Use Transfer.arena in a few more places, correctly set is_navigation on redirect

Following up to Request Interception PR (1) and Cookie Redirect PR (2) which
both introduced features that were useful to the other. This PR closes that
loop.

(1) #946
(2) #948

Author: karlseguin

src/cdp/domains/fetch.zig

@@ -244,21 +244,25 @@ fn continueRequest(cmd: anytype) !void {
         .new_url = params.url,
     });
 
+    const arena = transfer.arena.allocator();
     // Update the request with the new parameters
     if (params.url) |url| {
-        try transfer.updateURL(try page.arena.dupeZ(u8, url));
+        try transfer.updateURL(try arena.dupeZ(u8, url));
     }
     if (params.method) |method| {
         transfer.req.method = std.meta.stringToEnum(Http.Method, method) orelse return error.InvalidParams;
     }
 
     if (params.headers) |headers| {
+        // Not obvious, but cmd.arena is safe here, since the headers will get
+        // duped by libcurl. transfer.arena is more obvious/safe, but cmd.arena
+        // is more efficient (it's re-used)
         try transfer.replaceRequestHeaders(cmd.arena, headers);
     }
 
     if (params.postData) |b| {
         const decoder = std.base64.standard.Decoder;
-        const body = try bc.arena.alloc(u8, try decoder.calcSizeForSlice(b));
+        const body = try arena.alloc(u8, try decoder.calcSizeForSlice(b));
         try decoder.decode(body, b);
         transfer.req.body = body;
     }
@@ -304,7 +308,7 @@ fn fulfillRequest(cmd: anytype) !void {
     var body: ?[]const u8 = null;
     if (params.body) |b| {
         const decoder = std.base64.standard.Decoder;
-        const buf = try cmd.arena.alloc(u8, try decoder.calcSizeForSlice(b));
+        const buf = try transfer.arena.allocator().alloc(u8, try decoder.calcSizeForSlice(b));
         try decoder.decode(buf, b);
         body = buf;
     }

src/http/Client.zig

@@ -620,13 +620,16 @@ pub const Transfer = struct {
     // redirectionCookies manages cookies during redirections handled by Curl.
     // It sets the cookies from the current response to the cookie jar.
     // It also immediately sets cookies for the following request.
-    fn redirectionCookies(arena: Allocator, easy: *c.CURL, cookie_jar: *CookieJar, origin: *const std.Uri) !void {
+    fn redirectionCookies(transfer: *Transfer, easy: *c.CURL) !void {
+        const req = &transfer.req;
+        const arena = transfer.arena.allocator();
+
         // retrieve cookies from the redirect's response.
         var i: usize = 0;
         while (true) {
             const ct = getResponseHeader(easy, "set-cookie", i);
             if (ct == null) break;
-            try cookie_jar.populateFromResponse(origin, ct.?.value);
+            try req.cookie_jar.populateFromResponse(&transfer.uri, ct.?.value);
             i += 1;
             if (i >= ct.?.amount) break;
         }
@@ -644,10 +647,11 @@ pub const Transfer = struct {
         const uri = try std.Uri.parse(url);
 
         var cookies: std.ArrayListUnmanaged(u8) = .{};
-        try cookie_jar.forRequest(&uri, cookies.writer(arena), .{
+        try req.cookie_jar.forRequest(&uri, cookies.writer(arena), .{
             .is_http = true,
-            .is_navigation = true,
-            .origin_uri = origin,
+            .origin_uri = &transfer.uri,
+            // used to enforce samesite cookie rules
+            .is_navigation = req.resource_type == .document,
         });
         try cookies.append(arena, 0); //null terminate
         try errorCheck(c.curl_easy_setopt(easy, c.CURLOPT_COOKIE, @as([*c]const u8, @ptrCast(cookies.items.ptr))));
@@ -670,12 +674,7 @@ pub const Transfer = struct {
         if (transfer.response_header == null) {
             if (transfer._redirecting and buf_len == 2) {
                 // parse and set cookies for the redirection.
-                redirectionCookies(
-                    transfer.arena.allocator(),
-                    easy,
-                    transfer.req.cookie_jar,
-                    &transfer.uri,
-                ) catch |err| {
+                redirectionCookies(transfer, easy) catch |err| {
                     log.debug(.http, "redirection cookies", .{ .err = err });
                     return 0;
                 };