From 8f5488436b90d85969abb8bdcbb0ecf14d8936bd Mon Sep 17 00:00:00 2001
From: Arjun Satarkar <me@arjunsatarkar.net>
Date: Fri, 4 Aug 2023 22:09:08 +0530
Subject: Handle if a non-feed URL is given

---
 README.md |  2 --
 serve.py  |  8 +++++++-
 tagrss.py | 10 ++++++++++
 3 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/README.md b/README.md
index ece0e12..39b7e8b 100644
--- a/README.md
+++ b/README.md
@@ -15,8 +15,6 @@ See `LICENSE.txt` in the root of this repository for the text of the license.
 ## To do
 
 * Add JS to make the feed/tag input situation work like one would normally expect rather than like it's 1985. (Progressive enhancement, though.)
-* Do more user input validation
-* Handle more `requests` and `feedparser` error conditions
 * Add support for authentication
 * Allow specifying update interval on a per-feed basis
 
diff --git a/serve.py b/serve.py
index 9ad398f..ee51c99 100755
--- a/serve.py
+++ b/serve.py
@@ -228,6 +228,12 @@ def add_feed_effect():
                 )
         else:
             raise bottle.HTTPError(500, f"Failed to fetch feed from {feed_source}.")
+    except tagrss.NotAFeedError:
+        raise bottle.HTTPError(
+            400,
+            f"Could not add feed from {feed_source} as the content at the location is "
+            "not a valid feed.",
+        )
     return bottle.template(
         "add_feed",
         after_add=True,
@@ -316,7 +322,7 @@ def update_feeds(run_event: threading.Event):
             for feed in feeds:
                 try:
                     core.update_feed(feed.id)
-                except tagrss.FeedFetchError as e:
+                except (tagrss.FeedFetchError, tagrss.NotAFeedError) as e:
                     logging.error(
                         f"Failed to update feed {feed.id} with source {feed.source} "
                         f"due to the following error: {e}."
diff --git a/tagrss.py b/tagrss.py
index 9179035..ae9482c 100644
--- a/tagrss.py
+++ b/tagrss.py
@@ -59,6 +59,10 @@ class FeedFetchError(Exception):
             super().__init__(f"Get {feed_source} failed: {underlying}")
 
 
+class NotAFeedError(Exception):
+    pass
+
+
 FeedId = int
 Epoch = int
 ParsedFeed = feedparser.FeedParserDict
@@ -431,6 +435,12 @@ class TagRss:
             io.BytesIO(bytes(response.text, encoding="utf-8")),
             response_headers={"Content-Location": base},
         )
+        if not (
+            getattr(parsed.feed, "title", None)
+            or getattr(parsed.feed, "link", None)
+            or getattr(parsed.feed, "id", None)
+        ):
+            raise NotAFeedError(source)
         return (parsed, epoch_downloaded)
 
     def add_feed(
-- 
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