Fix fragment parameter case sensitivity

Bech32 fragment parameters should not be case sensitive. This fixes that
by converting params and bech32 HRPs they match against to uppercase.

Close payjoin#442

payjoin/src/uri/url_ext.rs

@@ -103,8 +103,8 @@ where
 {
     if let Some(fragment) = url.fragment() {
         for param in fragment.split('+') {
-            if param.starts_with(prefix) {
-                return parse(param);
+            if param.to_uppercase().starts_with(&prefix.to_uppercase()) {
+                return parse(&param.to_uppercase());
             }
         }
     }
@@ -297,4 +297,23 @@ mod tests {
         assert!(pjuri.extras.endpoint().ohttp().is_ok());
         assert_eq!(format!("{}", pjuri), uri);
     }
+
+    #[test]
+    fn test_case_insensitive_params() {
+        let mut url = Url::parse("https://example.com").unwrap();
+
+        let serialized = "OH1QYPM5JXYNS754Y4R45QWE336QFX6ZR8DQGVQCULVZTV20TFVEYDMFQC";
+        let ohttp_keys = OhttpKeys::from_str(serialized).unwrap();
+        url.set_ohttp(ohttp_keys.clone());
+
+        // Test lowercase parameter
+        let lowercase_url =
+            Url::parse(&format!("https://example.com#{}", serialized.to_lowercase())).unwrap();
+        assert_eq!(lowercase_url.ohttp().unwrap(), ohttp_keys);
+
+        // Test mixed case parameter
+        let mixed_case_url =
+            Url::parse(&format!("https://example.com#oh1{}", &serialized[3..])).unwrap();
+        assert_eq!(mixed_case_url.ohttp().unwrap(), ohttp_keys);
+    }
 }