more descriptive remote follow errors

- distinguish between invalid username, user not found, and remote follow not supported
- make helpers DRYer

bookwyrm/views/follow.py

@@ -12,6 +12,7 @@ from .helpers import (
     get_user_from_username,
     handle_remote_webfinger,
     subscribe_remote_webfinger,
+    WebFingerError,
 )
 
 
@@ -142,7 +143,7 @@ def ostatus_follow_success(request):
 
 
 def remote_follow_page(request):
-    """Display remote follow page"""
+    """display remote follow page"""
     user = get_user_from_username(request.user, request.GET.get("user"))
     data = {"user": user}
     return TemplateResponse(request, "ostatus/remote_follow.html", data)
@@ -152,10 +153,33 @@ def remote_follow_page(request):
 def remote_follow(request):
     """direct user to follow from remote account using ostatus subscribe protocol"""
     remote_user = request.POST.get("remote_user")
-    template = subscribe_remote_webfinger(remote_user)
-    if template is None:
-        data = {"account": remote_user, "user": None, "error": "remote_subscribe"}
-        return TemplateResponse(request, "ostatus/subscribe.html", data)
+    try:
+        if remote_user[0] == "@":
+            remote_user = remote_user[1:]
+        remote_domain = remote_user.split("@")[1]
+    except:
+        remote_domain = None
+
+    wf_response = subscribe_remote_webfinger(remote_user)
     user = get_object_or_404(models.User, id=request.POST.get("user"))
-    url = template.replace("{uri}", urllib.parse.quote(user.remote_id))
+
+    if wf_response is None:
+        data = {
+            "account": remote_user,
+            "user": user,
+            "error": "not_supported",
+            "remote_domain": remote_domain,
+        }
+        return TemplateResponse(request, "ostatus/subscribe.html", data)
+
+    if type(wf_response) == WebFingerError:
+        data = {
+            "account": remote_user,
+            "user": user,
+            "error": str(wf_response),
+            "remote_domain": remote_domain,
+        }
+        return TemplateResponse(request, "ostatus/subscribe.html", data)
+
+    url = wf_response.replace("{uri}", urllib.parse.quote(user.remote_id))
     return redirect(url)

bookwyrm/views/helpers.py

@@ -15,6 +15,27 @@ from bookwyrm.status import create_generated_note
 from bookwyrm.utils import regex
 
 
+class WebFingerError(Exception):
+    """error class for problems finding user information with webfinger"""
+
+    pass
+
+
+def get_domain_from_username(username):
+    # usernames could be @user@domain or user@domain
+    if not username:
+        return None
+
+    if username[0] == "@":
+        username = username[1:]
+
+    try:
+        domain = username.split("@")[1]
+        return domain
+    except IndexError:
+        return None
+
+
 def get_user_from_username(viewer, username):
     """helper function to resolve a localname or a username to a user"""
     if viewer.is_authenticated and viewer.localname == username:
@@ -52,17 +73,8 @@ def is_bookwyrm_request(request):
 def handle_remote_webfinger(query):
     """webfingerin' other servers"""
     user = None
-
-    # usernames could be @user@domain or user@domain
-    if not query:
-        return None
-
-    if query[0] == "@":
-        query = query[1:]
-
-    try:
-        domain = query.split("@")[1]
-    except IndexError:
+    domain = get_domain_from_username(query)
+    if domain is None:
         return None
 
     try:
@@ -88,24 +100,17 @@ def handle_remote_webfinger(query):
 def subscribe_remote_webfinger(query):
     """get subscribe template from other servers"""
     template = None
+    domain = get_domain_from_username(query)
 
-    # usernames could be @user@domain or user@domain
-    if not query:
-        return None
-
-    if query[0] == "@":
-        query = query[1:]
-
-    try:
-        domain = query.split("@")[1]
-    except IndexError:
-        return None
+    if domain is None:
+        return WebFingerError("invalid_username")
 
     url = f"https://{domain}/.well-known/webfinger?resource=acct:{query}"
+
     try:
         data = get_data(url)
     except (ConnectorException, HTTPError):
-        return None
+        return WebFingerError("user_not_found")
 
     for link in data.get("links"):
         if link.get("rel") == "http://ostatus.org/schema/1.0/subscribe":