Extensions not handled properly

[reynir]

It seems responses to SSH_AGENTC_EXTENSION can use SSH_AGENT_SUCCESS with data. For example, the query extension returns a list of ssh-wire strings of supported extensions after the SSH_AGENT_SUCCESS tag.

It is a bit unclear how extension responses work - presumably it is SSH_AGENT_SUCCESS followed by any number of bytes that are then interpreted according to the specific extension. Another Ssh_agent_extension_success of string-ish constructor should be added to reflect this special case, and the ssh_agent_message parser should be parameterized with whether the request was an extension request or not (sadly).

I have not been able to find any existing code that handles extensions.

[reynir]

A Ssh_agent_extension_success response has been added, and the parser is now parameterized with a boolean signifying if the request is an extension or not.

Keeping this open because I'm still not quite confident how extensions are supposed to work.

[reynir]

The logic is too strict about extension responses. The specification says:

Extension requests may return SSH_AGENT_SUCCESS on success or some other
extension-specific message

Perhaps a solution is to parse SSH_AGENT_FAILURE, SSH_AGENT_EXTENSION_FAILURE, and in all other cases just return the raw response body.

[reynir]

Extensions is a wild west. Just parse perhaps SSH_AGENT_FAILURE and otherwise return a generic ssh agent response type with all the message data as a binary blob.