| 1 | package main |
| 2 | |
| 3 | import ( |
| 4 | "encoding/base64" |
| 5 | "errors" |
| 6 | "net/url" |
| 7 | "os" |
| 8 | "path/filepath" |
| 9 | "strings" |
| 10 | ) |
| 11 | |
| 12 | // MarkdownImageView is the renderer-safe form of an assistant-provided image |
| 13 | // source. URL is always either a vetted data URI or a same-origin media/proxy |
| 14 | // URL; native file:// paths are never handed to the WebView as image sources. |
| 15 | type MarkdownImageView struct { |
| 16 | URL string `json:"url"` |
| 17 | Filename string `json:"filename,omitempty"` |
| 18 | Mime string `json:"mime,omitempty"` |
| 19 | Size int64 `json:"size,omitempty"` |
| 20 | OpenHref string `json:"openHref,omitempty"` |
| 21 | ErrorCode string `json:"errorCode,omitempty"` |
| 22 | } |
| 23 | |
| 24 | const markdownDataImageMaxEncodedBytes = remoteMarkdownImageMaxBytes*4/3 + 1024 |
| 25 | |
| 26 | // ResolveMarkdownImageForTab applies a tag-specific policy that is deliberately |
| 27 | // stricter than ordinary Markdown links. |
| 28 | func (a *App) ResolveMarkdownImageForTab(tabID, source string) MarkdownImageView { |
| 29 | source = strings.TrimSpace(source) |
| 30 | if source == "" { |
| 31 | return MarkdownImageView{ErrorCode: "invalid-source"} |
| 32 | } |
| 33 | if strings.HasPrefix(source, "//") { |
| 34 | source = "https:" + source |
| 35 | } |
| 36 | if strings.HasPrefix(strings.ToLower(source), "http://") || strings.HasPrefix(strings.ToLower(source), "https://") { |
| 37 | remote, err := validateRemoteMarkdownImageURL(source) |
| 38 | if err != nil { |
| 39 | return MarkdownImageView{OpenHref: source, ErrorCode: "blocked-remote"} |
| 40 | } |
| 41 | name := filepath.Base(strings.TrimSpace(mustURLPath(remote))) |
| 42 | if name == "." || name == string(filepath.Separator) { |
| 43 | name = "image" |
| 44 | } |
| 45 | return MarkdownImageView{ |
| 46 | URL: remoteMarkdownImagePath + "?url=" + url.QueryEscape(remote), |
| 47 | Filename: name, |
| 48 | OpenHref: remote, |
| 49 | } |
| 50 | } |
| 51 | if strings.HasPrefix(strings.ToLower(source), "data:") { |
| 52 | return resolveMarkdownDataImage(source) |
| 53 | } |
| 54 | |
| 55 | path, err := a.authorizedMarkdownImagePath(tabID, source) |
| 56 | if err != nil { |
| 57 | code := "invalid-path" |
| 58 | if errors.Is(err, os.ErrPermission) { |
| 59 | code = "forbidden" |
| 60 | } else if errors.Is(err, os.ErrNotExist) { |
| 61 | code = "not-found" |
| 62 | } |
| 63 | return MarkdownImageView{ErrorCode: code} |
| 64 | } |
| 65 | info, err := os.Lstat(path) |
| 66 | if err != nil { |
| 67 | return MarkdownImageView{ErrorCode: "not-found"} |
| 68 | } |
| 69 | openHref := localFileHref(path) |
| 70 | if info.Mode()&os.ModeSymlink != 0 { |
| 71 | return MarkdownImageView{OpenHref: openHref, ErrorCode: "forbidden"} |
| 72 | } |
| 73 | if info.IsDir() || !info.Mode().IsRegular() { |
| 74 | return MarkdownImageView{OpenHref: openHref, ErrorCode: "not-a-file"} |
| 75 | } |
| 76 | kind, mimeType := previewMediaKind(path) |
| 77 | if kind != "image" { |
| 78 | return MarkdownImageView{Filename: info.Name(), Size: info.Size(), OpenHref: openHref, ErrorCode: "unsupported-type"} |
| 79 | } |
| 80 | f, err := os.Open(path) |
| 81 | if err != nil { |
| 82 | return MarkdownImageView{Filename: info.Name(), OpenHref: openHref, ErrorCode: "not-found"} |
| 83 | } |
| 84 | defer f.Close() |
| 85 | opened, err := f.Stat() |
| 86 | if err != nil || !opened.Mode().IsRegular() || !os.SameFile(info, opened) { |
| 87 | return MarkdownImageView{Filename: info.Name(), OpenHref: openHref, ErrorCode: "invalid-path"} |
| 88 | } |
| 89 | if err := validateOpenMarkdownImageFile(f, mimeType, opened.Size()); err != nil { |
| 90 | code := "invalid-image" |
| 91 | if errors.Is(err, errMarkdownImageTooLarge) { |
| 92 | code = "too-large" |
| 93 | } |
| 94 | return MarkdownImageView{Filename: info.Name(), Size: opened.Size(), OpenHref: openHref, ErrorCode: code} |
| 95 | } |
| 96 | token := a.ensureMediaTokenStore().createMarkdownImage(path, info.Name(), mimeType, opened) |
| 97 | return MarkdownImageView{ |
| 98 | URL: "/__reasonix_workspace_media/" + token + "/" + url.PathEscape(info.Name()), |
| 99 | Filename: info.Name(), |
| 100 | Mime: mimeType, |
| 101 | Size: opened.Size(), |
| 102 | OpenHref: openHref, |
| 103 | } |
| 104 | } |
| 105 | |
| 106 | func mustURLPath(raw string) string { |
| 107 | u, err := url.Parse(raw) |
| 108 | if err != nil { |
| 109 | return "" |
| 110 | } |
| 111 | return u.Path |
| 112 | } |
| 113 | |
| 114 | func resolveMarkdownDataImage(source string) MarkdownImageView { |
| 115 | if len(source) > markdownDataImageMaxEncodedBytes { |
| 116 | return MarkdownImageView{ErrorCode: "too-large"} |
| 117 | } |
| 118 | comma := strings.IndexByte(source, ',') |
| 119 | if comma <= len("data:") { |
| 120 | return MarkdownImageView{ErrorCode: "invalid-data"} |
| 121 | } |
| 122 | header := strings.ToLower(strings.TrimSpace(source[len("data:"):comma])) |
| 123 | parts := strings.Split(header, ";") |
| 124 | declared := strings.TrimSpace(parts[0]) |
| 125 | allowed := declared == "image/png" || declared == "image/jpeg" || declared == "image/gif" || declared == "image/webp" |
| 126 | if !allowed { |
| 127 | return MarkdownImageView{ErrorCode: "unsupported-type"} |
| 128 | } |
| 129 | base64Encoded := false |
| 130 | for _, part := range parts[1:] { |
| 131 | if strings.TrimSpace(part) == "base64" { |
| 132 | base64Encoded = true |
| 133 | continue |
| 134 | } |
| 135 | return MarkdownImageView{ErrorCode: "invalid-data"} |
| 136 | } |
| 137 | payload := source[comma+1:] |
| 138 | var data []byte |
| 139 | var err error |
| 140 | if base64Encoded { |
| 141 | data, err = base64.StdEncoding.DecodeString(strings.Map(func(r rune) rune { |
| 142 | if r == '\r' || r == '\n' || r == '\t' || r == ' ' { |
| 143 | return -1 |
| 144 | } |
| 145 | return r |
| 146 | }, payload)) |
| 147 | } else { |
| 148 | var decoded string |
| 149 | decoded, err = url.PathUnescape(payload) |
| 150 | data = []byte(decoded) |
| 151 | } |
| 152 | if err != nil || len(data) == 0 { |
| 153 | return MarkdownImageView{ErrorCode: "invalid-data"} |
| 154 | } |
| 155 | if len(data) > remoteMarkdownImageMaxBytes { |
| 156 | return MarkdownImageView{ErrorCode: "too-large"} |
| 157 | } |
| 158 | validated, detected := safeRemoteMarkdownImage(data) |
| 159 | if detected != declared || detected == "image/svg+xml" { |
| 160 | return MarkdownImageView{ErrorCode: "invalid-data"} |
| 161 | } |
| 162 | if err := validateMarkdownImageBytes(validated, detected); err != nil { |
| 163 | if errors.Is(err, errMarkdownImageTooLarge) { |
| 164 | return MarkdownImageView{ErrorCode: "too-large"} |
| 165 | } |
| 166 | return MarkdownImageView{ErrorCode: "invalid-data"} |
| 167 | } |
| 168 | return MarkdownImageView{URL: source, Mime: detected, Size: int64(len(data))} |
| 169 | } |
| 170 | |
| 171 | func (a *App) authorizedMarkdownImagePath(tabID, source string) (string, error) { |
| 172 | root, ctrl, ok := a.workspaceTargetForTab(tabID) |
| 173 | if !ok { |
| 174 | return "", os.ErrNotExist |
| 175 | } |
| 176 | if browser := externalFolderRefBrowserFromController(ctrl); browser != nil { |
| 177 | if external, _, found := browser.ExternalFolderRefLocalPath(source); found { |
| 178 | return filepath.Clean(external), nil |
| 179 | } |
| 180 | } |
| 181 | |
| 182 | pathSource, err := localPathSource(source) |
| 183 | if err != nil { |
| 184 | return "", err |
| 185 | } |
| 186 | if filepath.IsAbs(pathSource) { |
| 187 | if authorizer, ok := ctrl.(interface { |
| 188 | AuthorizedExternalFolderLocalPath(string) (string, bool) |
| 189 | }); ok { |
| 190 | if external, allowed := authorizer.AuthorizedExternalFolderLocalPath(pathSource); allowed { |
| 191 | return external, nil |
| 192 | } |
| 193 | } |
| 194 | } |
| 195 | base, err := workspaceBaseFromRoot(root) |
| 196 | if err != nil { |
| 197 | return "", err |
| 198 | } |
| 199 | candidate, inside, err := workspacePathForBase(base, pathSource) |
| 200 | if err != nil || !inside { |
| 201 | return "", os.ErrPermission |
| 202 | } |
| 203 | contained, _, err := canonicalPathWithin(base, candidate) |
| 204 | return contained, err |
| 205 | } |
| 206 |