feat: add static http gateway routing (#515)

Adds a routing implementation that returns a static list of
gateways as providers for CIDs.

It's expected that these gateways are able to fetch content on our
behalf.

packages/routers/package.json

@@ -56,6 +56,7 @@
     "@helia/delegated-routing-v1-http-api-client": "^3.0.0",
     "@helia/interface": "^4.2.0",
     "@libp2p/interface": "^1.1.4",
+    "@multiformats/uri-to-multiaddr": "^8.0.0",
     "ipns": "^9.0.0",
     "it-first": "^3.0.4",
     "it-map": "^3.0.5",
@@ -66,6 +67,7 @@
     "@libp2p/peer-id": "^4.0.7",
     "@libp2p/peer-id-factory": "^4.0.7",
     "aegir": "^42.2.5",
+    "it-all": "^3.0.4",
     "it-drain": "^3.0.5",
     "sinon-ts": "^2.0.0"
   },

packages/routers/src/http-gateway-routing.ts

@@ -0,0 +1,93 @@
+import { peerIdSymbol } from '@libp2p/interface'
+import { uriToMultiaddr } from '@multiformats/uri-to-multiaddr'
+import { CID } from 'multiformats/cid'
+import { identity } from 'multiformats/hashes/identity'
+import { fromString as uint8ArrayFromString } from 'uint8arrays/from-string'
+import { toString as uint8ArrayToString } from 'uint8arrays/to-string'
+import type { Provider, Routing, RoutingOptions } from '@helia/interface'
+import type { PeerId, PeerInfo } from '@libp2p/interface'
+import type { MultihashDigest, Version } from 'multiformats'
+
+export interface HTTPGatwayRouterInit {
+  gateways?: Array<URL | string>
+}
+
+// these values are from https://github.com/multiformats/multicodec/blob/master/table.csv
+const TRANSPORT_IPFS_GATEWAY_HTTP_CODE = 0x0920
+const inspect = Symbol.for('nodejs.util.inspect.custom')
+
+class URLPeerId implements PeerId {
+  readonly type = 'url'
+  readonly multihash: MultihashDigest
+  readonly privateKey?: Uint8Array
+  readonly publicKey?: Uint8Array
+  readonly url: string
+
+  constructor (url: URL) {
+    this.url = url.toString()
+    this.multihash = identity.digest(uint8ArrayFromString(this.url))
+  }
+
+  [inspect] (): string {
+    return `PeerId(${this.url})`
+  }
+
+  readonly [peerIdSymbol] = true
+
+  toString (): string {
+    return this.toCID().toString()
+  }
+
+  toCID (): CID {
+    return CID.createV1(TRANSPORT_IPFS_GATEWAY_HTTP_CODE, this.multihash)
+  }
+
+  toBytes (): Uint8Array {
+    return this.toCID().bytes
+  }
+
+  equals (other?: PeerId | Uint8Array | string): boolean {
+    if (other == null) {
+      return false
+    }
+
+    if (other instanceof Uint8Array) {
+      other = uint8ArrayToString(other)
+    }
+
+    return other.toString() === this.toString()
+  }
+}
+
+function toPeerInfo (url: string | URL): PeerInfo {
+  url = url.toString()
+
+  return {
+    id: new URLPeerId(new URL(url)),
+    multiaddrs: [
+      uriToMultiaddr(url)
+    ]
+  }
+}
+
+class HTTPGatwayRouter implements Partial<Routing> {
+  private readonly gateways: PeerInfo[]
+
+  constructor (init: HTTPGatwayRouterInit = {}) {
+    this.gateways = (init.gateways ?? []).map(url => toPeerInfo(url))
+  }
+
+  async * findProviders (cid: CID<unknown, number, number, Version>, options?: RoutingOptions | undefined): AsyncIterable<Provider> {
+    yield * this.gateways.map(info => ({
+      ...info,
+      protocols: ['transport-ipfs-gateway-http']
+    }))
+  }
+}
+
+/**
+ * Returns a static list of HTTP Gateways as providers
+ */
+export function httpGatewayRouting (init: HTTPGatwayRouterInit = {}): Partial<Routing> {
+  return new HTTPGatwayRouter(init)
+}

packages/routers/src/index.ts

@@ -4,4 +4,5 @@
  * Abstraction layer over different content and peer routing mechanisms.
  */
 export { delegatedHTTPRouting } from './delegated-http-routing.js'
+export { httpGatewayRouting } from './http-gateway-routing.js'
 export { libp2pRouting } from './libp2p-routing.js'

packages/routers/test/http-gateway-routing.spec.ts

@@ -0,0 +1,23 @@
+import { expect } from 'aegir/chai'
+import all from 'it-all'
+import { CID } from 'multiformats'
+import { httpGatewayRouting } from '../src/http-gateway-routing.js'
+
+describe('http-gateway-routing', () => {
+  it('should find providers', async () => {
+    const gateway = 'https://example.com'
+    const routing = httpGatewayRouting({
+      gateways: [
+        gateway
+      ]
+    })
+
+    const cid = CID.parse('bafyreidykglsfhoixmivffc5uwhcgshx4j465xwqntbmu43nb2dzqwfvae')
+
+    const providers = await all(routing.findProviders?.(cid) ?? [])
+
+    expect(providers).to.have.lengthOf(1)
+    expect(providers).to.have.nested.property('[0].protocols').that.includes('transport-ipfs-gateway-http')
+    expect(providers[0].multiaddrs.map(ma => ma.toString())).to.include('/dns4/example.com/tcp/443/https')
+  })
+})