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ssh: add support for banners

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According to RFC 4252 section 5.4, the banner is sent between the
ssh-connection request and responding to user authentication.

Original support for server sending banner by joshua stein <jcs@jcs.org>

Fixes golang/go#19567

Change-Id: I729b3c8e5fd2c0068609d1590b61e92f40d87ea4
Reviewed-on: https://go-review.googlesource.com/71790
Run-TryBot: Han-Wen Nienhuys <hanwen@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Han-Wen Nienhuys <hanwen@google.com>
This commit is contained in:
Tugdual Saunier
2017-11-13 21:34:09 +00:00
committed by Han-Wen Nienhuys
parent 6a293f2d4b
commit 9f005a07e0
8 changed files with 157 additions and 7 deletions
Download Patch File Download Diff File Expand all files Collapse all files
ssh/client_auth.go
+27 -3
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@@ -283,7 +283,9 @@ func confirmKeyAck(key PublicKey, c packetConn) (bool, error) {
}
switch packet[0] {
case msgUserAuthBanner:
// TODO(gpaul): add callback to present the banner to the user
if err := handleBannerResponse(c, packet); err != nil {
return false, err
}
case msgUserAuthPubKeyOk:
var msg userAuthPubKeyOkMsg
if err := Unmarshal(packet, &msg); err != nil {
@@ -325,7 +327,9 @@ func handleAuthResponse(c packetConn) (bool, []string, error) {
switch packet[0] {
case msgUserAuthBanner:
// TODO: add callback to present the banner to the user
if err := handleBannerResponse(c, packet); err != nil {
return false, nil, err
}
case msgUserAuthFailure:
var msg userAuthFailureMsg
if err := Unmarshal(packet, &msg); err != nil {
@@ -340,6 +344,24 @@ func handleAuthResponse(c packetConn) (bool, []string, error) {
}
}
func handleBannerResponse(c packetConn, packet []byte) error {
var msg userAuthBannerMsg
if err := Unmarshal(packet, &msg); err != nil {
return err
}
transport, ok := c.(*handshakeTransport)
if !ok {
return nil
}
if transport.bannerCallback != nil {
return transport.bannerCallback(msg.Message)
}
return nil
}
// KeyboardInteractiveChallenge should print questions, optionally
// disabling echoing (e.g. for passwords), and return all the answers.
// Challenge may be called multiple times in a single session. After
@@ -385,7 +407,9 @@ func (cb KeyboardInteractiveChallenge) auth(session []byte, user string, c packe
// like handleAuthResponse, but with less options.
switch packet[0] {
case msgUserAuthBanner:
// TODO: Print banners during userauth.
if err := handleBannerResponse(c, packet); err != nil {
return false, nil, err
}
continue
case msgUserAuthInfoRequest:
// OK