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// SPDX-License-Identifier: AGPL-3.0-only
// SPDX-FileCopyrightText: Copyright (c) 2025 Runxi Yu <https://runxiyu.org>
package main
import (
"fmt"
"log/slog"
"net"
"os"
"strings"
gliderSSH "github.com/gliderlabs/ssh"
"go.lindenii.runxiyu.org/forge/ansiec"
"go.lindenii.runxiyu.org/forge/misc"
goSSH "golang.org/x/crypto/ssh"
)
// serveSSH serves SSH on a [net.Listener]. The listener should generally be a
// TCP listener, although AF_UNIX SOCK_STREAM listeners may be appropriate in
// rare cases.
func (s *server) serveSSH(listener net.Listener) error {
var hostKeyBytes []byte
var hostKey goSSH.Signer
var err error
var server *gliderSSH.Server
if hostKeyBytes, err = os.ReadFile(s.config.SSH.Key); err != nil {
return err
}
if hostKey, err = goSSH.ParsePrivateKey(hostKeyBytes); err != nil {
return err
}
s.serverPubkey = hostKey.PublicKey()
s.serverPubkeyString = misc.BytesToString(goSSH.MarshalAuthorizedKey(s.serverPubkey))
s.serverPubkeyFP = goSSH.FingerprintSHA256(s.serverPubkey)
server = &gliderSSH.Server{
Handler: func(session gliderSSH.Session) {
clientPubkey := session.PublicKey()
var clientPubkeyStr string
if clientPubkey != nil {
clientPubkeyStr = strings.TrimSuffix(misc.BytesToString(goSSH.MarshalAuthorizedKey(clientPubkey)), "\n")
}
slog.Info("incoming ssh", "addr", session.RemoteAddr().String(), "key", clientPubkeyStr, "command", session.RawCommand())
fmt.Fprintln(session.Stderr(), ansiec.Blue+"Lindenii Forge "+VERSION+", source at "+strings.TrimSuffix(s.config.HTTP.Root, "/")+"/-/source/"+ansiec.Reset+"\r")
cmd := session.Command()
if len(cmd) < 2 {
fmt.Fprintln(session.Stderr(), "Insufficient arguments\r")
return
}
switch cmd[0] {
case "git-upload-pack":
if len(cmd) > 2 {
fmt.Fprintln(session.Stderr(), "Too many arguments\r")
return
}
err = s.sshHandleUploadPack(session, clientPubkeyStr, cmd[1])
case "git-receive-pack":
if len(cmd) > 2 {
fmt.Fprintln(session.Stderr(), "Too many arguments\r")
return
}
err = s.sshHandleRecvPack(session, clientPubkeyStr, cmd[1])
default:
fmt.Fprintln(session.Stderr(), "Unsupported command: "+cmd[0]+"\r")
return
}
if err != nil {
fmt.Fprintln(session.Stderr(), err.Error())
return
}
},
PublicKeyHandler: func(_ gliderSSH.Context, _ gliderSSH.PublicKey) bool { return true },
KeyboardInteractiveHandler: func(_ gliderSSH.Context, _ goSSH.KeyboardInteractiveChallenge) bool { return true },
// It is intentional that we do not check any credentials and accept all connections.
// This allows all users to connect and clone repositories. However, the public key
// is passed to handlers, so e.g. the push handler could check the key and reject the
// push if it needs to.
} //exhaustruct:ignore
server.AddHostKey(hostKey)
if err = server.Serve(listener); err != nil {
slog.Error("error serving SSH", "error", err.Error())
os.Exit(1)
}
return nil
}
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