From b079595f2e903b820a027a68ea5c4c1e6697038b Mon Sep 17 00:00:00 2001
From: Daniel Stenberg <daniel@haxx.se>
Date: Wed, 13 May 2026 10:35:02 +0200
Subject: [PATCH] url: keep the question mark for empty queries

Reported-by: Bill Mill
Fixes #21544

Verified by test 1721

Closes #21584
---
 lib/url.c              |  5 +++--
 tests/data/Makefile.am |  2 +-
 tests/data/test1721    | 45 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 49 insertions(+), 3 deletions(-)
 create mode 100644 tests/data/test1721

diff --git a/lib/url.c b/lib/url.c
index bcd8f54aa8..ff1a9fd450 100644
--- a/lib/url.c
+++ b/lib/url.c
@@ -1543,7 +1543,7 @@ static CURLcode parseurlandfillconn(struct Curl_easy *data,
     }
 
     /* after it was parsed, get the generated normalized version */
-    uc = curl_url_get(uh, CURLUPART_URL, &newurl, 0);
+    uc = curl_url_get(uh, CURLUPART_URL, &newurl, CURLU_GET_EMPTY);
     if(uc) {
       result = Curl_uc_to_curlcode(uc);
       goto out;
@@ -1600,7 +1600,8 @@ static CURLcode parseurlandfillconn(struct Curl_easy *data,
     goto out;
   }
 
-  uc = curl_url_get(uh, CURLUPART_QUERY, &data->state.up.query, 0);
+  uc = curl_url_get(uh, CURLUPART_QUERY, &data->state.up.query,
+                    CURLU_GET_EMPTY);
   if(uc && (uc != CURLUE_NO_QUERY)) {
     result = CURLE_OUT_OF_MEMORY;
     goto out;
diff --git a/tests/data/Makefile.am b/tests/data/Makefile.am
index b63c9c06a0..3f520af253 100644
--- a/tests/data/Makefile.am
+++ b/tests/data/Makefile.am
@@ -228,7 +228,7 @@ test1680 test1681 test1682 test1683 test1684 test1685 \
 \
 test1700 test1701 test1702 test1703 test1704 test1705 test1706 test1707 \
 test1708 test1709 test1710 test1711 test1712 test1713 test1714 test1715 \
-test1720 \
+test1720 test1721 \
 \
 test1800 test1801 test1802 test1847 test1848 test1849 test1850 test1851 \
 \
diff --git a/tests/data/test1721 b/tests/data/test1721
new file mode 100644
index 0000000000..1b0e7a88f7
--- /dev/null
+++ b/tests/data/test1721
@@ -0,0 +1,45 @@
+<?xml version="1.0" encoding="US-ASCII"?>
+<testcase>
+<info>
+<keywords>
+HTTP
+HTTP GET
+</keywords>
+</info>
+
+<reply>
+<data crlf="headers">
+HTTP/1.1 200 OK
+Content-Length: 6
+Content-Type: text/html
+
+-foo-
+</data>
+</reply>
+
+<client>
+<server>
+http
+</server>
+<name>
+Keep question mark for empty query
+</name>
+<command>
+"http://%HOSTIP:%HTTPPORT/hello?" -w '%output{%LOGDIR/out%TESTNUMBER}%{url_effective}'
+</command>
+</client>
+
+# Verify data after the test has been "shot"
+<verify>
+<file nonewline="yes" name="%LOGDIR/out%TESTNUMBER">
+http://%HOSTIP:%HTTPPORT/hello?
+</file>
+<protocol crlf="headers">
+GET /hello? HTTP/1.1
+Host: %HOSTIP:%HTTPPORT
+User-Agent: curl/%VERSION
+Accept: */*
+
+</protocol>
+</verify>
+</testcase>