ERR; this overrides the default
// priority passed to `srslog.New` and the `srslog.Dial*` functions.
func (w *Writer) Err(m string) (err error) {
_, err = w.writeAndRetry(LOG_ERR, m)
return err
}
// Warning logs a message with severity LOG_WARNING; this overrides the default
// priority passed to `srslog.New` and the `srslog.Dial*` functions.
func (w *Writer) Warning(m string) (err error) {
_, err = w.writeAndRetry(LOG_WARNING, m)
return err
}
// Notice logs a message with severity LOG_NOTICE; this overrides the default
// priority passed to `srslog.New` and the `srslog.Dial*` functions.
func (w *Writer) Notice(m string) (err error) {
_, err = w.writeAndRetry(LOG_NOTICE, m)
return err
}
// Info logs a message with severity LOG_INFO; this overrides the default
// priority passed to `srslog.New` and the `srslog.Dial*` functions.
func (w *Writer) Info(m string) (err error) {
_, err = w.writeAndRetry(LOG_INFO, m)
return err
}
// Debug logs a message with severity LOG_DEBUG; this overrides the default
// priority passed to `srslog.New` and the `srslog.Dial*` functions.
func (w *Writer) Debug(m string) (err error) {
_, err = w.writeAndRetry(LOG_DEBUG, m)
return err
}
// writeAndRetry takes a severity and the string to write. Any facility passed to
// it as part of the severity Priority will be ignored.
func (w *Writer) writeAndRetry(severity Priority, s string) (int, error) {
pr := (w.priority & facilityMask) | (severity & severityMask)
return w.writeAndRetryWithPriority(pr, s)
}
// writeAndRetryWithPriority differs from writeAndRetry in that it allows setting
// of both the facility and the severity.
func (w *Writer) writeAndRetryWithPriority(p Priority, s string) (int, error) {
conn := w.getConn()
if conn != nil {
if n, err := w.write(conn, p, s); err == nil {
return n, err
}
}
var err error
if conn, err = w.connect(); err != nil {
return 0, err
}
return w.write(conn, p, s)
}
// write generates and writes a syslog formatted string. It formats the
// message based on the current Formatter and Framer.
func (w *Writer) write(conn serverConn, p Priority, msg string) (int, error) {
// ensure it ends in a \n
if !strings.HasSuffix(msg, "\n") {
msg += "\n"
}
err := conn.writeString(w.framer, w.formatter, p, w.hostname, w.tag, 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
}
|
