Refactor SSH init code, fix directory creation for TrustedUserCAKeys file (#20299)

* Refactor SSH init code, fix directory creation for TrustedUserCAKeys file

* Update modules/ssh/init.go

Co-authored-by: zeripath <art27@cantab.net>

* fix lint copyright

* Update modules/ssh/init.go

Co-authored-by: zeripath <art27@cantab.net>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

2 files changed, 57 insertions, 2 deletions

diff --git a/modules/ssh/init.go b/modules/ssh/init.go
new file mode 100644
index 0000000000..f6332bb18b
--- /dev/null
+++ b/modules/ssh/init.go
@@ -0,0 +1,55 @@
+// Copyright 2022 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package ssh
+
+import (
+	"fmt"
+	"net"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+
+	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/modules/setting"
+)
+
+func Init() error {
+	if setting.SSH.Disabled {
+		return nil
+	}
+
+	if setting.SSH.StartBuiltinServer {
+		Listen(setting.SSH.ListenHost, setting.SSH.ListenPort, setting.SSH.ServerCiphers, setting.SSH.ServerKeyExchanges, setting.SSH.ServerMACs)
+		log.Info("SSH server started on %s. Cipher list (%v), key exchange algorithms (%v), MACs (%v)",
+			net.JoinHostPort(setting.SSH.ListenHost, strconv.Itoa(setting.SSH.ListenPort)),
+			setting.SSH.ServerCiphers, setting.SSH.ServerKeyExchanges, setting.SSH.ServerMACs,
+		)
+		return nil
+	}
+
+	builtinUnused()
+
+	// FIXME: why 0o644 for a directory .....
+	if err := os.MkdirAll(setting.SSH.KeyTestPath, 0o644); err != nil {
+		return fmt.Errorf("failed to create directory %q for ssh key test: %w", setting.SSH.KeyTestPath, err)
+	}
+
+	if len(setting.SSH.TrustedUserCAKeys) > 0 && setting.SSH.AuthorizedPrincipalsEnabled {
+		caKeysFileName := setting.SSH.TrustedUserCAKeysFile
+		caKeysFileDir := filepath.Dir(caKeysFileName)
+
+		err := os.MkdirAll(caKeysFileDir, 0o700) // SSH.RootPath by default (That is `~/.ssh` in most cases)
+		if err != nil {
+			return fmt.Errorf("failed to create directory %q for ssh trusted ca keys: %w", caKeysFileDir, err)
+		}
+
+		if err := os.WriteFile(caKeysFileName, []byte(strings.Join(setting.SSH.TrustedUserCAKeys, "\n")), 0o600); err != nil {
+			return fmt.Errorf("failed to write ssh trusted ca keys to %q: %w", caKeysFileName, err)
+		}
+	}
+
+	return nil
+}
diff --git a/modules/ssh/ssh_graceful.go b/modules/ssh/ssh_graceful.go
index 98fe17b3bc..9b91baf09e 100644
--- a/modules/ssh/ssh_graceful.go
+++ b/modules/ssh/ssh_graceful.go
@@ -29,7 +29,7 @@ func listen(server *ssh.Server) {
 	log.Info("SSH Listener: %s Closed", server.Addr)
 }
 
-// Unused informs our cleanup routine that we will not be using a ssh port
-func Unused() {
+// builtinUnused informs our cleanup routine that we will not be using a ssh port
+func builtinUnused() {
 	graceful.GetManager().InformCleanup()
 }