fix regex handling for URLs containing newline characters (%0A) (remix-run#13490)

Author: rururux

packages/react-router/__tests__/matchPath-test.tsx

@@ -355,6 +355,17 @@ describe("matchPath *", () => {
       pathnameBase: "/users/foo*",
     });
   });
+
+  it("matches a URL with %0A (a newline character)", () => {
+    expect(matchPath("*", "/%0A")).toMatchObject({
+      pathname: "/%0A",
+      pathnameBase: "/",
+    })
+    expect(matchPath("*", "/new%0Aline")).toMatchObject({
+      pathname: "/new%0Aline",
+      pathnameBase: "/",
+    })
+  })
 });
 
 describe("matchPath warnings", () => {

packages/react-router/__tests__/matchRoutes-test.tsx

@@ -65,6 +65,11 @@ describe("matchRoutes", () => {
     expect(pickPaths(routes, "/hometypo")).toEqual(["*"]);
   });
 
+  it("matches root * routes for URLs containing %0A (a newline character)", () => {
+    expect(pickPaths(routes, "/%0A")).toEqual(["*"]);
+    expect(pickPaths(routes, "/new%0Aline")).toEqual(["*"]);
+  });
+
   it("matches index routes with path correctly", () => {
     expect(pickPaths(routes, "/withpath")).toEqual(["/withpath"]);
   });

packages/react-router/lib/router/utils.ts

@@ -1255,6 +1255,9 @@ export function compilePath(
           return isOptional ? "/?([^\\/]+)?" : "/([^\\/]+)";
         }
       );
+  // If the URL contains %0A (a newline character),
+  // the regular expression will not match correctly unless the s (single line) flag is set.
+  let regexpFlags = ["s"];
 
   if (path.endsWith("*")) {
     params.push({ paramName: "*" });
@@ -1278,7 +1281,9 @@ export function compilePath(
     // Nothing to match for "" or "/"
   }
 
-  let matcher = new RegExp(regexpSource, caseSensitive ? undefined : "i");
+  if (!caseSensitive) regexpFlags.push("i");
+
+  let matcher = new RegExp(regexpSource, regexpFlags.join(""));
 
   return [matcher, params];
 }