func handleConnection(conn *ss.Conn) {
var (
host string
remote net.Conn
)
connCnt++ // this maybe not accurate, but should be enough
if connCnt-nextLogConnCnt >= 0 {
// XXX There's no xadd in the atomic package, so it's difficult to log
// the message only once with low cost. Also note nextLogConnCnt maybe
// added twice for current peak connection number level.
log.Printf("Number of client connections reaches %d\n", nextLogConnCnt)
nextLogConnCnt += logCntDelta
}
// function arguments are always evaluated, so surround debug statement
// with if statement
if debug {
debug.Printf("new client %s->%s\n", conn.RemoteAddr().String(), conn.LocalAddr())
}
closed := false
defer func() {
if debug {
debug.Printf("closed pipe %s<->%s\n", conn.RemoteAddr(), host)
}
connCnt--
if !closed {
conn.Close()
}
}()
host, extra, err := getRequest(conn)
if err != nil {
log.Println("error getting request", conn.RemoteAddr(), conn.LocalAddr(), err)
return
}
debug.Println("connecting", host)
if (config.TcpFastOpen & 1) != 0 {
// dial with data
remote, err = ss.TfoDial("tcp", host, extra)
extra = nil
} else {
remote, err = net.Dial("tcp", host)
}
if err != nil {
if ne, ok := err.(*net.OpError); ok && (ne.Err == syscall.EMFILE || ne.Err == syscall.ENFILE) {
// log too many open file error
// EMFILE is process reaches open file limits, ENFILE is system limit
log.Println("dial error:", err)
} else {
log.Println("error connecting to:", host, err)
}
return
}
defer func() {
if !closed {
remote.Close()
}
}()
// write extra bytes read from
if extra != nil {
debug.Println("getRequest read extra data, writing to remote, len", len(extra))
if _, err = remote.Write(extra); err != nil {
debug.Println("write request extra error:", err)
return
}
}
if debug {
debug.Printf("piping %s<->%s", conn.RemoteAddr(), host)
}
go ss.PipeThenClose(conn, remote)
ss.PipeThenClose(remote, conn)
closed = true
return
}
