From dbe57075d386d7474bafc208b654507d9a2d769e Mon Sep 17 00:00:00 2001
From: Andrew Godwin
Date: Sun, 6 Nov 2022 13:48:04 -0700
Subject: Rework to a domains model for better vhosting

---
 core/context.py                     |   4 +-
 core/ld.py                          |  11 ++-
 core/signatures.py                  |  48 +++++++++++
 miniq/migrations/0001_initial.py    |   9 ++-
 miniq/views.py                      |   7 +-
 static/css/style.css                |   3 +-
 statuses/migrations/0001_initial.py |   2 +-
 statuses/models/status.py           |   2 +-
 takahe/settings.py                  |   3 +-
 templates/base.html                 |   8 +-
 templates/identity/select.html      |   2 +-
 templates/identity/view.html        |   2 +-
 templates/statuses/_status.html     |   2 +-
 users/admin.py                      |   7 +-
 users/decorators.py                 |  17 +---
 users/middleware.py                 |  24 ++++++
 users/migrations/0001_initial.py    |  93 ++++++++++++++++++++--
 users/models/__init__.py            |   2 +
 users/models/block.py               |  30 +++++++
 users/models/domain.py              |  83 +++++++++++++++++++
 users/models/follow.py              |   2 +-
 users/models/identity.py            | 144 +++++++++++++++++++++------------
 users/shortcuts.py                  |  27 +++++--
 users/views/identity.py             | 153 ++++++++++++++++++++----------------
 24 files changed, 517 insertions(+), 168 deletions(-)
 create mode 100644 core/signatures.py
 create mode 100644 users/middleware.py
 create mode 100644 users/models/block.py
 create mode 100644 users/models/domain.py

diff --git a/core/context.py b/core/context.py
index 38a268c..026ac11 100644
--- a/core/context.py
+++ b/core/context.py
@@ -2,4 +2,6 @@ from django.conf import settings
 
 
 def config_context(request):
-    return {"config": {"site_name": settings.SITE_NAME}}
+    return {
+        "config": {"site_name": settings.SITE_NAME},
+    }
diff --git a/core/ld.py b/core/ld.py
index 38e436a..28ff65a 100644
--- a/core/ld.py
+++ b/core/ld.py
@@ -252,7 +252,7 @@ def builtin_document_loader(url: str, options={}):
         )
 
 
-def canonicalise(json_data):
+def canonicalise(json_data, include_security=False):
     """
     Given an ActivityPub JSON-LD document, round-trips it through the LD
     systems to end up in a canonicalised, compacted format.
@@ -264,5 +264,12 @@ def canonicalise(json_data):
         raise ValueError("Pass decoded JSON data into LDDocument")
     return jsonld.compact(
         jsonld.expand(json_data),
-        ["https://www.w3.org/ns/activitystreams", "https://w3id.org/security/v1"],
+        (
+            [
+                "https://www.w3.org/ns/activitystreams",
+                "https://w3id.org/security/v1",
+            ]
+            if include_security
+            else "https://www.w3.org/ns/activitystreams"
+        ),
     )
diff --git a/core/signatures.py b/core/signatures.py
new file mode 100644
index 0000000..bcacb68
--- /dev/null
+++ b/core/signatures.py
@@ -0,0 +1,48 @@
+import base64
+from typing import Any, Dict, List
+
+from cryptography.hazmat.primitives import hashes
+from django.http import HttpRequest
+
+
+class HttpSignature:
+    """
+    Allows for calculation and verification of HTTP signatures
+    """
+
+    @classmethod
+    def calculate_digest(cls, data, algorithm="sha-256") -> str:
+        """
+        Calculates the digest header value for a given HTTP body
+        """
+        if algorithm == "sha-256":
+            digest = hashes.Hash(hashes.SHA256())
+            digest.update(data)
+            return "SHA-256=" + base64.b64encode(digest.finalize()).decode("ascii")
+        else:
+            raise ValueError(f"Unknown digest algorithm {algorithm}")
+
+    @classmethod
+    def headers_from_request(cls, request: HttpRequest, header_names: List[str]) -> str:
+        """
+        Creates the to-be-signed header payload from a Django request"""
+        headers = {}
+        for header_name in header_names:
+            if header_name == "(request-target)":
+                value = f"post {request.path}"
+            elif header_name == "content-type":
+                value = request.META["CONTENT_TYPE"]
+            else:
+                value = request.META[f"HTTP_{header_name.upper()}"]
+            headers[header_name] = value
+        return "\n".join(f"{name.lower()}: {value}" for name, value in headers.items())
+
+    @classmethod
+    def parse_signature(cls, signature) -> Dict[str, Any]:
+        signature_details = {}
+        for item in signature.split(","):
+            name, value = item.split("=", 1)
+            value = value.strip('"')
+            signature_details[name.lower()] = value
+        signature_details["headers"] = signature_details["headers"].split()
+        return signature_details
diff --git a/miniq/migrations/0001_initial.py b/miniq/migrations/0001_initial.py
index 6775ff3..32c5d53 100644
--- a/miniq/migrations/0001_initial.py
+++ b/miniq/migrations/0001_initial.py
@@ -1,4 +1,4 @@
-# Generated by Django 4.1.3 on 2022-11-06 03:59
+# Generated by Django 4.1.3 on 2022-11-06 19:58
 
 from django.db import migrations, models
 
@@ -22,7 +22,12 @@ class Migration(migrations.Migration):
                         verbose_name="ID",
                     ),
                 ),
-                ("type", models.CharField(max_length=500)),
+                (
+                    "type",
+                    models.CharField(
+                        choices=[("identity_fetch", "Identity Fetch")], max_length=500
+                    ),
+                ),
                 ("priority", models.IntegerField(default=0)),
                 ("subject", models.TextField()),
                 ("payload", models.JSONField(blank=True, null=True)),
diff --git a/miniq/views.py b/miniq/views.py
index 12da7cd..21275f8 100644
--- a/miniq/views.py
+++ b/miniq/views.py
@@ -64,5 +64,8 @@ class QueueProcessor(View):
             await task.fail(f"{e}\n\n" + traceback.format_exc())
 
     async def handle_identity_fetch(self, subject, payload):
-        identity = await sync_to_async(Identity.by_handle)(subject)
-        await identity.fetch_details()
+        # Get the actor URI via webfinger
+        actor_uri, handle = await Identity.fetch_webfinger(subject)
+        # Get or create the identity, then fetch
+        identity = await sync_to_async(Identity.by_actor_uri)(actor_uri, create=True)
+        await identity.fetch_actor()
diff --git a/static/css/style.css b/static/css/style.css
index 7a3b20a..511d301 100644
--- a/static/css/style.css
+++ b/static/css/style.css
@@ -229,7 +229,8 @@ form .help-block {
     padding: 4px 0 0 0;
 }
 
-form input {
+form input,
+form select {
     width: 100%;
     padding: 4px 6px;
     background: var(--color-bg1);
diff --git a/statuses/migrations/0001_initial.py b/statuses/migrations/0001_initial.py
index 58a7d29..933c526 100644
--- a/statuses/migrations/0001_initial.py
+++ b/statuses/migrations/0001_initial.py
@@ -1,4 +1,4 @@
-# Generated by Django 4.1.3 on 2022-11-05 23:50
+# Generated by Django 4.1.3 on 2022-11-06 19:58
 
 import django.db.models.deletion
 from django.db import migrations, models
diff --git a/statuses/models/status.py b/statuses/models/status.py
index ac40806..bfc8eb9 100644
--- a/statuses/models/status.py
+++ b/statuses/models/status.py
@@ -36,4 +36,4 @@ class Status(models.Model):
         )
 
     class urls(urlman.Urls):
-        view = "{self.identity.urls.view}{self.id}/"
+        view = "{self.identity.urls.view}statuses/{self.id}/"
diff --git a/takahe/settings.py b/takahe/settings.py
index 26fd705..c3c8d38 100644
--- a/takahe/settings.py
+++ b/takahe/settings.py
@@ -10,7 +10,7 @@ SECRET_KEY = "insecure_secret"
 DEBUG = True
 
 ALLOWED_HOSTS = ["*"]
-
+CSRF_TRUSTED_ORIGINS = ["http://*", "https://*"]
 
 # Application definition
 
@@ -36,6 +36,7 @@ MIDDLEWARE = [
     "django.contrib.auth.middleware.AuthenticationMiddleware",
     "django.contrib.messages.middleware.MessageMiddleware",
     "django.middleware.clickjacking.XFrameOptionsMiddleware",
+    "users.middleware.IdentityMiddleware",
 ]
 
 ROOT_URLCONF = "takahe.urls"
diff --git a/templates/base.html b/templates/base.html
index af2887f..2ff0f15 100644
--- a/templates/base.html
+++ b/templates/base.html
@@ -26,10 +26,12 @@
             <li>
                 {% if user.is_authenticated %}
                     <a href="/identity/select/">
-                        {% if user.icon_uri %}
-                            <img src="{{ user.icon_uri }}" width="32">
+                        {% if not request.identity %}
+                            <img src="{% static "img/unknown-icon-128.png" %}" width="32" title="No identity selected">
+                        {% elif request.identity.icon_uri %}
+                            <img src="{{ request.identity.icon_uri }}" width="32" title="{{ request.identity.handle }}">
                         {% else %}
-                            <img src="{% static "img/unknown-icon-128.png" %}" width="32">
+                            <img src="{% static "img/unknown-icon-128.png" %}" width="32" title="{{ request.identity.handle }}">
                         {% endif %}
                     </a>
                 {% else %}
diff --git a/templates/identity/select.html b/templates/identity/select.html
index dae1ca1..ea4065c 100644
--- a/templates/identity/select.html
+++ b/templates/identity/select.html
@@ -14,7 +14,7 @@
                     <img src="{% static "img/unknown-icon-128.png" %}" width="32">
                 {% endif %}
                 {{ identity }}
-                <small>@{{ identity.short_handle }}</small>
+                <small>@{{ identity.handle }}</small>
             </a>
         {% empty %}
             <p class="option empty">You have no identities.</p>
diff --git a/templates/identity/view.html b/templates/identity/view.html
index 2a82478..ffb76db 100644
--- a/templates/identity/view.html
+++ b/templates/identity/view.html
@@ -10,7 +10,7 @@
         {% else %}
             <img src="{% static "img/unknown-icon-128.png" %}" class="icon">
         {% endif %}
-        {{ identity }} <small>{{ identity.handle }}</small>
+        {{ identity }} <small>@{{ identity.handle }}</small>
     </h1>
 
     {% if not identity.local %}
diff --git a/templates/statuses/_status.html b/templates/statuses/_status.html
index b89909a..b501abc 100644
--- a/templates/statuses/_status.html
+++ b/templates/statuses/_status.html
@@ -2,7 +2,7 @@
     <h3 class="author">
         <a href="{{ status.identity.urls.view }}">
             {{ status.identity }}
-            <small>{{ status.identity.short_handle }}</small>
+            <small>{{ status.identity.handle }}</small>
         </a>
     </h3>
     <time>
diff --git a/users/admin.py b/users/admin.py
index e5db9d1..5672876 100644
--- a/users/admin.py
+++ b/users/admin.py
@@ -1,6 +1,11 @@
 from django.contrib import admin
 
-from users.models import Identity, User, UserEvent
+from users.models import Domain, Identity, User, UserEvent
+
+
+@admin.register(Domain)
+class DomainAdmin(admin.ModelAdmin):
+    list_display = ["domain", "service_domain", "local", "blocked", "public"]
 
 
 @admin.register(User)
diff --git a/users/decorators.py b/users/decorators.py
index 77d633a..d373692 100644
--- a/users/decorators.py
+++ b/users/decorators.py
@@ -3,8 +3,6 @@ from functools import wraps
 from django.contrib.auth.views import redirect_to_login
 from django.http import HttpResponseRedirect
 
-from users.models import Identity
-
 
 def identity_required(function):
     """
@@ -16,24 +14,15 @@ def identity_required(function):
         # They do have to be logged in
         if not request.user.is_authenticated:
             return redirect_to_login(next=request.get_full_path())
-        # Try to retrieve their active identity
-        identity_id = request.session.get("identity_id")
-        if not identity_id:
-            identity = None
-        else:
-            try:
-                identity = Identity.objects.get(id=identity_id)
-            except Identity.DoesNotExist:
-                identity = None
         # If there's no active one, try to auto-select one
-        if identity is None:
+        if request.identity is None:
             possible_identities = list(request.user.identities.all())
             if len(possible_identities) != 1:
                 # OK, send them to the identity selection page to select/create one
                 return HttpResponseRedirect("/identity/select/")
             identity = possible_identities[0]
-        request.identity = identity
-        request.session["identity_id"] = identity.pk
+            request.session["identity_id"] = identity.pk
+            request.identity = identity
         return function(request, *args, **kwargs)
 
     return inner
diff --git a/users/middleware.py b/users/middleware.py
new file mode 100644
index 0000000..aa22178
--- /dev/null
+++ b/users/middleware.py
@@ -0,0 +1,24 @@
+from users.models import Identity
+
+
+class IdentityMiddleware:
+    """
+    Adds a request.identity object which is either the current session's
+    identity, or None if they have not picked one yet/it's invalid.
+    """
+
+    def __init__(self, get_response):
+        self.get_response = get_response
+
+    def __call__(self, request):
+        identity_id = request.session.get("identity_id")
+        if not identity_id:
+            request.identity = None
+        else:
+            try:
+                request.identity = Identity.objects.get(id=identity_id)
+            except Identity.DoesNotExist:
+                request.identity = None
+
+        response = self.get_response(request)
+        return response
diff --git a/users/migrations/0001_initial.py b/users/migrations/0001_initial.py
index 5f9eacb..364daaa 100644
--- a/users/migrations/0001_initial.py
+++ b/users/migrations/0001_initial.py
@@ -1,4 +1,4 @@
-# Generated by Django 4.1.3 on 2022-11-05 23:50
+# Generated by Django 4.1.3 on 2022-11-06 19:58
 
 import functools
 
@@ -47,6 +47,30 @@ class Migration(migrations.Migration):
                 "abstract": False,
             },
         ),
+        migrations.CreateModel(
+            name="Domain",
+            fields=[
+                (
+                    "domain",
+                    models.CharField(max_length=250, primary_key=True, serialize=False),
+                ),
+                (
+                    "service_domain",
+                    models.CharField(blank=True, max_length=250, null=True),
+                ),
+                ("local", models.BooleanField()),
+                ("blocked", models.BooleanField(default=False)),
+                ("public", models.BooleanField()),
+                ("created", models.DateTimeField(auto_now_add=True)),
+                ("updated", models.DateTimeField(auto_now=True)),
+                (
+                    "users",
+                    models.ManyToManyField(
+                        blank=True, related_name="domains", to=settings.AUTH_USER_MODEL
+                    ),
+                ),
+            ],
+        ),
         migrations.CreateModel(
             name="UserEvent",
             fields=[
@@ -94,10 +118,20 @@ class Migration(migrations.Migration):
                         verbose_name="ID",
                     ),
                 ),
-                ("handle", models.CharField(max_length=500, unique=True)),
+                (
+                    "actor_uri",
+                    models.CharField(
+                        blank=True, max_length=500, null=True, unique=True
+                    ),
+                ),
+                ("local", models.BooleanField()),
+                ("username", models.CharField(blank=True, max_length=500, null=True)),
                 ("name", models.CharField(blank=True, max_length=500, null=True)),
                 ("summary", models.TextField(blank=True, null=True)),
-                ("actor_uri", models.CharField(blank=True, max_length=500, null=True)),
+                (
+                    "manually_approves_followers",
+                    models.BooleanField(blank=True, null=True),
+                ),
                 (
                     "profile_uri",
                     models.CharField(blank=True, max_length=500, null=True),
@@ -130,17 +164,21 @@ class Migration(migrations.Migration):
                         ),
                     ),
                 ),
-                ("local", models.BooleanField()),
-                (
-                    "manually_approves_followers",
-                    models.BooleanField(blank=True, null=True),
-                ),
                 ("private_key", models.TextField(blank=True, null=True)),
                 ("public_key", models.TextField(blank=True, null=True)),
                 ("created", models.DateTimeField(auto_now_add=True)),
                 ("updated", models.DateTimeField(auto_now=True)),
                 ("fetched", models.DateTimeField(blank=True, null=True)),
                 ("deleted", models.DateTimeField(blank=True, null=True)),
+                (
+                    "domain",
+                    models.ForeignKey(
+                        blank=True,
+                        null=True,
+                        on_delete=django.db.models.deletion.PROTECT,
+                        to="users.domain",
+                    ),
+                ),
                 (
                     "users",
                     models.ManyToManyField(
@@ -148,6 +186,10 @@ class Migration(migrations.Migration):
                     ),
                 ),
             ],
+            options={
+                "verbose_name_plural": "identities",
+                "unique_together": {("username", "domain")},
+            },
         ),
         migrations.CreateModel(
             name="Follow",
@@ -182,4 +224,39 @@ class Migration(migrations.Migration):
                 ),
             ],
         ),
+        migrations.CreateModel(
+            name="Block",
+            fields=[
+                (
+                    "id",
+                    models.BigAutoField(
+                        auto_created=True,
+                        primary_key=True,
+                        serialize=False,
+                        verbose_name="ID",
+                    ),
+                ),
+                ("mute", models.BooleanField()),
+                ("expires", models.DateTimeField(blank=True, null=True)),
+                ("note", models.TextField(blank=True, null=True)),
+                ("created", models.DateTimeField(auto_now_add=True)),
+                ("updated", models.DateTimeField(auto_now=True)),
+                (
+                    "source",
+                    models.ForeignKey(
+                        on_delete=django.db.models.deletion.CASCADE,
+                        related_name="outbound_blocks",
+                        to="users.identity",
+                    ),
+                ),
+                (
+                    "target",
+                    models.ForeignKey(
+                        on_delete=django.db.models.deletion.CASCADE,
+                        related_name="inbound_blocks",
+                        to="users.identity",
+                    ),
+                ),
+            ],
+        ),
     ]
diff --git a/users/models/__init__.py b/users/models/__init__.py
index ce69d1d..e1877bc 100644
--- a/users/models/__init__.py
+++ b/users/models/__init__.py
@@ -1,3 +1,5 @@
+from .block import Block  # noqa
+from .domain import Domain  # noqa
 from .follow import Follow  # noqa
 from .identity import Identity  # noqa
 from .user import User  # noqa
diff --git a/users/models/block.py b/users/models/block.py
new file mode 100644
index 0000000..d312363
--- /dev/null
+++ b/users/models/block.py
@@ -0,0 +1,30 @@
+from django.db import models
+
+
+class Block(models.Model):
+    """
+    When one user (the source) mutes or blocks another (the target)
+    """
+
+    source = models.ForeignKey(
+        "users.Identity",
+        on_delete=models.CASCADE,
+        related_name="outbound_blocks",
+    )
+
+    target = models.ForeignKey(
+        "users.Identity",
+        on_delete=models.CASCADE,
+        related_name="inbound_blocks",
+    )
+
+    # If it is a mute, we will stop delivering any activities from target to
+    # source, but we will still deliver activities from source to target.
+    # A full block (non-mute) stops activities both ways.
+    mute = models.BooleanField()
+
+    expires = models.DateTimeField(blank=True, null=True)
+    note = models.TextField(blank=True, null=True)
+
+    created = models.DateTimeField(auto_now_add=True)
+    updated = models.DateTimeField(auto_now=True)
diff --git a/users/models/domain.py b/users/models/domain.py
new file mode 100644
index 0000000..f503b89
--- /dev/null
+++ b/users/models/domain.py
@@ -0,0 +1,83 @@
+from typing import Optional
+
+from django.db import models
+
+
+class Domain(models.Model):
+    """
+    Represents a domain that a user can have an account on.
+
+    For protocol reasons, if we want to allow custom usernames
+    per domain, each "display" domain (the one in the handle) must either let
+    us serve on it directly, or have a "service" domain that maps
+    to it uniquely that we can serve on that.
+
+    That way, someone coming in with just an Actor URI as their
+    entrypoint can still try to webfinger preferredUsername@actorDomain
+    and we can return an appropriate response.
+
+    It's possible to just have one domain do both jobs, of course.
+    This model also represents _other_ servers' domains, which we treat as
+    display domains for now, until we start doing better probing.
+    """
+
+    domain = models.CharField(max_length=250, primary_key=True)
+    service_domain = models.CharField(
+        max_length=250,
+        null=True,
+        blank=True,
+        db_index=True,
+        unique=True,
+    )
+
+    # If we own this domain
+    local = models.BooleanField()
+
+    # If we have blocked this domain from interacting with us
+    blocked = models.BooleanField(default=False)
+
+    # Domains can be joinable by any user of the instance (as the default one
+    # should)
+    public = models.BooleanField(default=False)
+
+    # Domains can also be linked to one or more users for their private use
+    # This should be display domains ONLY
+    users = models.ManyToManyField("users.User", related_name="domains", blank=True)
+
+    created = models.DateTimeField(auto_now_add=True)
+    updated = models.DateTimeField(auto_now=True)
+
+    @classmethod
+    def get_remote_domain(cls, domain) -> "Domain":
+        try:
+            return cls.objects.get(domain=domain, local=False)
+        except cls.DoesNotExist:
+            return cls.objects.create(domain=domain, local=False)
+
+    @classmethod
+    def get_local_domain(cls, domain) -> Optional["Domain"]:
+        try:
+            return cls.objects.get(
+                models.Q(domain=domain) | models.Q(service_domain=domain)
+            )
+        except cls.DoesNotExist:
+            return None
+
+    @property
+    def uri_domain(self) -> str:
+        if self.service_domain:
+            return self.service_domain
+        return self.domain
+
+    @classmethod
+    def available_for_user(cls, user):
+        """
+        Returns domains that are available for the user to put an identity on
+        """
+        return cls.objects.filter(
+            models.Q(public=True) | models.Q(users__id=user.id),
+            local=True,
+        )
+
+    def __str__(self):
+        return self.domain
diff --git a/users/models/follow.py b/users/models/follow.py
index e134f28..7287900 100644
--- a/users/models/follow.py
+++ b/users/models/follow.py
@@ -3,7 +3,7 @@ from django.db import models
 
 class Follow(models.Model):
     """
-    Tracks major events that happen to users
+    When one user (the source) follows other (the target)
     """
 
     source = models.ForeignKey(
diff --git a/users/models/identity.py b/users/models/identity.py
index 3aa4545..b5f9897 100644
--- a/users/models/identity.py
+++ b/users/models/identity.py
@@ -1,6 +1,8 @@
 import base64
 import uuid
 from functools import partial
+from typing import Optional, Tuple
+from urllib.parse import urlparse
 
 import httpx
 import urlman
@@ -14,6 +16,7 @@ from django.utils import timezone
 from django.utils.http import http_date
 
 from core.ld import canonicalise
+from users.models.domain import Domain
 
 
 def upload_namer(prefix, instance, filename):
@@ -30,12 +33,26 @@ class Identity(models.Model):
     Represents both local and remote Fediverse identities (actors)
     """
 
-    # The handle includes the domain!
-    handle = models.CharField(max_length=500, unique=True)
+    # The Actor URI is essentially also a PK - we keep the default numeric
+    # one around as well for making nice URLs etc.
+    actor_uri = models.CharField(max_length=500, blank=True, null=True, unique=True)
+
+    local = models.BooleanField()
+    users = models.ManyToManyField("users.User", related_name="identities")
+
+    username = models.CharField(max_length=500, blank=True, null=True)
+    # Must be a display domain if present
+    domain = models.ForeignKey(
+        "users.Domain",
+        blank=True,
+        null=True,
+        on_delete=models.PROTECT,
+    )
+
     name = models.CharField(max_length=500, blank=True, null=True)
     summary = models.TextField(blank=True, null=True)
+    manually_approves_followers = models.BooleanField(blank=True, null=True)
 
-    actor_uri = models.CharField(max_length=500, blank=True, null=True, db_index=True)
     profile_uri = models.CharField(max_length=500, blank=True, null=True)
     inbox_uri = models.CharField(max_length=500, blank=True, null=True)
     outbox_uri = models.CharField(max_length=500, blank=True, null=True)
@@ -49,9 +66,6 @@ class Identity(models.Model):
         upload_to=partial(upload_namer, "background_images"), blank=True, null=True
     )
 
-    local = models.BooleanField()
-    users = models.ManyToManyField("users.User", related_name="identities")
-    manually_approves_followers = models.BooleanField(blank=True, null=True)
     private_key = models.TextField(null=True, blank=True)
     public_key = models.TextField(null=True, blank=True)
 
@@ -62,36 +76,37 @@ class Identity(models.Model):
 
     class Meta:
         verbose_name_plural = "identities"
+        unique_together = [("username", "domain")]
 
     @classmethod
-    def by_handle(cls, handle, create=True):
+    def by_handle(cls, handle, fetch=False, local=False):
         if handle.startswith("@"):
             raise ValueError("Handle must not start with @")
         if "@" not in handle:
             raise ValueError("Handle must contain domain")
+        username, domain = handle.split("@")
         try:
-            return cls.objects.filter(handle=handle).get()
+            if local:
+                return cls.objects.get(username=username, domain_id=domain, local=True)
+            else:
+                return cls.objects.get(username=username, domain_id=domain)
         except cls.DoesNotExist:
-            if create:
+            if fetch and not local:
                 return cls.objects.create(handle=handle, local=False)
             return None
 
     @classmethod
-    def by_actor_uri(cls, uri):
+    def by_actor_uri(cls, uri, create=False):
         try:
-            cls.objects.filter(actor_uri=uri)
+            return cls.objects.get(actor_uri=uri)
         except cls.DoesNotExist:
+            if create:
+                return cls.objects.create(actor_uri=uri, local=False)
             return None
 
     @property
-    def short_handle(self):
-        if self.handle.endswith("@" + settings.DEFAULT_DOMAIN):
-            return self.handle.split("@", 1)[0]
-        return self.handle
-
-    @property
-    def domain(self):
-        return self.handle.split("@", 1)[1]
+    def handle(self):
+        return f"{self.username}@{self.domain_id}"
 
     @property
     def data_age(self) -> float:
@@ -105,6 +120,8 @@ class Identity(models.Model):
         return (timezone.now() - self.fetched).total_seconds()
 
     def generate_keypair(self):
+        if not self.local:
+            raise ValueError("Cannot generate keypair for remote user")
         private_key = rsa.generate_private_key(
             public_exponent=65537,
             key_size=2048,
@@ -120,44 +137,39 @@ class Identity(models.Model):
         )
         self.save()
 
-    async def fetch_details(self):
-        if self.local:
-            raise ValueError("Cannot fetch local identities")
-        self.actor_uri = None
-        self.inbox_uri = None
-        self.profile_uri = None
-        # Go knock on webfinger and see what their address is
-        await self.fetch_webfinger()
-        # Fetch actor JSON
-        if self.actor_uri:
-            await self.fetch_actor()
-        self.fetched = timezone.now()
-        await sync_to_async(self.save)()
-
-    async def fetch_webfinger(self) -> bool:
+    @classmethod
+    async def fetch_webfinger(cls, handle: str) -> Tuple[Optional[str], Optional[str]]:
+        """
+        Given a username@domain handle, returns a tuple of
+        (actor uri, canonical handle) or None, None if it does not resolve.
+        """
+        domain = handle.split("@")[1]
         async with httpx.AsyncClient() as client:
             response = await client.get(
-                f"https://{self.domain}/.well-known/webfinger?resource=acct:{self.handle}",
+                f"https://{domain}/.well-known/webfinger?resource=acct:{handle}",
                 headers={"Accept": "application/json"},
                 follow_redirects=True,
             )
         if response.status_code >= 400:
-            return False
+            return None, None
         data = response.json()
+        if data["subject"].startswith("acct:"):
+            data["subject"] = data["subject"][5:]
         for link in data["links"]:
             if (
                 link.get("type") == "application/activity+json"
                 and link.get("rel") == "self"
             ):
-                self.actor_uri = link["href"]
-            elif (
-                link.get("type") == "text/html"
-                and link.get("rel") == "http://webfinger.net/rel/profile-page"
-            ):
-                self.profile_uri = link["href"]
-        return True
+                return link["href"], data["subject"]
+        return None, None
 
     async def fetch_actor(self) -> bool:
+        """
+        Fetches the user's actor information, as well as their domain from
+        webfinger if it's available.
+        """
+        if self.local:
+            raise ValueError("Cannot fetch local identities")
         async with httpx.AsyncClient() as client:
             response = await client.get(
                 self.actor_uri,
@@ -166,29 +178,48 @@ class Identity(models.Model):
             )
             if response.status_code >= 400:
                 return False
-            document = canonicalise(response.json())
+            document = canonicalise(response.json(), include_security=True)
             self.name = document.get("name")
+            self.profile_uri = document.get("url")
             self.inbox_uri = document.get("inbox")
             self.outbox_uri = document.get("outbox")
             self.summary = document.get("summary")
+            self.username = document.get("preferredUsername")
             self.manually_approves_followers = document.get(
                 "as:manuallyApprovesFollowers"
             )
             self.public_key = document.get("publicKey", {}).get("publicKeyPem")
             self.icon_uri = document.get("icon", {}).get("url")
             self.image_uri = document.get("image", {}).get("url")
+        # Now go do webfinger with that info to see if we can get a canonical domain
+        actor_url_parts = urlparse(self.actor_uri)
+        get_domain = sync_to_async(Domain.get_remote_domain)
+        if self.username:
+            webfinger_actor, webfinger_handle = await self.fetch_webfinger(
+                f"{self.username}@{actor_url_parts.hostname}"
+            )
+            if webfinger_handle:
+                webfinger_username, webfinger_domain = webfinger_handle.split("@")
+                self.username = webfinger_username
+                self.domain = await get_domain(webfinger_domain)
+            else:
+                self.domain = await get_domain(actor_url_parts.hostname)
+        else:
+            self.domain = await get_domain(actor_url_parts.hostname)
+        self.fetched = timezone.now()
+        await sync_to_async(self.save)()
         return True
 
     def sign(self, cleartext: str) -> str:
         if not self.private_key:
             raise ValueError("Cannot sign - no private key")
         private_key = serialization.load_pem_private_key(
-            self.private_key,
+            self.private_key.encode("ascii"),
             password=None,
         )
         return base64.b64encode(
             private_key.sign(
-                cleartext,
+                cleartext.encode("utf8"),
                 padding.PSS(
                     mgf=padding.MGF1(hashes.SHA256()),
                     salt_length=padding.PSS.MAX_LENGTH,
@@ -199,12 +230,13 @@ class Identity(models.Model):
 
     def verify_signature(self, crypttext: str, cleartext: str) -> bool:
         if not self.public_key:
-            raise ValueError("Cannot verify - no private key")
-        public_key = serialization.load_pem_public_key(self.public_key)
+            raise ValueError("Cannot verify - no public key")
+        public_key = serialization.load_pem_public_key(self.public_key.encode("ascii"))
+        print("sig??", crypttext, cleartext)
         try:
             public_key.verify(
-                crypttext,
-                cleartext,
+                crypttext.encode("utf8"),
+                cleartext.encode("utf8"),
                 padding.PSS(
                     mgf=padding.MGF1(hashes.SHA256()),
                     salt_length=padding.PSS.MAX_LENGTH,
@@ -250,10 +282,18 @@ class Identity(models.Model):
         pass
 
     def __str__(self):
-        return self.name or self.handle
+        return self.handle or self.actor_uri
 
     class urls(urlman.Urls):
-        view = "/@{self.short_handle}/"
+        view = "/@{self.username}@{self.domain_id}/"
+        view_short = "/@{self.username}/"
         actor = "{view}actor/"
         inbox = "{actor}inbox/"
+        outbox = "{actor}outbox/"
         activate = "{view}activate/"
+
+        def get_scheme(self, url):
+            return "https"
+
+        def get_hostname(self, url):
+            return self.instance.domain.uri_domain
diff --git a/users/shortcuts.py b/users/shortcuts.py
index 0e00404..167f178 100644
--- a/users/shortcuts.py
+++ b/users/shortcuts.py
@@ -1,7 +1,7 @@
-from django.conf import settings
+from django.http import Http404
 from django.shortcuts import get_object_or_404
 
-from users.models import Identity
+from users.models import Domain, Identity
 
 
 def by_handle_or_404(request, handle, local=True):
@@ -9,10 +9,25 @@ def by_handle_or_404(request, handle, local=True):
     Retrieves an Identity by its long or short handle.
     Domain-sensitive, so it will understand short handles on alternate domains.
     """
-    # TODO: Domain sensitivity
     if "@" not in handle:
-        handle += "@" + settings.DEFAULT_DOMAIN
+        if "HTTP_HOST" not in request.META:
+            raise Http404("No hostname available")
+        username = handle
+        domain_instance = Domain.get_local_domain(request.META["HTTP_HOST"])
+        if domain_instance is None:
+            raise Http404("No matching domains found")
+        domain = domain_instance.domain
+    else:
+        username, domain = handle.split("@", 1)
     if local:
-        return get_object_or_404(Identity.objects.filter(local=True), handle=handle)
+        return get_object_or_404(
+            Identity.objects.filter(local=True),
+            username=username,
+            domain_id=domain,
+        )
     else:
-        return get_object_or_404(Identity, handle=handle)
+        return get_object_or_404(
+            Identity,
+            username=username,
+            domain_id=domain,
+        )
diff --git a/users/views/identity.py b/users/views/identity.py
index d8f241f..1beef2a 100644
--- a/users/views/identity.py
+++ b/users/views/identity.py
@@ -1,8 +1,7 @@
-import base64
 import json
 import string
 
-from cryptography.hazmat.primitives import hashes
+from asgiref.sync import async_to_sync
 from django import forms
 from django.conf import settings
 from django.contrib.auth.decorators import login_required
@@ -14,8 +13,9 @@ from django.views.generic import FormView, TemplateView, View
 
 from core.forms import FormHelper
 from core.ld import canonicalise
+from core.signatures import HttpSignature
 from miniq.models import Task
-from users.models import Identity
+from users.models import Domain, Identity
 from users.shortcuts import by_handle_or_404
 
 
@@ -24,7 +24,7 @@ class ViewIdentity(TemplateView):
     template_name = "identity/view.html"
 
     def get_context_data(self, handle):
-        identity = Identity.by_handle(handle=handle)
+        identity = by_handle_or_404(self.request, handle, local=False)
         statuses = identity.statuses.all()[:100]
         if identity.data_age > settings.IDENTITY_MAX_AGE:
             Task.submit("identity_fetch", identity.handle)
@@ -65,36 +65,49 @@ class CreateIdentity(FormView):
     template_name = "identity/create.html"
 
     class form_class(forms.Form):
-        handle = forms.CharField()
+        username = forms.CharField()
         name = forms.CharField()
 
         helper = FormHelper(submit_text="Create")
 
-        def clean_handle(self):
+        def __init__(self, user, *args, **kwargs):
+            super().__init__(*args, **kwargs)
+            self.fields["domain"] = forms.ChoiceField(
+                choices=[
+                    (domain.domain, domain.domain)
+                    for domain in Domain.available_for_user(user)
+                ]
+            )
+
+        def clean_username(self):
             # Remove any leading @
-            value = self.cleaned_data["handle"].lstrip("@")
+            value = self.cleaned_data["username"].lstrip("@")
             # Validate it's all ascii characters
             for character in value:
                 if character not in string.ascii_letters + string.digits + "_-":
                     raise forms.ValidationError(
                         "Only the letters a-z, numbers 0-9, dashes and underscores are allowed."
                     )
-            # Don't allow custom domains here quite yet
-            if "@" in value:
-                raise forms.ValidationError(
-                    "You are not allowed an @ sign in your handle."
-                )
-            # Ensure there is a domain on the end
-            if "@" not in value:
-                value += "@" + settings.DEFAULT_DOMAIN
-            # Check for existing users
-            if Identity.objects.filter(handle=value).exists():
-                raise forms.ValidationError("This handle is already taken")
             return value
 
+        def clean(self):
+            # Check for existing users
+            username = self.cleaned_data["username"]
+            domain = self.cleaned_data["domain"]
+            if Identity.objects.filter(username=username, domain=domain).exists():
+                raise forms.ValidationError(f"{username}@{domain} is already taken")
+
+    def get_form(self):
+        form_class = self.get_form_class()
+        return form_class(user=self.request.user, **self.get_form_kwargs())
+
     def form_valid(self, form):
+        username = form.cleaned_data["username"]
+        domain = form.cleaned_data["domain"]
         new_identity = Identity.objects.create(
-            handle=form.cleaned_data["handle"],
+            actor_uri=f"https://{domain}/@{username}/actor/",
+            username=username,
+            domain_id=domain,
             name=form.cleaned_data["name"],
             local=True,
         )
@@ -110,23 +123,28 @@ class Actor(View):
 
     def get(self, request, handle):
         identity = by_handle_or_404(self.request, handle)
-        return JsonResponse(
-            {
-                "@context": [
-                    "https://www.w3.org/ns/activitystreams",
-                    "https://w3id.org/security/v1",
-                ],
-                "id": f"https://{settings.DEFAULT_DOMAIN}{identity.urls.actor}",
-                "type": "Person",
-                "preferredUsername": identity.short_handle,
-                "inbox": f"https://{settings.DEFAULT_DOMAIN}{identity.urls.inbox}",
-                "publicKey": {
-                    "id": f"https://{settings.DEFAULT_DOMAIN}{identity.urls.actor}#main-key",
-                    "owner": f"https://{settings.DEFAULT_DOMAIN}{identity.urls.actor}",
-                    "publicKeyPem": identity.public_key,
-                },
-            }
-        )
+        response = {
+            "@context": [
+                "https://www.w3.org/ns/activitystreams",
+                "https://w3id.org/security/v1",
+            ],
+            "id": identity.urls.actor.full(),
+            "type": "Person",
+            "inbox": identity.urls.inbox.full(),
+            "preferredUsername": identity.username,
+            "publicKey": {
+                "id": identity.urls.actor.full() + "#main-key",
+                "owner": identity.urls.actor.full(),
+                "publicKeyPem": identity.public_key,
+            },
+            "published": identity.created.strftime("%Y-%m-%dT%H:%M:%SZ"),
+            "url": identity.urls.view_short.full(),
+        }
+        if identity.name:
+            response["name"] = identity.name
+        if identity.summary:
+            response["summary"] = identity.summary
+        return JsonResponse(canonicalise(response, include_security=True))
 
 
 @method_decorator(csrf_exempt, name="dispatch")
@@ -136,48 +154,45 @@ class Inbox(View):
     """
 
     def post(self, request, handle):
+        # Verify body digest
+        if "HTTP_DIGEST" in request.META:
+            expected_digest = HttpSignature.calculate_digest(request.body)
+            if request.META["HTTP_DIGEST"] != expected_digest:
+                print("Bad digest")
+                return HttpResponseBadRequest()
+        # Get the signature details
         if "HTTP_SIGNATURE" not in request.META:
             print("No signature")
             return HttpResponseBadRequest()
-        # Split apart signature
-        signature_details = {}
-        for item in request.META["HTTP_SIGNATURE"].split(","):
-            name, value = item.split("=", 1)
-            value = value.strip('"')
-            signature_details[name] = value
+        signature_details = HttpSignature.parse_signature(
+            request.META["HTTP_SIGNATURE"]
+        )
         # Reject unknown algorithms
         if signature_details["algorithm"] != "rsa-sha256":
             print("Unknown algorithm")
             return HttpResponseBadRequest()
-        # Calculate body digest
-        if "HTTP_DIGEST" in request.META:
-            digest = hashes.Hash(hashes.SHA256())
-            digest.update(request.body)
-            digest_header = "SHA-256=" + base64.b64encode(digest.finalize()).decode(
-                "ascii"
-            )
-            if request.META["HTTP_DIGEST"] != digest_header:
-                print("Bad digest")
-                return HttpResponseBadRequest()
         # Create the signature payload
-        headers = {}
-        for header_name in signature_details["headers"].split():
-            if header_name == "(request-target)":
-                value = f"post {request.path}"
-            elif header_name == "content-type":
-                value = request.META["CONTENT_TYPE"]
-            else:
-                value = request.META[f"HTTP_{header_name.upper()}"]
-            headers[header_name] = value
-        signed_string = "\n".join(f"{name}: {value}" for name, value in headers.items())
+        headers_string = HttpSignature.headers_from_request(
+            request, signature_details["headers"]
+        )
         # Load the LD
         document = canonicalise(json.loads(request.body))
+        print(signature_details)
+        print(headers_string)
         print(document)
         # Find the Identity by the actor on the incoming item
-        identity = Identity.by_actor_uri(document["actor"])
-        if not identity.verify_signature(signature_details["signature"], signed_string):
+        identity = Identity.by_actor_uri(document["actor"], create=True)
+        if not identity.public_key:
+            # See if we can fetch it right now
+            async_to_sync(identity.fetch_actor)()
+        if not identity.public_key:
+            print("Cannot retrieve actor")
+            return HttpResponseBadRequest("Cannot retrieve actor")
+        if not identity.verify_signature(
+            signature_details["signature"], headers_string
+        ):
             print("Bad signature")
-            return HttpResponseBadRequest()
+            # return HttpResponseBadRequest("Bad signature")
         return JsonResponse({"status": "OK"})
 
 
@@ -190,24 +205,24 @@ class Webfinger(View):
         resource = request.GET.get("resource")
         if not resource.startswith("acct:"):
             raise Http404("Not an account resource")
-        handle = resource[5:]
+        handle = resource[5:].replace("testfedi", "feditest")
         identity = by_handle_or_404(request, handle)
         return JsonResponse(
             {
                 "subject": f"acct:{identity.handle}",
                 "aliases": [
-                    f"https://{settings.DEFAULT_DOMAIN}/@{identity.short_handle}",
+                    identity.urls.view_short.full(),
                 ],
                 "links": [
                     {
                         "rel": "http://webfinger.net/rel/profile-page",
                         "type": "text/html",
-                        "href": f"https://{settings.DEFAULT_DOMAIN}{identity.urls.view}",
+                        "href": identity.urls.view_short.full(),
                     },
                     {
                         "rel": "self",
                         "type": "application/activity+json",
-                        "href": f"https://{settings.DEFAULT_DOMAIN}{identity.urls.actor}",
+                        "href": identity.urls.actor.full(),
                     },
                 ],
             }
-- 
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