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// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package ssh
import (
"strconv"
)
// These are string constants in the SSH protocol.
const (
kexAlgoDH14SHA1 = "diffie-hellman-group14-sha1"
hostAlgoRSA = "ssh-rsa"
cipherAES128CTR = "aes128-ctr"
macSHA196 = "hmac-sha1-96"
compressionNone = "none"
serviceUserAuth = "ssh-userauth"
serviceSSH = "ssh-connection"
)
// UnexpectedMessageError results when the SSH message that we received didn't
// match what we wanted.
type UnexpectedMessageError struct {
expected, got uint8
}
func (u UnexpectedMessageError) String() string {
return "ssh: unexpected message type " + strconv.Itoa(int(u.got)) + " (expected " + strconv.Itoa(int(u.expected)) + ")"
}
// ParseError results from a malformed SSH message.
type ParseError struct {
msgType uint8
}
func (p ParseError) String() string {
return "ssh: parse error in message type " + strconv.Itoa(int(p.msgType))
}
func findCommonAlgorithm(clientAlgos []string, serverAlgos []string) (commonAlgo string, ok bool) {
for _, clientAlgo := range clientAlgos {
for _, serverAlgo := range serverAlgos {
if clientAlgo == serverAlgo {
return clientAlgo, true
}
}
}
return
}
func findAgreedAlgorithms(clientToServer, serverToClient *transport, clientKexInit, serverKexInit *kexInitMsg) (kexAlgo, hostKeyAlgo string, ok bool) {
kexAlgo, ok = findCommonAlgorithm(clientKexInit.KexAlgos, serverKexInit.KexAlgos)
if !ok {
return
}
hostKeyAlgo, ok = findCommonAlgorithm(clientKexInit.ServerHostKeyAlgos, serverKexInit.ServerHostKeyAlgos)
if !ok {
return
}
clientToServer.cipherAlgo, ok = findCommonAlgorithm(clientKexInit.CiphersClientServer, serverKexInit.CiphersClientServer)
if !ok {
return
}
serverToClient.cipherAlgo, ok = findCommonAlgorithm(clientKexInit.CiphersServerClient, serverKexInit.CiphersServerClient)
if !ok {
return
}
clientToServer.macAlgo, ok = findCommonAlgorithm(clientKexInit.MACsClientServer, serverKexInit.MACsClientServer)
if !ok {
return
}
serverToClient.macAlgo, ok = findCommonAlgorithm(clientKexInit.MACsServerClient, serverKexInit.MACsServerClient)
if !ok {
return
}
clientToServer.compressionAlgo, ok = findCommonAlgorithm(clientKexInit.CompressionClientServer, serverKexInit.CompressionClientServer)
if !ok {
return
}
serverToClient.compressionAlgo, ok = findCommonAlgorithm(clientKexInit.CompressionServerClient, serverKexInit.CompressionServerClient)
if !ok {
return
}
ok = true
return
}
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