source: code/trunk/ident.go@ 810

package suika

import (
        "bufio"
        "fmt"
        "net"
        "strconv"
        "strings"
        "sync"
        "time"
)

var identdTimeout = 10 * time.Second

type identKey struct {
        remoteHost string
        remotePort int
        localPort  int
}

func newIdentKey(remoteAddr, localAddr string) (*identKey, error) {
        remoteHost, remotePort, err := splitHostPort(remoteAddr)
        if err != nil {
                return nil, err
        }
        _, localPort, err := splitHostPort(localAddr)
        if err != nil {
                return nil, err
        }
        return &identKey{
                remoteHost: remoteHost,
                remotePort: remotePort,
                localPort:  localPort,
        }, nil
}

func splitHostPort(addr string) (host string, port int, err error) {
        host, portStr, err := net.SplitHostPort(addr)
        if err != nil {
                return "", 0, err
        }
        port, err = strconv.Atoi(portStr)
        return host, port, err
}

// Identd implements an ident server, as described in RFC 1413.
type Identd struct {
        entries map[identKey]string
        lock    sync.RWMutex
}

func NewIdentd() *Identd {
        return &Identd{entries: make(map[identKey]string)}
}

func (s *Identd) Store(remoteAddr, localAddr, ident string) {
        k, err := newIdentKey(remoteAddr, localAddr)
        if err != nil {
                return
        }
        s.lock.Lock()
        s.entries[*k] = ident
        s.lock.Unlock()
}

func (s *Identd) Delete(remoteAddr, localAddr string) {
        k, err := newIdentKey(remoteAddr, localAddr)
        if err != nil {
                return
        }
        s.lock.Lock()
        delete(s.entries, *k)
        s.lock.Unlock()
}

func (s *Identd) Serve(ln net.Listener) error {
        ln = &retryListener{Listener: ln}

        for {
                conn, err := ln.Accept()
                if err != nil {
                        return fmt.Errorf("failed to accept connection: %v", err)
                }

                go s.handle(conn)
        }
}

func (s *Identd) handle(c net.Conn) {
        defer c.Close()

        remoteHost, _, err := net.SplitHostPort(c.RemoteAddr().String())
        if err != nil {
                return
        }

        scanner := bufio.NewScanner(c)

        // We only read to read lines with two port numbers
        var buf [512]byte
        scanner.Buffer(buf[:], len(buf))

        for {
                c.SetDeadline(time.Now().Add(identdTimeout))
                if !scanner.Scan() {
                        break
                }
                l := scanner.Text()

                localPort, remotePort, err := parseIdentQuery(l)
                if err != nil {
                        fmt.Fprintf(c, "%s : ERROR : INVALID-PORT\r\n", l)
                        break
                }

                k := identKey{
                        remoteHost: remoteHost,
                        remotePort: remotePort,
                        localPort:  localPort,
                }

                s.lock.RLock()
                ident := s.entries[k]
                s.lock.RUnlock()

                if ident == "" {
                        fmt.Fprintf(c, "%s : ERROR : NO-USER\r\n", l)
                        break
                }

                fmt.Fprintf(c, "%s : USERID : OTHER : %s\r\n", l, ident)
        }
}

func parseIdentQuery(l string) (localPort, remotePort int, err error) {
        parts := strings.SplitN(l, ",", 2)
        if len(parts) != 2 {
                return 0, 0, fmt.Errorf("expected two ports")
        }
        localStr, remoteStr := strings.TrimSpace(parts[0]), strings.TrimSpace(parts[1])
        if localPort, err = strconv.Atoi(localStr); err != nil {
                return 0, 0, err
        }
        if remotePort, err = strconv.Atoi(remoteStr); err != nil {
                return 0, 0, err
        }
        if localPort <= 0 || remotePort <= 0 {
                return 0, 0, fmt.Errorf("invalid port")
        }
        return localPort, remotePort, nil
}