mugit/internal/ssh/ssh.go (view raw)
| 1 | package ssh |
| 2 | |
| 3 | import ( |
| 4 | "context" |
| 5 | "errors" |
| 6 | "fmt" |
| 7 | "io" |
| 8 | "strings" |
| 9 | |
| 10 | "olexsmir.xyz/mugit/internal/config" |
| 11 | "olexsmir.xyz/mugit/internal/git" |
| 12 | |
| 13 | gossh "golang.org/x/crypto/ssh" |
| 14 | ) |
| 15 | |
| 16 | type Shell struct { |
| 17 | cfg *config.Config |
| 18 | |
| 19 | keys []gossh.PublicKey |
| 20 | } |
| 21 | |
| 22 | func NewShell(cfg *config.Config) (*Shell, error) { |
| 23 | parsedKeys := make([]gossh.PublicKey, len(cfg.SSH.Keys)) |
| 24 | for i, key := range cfg.SSH.Keys { |
| 25 | pkey, _, _, _, err := gossh.ParseAuthorizedKey([]byte(key)) |
| 26 | if err != nil { |
| 27 | return nil, err |
| 28 | } |
| 29 | parsedKeys[i] = pkey |
| 30 | } |
| 31 | |
| 32 | return &Shell{ |
| 33 | cfg: cfg, |
| 34 | keys: parsedKeys, |
| 35 | }, nil |
| 36 | } |
| 37 | |
| 38 | var validCommands = map[string]bool{ |
| 39 | "git-upload-pack": true, |
| 40 | "git-upload-archive": true, |
| 41 | "git-receive-pack": true, |
| 42 | } |
| 43 | |
| 44 | func (s *Shell) HandleCommand(ctx context.Context, cmd string, stdin io.Reader, stdout, stderr io.Writer) error { |
| 45 | gitCmd, repoName, err := s.parseCommand(cmd) |
| 46 | if err != nil { |
| 47 | return s.replyWithGitError(stderr, "access denied: invalid command", err) |
| 48 | } |
| 49 | |
| 50 | if !validCommands[gitCmd] { |
| 51 | msg := "access denied: invalid git command" |
| 52 | return s.replyWithGitError(stderr, msg, errors.New(msg)) |
| 53 | } |
| 54 | |
| 55 | repoPath, err := git.ResolvePath(s.cfg.Repo.Dir, git.ResolveName(repoName)) |
| 56 | if err != nil { |
| 57 | return s.replyWithGitError(stderr, "access denied", err) |
| 58 | } |
| 59 | |
| 60 | repo, err := git.Open(repoPath, "") |
| 61 | if err != nil { |
| 62 | return s.replyWithGitError(stderr, "repository not found", err) |
| 63 | } |
| 64 | |
| 65 | switch gitCmd { |
| 66 | case "git-upload-pack": |
| 67 | err = repo.UploadPack(ctx, false, "", stdin, stdout) |
| 68 | case "git-upload-archive": |
| 69 | err = repo.UploadArchive(ctx, stdin, stdout) |
| 70 | case "git-receive-pack": |
| 71 | err = repo.ReceivePack(ctx, stdin, stdout, stderr) |
| 72 | default: |
| 73 | msg := "access denied: invalid git command" |
| 74 | return s.replyWithGitError(stderr, msg, errors.New(msg)) |
| 75 | } |
| 76 | |
| 77 | if err != nil { |
| 78 | return err |
| 79 | } |
| 80 | |
| 81 | return nil |
| 82 | } |
| 83 | |
| 84 | func (s *Shell) AuthorizedKeys(executablePath string) string { |
| 85 | var out strings.Builder |
| 86 | for _, key := range s.cfg.SSH.Keys { |
| 87 | fmt.Fprintf(&out, `command="%s shell",no-port-forwarding,no-X11-forwarding,no-agent-forwarding,no-pty %s`+"\n", |
| 88 | executablePath, key) |
| 89 | } |
| 90 | return out.String() |
| 91 | } |
| 92 | |
| 93 | func (s *Shell) parseCommand(cmd string) (gitCmd, repoName string, err error) { |
| 94 | cmdParts := strings.Fields(cmd) |
| 95 | if len(cmdParts) < 2 { |
| 96 | return "", "", fmt.Errorf("invalid command: expected 'git-cmd repo', got %q", cmd) |
| 97 | } |
| 98 | |
| 99 | gitCmd = cmdParts[0] |
| 100 | repoName = strings.Trim(cmdParts[1], "'\"") |
| 101 | if repoName == "" { |
| 102 | return "", "", fmt.Errorf("invalid command: empty repository name") |
| 103 | } |
| 104 | |
| 105 | return gitCmd, repoName, nil |
| 106 | } |
| 107 | |
| 108 | func (s *Shell) replyWithGitError(stderr io.Writer, msg string, cause error) error { |
| 109 | if _, err := fmt.Fprintf(stderr, "fatal: %s\n", msg); err != nil { |
| 110 | return err |
| 111 | } |
| 112 | |
| 113 | return cause |
| 114 | } |