Implement CORS preflights for Expect-CT reports

chrome/browser/ssl/chrome_expect_ct_reporter.h

Index: chrome/browser/ssl/chrome_expect_ct_reporter.h
diff --git a/chrome/browser/ssl/chrome_expect_ct_reporter.h b/chrome/browser/ssl/chrome_expect_ct_reporter.h
index f45d9ad509c204c2faeac9706284c2e7f8404e65..bb07a527474ff033f382e8419e7de56bf07ed4ed 100644
--- a/chrome/browser/ssl/chrome_expect_ct_reporter.h
+++ b/chrome/browser/ssl/chrome_expect_ct_reporter.h
@@ -5,10 +5,12 @@
 #ifndef CHROME_BROWSER_SSL_CHROME_EXPECT_CT_REPORTER_H_
 #define CHROME_BROWSER_SSL_CHROME_EXPECT_CT_REPORTER_H_
 
+#include <map>
 #include <memory>
 
 #include "base/macros.h"
 #include "net/http/transport_security_state.h"
+#include "net/url_request/url_request.h"
 
 namespace net {
 class ReportSender;
@@ -19,8 +21,14 @@ class URLRequestContext;
 // about failures for sites that have opted in. Must be deleted before
 // the URLRequestContext that is passed to the constructor, so that it
 // can cancel its requests.
+//
+// Since reports are sent with a non-CORS-whitelisted Content-Type, this class
+// sends CORS preflight requests before sending reports. Expect-CT is not
+// evaluated with a particular frame or request as context, so the preflight
+// request contains an `Origin: null` header instead of a particular origin.
 class ChromeExpectCTReporter
-    : public net::TransportSecurityState::ExpectCTReporter {
+    : public net::TransportSecurityState::ExpectCTReporter,
+      net::URLRequest::Delegate {
  public:
   explicit ChromeExpectCTReporter(net::URLRequestContext* request_context);
   ~ChromeExpectCTReporter() override;
@@ -34,13 +42,54 @@ class ChromeExpectCTReporter
                         const net::SignedCertificateTimestampAndStatusList&
                             signed_certificate_timestamps) override;
 
+  // net::URLRequest::Delegate:
+  void OnResponseStarted(net::URLRequest* request, int net_error) override;
+  void OnReadCompleted(net::URLRequest* request, int bytes_read) override;
+
  private:
+  // Used to keep track of in-flight CORS preflight requests. When |request|
+  // completes successfully and the CORS check passes, |serialized_report| will
+  // be sent to |report_uri| using |report_sender_|.
+  struct PreflightInProgress {
+    PreflightInProgress(std::unique_ptr<net::URLRequest> request,
+                        const std::string& serialized_report,
+                        const GURL& report_uri);
+    ~PreflightInProgress();
+    // The preflight request.
+    const std::unique_ptr<net::URLRequest> request;
+    // |serialized_report| should be sent to |report_uri| if the preflight
+    // succeeds.
+    const std::string serialized_report;
+    const GURL report_uri;
+  };
+
   FRIEND_TEST_ALL_PREFIXES(ChromeExpectCTReporterTest, FeatureDisabled);
   FRIEND_TEST_ALL_PREFIXES(ChromeExpectCTReporterTest, EmptyReportURI);
   FRIEND_TEST_ALL_PREFIXES(ChromeExpectCTReporterTest, SendReport);
+  FRIEND_TEST_ALL_PREFIXES(ChromeExpectCTReporterTest,
+                           BadCORSPreflightResponseOrigin);
+  FRIEND_TEST_ALL_PREFIXES(ChromeExpectCTReporterTest,
+                           BadCORSPreflightResponseMethods);
+  FRIEND_TEST_ALL_PREFIXES(ChromeExpectCTReporterTest,
+                           BadCORSPreflightResponseHeaders);
+
+  // Starts a CORS preflight request to obtain permission from the server to
+  // send a report with Content-Type: application/expect-ct-report+json. The
+  // preflight result is checked in OnResponseStarted(), and an actual report is
+  // sent with |report_sender_| if the preflight succeeds.
+  void SendPreflight(const GURL& report_uri,
+                     const std::string& serialized_report);
 
   std::unique_ptr<net::ReportSender> report_sender_;
 
+  net::URLRequestContext* request_context_;
+
+  // The CORS preflight requests, with corresponding report information, that
+  // are currently in-flight. Entries in this map are deleted when the
+  // preflight's OnResponseStarted() is called.
+  std::map<net::URLRequest*, std::unique_ptr<PreflightInProgress>>
+      inflight_preflights_;
+
   DISALLOW_COPY_AND_ASSIGN(ChromeExpectCTReporter);
 };