DevTools protocol interception, blocking & modification of requests

third_party/WebKit/Source/core/inspector/browser_protocol.json

 {
     "version": { "major": "1", "minor": "2" },
     "domains": [{
         "domain": "Inspector",
         "experimental": true,
         "types": [],
         "commands": [
             {
                 "name": "enable",
                 "description": "Enables inspector domain notifications."
@@ skipping 1094 matching lines @@
                 "id": "LoaderId",
                 "type": "string",
                 "description": "Unique loader identifier."
             },
             {
                 "id": "RequestId",
                 "type": "string",
                 "description": "Unique request identifier."
             },
             {
+                "id": "InterceptId",

[dgozman, 2017/05/22 22:27:04]

InterceptionId ?

[alex clarke (OOO till 29th), 2017/05/23 15:46:56]

Done.

+                "type": "string",
+                "description": "Unique intercepted request identifier."
+            },
+            {
+                "id": "ErrorReason",
+                "type": "string",
+                "enum": ["Failed", "Aborted", "TimedOut", "AccessDenied", "ConnectionClosed", "ConnectionReset", "ConnectionRefused", "ConnectionAborted", "ConnectionFailed", "NameNotResolved", "InternetDisconnected", "AddressUnreachable"],
+                "description": "Network level fetch failure reason."
+            },
+            {
                 "id": "Timestamp",
                 "type": "number",
                 "description": "Number of seconds since epoch."
             },
             {
                 "id": "Headers",
                 "type": "object",
                 "description": "Request / response headers as keys / values of JSON object."
             },
             {
@@ skipping 363 matching lines @@
             {
                 "name": "getCertificate",
                 "description": "Returns the DER-encoded certificate.",
                 "parameters": [
                     { "name": "origin", "type": "string", "description": "Origin to get certificate for." }
                 ],
                 "returns": [
                     { "name": "tableNames", "type": "array", "items": { "type": "string" } }
                 ],
                 "experimental": true
+            },
+            {
+                "name": "enableFetchInterception",
+                "parameters": [
+                    { "name": "enabled", "type": "boolean", "description": "Whether or not HTTP requests should be intercepted and Network.interceptedRequest events sent." }
+                ],
+                "experimental": true
+            },
+            {
+                "name": "allowRequest",
+                "description": "Response to Network.interceptedRequest which allows the request to proceed unchanged.",
+                "parameters": [
+                    { "name": "interceptId", "$ref": "InterceptId" }
+                ],
+                "experimental": true
+            },
+            {
+                "name": "blockRequest",
+                "description": "Response to Network.interceptedRequest which causes the request to fail.",
+                "parameters": [
+                    { "name": "interceptId", "$ref": "InterceptId" },
+                    { "name": "errorReason", "$ref": "ErrorReason" }
+                ],
+                "experimental": true
+            },
+            {
+                "name": "modifyRequest",

[dgozman, 2017/05/22 22:27:04]

What do you think about converging these methods into one?

continueRequest: {
  interceptId,
  errorReason,  // finish with error
  rawResponse,  // finish with response
  url, method, postData, headers  // optionally modify before sending to network
}

[alex clarke (OOO till 29th), 2017/05/23 15:46:56]

I guess it cuts down on the plumbing slightly.  Slightly less readable perhaps? 
Anyway it's done now.

+                "description": "Response to Network.interceptedRequest which modifies any or all fetch parameters before allowing the request to proceed.",
+                "parameters": [
+                    { "name": "interceptId", "$ref": "InterceptId" },
+                    { "name": "url", "type": "string", "optional": true },
+                    { "name": "method", "type": "string", "optional": true },
+                    { "name": "postData", "type": "string", "optional": true },
+                    { "name": "headers", "$ref": "Headers", "optional": true }
+                ],
+                "experimental": true
+            },
+            {
+                "name": "mockResponse",
+                "description": "Response to Network.interceptedRequest which makes the request complete with the provided mock response.",
+                "parameters": [
+                    { "name": "interceptId", "$ref": "InterceptId" },
+                    { "name": "rawResponse", "type": "string" }

[dgozman, 2017/05/22 22:27:04]

Is this base64-encoded?

[alex clarke (OOO till 29th), 2017/05/23 15:46:56]

Done.

+                ],
+                "experimental": true
             }
         ],
         "events": [
             {
                 "name": "resourceChangedPriority",
                 "description": "Fired when resource loading priority is changed",
                 "parameters": [
                     { "name": "requestId", "$ref": "RequestId", "description": "Request identifier." },
                     { "name": "newPriority", "$ref": "ResourcePriority", "description": "New priority" },
                     { "name": "timestamp", "$ref": "Timestamp", "description": "Timestamp." }
@@ skipping 140 matching lines @@
                 "name": "eventSourceMessageReceived",
                 "description": "Fired when EventSource message is received.",
                 "parameters": [
                     { "name": "requestId", "$ref": "RequestId", "description": "Request identifier." },
                     { "name": "timestamp", "$ref": "Timestamp", "description": "Timestamp." },
                     { "name": "eventName", "type": "string", "description": "Message type." },
                     { "name": "eventId", "type": "string", "description": "Message identifier." },
                     { "name": "data", "type": "string", "description": "Message content." }
                 ],
                 "experimental": true
+            },
+            {
+                "name": "interceptedRequest",

[dgozman, 2017/05/22 22:27:04]

We usually name events with noun first: requestIntercepted.

[alex clarke (OOO till 29th), 2017/05/23 15:46:56]

Done.

+                "description": "Details of an intercepted HTTP request, which must be either allowed, blocked, modified or mocked.",
+                "parameters": [
+                    { "name": "interceptId", "$ref": "InterceptId" },
+                    { "name": "request", "$ref": "Request" }
+                ],
+                "experimental": true 
+            },
+            {
+                "name": "interceptedRedirect",
+                "description": "Details of an intercepted HTTP redirect, which must be either allowed, blocked, modified or mocked.",
+                "parameters": [
+                    { "name": "interceptId", "$ref": "InterceptId" },

[dgozman, 2017/05/22 22:27:04]

Is this the same id as original request? Would it be easier to generate new id
and include original request to event? Something like:

requestIntercepted {
  interceptId,
  request,
  optional redirectUrl,
  optional redirectResponseHeaders,
  optional redirectStatusCode
}

[alex clarke (OOO till 29th), 2017/05/23 15:46:56]

I've merged them but not tried to generate a new id yet.  It would simplify
DevToolsURLRequestInterceptor::State a little bit to generate a new one but I'm
wondering if we're just shifting complexity over to the caller.  WDYT? 

+                    { "name": "responseHeaders", "$ref": "Headers", "description": "HTTP response headers." },
+                    { "name": "responseStatusCode", "type": "integer", "description": "HTTP response code."},
+                    { "name": "redirectUrl", "type": "string" }
+                ],
+                "experimental": true 
             }
         ]
     },
     {
         "domain": "Database",
         "experimental": true,
         "types": [
             {
                 "id": "DatabaseId",
                 "type": "string",
@@ skipping 3004 matching lines @@
                 "parameters": [
                     { "name": "windowId", "$ref": "WindowID", "description": "Browser window id." }
                 ],
                 "returns": [
                     { "name": "bounds", "$ref": "Bounds", "description": "Bounds information of the window. When window state is 'minimized', the restored window position and size are returned." }
                 ]
             }
         ]
     }]
 }