Fix the tests for the fuzzer mode.

It's useful to make sure our fuzzer mode works. Not all tests pass, but most
do. (Notably the negative tests for everything we've disabled don't work.) We
can also use then use runner to record fuzzer-mode transcripts with the ciphers
correctly nulled.

Change-Id: Ie41230d654970ce6cf612c0a9d3adf01005522c6
Reviewed-on: https://boringssl-review.googlesource.com/7288
Reviewed-by: Adam Langley <agl@google.com>

CMakeLists.txt

@@ -97,6 +97,7 @@ if(FUZZ)
   endif()
 
   add_definitions(-DBORINGSSL_UNSAFE_FUZZER_MODE)
+  set(RUNNER_ARGS "-fuzzer")
 
   set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fsanitize=address -fsanitize-coverage=edge,indirect-calls")
   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fsanitize=address -fsanitize-coverage=edge,indirect-calls")
@@ -186,6 +187,7 @@ add_custom_target(
             ${CMAKE_BINARY_DIR}
     COMMAND cd ssl/test/runner
     COMMAND ${GO_EXECUTABLE} test -shim-path $<TARGET_FILE:bssl_shim>
+            ${RUNNER_ARGS}
     WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
     DEPENDS all_tests bssl_shim
     ${MAYBE_USES_TERMINAL})

ssl/test/runner/common.go

@@ -822,6 +822,10 @@ type ProtocolBugs struct {
 	// RequireSessionTickets, if true, causes the client to require new
 	// sessions use session tickets instead of session IDs.
 	RequireSessionTickets bool
+
+	// NullAllCiphers, if true, causes every cipher to behave like the null
+	// cipher.
+	NullAllCiphers bool
 }
 
 func (c *Config) serverInit() {

ssl/test/runner/conn.go

@@ -189,6 +189,11 @@ func (hc *halfConn) changeCipherSpec(config *Config) error {
 	hc.nextMac = nil
 	hc.config = config
 	hc.incEpoch()
+
+	if config.Bugs.NullAllCiphers {
+		hc.cipher = nil
+		hc.mac = nil
+	}
 	return nil
 }
 

ssl/test/runner/runner.go

@@ -37,6 +37,7 @@ var (
 	numWorkers      = flag.Int("num-workers", runtime.NumCPU(), "The number of workers to run in parallel.")
 	shimPath        = flag.String("shim-path", "../../../build/ssl/test/bssl_shim", "The location of the shim binary.")
 	resourceDir     = flag.String("resource-dir", ".", "The directory in which to find certificate and key files.")
+	fuzzer          = flag.Bool("fuzzer", false, "If true, tests against a BoringSSL built in fuzzer mode.")
 )
 
 const (
@@ -686,6 +687,9 @@ func runTest(test *testCase, shimPath string, mallocNumToFail int64) error {
 			config.ServerName = "test"
 		}
 	}
+	if *fuzzer {
+		config.Bugs.NullAllCiphers = true
+	}
 
 	conn, err := acceptOrWait(listener, waitChan)
 	if err == nil {
@@ -713,6 +717,9 @@ func runTest(test *testCase, shimPath string, mallocNumToFail int64) error {
 				resumeConfig.ClientSessionCache = config.ClientSessionCache
 				resumeConfig.ServerSessionCache = config.ServerSessionCache
 			}
+			if *fuzzer {
+				resumeConfig.Bugs.NullAllCiphers = true
+			}
 		} else {
 			resumeConfig = config
 		}