diff options
Diffstat (limited to 'ssh/handshake.go')
| -rw-r--r-- | ssh/handshake.go | 34 |
1 files changed, 23 insertions, 11 deletions
diff --git a/ssh/handshake.go b/ssh/handshake.go index 07a1843..b95b112 100644 --- a/ssh/handshake.go +++ b/ssh/handshake.go @@ -461,19 +461,24 @@ func (t *handshakeTransport) sendKexInit() error { isServer := len(t.hostKeys) > 0 if isServer { for _, k := range t.hostKeys { - // If k is an AlgorithmSigner, presume it supports all signature algorithms - // associated with the key format. (Ideally AlgorithmSigner would have a - // method to advertise supported algorithms, but it doesn't. This means that - // adding support for a new algorithm is a breaking change, as we will - // immediately negotiate it even if existing implementations don't support - // it. If that ever happens, we'll have to figure something out.) - // If k is not an AlgorithmSigner, we can only assume it only supports the - // algorithms that matches the key format. (This means that Sign can't pick - // a different default.) + // If k is a MultiAlgorithmSigner, we restrict the signature + // algorithms. If k is a AlgorithmSigner, presume it supports all + // signature algorithms associated with the key format. If k is not + // an AlgorithmSigner, we can only assume it only supports the + // algorithms that matches the key format. (This means that Sign + // can't pick a different default). keyFormat := k.PublicKey().Type() - if _, ok := k.(AlgorithmSigner); ok { + + switch s := k.(type) { + case MultiAlgorithmSigner: + for _, algo := range algorithmsForKeyFormat(keyFormat) { + if contains(s.Algorithms(), underlyingAlgo(algo)) { + msg.ServerHostKeyAlgos = append(msg.ServerHostKeyAlgos, algo) + } + } + case AlgorithmSigner: msg.ServerHostKeyAlgos = append(msg.ServerHostKeyAlgos, algorithmsForKeyFormat(keyFormat)...) - } else { + default: msg.ServerHostKeyAlgos = append(msg.ServerHostKeyAlgos, keyFormat) } } @@ -685,9 +690,16 @@ func (a algorithmSignerWrapper) SignWithAlgorithm(rand io.Reader, data []byte, a func pickHostKey(hostKeys []Signer, algo string) AlgorithmSigner { for _, k := range hostKeys { + if s, ok := k.(MultiAlgorithmSigner); ok { + if !contains(s.Algorithms(), underlyingAlgo(algo)) { + continue + } + } + if algo == k.PublicKey().Type() { return algorithmSignerWrapper{k} } + k, ok := k.(AlgorithmSigner) if !ok { continue |