fuzz: bare bones HCM fuzzer. (envoyproxy#4118)

See caveats at the top of conn_manager_impl_fuzz_test.cc. HCM might not be the best place to be
investing fuzzing effort, would like to see if a basic fuzzer can provide some win before investing
more time in modeling HCM internals and building a corpus.

Risk level: Low
Testing: Supplied corpus has 56.7% coverage.

Signed-off-by: Harvey Tuch <htuch@google.com>

test/common/http/BUILD

@@ -91,6 +91,40 @@ envoy_cc_test_library(
     ],
 )
 
+envoy_proto_library(
+    name = "conn_manager_impl_fuzz_proto",
+    srcs = ["conn_manager_impl_fuzz.proto"],
+    external_deps = ["well_known_protos"],
+    generate_python = 0,
+    deps = [
+        "//test/fuzz:common_proto",
+    ],
+)
+
+envoy_cc_fuzz_test(
+    name = "conn_manager_impl_fuzz_test",
+    srcs = ["conn_manager_impl_fuzz_test.cc"],
+    corpus = "conn_manager_impl_corpus",
+    deps = [
+        ":conn_manager_impl_fuzz_proto",
+        "//source/common/common:empty_string",
+        "//source/common/http:conn_manager_lib",
+        "//source/common/http:date_provider_lib",
+        "//source/common/network:address_lib",
+        "//source/common/network:utility_lib",
+        "//test/fuzz:utility_lib",
+        "//test/mocks/access_log:access_log_mocks",
+        "//test/mocks/http:http_mocks",
+        "//test/mocks/local_info:local_info_mocks",
+        "//test/mocks/network:network_mocks",
+        "//test/mocks/runtime:runtime_mocks",
+        "//test/mocks/ssl:ssl_mocks",
+        "//test/mocks/tracing:tracing_mocks",
+        "//test/mocks/upstream:upstream_mocks",
+        "@envoy_api//envoy/config/filter/network/http_connection_manager/v2:http_connection_manager_cc",
+    ],
+)
+
 envoy_cc_test(
     name = "conn_manager_impl_test",
     srcs = ["conn_manager_impl_test.cc"],

test/common/http/conn_manager_impl_corpus/codec_exception

@@ -0,0 +1,18 @@
+actions {
+  new_stream {
+    request_headers {
+      headers {
+        key: "foo"
+        value: "bar"
+      }
+    }
+  }
+}
+actions {
+  stream_action {
+    stream_id: 0
+    request {
+      throw_decoder_exception {}
+    }
+  }
+}

test/common/http/conn_manager_impl_corpus/example

@@ -0,0 +1,120 @@
+actions {
+  new_stream {
+    request_headers {
+      headers {
+        key: ":method"
+        value: "GET"
+      }
+      headers {
+        key: ":path"
+        value: "/"
+      }
+      headers {
+        key: ":scheme"
+        value: "http"
+      }
+      headers {
+        key: ":authority"
+        value: "foo.com"
+      }
+      headers {
+        key: "blah"
+        value: "nosniff"
+      }
+      headers {
+        key: "cookie"
+        value: "foo=bar"
+      }
+      headers {
+        key: "cookie"
+        value: "foo2=bar2"
+      }
+    }
+  }
+}
+actions {
+  stream_action {
+    stream_id: 0
+    request {
+      data {
+        size: 3000000
+        decoder_filter_callback_action {
+          add_decoded_data {
+            size: 1000000
+          }
+        }
+        status: DATA_STOP_ITERATION_AND_BUFFER
+      }
+    }
+  }
+}
+actions {
+  stream_action {
+    stream_id: 0
+    request {
+      continue_decoding {}
+    }
+  }
+}
+actions {
+  stream_action {
+    stream_id: 0
+    response {
+      continue_100_headers {}
+    }
+  }
+}
+actions {
+  stream_action {
+    stream_id: 0
+    response {
+      headers {
+        headers {
+          key: ":status"
+          value: "200"
+        }
+      }
+    }
+  }
+}
+actions {
+  stream_action {
+    stream_id: 0
+    response {
+      data: 5
+    }
+  }
+}
+actions {
+  stream_action {
+    stream_id: 0
+    request {
+      trailers {
+        headers {
+          headers {
+            key: "foo"
+            value: "bar"
+          }
+        }
+        decoder_filter_callback_action {
+          add_decoded_data {
+            size: 1000000
+          }
+        }
+      }
+    }
+  }
+}
+actions {
+  stream_action {
+    stream_id: 0
+    response {
+      trailers {
+        headers {
+          key: "foo"
+          value: "bar"
+        }
+      }
+    }
+  }
+}

test/common/http/conn_manager_impl_corpus/missing_host

@@ -0,0 +1,10 @@
+actions {
+  new_stream {
+    request_headers {
+      headers {
+        key: "foo"
+        value: "bar"
+      }
+    }
+  }
+}

test/common/http/conn_manager_impl_fuzz.proto

@@ -0,0 +1,97 @@
+syntax = "proto3";
+
+package test.common.http;
+
+import "google/protobuf/empty.proto";
+
+import "test/fuzz/common.proto";
+
+// Structured input for conn_manager_impl_fuzz_test.
+
+message NewStream {
+  test.fuzz.Headers request_headers = 1;
+  bool end_stream = 2;
+  // TODO(htuch): Support stop/continue status with headers.
+}
+
+enum HeaderStatus {
+  HEADER_CONTINUE = 0;
+  HEADER_STOP_ITERATION = 1;
+}
+
+enum DataStatus {
+  DATA_CONTINUE = 0;
+  DATA_STOP_ITERATION_AND_BUFFER = 1;
+  DATA_STOP_ITERATION_AND_WATERMARK = 2;
+  DATA_STOP_ITERATION_NO_BUFFER = 3;
+}
+
+enum TrailerStatus {
+  TRAILER_CONTINUE = 0;
+  TRAILER_STOP_ITERATION = 1;
+}
+
+message DecoderFilterCallbackAction {
+  message AddDecodedData {
+    uint32 size = 1;
+    bool streaming = 2;
+  }
+  oneof decoder_filter_callback_action_selector {
+    // TODO(htuch): More decoder filer callback actions
+    AddDecodedData add_decoded_data = 1;
+  }
+}
+
+message RequestAction {
+  message DataAction {
+    uint32 size = 1;
+    bool end_stream = 2;
+    DataStatus status = 3;
+    DecoderFilterCallbackAction decoder_filter_callback_action = 4;
+  }
+  message TrailerAction {
+    test.fuzz.Headers headers = 1;
+    TrailerStatus status = 2;
+    DecoderFilterCallbackAction decoder_filter_callback_action = 3;
+  }
+  oneof request_action_selector {
+    DataAction data = 1;
+    TrailerAction trailers = 2;
+    google.protobuf.Empty continue_decoding = 3;
+    google.protobuf.Empty throw_decoder_exception = 4;
+    // TODO(htuch): Model and fuzz watermark events.
+  }
+}
+
+// TODO(htuch): Model and fuzz encoder filter buffering/resumption and different status returns.
+message ResponseAction {
+  oneof response_action_selector {
+    test.fuzz.Headers continue_100_headers = 1;
+    test.fuzz.Headers headers = 2;
+    uint32 data = 3;
+    test.fuzz.Headers trailers = 4;
+    // TODO(htuch): Model and fuzz watermark events.
+  }
+  bool end_stream = 7;
+}
+
+message StreamAction {
+  uint32 stream_id = 1;
+  oneof stream_action_selector {
+    RequestAction request = 2;
+    ResponseAction response = 3;
+  }
+}
+
+message Action {
+  oneof action_selector {
+    // Create new stream.
+    NewStream new_stream = 1;
+    // Perform an action on an existing stream.
+    StreamAction stream_action = 2;
+  }
+}
+
+message ConnManagerImplTestCase {
+  repeated Action actions = 1;
+}