| 1 | /* NIP-17 kind 15 attachments. File keys stay in the decrypted rumor and are |
| 2 | never copied into markup, URLs, local storage, or the clipboard. */ |
| 3 | (() => { |
| 4 | "use strict" ; |
| 5 | |
| 6 | const MAX_BYTES = 256 * 1024 * 1024; |
| 7 | const textDecoder = new TextDecoder(); |
| 8 | const sizeLabel = size => { |
| 9 | if (size === null) return "" ; |
| 10 | if (size < 1024) return size + " B" ; |
| 11 | if (size < 1024 * 1024) return (size / 1024).toFixed(1) + " KiB" ; |
| 12 | if (size < 1024 * 1024 * 1024) return (size / (1024 * 1024)).toFixed(1) + " MiB" ; |
| 13 | return (size / (1024 * 1024 * 1024)).toFixed(1) + " GiB" ; |
| 14 | }; |
| 15 | const bytes = value => globalThis.tiny.util.bytes(value); |
| 16 | const hex = value => globalThis.tiny.util.hex(value); |
| 17 | const fromHex = (value, message) => { |
| 18 | if (typeof value !== "string" || !/^[0-9a-f]+$/i.test(value) || value.length % 2) |
| 19 | throw Error(message); |
| 20 | return Uint8Array.from(value.match(/../g), pair => parseInt(pair, 16)); |
| 21 | }; |
| 22 | const tagValue = (tags, name) => { |
| 23 | const tag = (Array.isArray(tags) ? tags : []).find(item => item?.[0] === name); |
| 24 | return typeof tag?.[1] === "string" ? tag[1] : "" ; |
| 25 | }; |
| 26 | |
| 27 | function parse(rumor) { |
| 28 | if (!rumor || rumor.kind !== 15 || typeof rumor.content !== "string" ) |
| 29 | throw Error("expected a NIP-17 file message" ); |
| 30 | let url; |
| 31 | try { url = new URL(rumor.content); } catch { throw Error("attachment URL is invalid" ); } |
| 32 | if ((url.protocol !== "https:" && url.protocol !== "http:" ) || url.username || url.password) |
| 33 | throw Error("attachment URL must be HTTP(S) without credentials" ); |
| 34 | const algorithm = tagValue(rumor.tags, "encryption-algorithm" ).toLowerCase(); |
| 35 | if (algorithm !== "aes-gcm" ) throw Error("unsupported attachment encryption" ); |
| 36 | const keyText = tagValue(rumor.tags, "decryption-key" ); |
| 37 | const nonceText = tagValue(rumor.tags, "decryption-nonce" ); |
| 38 | const hash = tagValue(rumor.tags, "x" ).toLowerCase(); |
| 39 | const key = fromHex(keyText, "attachment key is invalid" ); |
| 40 | const nonce = fromHex(nonceText, "attachment nonce is invalid" ); |
| 41 | if (key.length !== 32) throw Error("attachment key is invalid" ); |
| 42 | if (nonce.length < 8 || nonce.length > 32) throw Error("attachment nonce is invalid" ); |
| 43 | if (!/^[0-9a-f]{64}$/.test(hash)) throw Error("attachment hash is invalid" ); |
| 44 | const plaintextHash = tagValue(rumor.tags, "ox" ).toLowerCase(); |
| 45 | if (plaintextHash && !/^[0-9a-f]{64}$/.test(plaintextHash)) throw Error("plaintext hash is invalid" ); |
| 46 | const sizeText = tagValue(rumor.tags, "size" ); |
| 47 | const size = sizeText ? Number(sizeText) : null; |
| 48 | if (size !== null && (!Number.isSafeInteger(size) || size < 0 || size > MAX_BYTES)) |
| 49 | throw Error("attachment is too large" ); |
| 50 | return Object.freeze({ |
| 51 | url: url.href, |
| 52 | mime: tagValue(rumor.tags, "file-type" ) || "application/octet-stream" , |
| 53 | name: tagValue(rumor.tags, "filename" ) || tagValue(rumor.tags, "name" ) || "attachment" , |
| 54 | hash, |
| 55 | plaintextHash, |
| 56 | size, |
| 57 | key, |
| 58 | nonce |
| 59 | }); |
| 60 | } |
| 61 | |
| 62 | async function responseBytes(response, signal) { |
| 63 | const declared = Number(response.headers?.get?.("content-length" )); |
| 64 | if (Number.isFinite(declared) && declared > MAX_BYTES) throw Error("attachment is too large" ); |
| 65 | if (response.body?.getReader) { |
| 66 | const reader = response.body.getReader(); |
| 67 | const chunks = []; |
| 68 | let total = 0; |
| 69 | try { |
| 70 | for (;;) { |
| 71 | if (signal?.aborted) throw Error("attachment opening canceled" ); |
| 72 | const part = await reader.read(); |
| 73 | if (part.done) break; |
| 74 | const chunk = bytes(part.value); |
| 75 | total += chunk.length; |
| 76 | if (total > MAX_BYTES) { |
| 77 | await reader.cancel(); |
| 78 | throw Error("attachment is too large" ); |
| 79 | } |
| 80 | chunks.push(chunk); |
| 81 | } |
| 82 | } finally { reader.releaseLock?.(); } |
| 83 | const output = new Uint8Array(total); |
| 84 | let offset = 0; |
| 85 | chunks.forEach(chunk => { output.set(chunk, offset); offset += chunk.length; }); |
| 86 | return output; |
| 87 | } |
| 88 | const output = bytes(await response.arrayBuffer()); |
| 89 | if (output.length > MAX_BYTES) throw Error("attachment is too large" ); |
| 90 | return output; |
| 91 | } |
| 92 | |
| 93 | async function fetchCiphertext(file, signal) { |
| 94 | const init = {method: "GET" , credentials: "omit" , referrerPolicy: "no-referrer" , signal}; |
| 95 | let response = await fetch(file.url, init); |
| 96 | if (!response.ok && new URL(file.url).origin === globalThis.location.origin && response.status === 401 && globalThis.tiny.signedFetch) { |
| 97 | const local = new URL(file.url).pathname + new URL(file.url).search; |
| 98 | response = await globalThis.tiny.signedFetch(local, "GET" , undefined, {signal}); |
| 99 | } |
| 100 | if (!response.ok) throw Error("attachment could not be fetched" ); |
| 101 | return responseBytes(response, signal); |
| 102 | } |
| 103 | |
| 104 | async function decrypt(file, ciphertext) { |
| 105 | const encrypted = bytes(ciphertext); |
| 106 | if (hex(await globalThis.tiny.util.sha256(encrypted)) !== file.hash) throw Error("attachment hash mismatch" ); |
| 107 | let plain; |
| 108 | try { |
| 109 | const cryptoKey = await crypto.subtle.importKey("raw" , file.key, {name: "AES-GCM" }, false, ["decrypt" ]); |
| 110 | plain = new Uint8Array(await crypto.subtle.decrypt({name: "AES-GCM" , iv: file.nonce}, cryptoKey, encrypted)); |
| 111 | } catch { throw Error("attachment decryption failed" ); } |
| 112 | if (file.plaintextHash && hex(await globalThis.tiny.util.sha256(plain)) !== file.plaintextHash) |
| 113 | throw Error("attachment plaintext hash mismatch" ); |
| 114 | return plain; |
| 115 | } |
| 116 | |
| 117 | function downloadLink(owner, file, plain) { |
| 118 | const url = URL.createObjectURL(new Blob([plain], {type: file.mime})); |
| 119 | owner._attachmentURLs ||= new Set(); |
| 120 | owner._attachmentURLs.add(url); |
| 121 | const link = document.createElement("a" ); |
| 122 | link.textContent = "Download" ; |
| 123 | link.download = file.name; |
| 124 | link.rel = "noopener" ; |
| 125 | link.href = url; |
| 126 | return link; |
| 127 | } |
| 128 | |
| 129 | function preview(node, plain, file, owner = node) { |
| 130 | const mime = file.mime.toLowerCase().split(";" , 1)[0]; |
| 131 | if (mime === "text/plain" || mime === "text/markdown" || mime === "application/json" ) { |
| 132 | const output = document.createElement("pre" ); |
| 133 | output.textContent = textDecoder.decode(plain.slice(0, 1024 * 1024)); |
| 134 | const footer = document.createElement("p" ); |
| 135 | footer.append(downloadLink(owner, file, plain)); |
| 136 | if (plain.length > 1024 * 1024) footer.append(" (preview truncated)" ); |
| 137 | node.replaceChildren(output, footer); |
| 138 | return; |
| 139 | } |
| 140 | if (mime.startsWith("image/" ) || mime.startsWith("video/" ) || mime.startsWith("audio/" )) { |
| 141 | const media = document.createElement(mime.startsWith("image/" ) ? "img" : mime.startsWith("video/" ) ? "video" : "audio" ); |
| 142 | media.controls = mime.startsWith("video/" ) || mime.startsWith("audio/" ); |
| 143 | if (media.localName === "img" ) media.alt = file.name; |
| 144 | if (media.localName === "video" ) media.preload = "metadata" ; |
| 145 | const url = URL.createObjectURL(new Blob([plain], {type: file.mime})); |
| 146 | media.src = url; |
| 147 | owner._attachmentURLs ||= new Set(); |
| 148 | owner._attachmentURLs.add(url); |
| 149 | const footer = document.createElement("p" ); |
| 150 | footer.append(downloadLink(owner, file, plain)); |
| 151 | node.replaceChildren(media, footer); |
| 152 | return; |
| 153 | } |
| 154 | const output = document.createElement("p" ); |
| 155 | output.append("Decrypted attachment is ready: " , downloadLink(owner, file, plain)); |
| 156 | node.replaceChildren(output); |
| 157 | } |
| 158 | |
| 159 | class DirectFile extends HTMLElement { |
| 160 | connectedCallback() { |
| 161 | this.revokeAttachments(); |
| 162 | this.generation = (this.generation || 0) + 1; |
| 163 | const generation = this.generation; |
| 164 | let file; |
| 165 | try { file = parse(this.rumor); } catch (error) { this.textContent = error.message; return; } |
| 166 | this.file = file; |
| 167 | this.innerHTML = "" ; |
| 168 | const article = document.createElement("article" ); |
| 169 | const label = document.createElement("span" ); |
| 170 | label.textContent = file.name + (file.size === null ? "" : " (" + sizeLabel(file.size) + ")" ); |
| 171 | const button = document.createElement("button" ); |
| 172 | button.type = "button" ; |
| 173 | button.textContent = "Open attachment" ; |
| 174 | const status = document.createElement("output" ); |
| 175 | button.addEventListener("click" , async () => { |
| 176 | button.disabled = true; |
| 177 | status.textContent = "Opening attachment..." ; |
| 178 | this.abort?.abort(); |
| 179 | this.abort = new AbortController(); |
| 180 | try { |
| 181 | const plain = await decrypt(file, await fetchCiphertext(file, this.abort.signal)); |
| 182 | if (this.generation !== generation || !this.isConnected) return; |
| 183 | preview(article, plain, file, this); |
| 184 | } catch (error) { if (this.generation === generation) status.textContent = error.message; } |
| 185 | finally { if (this.generation === generation) button.disabled = false; } |
| 186 | }); |
| 187 | article.append(label, button, status); |
| 188 | this.append(article); |
| 189 | } |
| 190 | revokeAttachments() { |
| 191 | for (const url of this._attachmentURLs || []) URL.revokeObjectURL(url); |
| 192 | this._attachmentURLs?.clear(); |
| 193 | } |
| 194 | disconnectedCallback() { |
| 195 | this.generation = (this.generation || 0) + 1; |
| 196 | this.abort?.abort(); |
| 197 | this.revokeAttachments(); |
| 198 | } |
| 199 | } |
| 200 | |
| 201 | globalThis.tiny = globalThis.tiny || {}; |
| 202 | globalThis.tiny.chat = globalThis.tiny.chat || {}; |
| 203 | globalThis.tiny.chat.files = Object.freeze({parse, decrypt, render: rumor => { |
| 204 | const node = document.createElement("direct-file" ); |
| 205 | node.rumor = rumor; |
| 206 | return node; |
| 207 | }, MAX_BYTES}); |
| 208 | if (globalThis.customElements && !customElements.get("direct-file" )) customElements.define("direct-file" , DirectFile); |
| 209 | })(); |
