1 // Copyright 2009 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 // +build !windows,!nacl,!plan9 6 7 package syslog 8 9 import ( 10 "errors" 11 "fmt" 12 "log" 13 "net" 14 "os" 15 "strings" 16 "sync" 17 "time" 18 ) 19 20 // The Priority is a combination of the syslog facility and 21 // severity. For example, LOG_ALERT | LOG_FTP sends an alert severity 22 // message from the FTP facility. The default severity is LOG_EMERG; 23 // the default facility is LOG_KERN. 24 type Priority int 25 26 const severityMask = 0x07 27 const facilityMask = 0xf8 28 29 const ( 30 // Severity. 31 32 // From /usr/include/sys/syslog.h. 33 // These are the same on Linux, BSD, and OS X. 34 LOG_EMERG Priority = iota 35 LOG_ALERT 36 LOG_CRIT 37 LOG_ERR 38 LOG_WARNING 39 LOG_NOTICE 40 LOG_INFO 41 LOG_DEBUG 42 ) 43 44 const ( 45 // Facility. 46 47 // From /usr/include/sys/syslog.h. 48 // These are the same up to LOG_FTP on Linux, BSD, and OS X. 49 LOG_KERN Priority = iota << 3 50 LOG_USER 51 LOG_MAIL 52 LOG_DAEMON 53 LOG_AUTH 54 LOG_SYSLOG 55 LOG_LPR 56 LOG_NEWS 57 LOG_UUCP 58 LOG_CRON 59 LOG_AUTHPRIV 60 LOG_FTP 61 _ // unused 62 _ // unused 63 _ // unused 64 _ // unused 65 LOG_LOCAL0 66 LOG_LOCAL1 67 LOG_LOCAL2 68 LOG_LOCAL3 69 LOG_LOCAL4 70 LOG_LOCAL5 71 LOG_LOCAL6 72 LOG_LOCAL7 73 ) 74 75 // A Writer is a connection to a syslog server. 76 type Writer struct { 77 priority Priority 78 tag string 79 hostname string 80 network string 81 raddr string 82 83 mu sync.Mutex // guards conn 84 conn serverConn 85 } 86 87 // This interface and the separate syslog_unix.go file exist for 88 // Solaris support as implemented by gccgo. On Solaris you can not 89 // simply open a TCP connection to the syslog daemon. The gccgo 90 // sources have a syslog_solaris.go file that implements unixSyslog to 91 // return a type that satisfies this interface and simply calls the C 92 // library syslog function. 93 type serverConn interface { 94 writeString(p Priority, hostname, tag, s, nl string) error 95 close() error 96 } 97 98 type netConn struct { 99 local bool 100 conn net.Conn 101 } 102 103 // New establishes a new connection to the system log daemon. Each 104 // write to the returned writer sends a log message with the given 105 // priority and prefix. 106 func New(priority Priority, tag string) (w *Writer, err error) { 107 return Dial("", "", priority, tag) 108 } 109 110 // Dial establishes a connection to a log daemon by connecting to 111 // address raddr on the specified network. Each write to the returned 112 // writer sends a log message with the given facility, severity and 113 // tag. 114 // If network is empty, Dial will connect to the local syslog server. 115 func Dial(network, raddr string, priority Priority, tag string) (*Writer, error) { 116 if priority < 0 || priority > LOG_LOCAL7|LOG_DEBUG { 117 return nil, errors.New("log/syslog: invalid priority") 118 } 119 120 if tag == "" { 121 tag = os.Args[0] 122 } 123 hostname, _ := os.Hostname() 124 125 w := &Writer{ 126 priority: priority, 127 tag: tag, 128 hostname: hostname, 129 network: network, 130 raddr: raddr, 131 } 132 133 w.mu.Lock() 134 defer w.mu.Unlock() 135 136 err := w.connect() 137 if err != nil { 138 return nil, err 139 } 140 return w, err 141 } 142 143 // connect makes a connection to the syslog server. 144 // It must be called with w.mu held. 145 func (w *Writer) connect() (err error) { 146 if w.conn != nil { 147 // ignore err from close, it makes sense to continue anyway 148 w.conn.close() 149 w.conn = nil 150 } 151 152 if w.network == "" { 153 w.conn, err = unixSyslog() 154 if w.hostname == "" { 155 w.hostname = "localhost" 156 } 157 } else { 158 var c net.Conn 159 c, err = net.Dial(w.network, w.raddr) 160 if err == nil { 161 w.conn = &netConn{conn: c} 162 if w.hostname == "" { 163 w.hostname = c.LocalAddr().String() 164 } 165 } 166 } 167 return 168 } 169 170 // Write sends a log message to the syslog daemon. 171 func (w *Writer) Write(b []byte) (int, error) { 172 return w.writeAndRetry(w.priority, string(b)) 173 } 174 175 // Close closes a connection to the syslog daemon. 176 func (w *Writer) Close() error { 177 w.mu.Lock() 178 defer w.mu.Unlock() 179 180 if w.conn != nil { 181 err := w.conn.close() 182 w.conn = nil 183 return err 184 } 185 return nil 186 } 187 188 // Emerg logs a message with severity LOG_EMERG, ignoring the severity 189 // passed to New. 190 func (w *Writer) Emerg(m string) (err error) { 191 _, err = w.writeAndRetry(LOG_EMERG, m) 192 return err 193 } 194 195 // Alert logs a message with severity LOG_ALERT, ignoring the severity 196 // passed to New. 197 func (w *Writer) Alert(m string) (err error) { 198 _, err = w.writeAndRetry(LOG_ALERT, m) 199 return err 200 } 201 202 // Crit logs a message with severity LOG_CRIT, ignoring the severity 203 // passed to New. 204 func (w *Writer) Crit(m string) (err error) { 205 _, err = w.writeAndRetry(LOG_CRIT, m) 206 return err 207 } 208 209 // Err logs a message with severity LOG_ERR, ignoring the severity 210 // passed to New. 211 func (w *Writer) Err(m string) (err error) { 212 _, err = w.writeAndRetry(LOG_ERR, m) 213 return err 214 } 215 216 // Warning logs a message with severity LOG_WARNING, ignoring the 217 // severity passed to New. 218 func (w *Writer) Warning(m string) (err error) { 219 _, err = w.writeAndRetry(LOG_WARNING, m) 220 return err 221 } 222 223 // Notice logs a message with severity LOG_NOTICE, ignoring the 224 // severity passed to New. 225 func (w *Writer) Notice(m string) (err error) { 226 _, err = w.writeAndRetry(LOG_NOTICE, m) 227 return err 228 } 229 230 // Info logs a message with severity LOG_INFO, ignoring the severity 231 // passed to New. 232 func (w *Writer) Info(m string) (err error) { 233 _, err = w.writeAndRetry(LOG_INFO, m) 234 return err 235 } 236 237 // Debug logs a message with severity LOG_DEBUG, ignoring the severity 238 // passed to New. 239 func (w *Writer) Debug(m string) (err error) { 240 _, err = w.writeAndRetry(LOG_DEBUG, m) 241 return err 242 } 243 244 func (w *Writer) writeAndRetry(p Priority, s string) (int, error) { 245 pr := (w.priority & facilityMask) | (p & severityMask) 246 247 w.mu.Lock() 248 defer w.mu.Unlock() 249 250 if w.conn != nil { 251 if n, err := w.write(pr, s); err == nil { 252 return n, err 253 } 254 } 255 if err := w.connect(); err != nil { 256 return 0, err 257 } 258 return w.write(pr, s) 259 } 260 261 // write generates and writes a syslog formatted string. The 262 // format is as follows: <PRI>TIMESTAMP HOSTNAME TAG[PID]: MSG 263 func (w *Writer) write(p Priority, msg string) (int, error) { 264 // ensure it ends in a \n 265 nl := "" 266 if !strings.HasSuffix(msg, "\n") { 267 nl = "\n" 268 } 269 270 err := w.conn.writeString(p, w.hostname, w.tag, msg, nl) 271 if err != nil { 272 return 0, err 273 } 274 // Note: return the length of the input, not the number of 275 // bytes printed by Fprintf, because this must behave like 276 // an io.Writer. 277 return len(msg), nil 278 } 279 280 func (n *netConn) writeString(p Priority, hostname, tag, msg, nl string) error { 281 if n.local { 282 // Compared to the network form below, the changes are: 283 // 1. Use time.Stamp instead of time.RFC3339. 284 // 2. Drop the hostname field from the Fprintf. 285 timestamp := time.Now().Format(time.Stamp) 286 _, err := fmt.Fprintf(n.conn, "<%d>%s %s[%d]: %s%s", 287 p, timestamp, 288 tag, os.Getpid(), msg, nl) 289 return err 290 } 291 timestamp := time.Now().Format(time.RFC3339) 292 _, err := fmt.Fprintf(n.conn, "<%d>%s %s %s[%d]: %s%s", 293 p, timestamp, hostname, 294 tag, os.Getpid(), msg, nl) 295 return err 296 } 297 298 func (n *netConn) close() error { 299 return n.conn.Close() 300 } 301 302 // NewLogger creates a log.Logger whose output is written to 303 // the system log service with the specified priority. The logFlag 304 // argument is the flag set passed through to log.New to create 305 // the Logger. 306 func NewLogger(p Priority, logFlag int) (*log.Logger, error) { 307 s, err := New(p, "") 308 if err != nil { 309 return nil, err 310 } 311 return log.New(s, "", logFlag), nil 312 } 313
