Add missing ident.go

Forgot to check in this file.

Fixes: 65302d3c1e ("Add an ident server")

ident.go

@@ -0,0 +1,150 @@
+package soju
+
+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
+	}
+	fmt.Println(remoteAddr, localAddr, ident)
+	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 {
+	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
+}