rudeshark.net/packages/backend/src/remote/resolve-user.ts

import { URL } from "node:url";
import chalk from "chalk";
import { IsNull } from "typeorm";
import config from "@/config/index.js";
import type { User, IRemoteUser } from "@/models/entities/user.js";
import { Users } from "@/models/index.js";
import { toPuny } from "@/misc/convert-host.js";
import webFinger from "./webfinger.js";
import { createPerson, updatePerson } from "./activitypub/models/person.js";
import { remoteLogger } from "./logger.js";

const logger = remoteLogger.createSubLogger("resolve-user");

export async function resolveUser(
	username: string,
	host: string | null,
): Promise<User> {
	const usernameLower = username.toLowerCase();

	if (host == null) {
		logger.info(`return local user: ${usernameLower}`);
		return await Users.findOneBy({ usernameLower, host: IsNull() }).then(
			(u) => {
				if (u == null) {
					throw new Error("user not found");
				} else {
					return u;
				}
			},
		);
	}

	host = toPuny(host);

	if (config.host === host) {
		logger.info(`return local user: ${usernameLower}`);
		return await Users.findOneBy({ usernameLower, host: IsNull() }).then(
			(u) => {
				if (u == null) {
					throw new Error("user not found");
				} else {
					return u;
				}
			},
		);
	}

	const user = (await Users.findOneBy({
		usernameLower,
		host,
	})) as IRemoteUser | null;

	const acctLower = `${usernameLower}@${host}`;

	if (user == null) {
		const self = await resolveSelf(acctLower);

		logger.succ(`return new remote user: ${chalk.magenta(acctLower)}`);
		return await createPerson(self.href);
	}

	// If user information is out of date, return it by starting over from WebFilger
	if (
		user.lastFetchedAt == null ||
		Date.now() - user.lastFetchedAt.getTime() > 1000 * 60 * 60 * 24
	) {
		// Prevent multiple attempts to connect to unconnected instances, update before each attempt to prevent subsequent similar attempts
		await Users.update(user.id, {
			lastFetchedAt: new Date(),
		});

		logger.info(`try resync: ${acctLower}`);
		const self = await resolveSelf(acctLower);

		if (user.uri !== self.href) {
			// if uri mismatch, Fix (user@host <=> AP's Person id(IRemoteUser.uri)) mapping.
			logger.info(`uri missmatch: ${acctLower}`);
			logger.info(
				`recovery missmatch uri for (username=${username}, host=${host}) from ${user.uri} to ${self.href}`,
			);

			// validate uri
			const uri = new URL(self.href);
			if (uri.hostname !== host) {
				throw new Error("Invalid uri");
			}

			await Users.update(
				{
					usernameLower,
					host: host,
				},
				{
					uri: self.href,
				},
			);
		} else {
			logger.info(`uri is fine: ${acctLower}`);
		}

		await updatePerson(self.href);

		logger.info(`return resynced remote user: ${acctLower}`);
		return await Users.findOneBy({ uri: self.href }).then((u) => {
			if (u == null) {
				throw new Error("user not found");
			} else {
				return u;
			}
		});
	}

	logger.info(`return existing remote user: ${acctLower}`);
	return user;
}

async function resolveSelf(acctLower: string) {
	logger.info(`WebFinger for ${chalk.yellow(acctLower)}`);
	const finger = await webFinger(acctLower).catch((e) => {
		logger.error(
			`Failed to WebFinger for ${chalk.yellow(acctLower)}: ${
				e.statusCode || e.message
			}`,
		);
		throw new Error(
			`Failed to WebFinger for ${acctLower}: ${e.statusCode || e.message}`,
		);
	});
	const self = finger.links.find(
		(link) => link.rel != null && link.rel.toLowerCase() === "self",
	);
	if (!self) {
		logger.error(
			`Failed to WebFinger for ${chalk.yellow(acctLower)}: self link not found`,
		);
		throw new Error("self link not found");
	}
	return self;
}