From 23ba66ae81269fe336a95989e8d3ffb60fc3d6ac Mon Sep 17 00:00:00 2001
From: Guilherme Gazzo <guilherme@gazzo.xyz>
Date: Fri, 26 Sep 2025 18:30:01 -0300
Subject: [PATCH] feat(federation): add verifyMatrixIds method and API 
 (#37080)

---
 apps/meteor/ee/server/api/federation.ts       | 40 +++++++++++++++-
 .../federation-matrix/src/FederationMatrix.ts | 47 +++++++++++++++++++
 .../src/types/IFederationMatrixService.ts     |  1 +
 3 files changed, 87 insertions(+), 1 deletion(-)

diff --git a/apps/meteor/ee/server/api/federation.ts b/apps/meteor/ee/server/api/federation.ts
index 278282ed0ec..e0b99cd8185 100644
--- a/apps/meteor/ee/server/api/federation.ts
+++ b/apps/meteor/ee/server/api/federation.ts
@@ -1,13 +1,51 @@
 import type { IFederationMatrixService } from '@rocket.chat/core-services';
 import { Logger } from '@rocket.chat/logger';
+import { ajv } from '@rocket.chat/rest-typings';
 import type express from 'express';
 import { WebApp } from 'meteor/webapp';
 
+import { API } from '../../../app/api/server';
 import { isRunningMs } from '../../../server/lib/isRunningMs';
 
 const logger = new Logger('FederationRoutes');
 
-export async function registerFederationRoutes(federationService: IFederationMatrixService): Promise<void> {
+let federationService: IFederationMatrixService | undefined;
+API.v1.get(
+	'/federation/matrixIds.verify',
+	{
+		authRequired: true,
+		query: ajv.compile<{
+			matrixIds: string[];
+		}>({
+			type: 'object',
+			properties: {
+				matrixIds: { type: 'array', items: { type: 'string' } },
+			},
+		}),
+		response: {
+			200: ajv.compile<{
+				results: { [key: string]: string };
+			}>({
+				type: 'object',
+				properties: {
+					results: { type: 'object', additionalProperties: { type: 'string' } },
+				},
+			}),
+		},
+	},
+	async function () {
+		const { matrixIds } = this.queryParams;
+		if (!federationService) {
+			throw new Error('Federation service not registered');
+		}
+		return API.v1.success({
+			results: await federationService.verifyMatrixIds(matrixIds),
+		});
+	},
+);
+
+export async function registerFederationRoutes(f: IFederationMatrixService): Promise<void> {
+	federationService = f;
 	if (isRunningMs()) {
 		return;
 	}
diff --git a/ee/packages/federation-matrix/src/FederationMatrix.ts b/ee/packages/federation-matrix/src/FederationMatrix.ts
index ea0f33eb5df..b185cc89376 100644
--- a/ee/packages/federation-matrix/src/FederationMatrix.ts
+++ b/ee/packages/federation-matrix/src/FederationMatrix.ts
@@ -944,4 +944,51 @@ export class FederationMatrix extends ServiceClass implements IFederationMatrixS
 
 		void this.homeserverServices.edu.sendTypingNotification(room.federation.mrid, userMui, isTyping);
 	}
+
+	async verifyMatrixIds(matrixIds: string[]): Promise<{ [key: string]: string }> {
+		const results = Object.fromEntries(
+			await Promise.all(
+				matrixIds.map(async (matrixId) => {
+					// Split only on the first ':' (after the leading '@') so we keep any port in the homeserver
+					const separatorIndex = matrixId.indexOf(':', 1);
+					if (separatorIndex === -1) {
+						return [matrixId, 'UNABLE_TO_VERIFY'];
+					}
+					const userId = matrixId.slice(0, separatorIndex);
+					const homeserverUrl = matrixId.slice(separatorIndex + 1);
+
+					if (homeserverUrl === this.serverName) {
+						const user = await Users.findOneByUsername(userId.slice(1));
+						return [matrixId, user ? 'VERIFIED' : 'UNVERIFIED'];
+					}
+
+					if (!homeserverUrl) {
+						return [matrixId, 'UNABLE_TO_VERIFY'];
+					}
+					try {
+						const result = await this.homeserverServices.request.get<
+							| {
+									avatar_url: string;
+									displayname: string;
+							  }
+							| {
+									errcode: string;
+									error: string;
+							  }
+						>(homeserverUrl, `/_matrix/federation/v1/query/profile`, { user_id: matrixId });
+
+						if ('errcode' in result && result.errcode === 'M_NOT_FOUND') {
+							return [matrixId, 'UNVERIFIED'];
+						}
+
+						return [matrixId, 'VERIFIED'];
+					} catch (e) {
+						return [matrixId, 'UNABLE_TO_VERIFY'];
+					}
+				}),
+			),
+		);
+
+		return results;
+	}
 }
diff --git a/packages/core-services/src/types/IFederationMatrixService.ts b/packages/core-services/src/types/IFederationMatrixService.ts
index 893bca7be5f..c44cb226dd6 100644
--- a/packages/core-services/src/types/IFederationMatrixService.ts
+++ b/packages/core-services/src/types/IFederationMatrixService.ts
@@ -27,4 +27,5 @@ export interface IFederationMatrixService {
 	): Promise<void>;
 	inviteUsersToRoom(room: IRoomFederated, usersUserName: string[], inviter: IUser): Promise<void>;
 	notifyUserTyping(rid: string, user: string, isTyping: boolean): Promise<void>;
+	verifyMatrixIds(matrixIds: string[]): Promise<{ [key: string]: string }>;
 }