1 files changed, 96 insertions, 0 deletions
diff --git a/forged/internal/unsorted/ssh_server.go b/forged/internal/unsorted/ssh_server.go
new file mode 100644
index 0000000..43cc0c4
--- /dev/null
+++ b/forged/internal/unsorted/ssh_server.go
@@ -0,0 +1,96 @@
+// SPDX-License-Identifier: AGPL-3.0-only
+// SPDX-FileCopyrightText: Copyright (c) 2025 Runxi Yu <https://runxiyu.org>
+
+package unsorted
+
+import (
+	"fmt"
+	"log/slog"
+	"net"
+	"os"
+	"strings"
+
+	gliderSSH "github.com/gliderlabs/ssh"
+	"go.lindenii.runxiyu.org/forge/forged/internal/ansiec"
+	"go.lindenii.runxiyu.org/forge/forged/internal/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
+}