Add service for Linked URL feature

develop/README.md

@@ -68,6 +68,7 @@ each service:
 | `references`       | 9238 |
 | `history-v1`       | 9239 |
 | `project-history`  | 9240 |
+| `linked-url-proxy` | 9241 |
 
 To attach to a service using Chrome's _remote debugging_, go to
 <chrome://inspect/> and make sure _Discover network targets_ is checked. Next

develop/dev.env

@@ -8,6 +8,7 @@ FILESTORE_HOST=filestore
 GRACEFUL_SHUTDOWN_DELAY_SECONDS=0
 HISTORY_V1_HOST=history-v1
 HISTORY_REDIS_HOST=redis
+LINKED_URL_PROXY_HOST=linked-url-proxy
 LISTEN_ADDRESS=0.0.0.0
 MONGO_HOST=mongo
 MONGO_URL=mongodb://mongo/sharelatex?directConnection=true

develop/docker-compose.dev.yml

@@ -79,6 +79,17 @@ services:
       - ../services/history-v1/knexfile.js:/overleaf/services/history-v1/knexfile.js
       - ../services/history-v1/migrations:/overleaf/services/history-v1/migrations
 
+  linked-url-proxy:
+    command: ["node", "--watch", "app.mjs"]
+    environment:
+      - NODE_OPTIONS=--inspect=0.0.0.0:9229
+    ports:
+      - "127.0.0.1:9241:9229"
+    volumes:
+      - ../services/linked-url-proxy/app:/overleaf/services/linked-url-proxy/app
+      - ../services/linked-url-proxy/config:/overleaf/services/linked-url-proxy/config
+      - ../services/linked-url-proxy/app.js:/overleaf/services/linked-url-proxy/app.js
+
   notifications:
     command: ["node", "--watch", "app.ts"]
     environment:

develop/docker-compose.yml

@@ -95,6 +95,13 @@ services:
     volumes:
       - history-v1-buckets:/buckets
 
+  linked-url-proxy:
+    build:
+      context: ..
+      dockerfile: services/linked-url-proxy/Dockerfile
+    env_file:
+      - dev.env
+
   mongo:
     image: mongo:8
     command: --replSet overleaf
@@ -173,6 +180,7 @@ services:
       - document-updater
       - filestore
       - history-v1
+      - linked-url-proxy
       - notifications
       - project-history
       - real-time

server-ce/config/env.sh

@@ -6,6 +6,7 @@ export DOCUMENT_UPDATER_HOST=127.0.0.1
 export DOCUPDATER_HOST=127.0.0.1
 export FILESTORE_HOST=127.0.0.1
 export HISTORY_V1_HOST=127.0.0.1
+export LINKED_URL_PROXY_HOST=127.0.0.1
 export NOTIFICATIONS_HOST=127.0.0.1
 export PROJECT_HISTORY_HOST=127.0.0.1
 export REALTIME_HOST=127.0.0.1

server-ce/runit/linked-url-proxy-overleaf/run

@@ -0,0 +1,12 @@
+#!/bin/bash
+
+NODE_PARAMS=""
+if [ "$DEBUG_NODE" == "true" ]; then
+    echo "running debug - linked-url-proxy"
+    NODE_PARAMS="--inspect=0.0.0.0:30660"
+fi
+
+source /etc/overleaf/env.sh
+export LISTEN_ADDRESS=127.0.0.1
+
+exec /sbin/setuser www-data /usr/bin/node $NODE_PARAMS /overleaf/services/linked-url-proxy/app.mjs >> /var/log/overleaf/linked-url-proxy.log 2>&1

server-ce/services.js

@@ -35,6 +35,9 @@ module.exports = [
   {
     name: 'history-v1',
   },
+  {
+    name: 'linked-url-proxy',
+  },
 ]
 
 if (require.main === module) {

services/linked-url-proxy/.nvmrc

@@ -0,0 +1 @@
+22.18.0

services/linked-url-proxy/Dockerfile

@@ -0,0 +1,32 @@
+# This file was auto-generated, do not edit it directly.
+# Instead run bin/update_build_scripts from
+# https://github.com/overleaf/internal/
+
+FROM node:20.18.2 AS base
+
+WORKDIR /overleaf/services/linked-url-proxy
+
+# Google Cloud Storage needs a writable $HOME/.config for resumable uploads
+# (see https://googleapis.dev/nodejs/storage/latest/File.html#createWriteStream)
+RUN mkdir /home/node/.config && chown node:node /home/node/.config
+
+FROM base AS app
+
+COPY package.json package-lock.json /overleaf/
+COPY libraries/logger/package.json /overleaf/libraries/logger/package.json
+COPY libraries/metrics/package.json /overleaf/libraries/metrics/package.json
+COPY libraries/settings/package.json /overleaf/libraries/settings/package.json
+COPY services/linked-url-proxy/package.json /overleaf/services/linked-url-proxy/package.json
+COPY patches/ /overleaf/patches/
+
+RUN cd /overleaf && npm ci --quiet
+
+COPY libraries/logger/ /overleaf/libraries/logger/
+COPY libraries/metrics/ /overleaf/libraries/metrics/
+COPY libraries/settings/ /overleaf/libraries/settings/
+COPY services/linked-url-proxy/ /overleaf/services/linked-url-proxy/
+
+FROM app
+USER node
+
+CMD ["node", "--expose-gc", "app.mjs"]

services/linked-url-proxy/LICENSE

@@ -0,0 +1,662 @@
+
+                    GNU AFFERO GENERAL PUBLIC LICENSE
+                       Version 3, 19 November 2007
+
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+  If you convey a covered work, knowingly relying on a patent license,
+and the Corresponding Source of the work is not available for anyone
+to copy, free of charge and under the terms of this License, through a
+publicly available network server or other readily accessible means,
+then you must either (1) cause the Corresponding Source to be so
+available, or (2) arrange to deprive yourself of the benefit of the
+patent license for this particular work, or (3) arrange, in a manner
+consistent with the requirements of this License, to extend the patent
+license to downstream recipients.  "Knowingly relying" means you have
+actual knowledge that, but for the patent license, your conveying the
+covered work in a country, or your recipient's use of the covered work
+in a country, would infringe one or more identifiable patents in that
+country that you have reason to believe are valid.
+
+  If, pursuant to or in connection with a single transaction or
+arrangement, you convey, or propagate by procuring conveyance of, a
+covered work, and grant a patent license to some of the parties
+receiving the covered work authorizing them to use, propagate, modify
+or convey a specific copy of the covered work, then the patent license
+you grant is automatically extended to all recipients of the covered
+work and works based on it.
+
+  A patent license is "discriminatory" if it does not include within
+the scope of its coverage, prohibits the exercise of, or is
+conditioned on the non-exercise of one or more of the rights that are
+specifically granted under this License.  You may not convey a covered
+work if you are a party to an arrangement with a third party that is
+in the business of distributing software, under which you make payment
+to the third party based on the extent of your activity of conveying
+the work, and under which the third party grants, to any of the
+parties who would receive the covered work from you, a discriminatory
+patent license (a) in connection with copies of the covered work
+conveyed by you (or copies made from those copies), or (b) primarily
+for and in connection with specific products or compilations that
+contain the covered work, unless you entered into that arrangement,
+or that patent license was granted, prior to 28 March 2007.
+
+  Nothing in this License shall be construed as excluding or limiting
+any implied license or other defenses to infringement that may
+otherwise be available to you under applicable patent law.
+
+  12. No Surrender of Others' Freedom.
+
+  If conditions are imposed on you (whether by court order, agreement or
+otherwise) that contradict the conditions of this License, they do not
+excuse you from the conditions of this License.  If you cannot convey a
+covered work so as to satisfy simultaneously your obligations under this
+License and any other pertinent obligations, then as a consequence you may
+not convey it at all.  For example, if you agree to terms that obligate you
+to collect a royalty for further conveying from those to whom you convey
+the Program, the only way you could satisfy both those terms and this
+License would be to refrain entirely from conveying the Program.
+
+  13. Remote Network Interaction; Use with the GNU General Public License.
+
+  Notwithstanding any other provision of this License, if you modify the
+Program, your modified version must prominently offer all users
+interacting with it remotely through a computer network (if your version
+supports such interaction) an opportunity to receive the Corresponding
+Source of your version by providing access to the Corresponding Source
+from a network server at no charge, through some standard or customary
+means of facilitating copying of software.  This Corresponding Source
+shall include the Corresponding Source for any work covered by version 3
+of the GNU General Public License that is incorporated pursuant to the
+following paragraph.
+
+  Notwithstanding any other provision of this License, you have
+permission to link or combine any covered work with a work licensed
+under version 3 of the GNU General Public License into a single
+combined work, and to convey the resulting work.  The terms of this
+License will continue to apply to the part which is the covered work,
+but the work with which it is combined will remain governed by version
+3 of the GNU General Public License.
+
+  14. Revised Versions of this License.
+
+  The Free Software Foundation may publish revised and/or new versions of
+the GNU Affero General Public License from time to time.  Such new versions
+will be similar in spirit to the present version, but may differ in detail to
+address new problems or concerns.
+
+  Each version is given a distinguishing version number.  If the
+Program specifies that a certain numbered version of the GNU Affero General
+Public License "or any later version" applies to it, you have the
+option of following the terms and conditions either of that numbered
+version or of any later version published by the Free Software
+Foundation.  If the Program does not specify a version number of the
+GNU Affero General Public License, you may choose any version ever published
+by the Free Software Foundation.
+
+  If the Program specifies that a proxy can decide which future
+versions of the GNU Affero General Public License can be used, that proxy's
+public statement of acceptance of a version permanently authorizes you
+to choose that version for the Program.
+
+  Later license versions may give you additional or different
+permissions.  However, no additional obligations are imposed on any
+author or copyright holder as a result of your choosing to follow a
+later version.
+
+  15. Disclaimer of Warranty.
+
+  THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
+APPLICABLE LAW.  EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
+HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY
+OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO,
+THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+PURPOSE.  THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM
+IS WITH YOU.  SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF
+ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
+
+  16. Limitation of Liability.
+
+  IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
+THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
+GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
+USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
+DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
+PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
+EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGES.
+
+  17. Interpretation of Sections 15 and 16.
+
+  If the disclaimer of warranty and limitation of liability provided
+above cannot be given local legal effect according to their terms,
+reviewing courts shall apply local law that most closely approximates
+an absolute waiver of all civil liability in connection with the
+Program, unless a warranty or assumption of liability accompanies a
+copy of the Program in return for a fee.
+
+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+Also add information on how to contact you by electronic and paper mail.
+
+  If your software can interact with users remotely through a computer
+network, you should also make sure that it provides a way for users to
+get its source.  For example, if your program is a web application, its
+interface could display a "Source" link that leads users to an archive
+of the code.  There are many ways you could offer source, and different
+solutions will be better for different programs; see section 13 for the
+specific requirements.
+
+  You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU AGPL, see
+<http://www.gnu.org/licenses/>.

services/linked-url-proxy/Makefile

@@ -0,0 +1,174 @@
+# This file was auto-generated, do not edit it directly.
+# Instead run bin/update_build_scripts from
+# https://github.com/overleaf/internal/
+
+BUILD_NUMBER ?= local
+BRANCH_NAME ?= $(shell git rev-parse --abbrev-ref HEAD)
+PROJECT_NAME = linked-url-proxy
+BUILD_DIR_NAME = $(shell pwd | xargs basename | tr -cd '[a-zA-Z0-9_.\-]')
+HERE=$(shell pwd)
+export MONOREPO ?= $(shell cd ../../ && pwd)
+IMAGE_CI ?= ci/$(PROJECT_NAME):$(BRANCH_NAME)-$(BUILD_NUMBER)
+IMAGE_REPO ?= us-east1-docker.pkg.dev/overleaf-ops/ol-docker/$(PROJECT_NAME)
+IMAGE_REPO_FINAL ?= $(IMAGE_REPO):$(BRANCH_NAME)-$(BUILD_NUMBER)
+IMAGE_CACHE ?= $(IMAGE_REPO):cache-$(shell cat \
+	$(MONOREPO)/package.json \
+	$(MONOREPO)/package-lock.json \
+	$(MONOREPO)/libraries/fetch-utils/package.json \
+	$(MONOREPO)/libraries/logger/package.json \
+	$(MONOREPO)/libraries/metrics/package.json \
+	$(MONOREPO)/libraries/o-error/package.json \
+	$(MONOREPO)/libraries/overleaf-editor-core/package.json \
+	$(MONOREPO)/libraries/promise-utils/package.json \
+	$(MONOREPO)/libraries/settings/package.json \
+	$(MONOREPO)/libraries/stream-utils/package.json \
+	$(MONOREPO)/services/linked-url-proxy/package.json \
+	$(MONOREPO)/patches/* \
+| sha256sum | cut -d '-' -f1)
+
+DOCKER_COMPOSE_FLAGS ?= -f docker-compose.yml
+DOCKER_COMPOSE := BUILD_NUMBER=$(BUILD_NUMBER) \
+	BRANCH_NAME=$(BRANCH_NAME) \
+	PROJECT_NAME=$(PROJECT_NAME) \
+	MOCHA_GREP=${MOCHA_GREP} \
+	docker compose ${DOCKER_COMPOSE_FLAGS}
+
+COMPOSE_PROJECT_NAME_TEST_ACCEPTANCE ?= test_acceptance_$(BUILD_DIR_NAME)
+DOCKER_COMPOSE_TEST_ACCEPTANCE = \
+	COMPOSE_PROJECT_NAME=$(COMPOSE_PROJECT_NAME_TEST_ACCEPTANCE) $(DOCKER_COMPOSE)
+
+COMPOSE_PROJECT_NAME_TEST_UNIT ?= test_unit_$(BUILD_DIR_NAME)
+DOCKER_COMPOSE_TEST_UNIT = \
+	COMPOSE_PROJECT_NAME=$(COMPOSE_PROJECT_NAME_TEST_UNIT) $(DOCKER_COMPOSE)
+
+clean:
+	-docker rmi $(IMAGE_CI)
+	-docker rmi $(IMAGE_REPO_FINAL)
+	-$(DOCKER_COMPOSE_TEST_UNIT) down --remove-orphans --rmi local --timeout 0 --volumes
+	-$(DOCKER_COMPOSE_TEST_ACCEPTANCE) down --remove-orphans --rmi local --timeout 0 --volumes
+	-rm -rf reports/
+
+# Run the linting commands in the scope of the monorepo.
+# Eslint and prettier (plus some configs) are on the root.
+RUN_LINTING = docker run --rm -v $(MONOREPO):$(MONOREPO) -w $(HERE) node:22.18.0 npm run --silent
+
+RUN_LINTING_CI = docker run --rm --volume $(MONOREPO)/.editorconfig:/overleaf/.editorconfig --volume $(MONOREPO)/.eslintignore:/overleaf/.eslintignore --volume $(MONOREPO)/.eslintrc:/overleaf/.eslintrc --volume $(MONOREPO)/.prettierignore:/overleaf/.prettierignore --volume $(MONOREPO)/.prettierrc:/overleaf/.prettierrc --volume $(MONOREPO)/tsconfig.backend.json:/overleaf/tsconfig.backend.json --volume $(MONOREPO)/services/linked-url-proxy/reports:/overleaf/services/linked-url-proxy/reports $(IMAGE_CI) npm run --silent
+
+# Same but from the top of the monorepo
+RUN_LINTING_MONOREPO = docker run --rm -v $(MONOREPO):$(MONOREPO) -w $(MONOREPO) node:22.18.0 npm run --silent
+
+SHELLCHECK_OPTS = \
+	--shell=bash \
+	--external-sources
+SHELLCHECK_COLOR := $(if $(CI),--color=never,--color)
+SHELLCHECK_FILES := { git ls-files "*.sh" -z; git grep -Plz "\A\#\!.*bash"; } | sort -zu
+
+shellcheck:
+	@$(SHELLCHECK_FILES) | xargs -0 -r docker run --rm -v $(HERE):/mnt -w /mnt \
+		koalaman/shellcheck:stable $(SHELLCHECK_OPTS) $(SHELLCHECK_COLOR)
+
+shellcheck_fix:
+	@$(SHELLCHECK_FILES) | while IFS= read -r -d '' file; do \
+		diff=$$(docker run --rm -v $(HERE):/mnt -w /mnt koalaman/shellcheck:stable $(SHELLCHECK_OPTS) --format=diff "$$file" 2>/dev/null); \
+		if [ -n "$$diff" ] && ! echo "$$diff" | patch -p1 >/dev/null 2>&1; then echo "\033[31m$$file\033[0m"; \
+		elif [ -n "$$diff" ]; then echo "$$file"; \
+		else echo "\033[2m$$file\033[0m"; fi \
+	done
+
+format:
+	$(RUN_LINTING) format
+
+format_ci:
+	$(RUN_LINTING_CI) format
+
+format_fix:
+	$(RUN_LINTING) format:fix
+
+lint:
+	$(RUN_LINTING) lint
+
+lint_ci:
+	-$(RUN_LINTING_CI) lint -- --format json --output-file reports/eslint.json
+	sed -i 's_"filePath":"/overleaf_"filePath":"$(MONOREPO)_g' reports/eslint.json
+
+lint_fix:
+	$(RUN_LINTING) lint:fix
+
+typecheck:
+	$(RUN_LINTING) types:check
+
+typecheck_ci:
+	$(RUN_LINTING_CI) types:check
+
+test: format lint typecheck shellcheck test_unit test_acceptance
+
+test_unit:
+ifneq (,$(wildcard test/unit))
+	$(DOCKER_COMPOSE_TEST_UNIT) run --rm test_unit
+endif
+
+test_clean: test_unit_clean
+test_unit_clean:
+ifneq (,$(wildcard test/unit))
+	$(DOCKER_COMPOSE_TEST_UNIT) down -v -t 0
+endif
+
+test_acceptance: test_acceptance_clean test_acceptance_pre_run test_acceptance_run
+	$(MAKE) test_acceptance_clean
+
+test_acceptance_debug: test_acceptance_clean test_acceptance_pre_run test_acceptance_run_debug
+	$(MAKE) test_acceptance_clean
+
+test_acceptance_run:
+ifneq (,$(wildcard test/acceptance))
+	$(DOCKER_COMPOSE_TEST_ACCEPTANCE) run --rm test_acceptance
+endif
+
+test_acceptance_run_debug:
+ifneq (,$(wildcard test/acceptance))
+	$(DOCKER_COMPOSE_TEST_ACCEPTANCE) run -p 127.0.0.9:19999:19999 --rm test_acceptance npm run test:acceptance -- --inspect=0.0.0.0:19999 --inspect-brk
+endif
+
+test_clean: test_acceptance_clean
+test_acceptance_clean:
+	$(DOCKER_COMPOSE_TEST_ACCEPTANCE) down -v -t 0
+
+test_acceptance_pre_run:
+ifneq (,$(wildcard test/acceptance/js/scripts/pre-run))
+	$(DOCKER_COMPOSE_TEST_ACCEPTANCE) run --rm test_acceptance test/acceptance/js/scripts/pre-run
+endif
+
+benchmarks:
+	$(DOCKER_COMPOSE_TEST_ACCEPTANCE) run --rm test_acceptance npm run benchmarks
+
+build:
+	docker build \
+		--pull \
+		--build-arg BUILDKIT_INLINE_CACHE=1 \
+		--tag $(IMAGE_CI) \
+		--tag $(IMAGE_CACHE) \
+		--tag $(IMAGE_REPO_FINAL) \
+		--cache-from $(IMAGE_CACHE) \
+		--file Dockerfile \
+		../..
+
+tar:
+	$(DOCKER_COMPOSE) up tar
+
+push:
+	docker push $(IMAGE_REPO_FINAL)
+
+push_branch:
+	docker push $(IMAGE_CACHE)
+
+.PHONY: clean \
+	format format_fix \
+	lint lint_fix \
+	build_types typecheck \
+	lint_ci format_ci typecheck_ci \
+	shellcheck shellcheck_fix \
+	test test_clean test_unit test_unit_clean \
+	test_acceptance test_acceptance_debug test_acceptance_pre_run \
+	test_acceptance_run test_acceptance_run_debug test_acceptance_clean \
+	benchmarks \
+	build tar publish \

services/linked-url-proxy/README.md

@@ -0,0 +1,10 @@
+overleaf/linked-url-proxy
+===============
+
+An API for providing linked url proxy
+
+License
+=======
+The code in this repository is released under the GNU AFFERO GENERAL PUBLIC LICENSE, version 3.
+
+Copyright (c) yu-i-i (https://github.com/yu-i-i/overleaf-cep), 2025.

services/linked-url-proxy/app.mjs

@@ -0,0 +1,39 @@
+import '@overleaf/metrics/initialize.js'
+
+import express from 'express'
+import Settings from '@overleaf/settings'
+import logger from '@overleaf/logger'
+import Metrics from '@overleaf/metrics'
+import LinkedUrlProxyController from './app/js/LinkedUrlProxyController.mjs'
+
+Metrics.open_sockets.monitor(true)
+Metrics.memory.monitor(logger)
+Metrics.leaked_sockets.monitor(logger)
+
+const app = express()
+
+Metrics.injectMetricsRoute(app)
+app.use(Metrics.http.monitor(logger))
+
+app.get('/', LinkedUrlProxyController.proxy)
+app.get('/status', (req, res) => res.send({ status: 'linked-url-proxy is up' }))
+
+const host = Settings.internal.linkedUrlProxy.host
+const port = Settings.internal.linkedUrlProxy.port
+
+logger.debug('Listening at', { host, port })
+
+const server = app.listen(port, host, function (error) {
+  if (error) {
+    throw error
+  }
+  logger.info({ host, port }, 'linked-url-proxy HTTP server starting up')
+})
+
+process.on('SIGTERM', () => {
+  server.close(() => {
+    logger.info({ host, port }, 'linked-url-proxy HTTP server closed')
+    metrics.close()
+  })
+})
+

services/linked-url-proxy/app/js/LinkedUrlProxyController.mjs

@@ -0,0 +1,180 @@
+import dns from 'dns/promises'
+import ipaddr from 'ipaddr.js'
+import { URL } from 'node:url'
+import { Transform } from 'node:stream'
+import logger from '@overleaf/logger'
+import Settings from '@overleaf/settings'
+import { fetchStreamWithResponse, RequestFailedError } from '@overleaf/fetch-utils'
+
+function isAllowedResource(targetUrl) {
+  if (!Settings.allowedResources) return false
+  return Settings.allowedResources.test(targetUrl)
+}
+
+function isBlockedIp(ipStr, targetUrl) {
+  const addr = ipaddr.parse(ipStr)
+  if (addr.kind() === 'ipv6' && addr.isIPv4MappedAddress()) {
+    return isBlockedIp(addr.toIPv4Address().toString(), targetUrl)
+  }
+
+  const range = addr.range()
+  if ([
+    'loopback',
+    'private',
+    'linkLocal',
+    'multicast',
+    'reserved',
+    'broadcast',
+    'unspecified'
+  ].includes(range)) {
+    return true
+  }
+
+  for (const blocked of Settings.blockedNetworks) {
+    try {
+      const net = ipaddr.parseCIDR(blocked)
+      if (addr.match(net)) return true
+    } catch (e) {
+      logger.error({ blocked, error: e }, 'Invalid blockedNetworks entry')
+      const err = new Error(`Invalid blockedNetworks entry: ${blocked}`)
+      err.info = { status: 500 }
+      throw err
+    }
+  }
+  return false
+}
+
+async function validateSourceUrl(hostname, targetUrl) {
+  const records = await dns.lookup(hostname, { all: true }).catch(() => [])
+  if (!records.length) {
+    const err = new Error(`DNS lookup failed for ${hostname}`)
+    err.info = { status: 421 }
+    throw err
+  }
+// Permit explicitly allowed resources without checking blocked IPs
+  if (isAllowedResource(targetUrl)) return
+  for (const { address } of records) {
+    if (isBlockedIp(address, targetUrl)) {
+      const err = new Error(`Blocked IP address: ${address}`)
+      err.info = { status: 403 }
+      throw err
+    }
+  }
+}
+
+async function fetchValidated(urlStr, redirectCount = 0) {
+  if (redirectCount > Settings.maxRedirects) {
+    const err = new Error('Too many redirects')
+    err.info = { status: 421 }
+    throw err
+  }
+
+  const url = new URL(urlStr)
+  if (!['http:', 'https:'].includes(url.protocol)) {
+    const err = new Error(`${url.protocol} protocol is not allowed`)
+    err.info = { status: 400 }
+    throw err
+  }
+
+  // Validate DNS and blocked IPs
+  await validateSourceUrl(url.hostname, urlStr)
+
+  const opts = {
+    redirect: 'manual',
+    timeout: Settings.fetchTimeoutMs,
+    headers: Settings.userAgentHeader,
+  }
+
+  try {
+    const { stream, response } = await fetchStreamWithResponse(urlStr, opts)
+
+    const contentLengthHeader = response.headers.get('content-length')
+    if (contentLengthHeader) {
+      const n = parseInt(contentLengthHeader, 10)
+      if (!Number.isNaN(n) && n > Settings.maxUploadSize) {
+        const err = new Error('file too large')
+	err.info = { status: 413 }
+        try { stream.destroy() } catch (_) {}
+        throw err
+      }
+    }
+
+    return {
+      stream,
+      response,
+      headers: Object.fromEntries(response.headers.entries()),
+    }
+  } catch (err) {
+    if (err instanceof RequestFailedError) {
+      const status = err.info.status
+
+      // Handle redirects
+      if (status >= 300 && status < 400) {
+        const location = err.response.headers.get('Location')
+        if (location) {
+          const nextUrl = new URL(location, url).toString()
+          return fetchValidated(nextUrl, redirectCount + 1)
+        } else {
+          const e = new Error('Redirect response missing Location header')
+	  e.info = { status: 421 }
+          throw e
+        }
+      }
+      throw err
+    }
+    if (!err?.info?.status) {
+      if(err.type === "request-timeout") {
+        err.info = { status: 408 }
+      } else err.info = { status: 422 }
+    }
+    throw err
+  }
+}
+
+async function proxy(req, res) {
+  try {
+    const u = new URL(req.url, `http://${req.headers.host}`)
+    const targetUrl = u.searchParams.get('url')
+    if (!targetUrl) {
+      res.writeHead(400, { 'Content-Type': 'text/plain' })
+      res.end('Missing ?url parameter')
+      return
+    }
+
+    const { stream: upstreamStream, response, headers } = await fetchValidated(targetUrl)
+
+    res.statusCode = response.status || 200
+    res.setHeader('Content-Type', headers['content-type'] || 'application/octet-stream')
+    res.setHeader('Cache-Control', 'no-store')
+
+    function onError(err) {
+      logger.warn({ err, url: req.url }, 'linked-url-proxy request failed')
+      try { upstreamStream.destroy() } catch (_) {}
+      if (!res.headersSent) {
+	let body = `Error: ${err?.message ?? String(err)}`
+        res.writeHead(err?.info?.status || 503, { 'Content-Type': 'text/plain' })
+        res.end(body)
+      } else {
+        try { res.destroy() } catch (_) {}
+      }
+    }
+
+    upstreamStream.on('error', onError)
+    upstreamStream.pipe(res)
+
+  } catch (err) {
+    logger.warn({ err, url: req.url }, 'linked-url-proxy request failed')
+
+    let status = err.info.status
+    let body = `Error: ${err.message || String(err)}`
+
+    try {
+      res.writeHead(status, { 'Content-Type': 'text/plain' })
+      res.end(body)
+    } catch {
+      try { res.end() } catch {}
+    }
+  }
+}
+
+export default { proxy }

services/linked-url-proxy/buildscript.txt

@@ -0,0 +1,6 @@
+linked-url-proxy
+--env-add=
+--env-pass-through=
+--esmock-loader=False
+--node-version=22.18.0
+--public-repo=False

services/linked-url-proxy/config/settings.defaults.cjs

@@ -0,0 +1,27 @@
+const blockedNetworks = (process.env.OVERLEAF_LINKED_URL_BLOCKED_NETWORKS || '')
+  .split(/[,\s]+/)
+  .filter(Boolean)
+  .map(cidr => cidr.trim())
+
+const allowedResources = process.env.OVERLEAF_LINKED_URL_ALLOWED_RESOURCES
+  ? new RegExp(process.env.OVERLEAF_LINKED_URL_ALLOWED_RESOURCES)
+  : null
+
+module.exports = {
+  maxRedirects: 5,
+  fetchTimeoutMs: 30000,
+  blockedNetworks,
+  allowedResources,
+  userAgentHeader: {
+     'User-Agent': 'Overleaf Extended CE - LinkedURLProxy (https://github.com/yu-i-i/overleaf-cep)'
+  },
+  maxUploadSize: process.env.MAX_UPLOAD_SIZE
+    ? parseInt(process.env.MAX_UPLOAD_SIZE, 10) * 1024 * 1024
+    : 50 * 1024 * 1024, // 50 MB
+  internal: {
+    linkedUrlProxy: {
+      port: 3066,
+      host: process.env.LINKED_URL_PROXY_HOST || '127.0.0.1',
+    },
+  },
+}

services/linked-url-proxy/docker-compose.ci.yml

@@ -0,0 +1,32 @@
+# This file was auto-generated, do not edit it directly.
+# Instead run bin/update_build_scripts from
+# https://github.com/overleaf/internal/
+
+services:
+  test_unit:
+    image: ci/$PROJECT_NAME:$BRANCH_NAME-$BUILD_NUMBER
+    user: node
+    command: npm run test:unit:_run
+    environment:
+      NODE_ENV: test
+      NODE_OPTIONS: "--unhandled-rejections=strict"
+
+  test_acceptance:
+    build: .
+    image: ci/$PROJECT_NAME:$BRANCH_NAME-$BUILD_NUMBER
+    environment:
+      ELASTIC_SEARCH_DSN: es:9200
+      POSTGRES_HOST: postgres
+      MOCHA_GREP: ${MOCHA_GREP}
+      NODE_ENV: test
+      NODE_OPTIONS: "--unhandled-rejections=strict"
+    user: node
+    command: npm run test:acceptance
+
+  tar:
+    build: .
+    image: ci/$PROJECT_NAME:$BRANCH_NAME-$BUILD_NUMBER
+    volumes:
+      - ./:/tmp/build/
+    command: tar -czf /tmp/build/build.tar.gz --exclude=build.tar.gz --exclude-vcs .
+    user: root

services/linked-url-proxy/docker-compose.yml

@@ -0,0 +1,36 @@
+# This file was auto-generated, do not edit it directly.
+# Instead run bin/update_build_scripts from
+# https://github.com/overleaf/internal/
+
+services:
+  test_unit:
+    image: node:22.18.0
+    volumes:
+      - .:/overleaf/services/linked-url-proxy
+      - ../../node_modules:/overleaf/node_modules
+      - ../../libraries:/overleaf/libraries
+    working_dir: /overleaf/services/linked-url-proxy
+    environment:
+      MOCHA_GREP: ${MOCHA_GREP}
+      LOG_LEVEL: ${LOG_LEVEL:-}
+      NODE_ENV: test
+      NODE_OPTIONS: "--unhandled-rejections=strict"
+    command: npm run --silent test:unit
+    user: node
+
+  test_acceptance:
+    image: node:22.18.0
+    volumes:
+      - .:/overleaf/services/linked-url-proxy
+      - ../../node_modules:/overleaf/node_modules
+      - ../../libraries:/overleaf/libraries
+    working_dir: /overleaf/services/linked-url-proxy
+    environment:
+      ELASTIC_SEARCH_DSN: es:9200
+      POSTGRES_HOST: postgres
+      MOCHA_GREP: ${MOCHA_GREP}
+      LOG_LEVEL: ${LOG_LEVEL:-}
+      NODE_ENV: test
+      NODE_OPTIONS: "--unhandled-rejections=strict"
+    user: node
+    command: npm run --silent test:acceptance

services/linked-url-proxy/package.json

@@ -0,0 +1,19 @@
+{
+  "name": "@overleaf/linked-url-proxy",
+  "description": "An API for providing linked url proxy",
+  "private": true,
+  "type": "module",
+  "main": "app.mjs",
+  "scripts": {
+    "start": "node app.mjs"
+  },
+  "version": "0.1.0",
+  "dependencies": {
+    "@overleaf/settings": "*",
+    "@overleaf/logger": "*",
+    "@overleaf/metrics": "*",
+    "async": "^3.2.5",
+    "express": "^4.21.2"
+    "ipaddr.js": "^1.9.1"
+  }
+}

services/linked-url-proxy/tsconfig.json

@@ -0,0 +1,13 @@
+{
+  "extends": "../../tsconfig.backend.json",
+  "include": [
+    "app.js",
+    "app.ts",
+    "app/js/**/*",
+    "benchmarks/**/*",
+    "config/**/*",
+    "scripts/**/*",
+    "test/**/*",
+    "types"
+  ]
+}

services/web/config/settings.defaults.js

@@ -264,6 +264,9 @@ module.exports = {
     realTime: {
       url: `http://${process.env.REALTIME_HOST || '127.0.0.1'}:3026`,
     },
+    linkedUrlProxy: {
+      url: `http://${process.env.LINKED_URL_PROXY_HOST || '127.0.0.1'}:3066`,
+    },
     notifications: {
       url: `http://${process.env.NOTIFICATIONS_HOST || '127.0.0.1'}:3042`,
     },