fix(cli/fetch): fix relative redirect (#6715)

cli/js/web/fetch.ts

@@ -342,11 +342,7 @@ export async function fetch(
             !redirectUrl.startsWith("http://") &&
             !redirectUrl.startsWith("https://")
           ) {
-            redirectUrl =
-              url.split("//")[0] +
-              "//" +
-              url.split("//")[1].split("/")[0] +
-              redirectUrl; // TODO: handle relative redirection more gracefully
+            redirectUrl = new URL(redirectUrl, url).href;
           }
           url = redirectUrl;
           redirected = true;

cli/tests/unit/fetch_test.ts

@@ -335,6 +335,27 @@ unitTest(
   }
 );
 
+unitTest(
+  {
+    perms: { net: true },
+  },
+  async function fetchWithRelativeRedirectionUrl(): Promise<void> {
+    const cases = [
+      ["end", "http://localhost:4550/a/b/end"],
+      ["/end", "http://localhost:4550/end"],
+    ];
+    for (const [loc, redUrl] of cases) {
+      const response = await fetch("http://localhost:4550/a/b/c", {
+        headers: new Headers([["x-location", loc]]),
+      });
+      assertEquals(response.url, redUrl);
+      assertEquals(response.redirected, true);
+      assertEquals(response.status, 404);
+      assertEquals(await response.text(), "");
+    }
+  }
+);
+
 unitTest(
   {
     perms: { net: true },

cli/tests/unit/url_test.ts

@@ -240,6 +240,19 @@ unitTest(function urlBaseURL(): void {
   );
   const url = new URL("/foo/bar?baz=foo#qux", base);
   assertEquals(url.href, "https://foo:bar@baz.qat:8000/foo/bar?baz=foo#qux");
+
+  assertEquals(
+    new URL("D", "https://foo.bar/path/a/b/c/d").href,
+    "https://foo.bar/path/a/b/c/D"
+  );
+
+  assertEquals(new URL("D", "https://foo.bar").href, "https://foo.bar/D");
+  assertEquals(new URL("D", "https://foo.bar/").href, "https://foo.bar/D");
+
+  assertEquals(
+    new URL("/d", "https://foo.bar/path/a/b/c/d").href,
+    "https://foo.bar/d"
+  );
 });
 
 unitTest(function urlBaseString(): void {

test_util/src/lib.rs

@@ -146,6 +146,14 @@ pub async fn run_all_servers() {
       let u = url.parse::<Uri>().unwrap();
       warp::redirect(u)
     })
+    .or(
+      warp::path!("a" / "b" / "c")
+        .and(warp::header::<String>("x-location"))
+        .map(|token: String| {
+          let uri: Uri = token.parse().unwrap();
+          warp::redirect(uri)
+        }),
+    )
     .or(
       warp::any()
         .and(warp::path::peek())