| 1 | package main |
| 2 | |
| 3 | import ( |
| 4 | "net/url" |
| 5 | "os" |
| 6 | "path/filepath" |
| 7 | "runtime" |
| 8 | "strings" |
| 9 | ) |
| 10 | |
| 11 | // localPathSource parses Markdown image sources, whose relative path is URL |
| 12 | // encoded by the Markdown pipeline. Chat references use localChatPathSource so |
| 13 | // ordinary filesystem characters are never mistaken for URL syntax. |
| 14 | func localPathSource(source string) (string, error) { |
| 15 | source = strings.TrimSpace(source) |
| 16 | if source == "" || strings.ContainsRune(source, 0) { |
| 17 | return "", os.ErrInvalid |
| 18 | } |
| 19 | // Raw Windows drive/UNC paths are valid sources even though net/url would |
| 20 | // otherwise interpret the drive letter as a URL scheme. |
| 21 | if filepath.IsAbs(source) && !strings.ContainsAny(source, "?#") { |
| 22 | return filepath.Clean(source), nil |
| 23 | } |
| 24 | if strings.HasPrefix(strings.ToLower(source), "file:") { |
| 25 | u, err := url.Parse(source) |
| 26 | if err != nil || !strings.EqualFold(u.Scheme, "file") || u.User != nil || u.RawQuery != "" || u.Fragment != "" { |
| 27 | return "", os.ErrInvalid |
| 28 | } |
| 29 | if u.Host != "" && !strings.EqualFold(u.Host, "localhost") { |
| 30 | return "", os.ErrPermission |
| 31 | } |
| 32 | path := u.Path |
| 33 | if strings.ContainsRune(path, 0) { |
| 34 | return "", os.ErrInvalid |
| 35 | } |
| 36 | if runtime.GOOS == "windows" && len(path) >= 3 && path[0] == '/' && path[2] == ':' { |
| 37 | path = path[1:] |
| 38 | } |
| 39 | return filepath.FromSlash(path), nil |
| 40 | } |
| 41 | u, err := url.Parse(source) |
| 42 | if err != nil || u.Scheme != "" { |
| 43 | return "", os.ErrInvalid |
| 44 | } |
| 45 | path := u.Path |
| 46 | if strings.ContainsRune(path, 0) { |
| 47 | return "", os.ErrInvalid |
| 48 | } |
| 49 | return filepath.FromSlash(path), nil |
| 50 | } |
| 51 | |
| 52 | // localChatPathSource follows Harness' file-resource boundary: an ordinary |
| 53 | // path reaches the owning host unchanged, while an explicit file URL is decoded |
| 54 | // exactly once. In particular, %, ? and # are legal raw filename characters on |
| 55 | // POSIX and must not select a different file. |
| 56 | func localChatPathSource(source string) (string, error) { |
| 57 | source = strings.TrimSpace(source) |
| 58 | if source == "" || strings.ContainsRune(source, 0) { |
| 59 | return "", os.ErrInvalid |
| 60 | } |
| 61 | if strings.HasPrefix(strings.ToLower(source), "file:") { |
| 62 | return localPathSource(source) |
| 63 | } |
| 64 | return filepath.Clean(source), nil |
| 65 | } |
| 66 | |
| 67 | // canonicalPathWithin resolves symlinks on both sides before comparing, so a |
| 68 | // link inside the root cannot be used to reach a file outside it. |
| 69 | // |
| 70 | // It returns the resolved root as well as the resolved candidate: a caller that |
| 71 | // derives a display path must measure from the same resolved root, or a |
| 72 | // symlinked workspace (macOS /tmp, a linked home) would produce a ../ chain |
| 73 | // instead of the relative path the file tree uses. |
| 74 | func canonicalPathWithin(root, candidate string) (resolved, resolvedRoot string, err error) { |
| 75 | realRoot, err := filepath.EvalSymlinks(root) |
| 76 | if err != nil { |
| 77 | return "", "", err |
| 78 | } |
| 79 | realCandidate, err := filepath.EvalSymlinks(candidate) |
| 80 | if err != nil { |
| 81 | return "", "", err |
| 82 | } |
| 83 | rel, err := filepath.Rel(realRoot, realCandidate) |
| 84 | if err != nil || rel == ".." || strings.HasPrefix(rel, ".."+string(os.PathSeparator)) { |
| 85 | return "", "", os.ErrPermission |
| 86 | } |
| 87 | return filepath.Clean(realCandidate), filepath.Clean(realRoot), nil |
| 88 | } |
| 89 | |
| 90 | func localFileHref(path string) string { |
| 91 | slash := filepath.ToSlash(path) |
| 92 | if runtime.GOOS == "windows" && len(slash) >= 2 && slash[1] == ':' { |
| 93 | slash = "/" + slash |
| 94 | } |
| 95 | return (&url.URL{Scheme: "file", Path: slash}).String() |
| 96 | } |
| 97 |