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// Copyright (c) Liam Stanley <me@liamstanley.io>. All rights reserved. Use
// of this source code is governed by the MIT license that can be found in
// the LICENSE file.
package girc
import (
"encoding/base64"
"fmt"
)
// SASLMech is an representation of what a SASL mechanism should support.
// See SASLExternal and SASLPlain for implementations of this.
type SASLMech interface {
// Method returns the uppercase version of the SASL mechanism name.
Method() string
// Encode returns the response that the SASL mechanism wants to use. If
// the returned string is empty (e.g. the mechanism gives up), the handler
// will attempt to panic, as expectation is that if SASL authentication
// fails, the client will disconnect.
Encode(params []string) (output string)
}
// SASLExternal implements the "EXTERNAL" SASL type.
type SASLExternal struct {
// Identity is an optional field which allows the client to specify
// pre-authentication identification. This means that EXTERNAL will
// supply this in the initial response. This usually isn't needed (e.g.
// CertFP).
Identity string `json:"identity"`
}
// Method identifies what type of SASL this implements.
func (sasl *SASLExternal) Method() string {
return "EXTERNAL"
}
// Encode for external SALS authentication should really only return a "+",
// unless the user has specified pre-authentication or identification data.
// See https://tools.ietf.org/html/rfc4422#appendix-A for more info.
func (sasl *SASLExternal) Encode(params []string) string {
if len(params) != 1 || params[0] != "+" {
return ""
}
if sasl.Identity != "" {
return sasl.Identity
}
return "+"
}
// SASLPlain contains the user and password needed for PLAIN SASL authentication.
type SASLPlain struct {
User string `json:"user"` // User is the username for SASL.
Pass string `json:"pass"` // Pass is the password for SASL.
}
// Method identifies what type of SASL this implements.
func (sasl *SASLPlain) Method() string {
return "PLAIN"
}
// Encode encodes the plain user+password into a SASL PLAIN implementation.
// See https://tools.ietf.org/rfc/rfc4422.txt for more info.
func (sasl *SASLPlain) Encode(params []string) string {
if len(params) != 1 || params[0] != "+" {
return ""
}
in := []byte(sasl.User)
in = append(in, 0x0)
in = append(in, []byte(sasl.User)...)
in = append(in, 0x0)
in = append(in, []byte(sasl.Pass)...)
return base64.StdEncoding.EncodeToString(in)
}
const saslChunkSize = 400
func handleSASL(c *Client, e Event) {
if e.Command == RPL_SASLSUCCESS || e.Command == ERR_SASLALREADY {
// Let the server know that we're done.
c.write(&Event{Command: CAP, Params: []string{CAP_END}})
return
}
// Assume they want us to handle sending auth.
auth := c.Config.SASL.Encode(e.Params)
if auth == "" {
// Assume the SASL authentication method doesn't want to respond for
// some reason. The SASL spec and IRCv3 spec do not define a clear
// way to abort a SASL exchange, other than to disconnect, or proceed
// with CAP END.
c.receive(&Event{Command: ERROR, Params: []string{
fmt.Sprintf("closing connection: SASL %s failed: %s", c.Config.SASL.Method(), e.Last()),
}})
return
}
// Send in "saslChunkSize"-length byte chunks. If the last chuck is
// exactly "saslChunkSize" bytes, send a "AUTHENTICATE +" 0-byte
// acknowledgement response to let the server know that we're done.
for {
if len(auth) > saslChunkSize {
c.write(&Event{Command: AUTHENTICATE, Params: []string{auth[0 : saslChunkSize-1]}, Sensitive: true})
auth = auth[saslChunkSize:]
continue
}
if len(auth) <= saslChunkSize {
c.write(&Event{Command: AUTHENTICATE, Params: []string{auth}, Sensitive: true})
if len(auth) == 400 {
c.write(&Event{Command: AUTHENTICATE, Params: []string{"+"}})
}
break
}
}
}
func handleSASLError(c *Client, e Event) {
if c.Config.SASL == nil {
c.write(&Event{Command: CAP, Params: []string{CAP_END}})
return
}
// Authentication failed. The SASL spec and IRCv3 spec do not define a
// clear way to abort a SASL exchange, other than to disconnect, or
// proceed with CAP END.
c.receive(&Event{Command: ERROR, Params: []string{"closing connection: " + e.Last()}})
}
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