Implement Network.getResponseBody

karlseguin · karlseguin · commit cd33e9ad0eea · 2025-08-21T10:33:53.000+08:00
Add response_data event, CDP now captures the full body so that it can respond
to the Network.getResponseBody. This isn't memory efficient, but I don't see
another way to do it. At least this way, it's only capturing/storing every
response body when (a) CDP is used and (b) Network.enabled is called. That is,
as opposed to baking this into Http/Client.zig, which would force the memory
consumption for all use-cases.

There's arguably some optimizations we could make for XHR requests, which also
dupe/own the response. As of now, the response is dupe'd separately for CDP
and XHR.
diff --git a/src/cdp/cdp.zig b/src/cdp/cdp.zig
@@ -344,6 +344,15 @@ pub fn BrowserContext(comptime CDP_T: type) type {
 
         intercept_state: InterceptState,
 
+        // When network is enabled, we'll capture the transfer.id -> body
+        // This is awfully memory intensive, but our underlying http client and
+        // its users (script manager and page) correctly do not hold the body
+        // memory longer than they have to. In fact, the main request is only
+        // ever streamed. So if CDP is the only thing that needs bodies in
+        // memory for an arbitrary amount of time, then that's where we're going
+        // to store the,
+        captured_responses: std.AutoHashMapUnmanaged(usize, std.ArrayListUnmanaged(u8)),
+
         const Self = @This();
 
         fn init(self: *Self, id: []const u8, cdp: *CDP_T) !void {
@@ -374,6 +383,7 @@ pub fn BrowserContext(comptime CDP_T: type) type {
                 .inspector = inspector,
                 .notification_arena = cdp.notification_arena.allocator(),
                 .intercept_state = try InterceptState.init(allocator),
+                .captured_responses = .empty,
             };
             self.node_search_list = Node.Search.List.init(allocator, &self.node_registry);
             errdefer self.deinit();
@@ -454,15 +464,17 @@ pub fn BrowserContext(comptime CDP_T: type) type {
         pub fn networkEnable(self: *Self) !void {
             try self.cdp.browser.notification.register(.http_request_fail, self, onHttpRequestFail);
             try self.cdp.browser.notification.register(.http_request_start, self, onHttpRequestStart);
-            try self.cdp.browser.notification.register(.http_headers_done, self, onHttpHeadersDone);
             try self.cdp.browser.notification.register(.http_request_done, self, onHttpRequestDone);
+            try self.cdp.browser.notification.register(.http_response_data, self, onHttpResponseData);
+            try self.cdp.browser.notification.register(.http_response_header_done, self, onHttpResponseHeadersDone);
         }
 
         pub fn networkDisable(self: *Self) void {
             self.cdp.browser.notification.unregister(.http_request_fail, self);
             self.cdp.browser.notification.unregister(.http_request_start, self);
-            self.cdp.browser.notification.unregister(.http_headers_done, self);
             self.cdp.browser.notification.unregister(.http_request_done, self);
+            self.cdp.browser.notification.unregister(.http_response_data, self);
+            self.cdp.browser.notification.unregister(.http_response_header_done, self);
         }
 
         pub fn fetchEnable(self: *Self) !void {
@@ -483,45 +495,57 @@ pub fn BrowserContext(comptime CDP_T: type) type {
             return @import("domains/page.zig").pageCreated(self, page);
         }
 
-        pub fn onPageNavigate(ctx: *anyopaque, data: *const Notification.PageNavigate) !void {
+        pub fn onPageNavigate(ctx: *anyopaque, msg: *const Notification.PageNavigate) !void {
             const self: *Self = @alignCast(@ptrCast(ctx));
             defer self.resetNotificationArena();
-            return @import("domains/page.zig").pageNavigate(self.notification_arena, self, data);
+            return @import("domains/page.zig").pageNavigate(self.notification_arena, self, msg);
         }
 
-        pub fn onPageNavigated(ctx: *anyopaque, data: *const Notification.PageNavigated) !void {
+        pub fn onPageNavigated(ctx: *anyopaque, msg: *const Notification.PageNavigated) !void {
             const self: *Self = @alignCast(@ptrCast(ctx));
-            return @import("domains/page.zig").pageNavigated(self, data);
+            return @import("domains/page.zig").pageNavigated(self, msg);
         }
 
-        pub fn onHttpRequestStart(ctx: *anyopaque, data: *const Notification.RequestStart) !void {
+        pub fn onHttpRequestStart(ctx: *anyopaque, msg: *const Notification.RequestStart) !void {
             const self: *Self = @alignCast(@ptrCast(ctx));
             defer self.resetNotificationArena();
-            try @import("domains/network.zig").httpRequestStart(self.notification_arena, self, data);
+            try @import("domains/network.zig").httpRequestStart(self.notification_arena, self, msg);
         }
 
-        pub fn onHttpRequestIntercept(ctx: *anyopaque, data: *const Notification.RequestIntercept) !void {
+        pub fn onHttpRequestIntercept(ctx: *anyopaque, msg: *const Notification.RequestIntercept) !void {
             const self: *Self = @alignCast(@ptrCast(ctx));
             defer self.resetNotificationArena();
-            try @import("domains/fetch.zig").requestIntercept(self.notification_arena, self, data);
+            try @import("domains/fetch.zig").requestIntercept(self.notification_arena, self, msg);
         }
 
-        pub fn onHttpRequestFail(ctx: *anyopaque, data: *const Notification.RequestFail) !void {
+        pub fn onHttpRequestFail(ctx: *anyopaque, msg: *const Notification.RequestFail) !void {
             const self: *Self = @alignCast(@ptrCast(ctx));
             defer self.resetNotificationArena();
-            return @import("domains/network.zig").httpRequestFail(self.notification_arena, self, data);
+            return @import("domains/network.zig").httpRequestFail(self.notification_arena, self, msg);
         }
 
-        pub fn onHttpHeadersDone(ctx: *anyopaque, data: *const Notification.ResponseHeadersDone) !void {
+        pub fn onHttpResponseHeadersDone(ctx: *anyopaque, msg: *const Notification.ResponseHeaderDone) !void {
             const self: *Self = @alignCast(@ptrCast(ctx));
             defer self.resetNotificationArena();
-            return @import("domains/network.zig").httpHeadersDone(self.notification_arena, self, data);
+            return @import("domains/network.zig").httpResponseHeaderDone(self.notification_arena, self, msg);
         }
 
-        pub fn onHttpRequestDone(ctx: *anyopaque, data: *const Notification.RequestDone) !void {
+        pub fn onHttpRequestDone(ctx: *anyopaque, msg: *const Notification.RequestDone) !void {
             const self: *Self = @alignCast(@ptrCast(ctx));
             defer self.resetNotificationArena();
-            return @import("domains/network.zig").httpRequestDone(self.notification_arena, self, data);
+            return @import("domains/network.zig").httpRequestDone(self.notification_arena, self, msg);
+        }
+
+        pub fn onHttpResponseData(ctx: *anyopaque, msg: *const Notification.ResponseData) !void {
+            const self: *Self = @alignCast(@ptrCast(ctx));
+            const arena = self.arena;
+
+            const id = msg.transfer.id;
+            const gop = try self.captured_responses.getOrPut(arena, id);
+            if (!gop.found_existing) {
+                gop.value_ptr.* = .{};
+            }
+            try gop.value_ptr.appendSlice(arena, try arena.dupe(u8, msg.data));
         }
 
         fn resetNotificationArena(self: *Self) void {
diff --git a/src/cdp/domains/network.zig b/src/cdp/domains/network.zig
@@ -54,16 +54,6 @@ pub fn processMessage(cmd: anytype) !void {
     }
 }
 
-const Response = struct {
-    status: u16,
-    headers: std.StringArrayHashMapUnmanaged([]const u8) = .empty,
-    // These may not be complete yet, but we only tell the client
-    // Network.responseReceived when all the headers are in.
-    // Later should store body as well to support getResponseBody which should
-    // only work once Network.loadingFinished is sent but the body itself would
-    // be loaded with each chunks as Network.dataReceiveds are coming in.
-};
-
 fn enable(cmd: anytype) !void {
     const bc = cmd.browser_context orelse return error.BrowserContextNotLoaded;
     try bc.networkEnable();
@@ -209,15 +199,17 @@ fn getResponseBody(cmd: anytype) !void {
         requestId: []const u8, // "REQ-{d}"
     })) orelse return error.InvalidParams;
 
-    _ = params;
+    const request_id = try idFromRequestId(params.requestId);
+    const bc = cmd.browser_context orelse return error.BrowserContextNotLoaded;
+    const buf = bc.captured_responses.getPtr(request_id) orelse return error.RequestNotFound;
 
     try cmd.sendResult(.{
-        .body = "TODO",
+        .body = buf.items,
         .base64Encoded = false,
     }, .{});
 }
 
-pub fn httpRequestFail(arena: Allocator, bc: anytype, data: *const Notification.RequestFail) !void {
+pub fn httpRequestFail(arena: Allocator, bc: anytype, msg: *const Notification.RequestFail) !void {
     // It's possible that the request failed because we aborted when the client
     // sent Target.closeTarget. In that case, bc.session_id will be cleared
     // already, and we can skip sending these messages to the client.
@@ -229,15 +221,15 @@ pub fn httpRequestFail(arena: Allocator, bc: anytype, data: *const Notification.
 
     // We're missing a bunch of fields, but, for now, this seems like enough
     try bc.cdp.sendEvent("Network.loadingFailed", .{
-        .requestId = try std.fmt.allocPrint(arena, "REQ-{d}", .{data.transfer.id}),
+        .requestId = try std.fmt.allocPrint(arena, "REQ-{d}", .{msg.transfer.id}),
         // Seems to be what chrome answers with. I assume it depends on the type of error?
         .type = "Ping",
-        .errorText = data.err,
+        .errorText = msg.err,
         .canceled = false,
     }, .{ .session_id = session_id });
 }
 
-pub fn httpRequestStart(arena: Allocator, bc: anytype, data: *const Notification.RequestStart) !void {
+pub fn httpRequestStart(arena: Allocator, bc: anytype, msg: *const Notification.RequestStart) !void {
     // Isn't possible to do a network request within a Browser (which our
     // notification is tied to), without a page.
     std.debug.assert(bc.session.page != null);
@@ -251,15 +243,15 @@ pub fn httpRequestStart(arena: Allocator, bc: anytype, data: *const Notification
 
     // Modify request with extra CDP headers
     for (bc.extra_headers.items) |extra| {
-        try data.transfer.req.headers.add(extra);
+        try msg.transfer.req.headers.add(extra);
     }
 
-    const transfer = data.transfer;
+    const transfer = msg.transfer;
     // We're missing a bunch of fields, but, for now, this seems like enough
     try cdp.sendEvent("Network.requestWillBeSent", .{ .requestId = try std.fmt.allocPrint(arena, "REQ-{d}", .{transfer.id}), .frameId = target_id, .loaderId = bc.loader_id, .documentUrl = DocumentUrlWriter.init(&page.url.uri), .request = TransferAsRequestWriter.init(transfer) }, .{ .session_id = session_id });
 }
 
-pub fn httpHeadersDone(arena: Allocator, bc: anytype, data: *const Notification.ResponseHeadersDone) !void {
+pub fn httpResponseHeaderDone(arena: Allocator, bc: anytype, msg: *const Notification.ResponseHeaderDone) !void {
     // Isn't possible to do a network request within a Browser (which our
     // notification is tied to), without a page.
     std.debug.assert(bc.session.page != null);
@@ -272,14 +264,14 @@ pub fn httpHeadersDone(arena: Allocator, bc: anytype, data: *const Notification.
 
     // We're missing a bunch of fields, but, for now, this seems like enough
     try cdp.sendEvent("Network.responseReceived", .{
-        .requestId = try std.fmt.allocPrint(arena, "REQ-{d}", .{data.transfer.id}),
+        .requestId = try std.fmt.allocPrint(arena, "REQ-{d}", .{msg.transfer.id}),
         .loaderId = bc.loader_id,
         .frameId = target_id,
-        .response = TransferAsResponseWriter.init(data.transfer),
+        .response = TransferAsResponseWriter.init(msg.transfer),
     }, .{ .session_id = session_id });
 }
 
-pub fn httpRequestDone(arena: Allocator, bc: anytype, data: *const Notification.RequestDone) !void {
+pub fn httpRequestDone(arena: Allocator, bc: anytype, msg: *const Notification.RequestDone) !void {
     // Isn't possible to do a network request within a Browser (which our
     // notification is tied to), without a page.
     std.debug.assert(bc.session.page != null);
@@ -290,8 +282,8 @@ pub fn httpRequestDone(arena: Allocator, bc: anytype, data: *const Notification.
     const session_id = bc.session_id orelse unreachable;
 
     try cdp.sendEvent("Network.loadingFinished", .{
-        .requestId = try std.fmt.allocPrint(arena, "REQ-{d}", .{data.transfer.id}),
-        .encodedDataLength = data.transfer.bytes_received,
+        .requestId = try std.fmt.allocPrint(arena, "REQ-{d}", .{msg.transfer.id}),
+        .encodedDataLength = msg.transfer.bytes_received,
     }, .{ .session_id = session_id });
 }
 
@@ -439,6 +431,13 @@ const DocumentUrlWriter = struct {
     }
 };
 
+fn idFromRequestId(request_id: []const u8) !u64 {
+    if (!std.mem.startsWith(u8, request_id, "REQ-")) {
+        return error.InvalidParams;
+    }
+    return std.fmt.parseInt(u64, request_id[4..], 10) catch return error.InvalidParams;
+}
+
 const testing = @import("../testing.zig");
 test "cdp.network setExtraHTTPHeaders" {
     var ctx = testing.context();
diff --git a/src/http/Client.zig b/src/http/Client.zig
@@ -757,7 +757,7 @@ pub const Transfer = struct {
             };
 
             if (transfer.client.notification) |notification| {
-                notification.dispatch(.http_headers_done, &.{
+                notification.dispatch(.http_response_header_done, &.{
                     .transfer = transfer,
                 });
             }
@@ -780,10 +780,19 @@ pub const Transfer = struct {
         }
 
         transfer.bytes_received += chunk_len;
-        transfer.req.data_callback(transfer, buffer[0..chunk_len]) catch |err| {
+        const chunk = buffer[0..chunk_len];
+        transfer.req.data_callback(transfer, chunk) catch |err| {
             log.err(.http, "data_callback", .{ .err = err, .req = transfer });
             return c.CURL_WRITEFUNC_ERROR;
         };
+
+        if (transfer.client.notification) |notification| {
+            notification.dispatch(.http_response_data, &.{
+                .data = chunk,
+                .transfer = transfer,
+            });
+        }
+
         return chunk_len;
     }
 
diff --git a/src/notification.zig b/src/notification.zig
@@ -63,8 +63,9 @@ pub const Notification = struct {
         http_request_fail: List = .{},
         http_request_start: List = .{},
         http_request_intercept: List = .{},
-        http_headers_done: List = .{},
         http_request_done: List = .{},
+        http_response_data: List = .{},
+        http_response_header_done: List = .{},
         notification_created: List = .{},
     };
 
@@ -76,8 +77,9 @@ pub const Notification = struct {
         http_request_fail: *const RequestFail,
         http_request_start: *const RequestStart,
         http_request_intercept: *const RequestIntercept,
-        http_headers_done: *const ResponseHeadersDone,
         http_request_done: *const RequestDone,
+        http_response_data: *const ResponseData,
+        http_response_header_done: *const ResponseHeaderDone,
         notification_created: *Notification,
     };
     const EventType = std.meta.FieldEnum(Events);
@@ -104,7 +106,12 @@ pub const Notification = struct {
         wait_for_interception: *bool,
     };
 
-    pub const ResponseHeadersDone = struct {
+    pub const ResponseData = struct {
+        data: []const u8,
+        transfer: *Transfer,
+    };
+
+    pub const ResponseHeaderDone = struct {
         transfer: *Transfer,
     };
 
