From 8ab5fddafd637aee39b3045af5f313ef333c4427 Mon Sep 17 00:00:00 2001
From: Hypolite Petovan <hypolite@mrpetovan.com>
Date: Sun, 26 Mar 2023 18:46:16 -0400
Subject: [PATCH] Don't try to follow remote item from non-URI or scheme-less
 URI

- Address https://github.com/friendica/friendica/issues/12486#issuecomment-1407679388
- Address https://github.com/friendica/friendica/issues/12486#issuecomment-1433112562
---
 src/Module/Contact/Follow.php | 30 ++++++++++++++++++++----------
 1 file changed, 20 insertions(+), 10 deletions(-)

diff --git a/src/Module/Contact/Follow.php b/src/Module/Contact/Follow.php
index 57e9ff634a..0199aca78f 100644
--- a/src/Module/Contact/Follow.php
+++ b/src/Module/Contact/Follow.php
@@ -40,6 +40,7 @@ use Friendica\Network\HTTPException\ForbiddenException;
 use Friendica\Network\Probe;
 use Friendica\Util\Profiler;
 use Friendica\Util\Strings;
+use GuzzleHttp\Psr7\Uri;
 use Psr\Log\LoggerInterface;
 
 class Follow extends BaseModule
@@ -223,17 +224,26 @@ class Follow extends BaseModule
 
 	protected function followRemoteItem(string $url)
 	{
-		$itemId = Item::fetchByLink($url, $this->session->getLocalUserId());
-		if (!$itemId) {
-			// If the user-specific search failed, we search and probe a public post
-			$itemId = Item::fetchByLink($url);
-		}
-
-		if (!empty($itemId)) {
-			$item = Post::selectFirst(['guid'], ['id' => $itemId]);
-			if (!empty($item['guid'])) {
-				$this->baseUrl->redirect('display/' . $item['guid']);
+		try {
+			$uri = new Uri($url);
+			if (!$uri->getScheme()) {
+				return;
 			}
+
+			$itemId = Item::fetchByLink($url, $this->session->getLocalUserId());
+			if (!$itemId) {
+				// If the user-specific search failed, we search and probe a public post
+				$itemId = Item::fetchByLink($url);
+			}
+
+			if (!empty($itemId)) {
+				$item = Post::selectFirst(['guid'], ['id' => $itemId]);
+				if (!empty($item['guid'])) {
+					$this->baseUrl->redirect('display/' . $item['guid']);
+				}
+			}
+		} catch (\InvalidArgumentException $e) {
+			return;
 		}
 	}
 }