feat: add inbox

internal/inbox/sshconfig.go

@@ -0,0 +1,77 @@
+package inbox
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+const (
+	sshConfigBegin = "# BEGIN agent-notify inbox"
+	sshConfigEnd   = "# END agent-notify inbox"
+)
+
+func DefaultSSHConfigPath() string {
+	return filepath.Join(os.Getenv("HOME"), ".ssh", "config")
+}
+
+func SSHConfigBlock(remoteSocket, localSocket string) string {
+	return strings.Join([]string{
+		sshConfigBegin,
+		"Host *",
+		"    RemoteForward " + remoteSocket + " " + localSocket,
+		"    ExitOnForwardFailure no",
+		"    ServerAliveInterval 30",
+		sshConfigEnd,
+		"",
+	}, "\n")
+}
+
+func InstallSSHConfig(path, remoteSocket, localSocket string) (string, error) {
+	if path == "" {
+		path = DefaultSSHConfigPath()
+	}
+	block := SSHConfigBlock(remoteSocket, localSocket)
+	if err := os.MkdirAll(filepath.Dir(path), 0700); err != nil {
+		return "", err
+	}
+
+	var current string
+	if data, err := os.ReadFile(path); err == nil {
+		current = string(data)
+	} else if !os.IsNotExist(err) {
+		return "", err
+	}
+
+	next := replaceManagedBlock(current, block)
+	if err := os.WriteFile(path, []byte(next), 0600); err != nil {
+		return "", err
+	}
+	return block, nil
+}
+
+func replaceManagedBlock(current, block string) string {
+	start := strings.Index(current, sshConfigBegin)
+	end := strings.Index(current, sshConfigEnd)
+	if start >= 0 && end >= start {
+		end += len(sshConfigEnd)
+		for end < len(current) && (current[end] == '\n' || current[end] == '\r') {
+			end++
+		}
+		prefix := strings.TrimRight(current[:start], "\n")
+		suffix := strings.TrimLeft(current[end:], "\n")
+		var parts []string
+		if prefix != "" {
+			parts = append(parts, prefix)
+		}
+		parts = append(parts, strings.TrimRight(block, "\n"))
+		if suffix != "" {
+			parts = append(parts, suffix)
+		}
+		return strings.Join(parts, "\n\n") + "\n"
+	}
+	if strings.TrimSpace(current) == "" {
+		return block
+	}
+	return strings.TrimRight(current, "\n") + "\n\n" + block
+}