fix #782 (bring vendor into the main tree)

vendor/github.com/oragono/go-ident/client.go

@@ -0,0 +1,108 @@
+// Package ident implements an RFC 1413 client
+package ident
+
+import (
+	"bufio"
+	"fmt"
+	"net"
+	"strings"
+	"time"
+)
+
+// Response is a successful answer to our query to the identd server.
+type Response struct {
+	OS         string
+	Charset    string
+	Identifier string
+}
+
+// ResponseError indicates that the identd server returned an error rather than an
+// identifying string.
+type ResponseError struct {
+	Type string
+}
+
+func (e ResponseError) Error() string {
+	return fmt.Sprintf("Ident error: %s", e.Type)
+}
+
+// ProtocolError indicates that an error occurred with the protocol itself, that the response
+// could not be successfully parsed or was malformed.
+type ProtocolError struct {
+	Line string
+}
+
+func (e ProtocolError) Error() string {
+	return fmt.Sprintf("Unexpected response from server: %s", e.Line)
+}
+
+// Query makes an Ident query, if timeout is >0 the query is timed out after that many seconds.
+func Query(ip string, portOnServer, portOnClient int, timeout float64) (Response, error) {
+	var (
+		conn   net.Conn
+		err    error
+		fields []string
+		r      *bufio.Reader
+		resp   string
+	)
+
+	if timeout > 0 {
+		conn, err = net.DialTimeout("tcp", net.JoinHostPort(ip, "113"), time.Duration(timeout)*time.Second)
+	} else {
+		conn, err = net.Dial("tcp", net.JoinHostPort(ip, "113"))
+	}
+	if err != nil {
+		return Response{}, err
+	}
+
+	// stop the ident read after <timeout> seconds
+	if timeout > 0 {
+		conn.SetDeadline(time.Now().Add(time.Second * time.Duration(timeout)))
+	}
+
+	_, err = conn.Write([]byte(fmt.Sprintf("%d, %d", portOnClient, portOnServer) + "\r\n"))
+	if err != nil {
+		return Response{}, err
+	}
+
+	r = bufio.NewReader(conn)
+	resp, err = r.ReadString('\n')
+	if err != nil {
+		return Response{}, err
+	}
+
+	fields = strings.SplitN(strings.TrimSpace(resp), " : ", 4)
+	if len(fields) < 3 {
+		return Response{}, ProtocolError{resp}
+	}
+
+	switch fields[1] {
+	case "USERID":
+		if len(fields) != 4 {
+			return Response{}, ProtocolError{resp}
+		}
+
+		var os, charset string
+		osAndCharset := strings.SplitN(fields[2], ",", 2)
+		if len(osAndCharset) == 2 {
+			os = osAndCharset[0]
+			charset = osAndCharset[1]
+		} else {
+			os = osAndCharset[0]
+			charset = "US-ASCII"
+		}
+
+		return Response{
+			OS:         os,
+			Charset:    charset,
+			Identifier: fields[3],
+		}, nil
+	case "ERROR":
+		if len(fields) != 3 {
+			return Response{}, ProtocolError{resp}
+		}
+
+		return Response{}, ResponseError{fields[2]}
+	}
+	return Response{}, err
+}