Add Fuzzit integration

Add a basic fuzz test for the httprule package, run regression tests
locally on every PR and continuous fuzzing on fuzzit.dev.

.circleci/config.yml

@@ -48,6 +48,14 @@ jobs:
       - checkout
       - run: go get golang.org/x/lint/golint
       - run: make lint
+  fuzzit:
+    docker:
+      - image: fuzzitdev/golang:1.12.7-buster
+    working_directory: /go/src/github.com/grpc-gateway/grpc-gateway
+    steps:
+      - checkout
+      - setup_remote_docker
+      - run: ./fuzzit.sh
   bazel:
     docker:
       - image: l.gcr.io/google/bazel:latest
@@ -88,6 +96,10 @@ workflows:
     jobs:
       - build
       - test
+      - fuzzit:
+          filters:
+            branches:
+              only: master
       - node_test
       - generate
       - lint

protoc-gen-grpc-gateway/httprule/fuzz.go

@@ -0,0 +1,11 @@
+// +build gofuzz
+
+package httprule
+
+func Fuzz(data []byte) int {
+	_, err := Parse(string(data))
+	if err != nil {
+		return 0
+	}
+	return 0
+}