server/api/users/:uuid/inbox/index.ts

import { apiRoute, applyConfig, debugRequest } from "@/api";
import { sentry } from "@/sentry";
import { createRoute } from "@hono/zod-openapi";
import { getLogger } from "@logtape/logtape";
import {
    EntityValidator,
    RequestParserHandler,
    SignatureValidator,
} from "@versia/federation";
import type { Entity } from "@versia/federation/types";
import { eq } from "drizzle-orm";
import { matches } from "ip-matching";
import { z } from "zod";
import { type ValidationError, isValidationError } from "zod-validation-error";
import { Note } from "~/classes/database/note";
import { Relationship } from "~/classes/database/relationship";
import { User } from "~/classes/database/user";
import { sendFollowAccept } from "~/classes/functions/user";
import { db } from "~/drizzle/db";
import { Notes, Notifications } from "~/drizzle/schema";
import { config } from "~/packages/config-manager";
import { ErrorSchema } from "~/types/api";

export const meta = applyConfig({
    auth: {
        required: false,
    },
    ratelimits: {
        duration: 60,
        max: 500,
    },
    route: "/users/:uuid/inbox",
});

export const schemas = {
    param: z.object({
        uuid: z.string().uuid(),
    }),
    header: z.object({
        "x-signature": z.string(),
        "x-nonce": z.string(),
        "x-signed-by": z.string().url().or(z.literal("instance")),
        authorization: z.string().optional(),
    }),
    body: z.any(),
};

const route = createRoute({
    method: "post",
    path: "/users/{uuid}/inbox",
    summary: "Receive federation inbox",
    request: {
        params: schemas.param,
        headers: schemas.header,
        body: {
            content: {
                "application/json": {
                    schema: schemas.body,
                },
            },
        },
    },
    responses: {
        200: {
            description: "Request processed",
        },
        201: {
            description: "Request accepted",
        },
        400: {
            description: "Bad request",
            content: {
                "application/json": {
                    schema: ErrorSchema,
                },
            },
        },
        401: {
            description: "Signature could not be verified",
            content: {
                "application/json": {
                    schema: ErrorSchema,
                },
            },
        },
        403: {
            description: "Cannot view users from remote instances",
            content: {
                "application/json": {
                    schema: ErrorSchema,
                },
            },
        },
        404: {
            description: "Not found",
            content: {
                "application/json": {
                    schema: ErrorSchema,
                },
            },
        },
        500: {
            description: "Internal server error",
            content: {
                "application/json": {
                    schema: z.object({
                        error: z.string(),
                        message: z.string(),
                    }),
                },
            },
        },
    },
});

export default apiRoute((app) =>
    app.openapi(route, async (context) => {
        const { uuid } = context.req.valid("param");
        const {
            "x-signature": signature,
            "x-nonce": nonce,
            "x-signed-by": signedBy,
            authorization,
        } = context.req.valid("header");
        const logger = getLogger(["federation", "inbox"]);

        const body: Entity = await context.req.valid("json");

        if (config.debug.federation) {
            // Debug request
            await debugRequest(
                new Request(context.req.url, {
                    method: context.req.method,
                    headers: context.req.raw.headers,
                    body: await context.req.text(),
                }),
            );
        }

        const user = await User.fromId(uuid);

        if (!user) {
            return context.json({ error: "User not found" }, 404);
        }

        if (user.isRemote()) {
            return context.json(
                { error: "Cannot view users from remote instances" },
                403,
            );
        }

        const requestIp = context.env?.ip;

        let checkSignature = true;

        if (config.federation.bridge.enabled) {
            const token = authorization?.split("Bearer ")[1];
            if (token) {
                // Request is bridge request
                if (token !== config.federation.bridge.token) {
                    return context.json(
                        {
                            error: "An invalid token was passed in the Authorization header. Please use the correct token, or remove the Authorization header.",
                        },
                        401,
                    );
                }

                if (requestIp?.address) {
                    if (config.federation.bridge.allowed_ips.length > 0) {
                        checkSignature = false;
                    }

                    for (const ip of config.federation.bridge.allowed_ips) {
                        if (matches(ip, requestIp?.address)) {
                            checkSignature = false;
                            break;
                        }
                    }
                } else {
                    return context.json(
                        {
                            error: "Request IP address is not available",
                        },
                        500,
                    );
                }
            }
        }

        const sender = await User.resolve(signedBy);

        if (sender?.isLocal()) {
            return context.json(
                { error: "Cannot send federation requests to local users" },
                400,
            );
        }

        const hostname = sender?.data.instance?.baseUrl ?? "";

        // Check if Origin is defederated
        if (
            config.federation.blocked.find(
                (blocked) =>
                    blocked.includes(hostname) || hostname.includes(blocked),
            )
        ) {
            // Pretend to accept request
            return context.newResponse(null, 201);
        }

        // Verify request signature
        if (checkSignature) {
            if (!sender) {
                return context.json({ error: "Could not resolve sender" }, 400);
            }

            if (config.debug.federation) {
                // Log public key
                logger.debug`Sender public key: ${sender.data.publicKey}`;
            }

            const validator = await SignatureValidator.fromStringKey(
                sender.data.publicKey,
            );

            const isValid = await validator
                .validate(
                    new Request(context.req.url, {
                        method: context.req.method,
                        headers: {
                            "X-Signature": signature,
                            "X-Nonce": nonce,
                        },
                        body: await context.req.text(),
                    }),
                )
                .catch((e) => {
                    logger.error`${e}`;
                    sentry?.captureException(e);
                    return false;
                });

            if (!isValid) {
                return context.json(
                    { error: "Signature could not be verified" },
                    401,
                );
            }
        }

        const validator = new EntityValidator();
        const handler = new RequestParserHandler(body, validator);

        try {
            return await handler.parseBody<Response>({
                note: async (note) => {
                    const account = await User.resolve(note.author);

                    if (!account) {
                        return context.json({ error: "Author not found" }, 404);
                    }

                    const newStatus = await Note.fromVersia(
                        note,
                        account,
                    ).catch((e) => {
                        logger.error`${e}`;
                        sentry?.captureException(e);
                        return null;
                    });

                    if (!newStatus) {
                        return context.json(
                            { error: "Failed to add status" },
                            500,
                        );
                    }

                    return context.text("Note created", 201);
                },
                follow: async (follow) => {
                    const account = await User.resolve(follow.author);

                    if (!account) {
                        return context.json({ error: "Author not found" }, 400);
                    }

                    const foundRelationship =
                        await Relationship.fromOwnerAndSubject(account, user);

                    if (foundRelationship.data.following) {
                        return context.text("Already following", 200);
                    }

                    await foundRelationship.update({
                        following: !user.data.isLocked,
                        requested: user.data.isLocked,
                        showingReblogs: true,
                        notifying: true,
                        languages: [],
                    });

                    await db.insert(Notifications).values({
                        accountId: account.id,
                        type: user.data.isLocked ? "follow_request" : "follow",
                        notifiedId: user.id,
                    });

                    if (!user.data.isLocked) {
                        await sendFollowAccept(account, user);
                    }

                    return context.text("Follow request sent", 200);
                },
                followAccept: async (followAccept) => {
                    const account = await User.resolve(followAccept.author);

                    if (!account) {
                        return context.json({ error: "Author not found" }, 400);
                    }

                    const foundRelationship =
                        await Relationship.fromOwnerAndSubject(user, account);

                    if (!foundRelationship.data.requested) {
                        return context.text(
                            "There is no follow request to accept",
                            200,
                        );
                    }

                    await foundRelationship.update({
                        requested: false,
                        following: true,
                    });

                    return context.text("Follow request accepted", 200);
                },
                followReject: async (followReject) => {
                    const account = await User.resolve(followReject.author);

                    if (!account) {
                        return context.json({ error: "Author not found" }, 400);
                    }

                    const foundRelationship =
                        await Relationship.fromOwnerAndSubject(user, account);

                    if (!foundRelationship.data.requested) {
                        return context.text(
                            "There is no follow request to reject",
                            200,
                        );
                    }

                    await foundRelationship.update({
                        requested: false,
                        following: false,
                    });

                    return context.text("Follow request rejected", 200);
                },
                // "delete" is a reserved keyword in JS
                delete: async (delete_) => {
                    // Delete the specified object from database, if it exists and belongs to the user
                    const toDelete = delete_.deleted;

                    switch (delete_.deleted_type) {
                        case "Note": {
                            const note = await Note.fromSql(
                                eq(Notes.uri, toDelete),
                                eq(Notes.authorId, user.id),
                            );

                            if (note) {
                                await note.delete();
                                return context.text("Note deleted", 200);
                            }

                            break;
                        }
                        case "User": {
                            const otherUser = await User.resolve(toDelete);

                            if (otherUser) {
                                if (otherUser.id === user.id) {
                                    // Delete own account
                                    await user.delete();
                                    return context.text("Account deleted", 200);
                                }
                                return context.json(
                                    {
                                        error: "Cannot delete other users than self",
                                    },
                                    400,
                                );
                            }

                            break;
                        }
                        default: {
                            return context.json(
                                {
                                    error: `Deletetion of object ${toDelete} not implemented`,
                                },
                                400,
                            );
                        }
                    }

                    return context.json(
                        { error: "Object not found or not owned by user" },
                        404,
                    );
                },
                user: async (user) => {
                    // Refetch user to ensure we have the latest data
                    const updatedAccount = await User.saveFromRemote(user.uri);

                    if (!updatedAccount) {
                        return context.json(
                            { error: "Failed to update user" },
                            500,
                        );
                    }

                    return context.text("User refreshed", 200);
                },
                unknown: () => {
                    return context.json({ error: "Unknown entity type" }, 400);
                },
            });
        } catch (e) {
            if (isValidationError(e)) {
                return context.json(
                    {
                        error: "Failed to process request",
                        error_description: (e as ValidationError).message,
                    },
                    400,
                );
            }
            logger.error`${e}`;
            sentry?.captureException(e);
            return context.json(
                {
                    error: "Failed to process request",
                    message: (e as Error).message,
                },
                500,
            );
        }
    }),
);