feat: implement jwt transport

src/transport/jwt.js

@@ -0,0 +1,85 @@
+import * as API from "../api.js"
+import { isLink, pack, unpack } from "./packet.js"
+import * as Transport from "./api.js"
+import * as UCAN from "@ipld/dag-ucan"
+import * as UTF8 from "../utf8.js"
+import { Invocation } from "../view.js"
+
+const HEADER_PREFIX = "x-auth-"
+
+const HEADERS = Object.freeze({
+  "content-type": "application/car",
+})
+
+/**
+ * Encodes invocation batch into an HTTPRequest.
+ *
+ * @template {API.IssuedInvocation[]} I
+ * @param {API.Batch<I>} batch
+ * @returns {Promise<Transport.HTTPRequest<I>>}
+ */
+export const encode = async batch => {
+  /** @type {Record<string, string>} */
+  const headers = {}
+  /** @type {string[]} */
+  const body = []
+  const { invocations, delegations } = await pack(batch)
+  for (const invocation of invocations) {
+    headers[`${HEADER_PREFIX}${invocation.cid}`] = UCAN.format(invocation.data)
+    body.push(`${invocation.cid}`)
+  }
+  for (const delegation of Object.values(delegations)) {
+    headers[`${HEADER_PREFIX}${delegation.cid}`] = UCAN.format(delegation.data)
+  }
+
+  return {
+    headers: HEADERS,
+    body: UTF8.encode(JSON.stringify(body)),
+  }
+}
+
+/**
+ * Decodes HTTPRequest to an invocation batch.
+ *
+ * @template {API.Invocation[]} Invocations
+ * @param {Transport.HTTPRequest<Invocations>} request
+ * @returns {Promise<API.Batch<Invocations>>}
+ */
+export const decode = async ({ headers, body }) => {
+  const contentType = headers["content-type"] || headers["Content-Type"]
+  if (contentType !== "application/car") {
+    throw TypeError(
+      `Only 'content-type: application/car' is supported, intsead got '${contentType}'`
+    )
+  }
+  /** @type {Transport.Block[]} */
+  const invocations = []
+  const delegations = new Map()
+  for (const [name, value] of Object.entries(headers)) {
+    if (name.startsWith(HEADER_PREFIX)) {
+      const key = name.slice(HEADER_PREFIX.length)
+      const data = UCAN.parse(value)
+      const { cid, bytes } = await UCAN.write(data)
+
+      if (cid.toString() != key) {
+        throw TypeError(
+          `Invalid request, proof with key ${key} has mismatching cid ${cid}`
+        )
+      }
+      delegations.set(cid.toString(), { data, cid, bytes })
+    }
+  }
+
+  for (const cid of JSON.parse(UTF8.decode(body))) {
+    const block = delegations.get(cid.toString())
+    if (!block) {
+      throw TypeError(
+        `Invalid request proof of invocation ${cid} is not provided`
+      )
+    }
+    invocations.push(block)
+    delegations.delete(block)
+  }
+
+  return unpack({ invocations, delegations })
+}