From 1f024ecfcdc248214c5b4ad8f7b1c8a959fd522c Mon Sep 17 00:00:00 2001
From: Bryan Honof <bryanhonof@gmail.com>
Date: Mon, 30 Sep 2024 14:42:47 +0200
Subject: [PATCH] fix: warn on malformed URI query parameter

---
 src/libflake/flake/flakeref.cc |  2 +-
 src/libutil/url.cc             | 12 ++++++++----
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/src/libflake/flake/flakeref.cc b/src/libflake/flake/flakeref.cc
index a57fce9f3..01fe747f9 100644
--- a/src/libflake/flake/flakeref.cc
+++ b/src/libflake/flake/flakeref.cc
@@ -88,7 +88,7 @@ std::pair<FlakeRef, std::string> parsePathFlakeRefWithFragment(
     if (fragmentStart != std::string::npos) {
         fragment = percentDecode(url.substr(fragmentStart+1));
     }
-    if (pathEnd != std::string::npos && fragmentStart != std::string::npos) {
+    if (pathEnd != std::string::npos && fragmentStart != std::string::npos && url[pathEnd] == '?') {
         query = decodeQuery(url.substr(pathEnd+1, fragmentStart-pathEnd-1));
     }
 
diff --git a/src/libutil/url.cc b/src/libutil/url.cc
index bcbe9ea4e..9ed49dcbe 100644
--- a/src/libutil/url.cc
+++ b/src/libutil/url.cc
@@ -79,10 +79,14 @@ std::map<std::string, std::string> decodeQuery(const std::string & query)
 
     for (auto s : tokenizeString<Strings>(query, "&")) {
         auto e = s.find('=');
-        if (e != std::string::npos)
-            result.emplace(
-                s.substr(0, e),
-                percentDecode(std::string_view(s).substr(e + 1)));
+        if (e == std::string::npos) {
+            warn("dubious URI query '%s' is missing equal sign '%s', ignoring", s, "=");
+            continue;
+        }
+
+        result.emplace(
+            s.substr(0, e),
+            percentDecode(std::string_view(s).substr(e + 1)));
     }
 
     return result;