Add a form for submitting Signal CAPTCHA solutions

CHANGELOG.md

@@ -6,6 +6,7 @@ All notable changes to this project will be documented in this file.
 ### Improvements
 - Upgrade to fido2 1.1.0 and simplify hc.lib.webauthn
 - Add handling for ipv4address:port values in the X-Forwarded-For header (#714)
+- Add a form for submitting Signal CAPTCHA solutions
 
 ## v2.4.1 - 2022-10-18
 

hc/api/models.py

@@ -10,6 +10,7 @@ from datetime import datetime
 from datetime import timedelta as td
 from datetime import timezone
 from typing import TypedDict
+from urllib.parse import urlencode
 
 from cronsim import CronSim
 from django.conf import settings
@@ -599,9 +600,15 @@ class Channel(models.Model):
         subject = "Signal CAPTCHA proof required"
         message = f"Challenge token: {challenge}"
         hostname = socket.gethostname()
+        submit_url = settings.SITE_ROOT + reverse("hc-signal-captcha")
+        submit_url += urlencode({"host": hostname, "challenge": challenge})
         html_message = f"""
             On host <b>{hostname}</b>, run:<br>
             <pre>manage.py submitchallenge {challenge} CAPTCHA-SOLUTION-HERE</pre><br>
+            <br>
+            Alternatively, submit CAPTCHA solution here: <br>
+            {submit_url}<br>
+            <br>
             Message from Signal:<br>
             <pre>{raw}</pre>
         """

hc/front/urls.py

@@ -111,4 +111,5 @@ urlpatterns = [
     path("docs/cron/", views.docs_cron, name="hc-docs-cron"),
     path("docs/search/", views.docs_search, name="hc-docs-search"),
     path("docs/<slug:doc>/", views.serve_doc, name="hc-serve-doc"),
+    path("signal_captcha/", views.signal_captcha, name="hc-signal-captcha"),
 ]

hc/front/views.py

@@ -6,6 +6,7 @@ import os
 import re
 import sqlite3
 import sys
+import uuid
 from collections import defaultdict
 from datetime import timedelta as td
 from secrets import token_urlsafe
@@ -45,7 +46,7 @@ from hc.api.models import (
     Notification,
     Ping,
 )
-from hc.api.transports import Telegram, TransportError
+from hc.api.transports import Signal, Telegram, TransportError
 from hc.front import forms
 from hc.front.decorators import require_setting
 from hc.front.schemas import telegram_callback
@@ -2277,4 +2278,35 @@ def add_gotify(request, code):
     return render(request, "integrations/add_gotify.html", ctx)
 
 
+@login_required
+def signal_captcha(request: HttpRequest) -> HttpResponse:
+    if not request.user.is_superuser:
+        return HttpResponseForbidden()
+
+    ctx = {"challenge": request.GET.get("challenge", "")}
+    if request.method == "POST":
+        challenge = request.POST.get("challenge")
+        captcha = request.POST.get("captcha")
+        payload = {
+            "jsonrpc": "2.0",
+            "method": "submitRateLimitChallenge",
+            "params": {"challenge": str(challenge), "captcha": captcha},
+            "id": str(uuid.uuid4()),
+        }
+
+        payload_bytes = (json.dumps(payload) + "\n").encode()
+        for reply_bytes in Signal(None)._read_replies(payload_bytes):
+            try:
+                reply = json.loads(reply_bytes.decode())
+            except ValueError:
+                ctx["result"] = "submitRateLimitChallenge failed"
+                break
+
+            if reply.get("id") == payload["id"]:
+                ctx["result"] = reply_bytes.decode()
+                break
+
+    return render(request, "front/signal_captcha.html", ctx)
+
+
 # Forks: add custom views after this line

templates/front/signal_captcha.html

@@ -0,0 +1,44 @@
+{% extends "base.html" %}
+{% load compress static hc_extras %}
+
+{% block content %}
+<div class="row">
+    <div class="col-sm-12">
+        <h1>Signal CAPTCHA</h1>
+
+        {% if result %}
+        <p>Result:</p>
+        <pre>{{ result }}</pre>
+        <hr />
+        {% endif %}
+
+        <p>
+            First, solve a CAPTCHA
+            <a href="https://signalcaptchas.org/challenge/generate.html" target="_blank">here</a>,
+            then paste it below:
+        </p>
+        <form method="post">
+            {% csrf_token %}
+            <div class="form-group">
+                <label for="captcha">Challenge</label>
+                <input
+                    name="challenge"
+                    required
+                    class="form-control"
+                    value="{{ challenge }}" />
+            </div>
+
+            <div class="form-group">
+                <label for="captcha">CAPTCHA</label>
+                <textarea
+                    id="captcha"
+                    name="captcha"
+                    required
+                    class="form-control"
+                    rows="10"></textarea>
+            </div>
+            <button type="submit" class="btn btn-default">Submit</button>
+        </form>
+    </div>
+</div>
+{% endblock %}