[fuzz] Added random load balancer fuzz

test/common/upstream/BUILD

@@ -242,6 +242,54 @@ envoy_cc_test(
     ],
 )
 
+envoy_cc_test_library(
+    name = "load_balancer_fuzz_lib",
+    srcs = ["load_balancer_fuzz_base.cc"],
+    hdrs = ["load_balancer_fuzz_base.h"],
+    deps = [
+        ":load_balancer_fuzz_proto_cc_proto",
+        ":utility_lib",
+        "//source/common/upstream:load_balancer_lib",
+        "//test/mocks:common_lib",
+        "//test/mocks/runtime:runtime_mocks",
+        "//test/mocks/upstream:cluster_info_mocks",
+        "//test/mocks/upstream:host_set_mocks",
+        "//test/mocks/upstream:load_balancer_context_mock",
+        "//test/mocks/upstream:priority_set_mocks",
+        "@envoy_api//envoy/config/cluster/v3:pkg_cc_proto",
+    ],
+)
+
+envoy_proto_library(
+    name = "load_balancer_fuzz_proto",
+    srcs = ["load_balancer_fuzz.proto"],
+    deps = [
+        "//test/fuzz:common_proto",
+        "@envoy_api//envoy/config/cluster/v3:pkg",
+    ],
+)
+
+envoy_proto_library(
+    name = "random_load_balancer_fuzz_proto",
+    srcs = ["random_load_balancer_fuzz.proto"],
+    deps = [
+        "//test/common/upstream:load_balancer_fuzz_proto",
+    ],
+)
+
+envoy_cc_fuzz_test(
+    name = "random_load_balancer_fuzz_test",
+    srcs = ["random_load_balancer_fuzz_test.cc"],
+    corpus = "//test/common/upstream:load_balancer_corpus",
+    deps = [
+        ":load_balancer_fuzz_lib",
+        ":load_balancer_fuzz_proto_cc_proto",
+        ":random_load_balancer_fuzz_proto_cc_proto",
+        ":utility_lib",
+        "//test/fuzz:utility_lib",
+    ],
+)
+
 envoy_cc_test(
     name = "load_balancer_simulation_test",
     srcs = ["load_balancer_simulation_test.cc"],

test/common/upstream/load_balancer_fuzz.proto

@@ -0,0 +1,37 @@
+syntax = "proto3";
+
+package test.common.upstream;
+
+import "validate/validate.proto";
+import "envoy/config/cluster/v3/cluster.proto";
+import "google/protobuf/empty.proto";
+
+message UpdateHealthFlags {
+  bool failover_host_set = 1;
+  uint32 num_healthy_hosts = 2;
+  uint32 num_degraded_hosts = 3;
+  uint32 num_excluded_hosts = 4;
+}
+
+message LbAction {
+  oneof action_selector {
+    option (validate.required) = true;
+    UpdateHealthFlags update_health_flags = 1;
+    google.protobuf.Empty prefetch = 2;
+    google.protobuf.Empty choose_host = 3;
+  }
+}
+
+//This message represents what LoadBalancerFuzzBase will interact with, performing setup of host sets and calling into load balancers.
+//The logic that this message represents and the base class for load balancing fuzzing will be logic that maps to all types of load balancing
+//and can be modularly used at the highest level for each load balancer.
+message LoadBalancerTestCase {
+  envoy.config.cluster.v3.Cluster.CommonLbConfig common_lb_config = 1
+      [(validate.rules).message.required = true];
+  repeated LbAction actions = 2;
+  //This is capped at the max port value on an ip address - 80
+  uint32 num_hosts_in_priority_set = 3 [(validate.rules).uint32.lt = 65455];
+  uint32 num_hosts_in_failover_set = 4 [(validate.rules).uint32.lt = 65455];
+  repeated uint64 bytestring_for_random_calls = 5
+      [(validate.rules).repeated = {min_items: 1, max_items: 50}];
+}

test/common/upstream/load_balancer_fuzz_base.cc

@@ -0,0 +1,115 @@
+#include "test/common/upstream/load_balancer_fuzz_base.h"
+
+#include "test/common/upstream/utility.h"
+
+namespace Envoy {
+
+namespace Random {
+uint64_t FakeRandomGenerator::random() {
+  uint8_t index_of_data = counter % bytestring_.size();
+  ++counter;
+  ENVOY_LOG_MISC(trace, "random() returned: {}", bytestring_.at(index_of_data));
+  return bytestring_.at(index_of_data);
+}
+} // namespace Random
+
+namespace Upstream {
+
+// Anonymous namespace for helper functions
+namespace {
+std::vector<uint64_t>
+constructByteVectorForRandom(const Protobuf::RepeatedField<uint64_t>& byteString) {
+  std::vector<uint64_t> byteVector;
+  for (int i = 0; i < byteString.size(); ++i) {
+    byteVector.push_back(byteString.at(i));
+  }
+  return byteVector;
+}
+} // namespace
+
+void LoadBalancerFuzzBase::initializeFixedHostSets(uint32_t num_hosts_in_priority_set,
+                                                   uint32_t num_hosts_in_failover_set) {
+  int port = 80;
+  for (uint32_t i = 0; i < num_hosts_in_priority_set; ++i) {
+    host_set_.hosts_.push_back(makeTestHost(info_, "tcp://127.0.0.1:" + std::to_string(port)));
+    ++port;
+  }
+  for (uint32_t i = 0; i < num_hosts_in_failover_set; ++i) {
+    failover_host_set_.hosts_.push_back(
+        makeTestHost(info_, "tcp://127.0.0.1:" + std::to_string(port)));
+    ++port;
+  }
+  // TODO: More than two hosts?
+}
+
+// Initializes random and fixed host sets
+void LoadBalancerFuzzBase::initializeLbComponents(
+    test::common::upstream::LoadBalancerTestCase input) {
+  random_.bytestring_ = constructByteVectorForRandom(input.bytestring_for_random_calls());
+  initializeFixedHostSets(input.num_hosts_in_priority_set(), input.num_hosts_in_failover_set());
+}
+
+// Updating host sets is shared amongst all the load balancer tests. Since logically, we're just
+// setting the mock priority set to have certain values, and all load balancers interface with host
+// sets and their health statuses, this action maps to all load balancers.
+void LoadBalancerFuzzBase::updateHealthFlagsForAHostSet(bool failover_host_set,
+                                                        uint32_t num_healthy_hosts,
+                                                        uint32_t num_degraded_hosts,
+                                                        uint32_t num_excluded_hosts) {
+  MockHostSet& host_set = *priority_set_.getMockHostSet(int(failover_host_set));
+  uint32_t i = 0;
+  for (; i < num_healthy_hosts && i < host_set.hosts_.size(); ++i) {
+    host_set.healthy_hosts_.push_back(host_set.hosts_[i]);
+  }
+  for (; i < (num_healthy_hosts + num_degraded_hosts) && i < host_set.hosts_.size(); ++i) {
+    host_set.degraded_hosts_.push_back(host_set.hosts_[i]);
+  }
+
+  for (; i < (num_healthy_hosts + num_degraded_hosts + num_excluded_hosts) &&
+         i < host_set.hosts_.size();
+       ++i) {
+    host_set.excluded_hosts_.push_back(host_set.hosts_[i]);
+  }
+
+  host_set.runCallbacks({}, {});
+}
+
+void LoadBalancerFuzzBase::prefetch() {
+  // TODO: context, could generate it in proto action
+  lb_->peekAnotherHost(nullptr);
+}
+
+void LoadBalancerFuzzBase::chooseHost() {
+  // TODO: context, could generate it in proto action
+  lb_->chooseHost(nullptr);
+}
+
+void LoadBalancerFuzzBase::replay(
+    const Protobuf::RepeatedPtrField<test::common::upstream::LbAction>& actions) {
+  constexpr auto max_actions = 64;
+  for (int i = 0; i < std::min(max_actions, actions.size()); ++i) {
+    const auto& event = actions.at(i);
+    ENVOY_LOG_MISC(trace, "Action: {}", event.DebugString());
+    switch (event.action_selector_case()) {
+    case test::common::upstream::LbAction::kUpdateHealthFlags: {
+      updateHealthFlagsForAHostSet(event.update_health_flags().failover_host_set(),
+                                   event.update_health_flags().num_degraded_hosts(),
+                                   event.update_health_flags().num_excluded_hosts());
+      break;
+    }
+    case test::common::upstream::LbAction::kPrefetch: {
+      prefetch();
+      break;
+    }
+    case test::common::upstream::LbAction::kChooseHost: {
+      chooseHost();
+      break;
+    }
+    default:
+      break;
+    }
+  }
+}
+
+} // namespace Upstream
+} // namespace Envoy