identity/asset-api/index.js

import { readFile } from "node:fs/promises"
import { createWriteStream, readFileSync, writeFileSync } from "node:fs";
import { createSign, generateKeyPairSync, randomUUID } from "node:crypto";
import Fastify from "fastify";
import multipart from '@fastify/multipart'
import { join } from "node:path";
import mime from "mime"
import { promisify } from "node:util";
import { pipeline } from "node:stream";

const M2M_ALGORITHM = "RSA-SHA512"
const { private: M2M_PRIVATE_KEY, public: M2M_PUBLIC_KEY } = loadM2MKeys()
if (M2M_PRIVATE_KEY == null || M2M_PUBLIC_KEY == null) {
    console.error("Couldn't load keys")
    process.exit(1)
}

const ASSETS_FOLDER = "./.assets/"
const ASSET_API_LANDING_MESSAGE = "asset-api v1.0.0"

const IDENTITY_API_ENDPOINT = "http://localhost:3000"

const fastify = new Fastify({
    logger: true,
})

fastify.register(multipart)

fastify.get("/", async (request, reply) => {
    return signString(ASSET_API_LANDING_MESSAGE)
})

fastify.get("/crypto/cert", async (request, reply) => {
    return M2M_PUBLIC_KEY
})

fastify.get("/crypto/algo", (request, reply) => {
    return M2M_ALGORITHM
})

fastify.put("/asset", {
    async handler(request, reply) {
        await userFromSessionKey(request.query.session_key)
        let file = await request.file()

        let id = randomUUID().toString()
        let extension = mime.getExtension(file.mimetype) || ".bin"
        let full_id = `${id}.${extension}`

        let url = new URL(IDENTITY_API_ENDPOINT)
        url.pathname = "/m2m/asset"

        await fetch(url, {
            method: "PUT",
            body: signObject({
                session_key: request.query.session_key,
                asset_id: full_id,
            })
        })

        promisify(pipeline)(file.file, createWriteStream(`.assets/${full_id}`))
    },
    schema: {
        query: {
            type: "object",
            properties: {
                session_key: { type: "string" },
            },
            required: ["session_key"],
        },
    },
})

fastify.get("/asset", {
    async handler(request, reply) {
        let user = await userFromSessionKey(request.query.session_key)

        if (user.assets.includes(request.query.asset_id)) {
            let path = join(ASSETS_FOLDER, request.query.asset_id)

            reply.type(mime.getType(path))
            reply.send(await readFile(path))
        } else {
            return "Not authorized"
        }
    },
    schema: {
        query: {
            type: "object",
            properties: {
                asset_id: { type: "string" },
                session_key: { type: "string" },
            },
            required: ["asset_id", "session_key"],
        },
    },
})

fastify.listen({ port: 3001 })

function loadM2MKeys() {
    try {
        return {
            private: readFileSync("./.keys/m2m.pem").toString("ascii"),
            public: readFileSync("./.keys/m2m.pub").toString("ascii"),
        }
    } catch (e) {
        console.warn("Generating M2M key pair!")

        let { publicKey, privateKey } = generateKeyPairSync("rsa", {
            modulusLength: 4096,
            publicKeyEncoding: {
                type: 'spki',
                format: 'pem',
            },
            privateKeyEncoding: {
                type: 'pkcs8',
                format: 'pem',
            },
        })

        writeFileSync("./.keys/m2m.pem", privateKey)
        writeFileSync("./.keys/m2m.pub", publicKey)

        return loadM2MKeys()
    }
}

function signString(content) {
    let sign = createSign(M2M_ALGORITHM)
    sign.update(content)
    return `-----BEGIN SIGNED MESSAGE-----\n\n${content}\n\n-----BEGIN SIGNATURE-----\n\n${sign.sign(M2M_PRIVATE_KEY, "base64")}\n-----END SIGNATURE-----`
}

function signObject(content) {
    return signString(JSON.stringify(content))
}

async function userFromSessionKey(session_key) {
    let url = new URL(IDENTITY_API_ENDPOINT)
    url.pathname = "/m2m/account"

    let res1 = await fetch(url, {
        method: "POST",
        body: signObject({
            session_key,
        })
    })

    return await res1.json()
}