1 files changed, 384 insertions, 0 deletions
diff --git a/src/core/ext/filters/client_channel/resolver_result_parsing.cc b/src/core/ext/filters/client_channel/resolver_result_parsing.cc
new file mode 100644
index 0000000000..82a26ace63
--- /dev/null
+++ b/src/core/ext/filters/client_channel/resolver_result_parsing.cc
@@ -0,0 +1,384 @@
+/*
+ *
+ * Copyright 2018 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#include <grpc/support/port_platform.h>
+
+#include "src/core/ext/filters/client_channel/resolver_result_parsing.h"
+
+#include <ctype.h>
+#include <stdio.h>
+#include <string.h>
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+#include <grpc/support/string_util.h>
+
+#include "src/core/ext/filters/client_channel/client_channel.h"
+#include "src/core/ext/filters/client_channel/lb_policy_registry.h"
+#include "src/core/lib/channel/status_util.h"
+#include "src/core/lib/gpr/string.h"
+#include "src/core/lib/gprpp/memory.h"
+
+// As per the retry design, we do not allow more than 5 retry attempts.
+#define MAX_MAX_RETRY_ATTEMPTS 5
+
+namespace grpc_core {
+namespace internal {
+
+namespace {
+
+// Converts string format from JSON to proto.
+grpc_core::UniquePtr<char> ConvertCamelToSnake(const char* camel) {
+  const size_t size = strlen(camel);
+  char* snake = static_cast<char*>(gpr_malloc(size * 2));
+  size_t j = 0;
+  for (size_t i = 0; i < size; ++i) {
+    if (isupper(camel[i])) {
+      snake[j++] = '_';
+      snake[j++] = tolower(camel[i]);
+    } else {
+      snake[j++] = camel[i];
+    }
+  }
+  snake[j] = '\0';
+  return grpc_core::UniquePtr<char>(snake);
+}
+
+}  // namespace
+
+ProcessedResolverResult::ProcessedResolverResult(
+    const grpc_channel_args* resolver_result, bool parse_retry) {
+  ProcessServiceConfig(resolver_result, parse_retry);
+  // If no LB config was found above, just find the LB policy name then.
+  if (lb_policy_config_ == nullptr) ProcessLbPolicyName(resolver_result);
+}
+
+void ProcessedResolverResult::ProcessServiceConfig(
+    const grpc_channel_args* resolver_result, bool parse_retry) {
+  const grpc_arg* channel_arg =
+      grpc_channel_args_find(resolver_result, GRPC_ARG_SERVICE_CONFIG);
+  const char* service_config_json = grpc_channel_arg_get_string(channel_arg);
+  if (service_config_json != nullptr) {
+    service_config_json_.reset(gpr_strdup(service_config_json));
+    service_config_ = grpc_core::ServiceConfig::Create(service_config_json);
+    if (service_config_ != nullptr) {
+      if (parse_retry) {
+        channel_arg =
+            grpc_channel_args_find(resolver_result, GRPC_ARG_SERVER_URI);
+        const char* server_uri = grpc_channel_arg_get_string(channel_arg);
+        GPR_ASSERT(server_uri != nullptr);
+        grpc_uri* uri = grpc_uri_parse(server_uri, true);
+        GPR_ASSERT(uri->path[0] != '\0');
+        server_name_ = uri->path[0] == '/' ? uri->path + 1 : uri->path;
+        service_config_->ParseGlobalParams(ParseServiceConfig, this);
+        grpc_uri_destroy(uri);
+      } else {
+        service_config_->ParseGlobalParams(ParseServiceConfig, this);
+      }
+      method_params_table_ = service_config_->CreateMethodConfigTable(
+          ClientChannelMethodParams::CreateFromJson);
+    }
+  }
+}
+
+void ProcessedResolverResult::ProcessLbPolicyName(
+    const grpc_channel_args* resolver_result) {
+  const char* lb_policy_name = nullptr;
+  // Prefer the LB policy name found in the service config. Note that this is
+  // checking the deprecated loadBalancingPolicy field, rather than the new
+  // loadBalancingConfig field.
+  if (service_config_ != nullptr) {
+    lb_policy_name = service_config_->GetLoadBalancingPolicyName();
+  }
+  // Otherwise, find the LB policy name set by the client API.
+  if (lb_policy_name == nullptr) {
+    const grpc_arg* channel_arg =
+        grpc_channel_args_find(resolver_result, GRPC_ARG_LB_POLICY_NAME);
+    lb_policy_name = grpc_channel_arg_get_string(channel_arg);
+  }
+  // Special case: If at least one balancer address is present, we use
+  // the grpclb policy, regardless of what the resolver has returned.
+  const grpc_arg* channel_arg =
+      grpc_channel_args_find(resolver_result, GRPC_ARG_LB_ADDRESSES);
+  if (channel_arg != nullptr && channel_arg->type == GRPC_ARG_POINTER) {
+    grpc_lb_addresses* addresses =
+        static_cast<grpc_lb_addresses*>(channel_arg->value.pointer.p);
+    if (grpc_lb_addresses_contains_balancer_address(*addresses)) {
+      if (lb_policy_name != nullptr &&
+          gpr_stricmp(lb_policy_name, "grpclb") != 0) {
+        gpr_log(GPR_INFO,
+                "resolver requested LB policy %s but provided at least one "
+                "balancer address -- forcing use of grpclb LB policy",
+                lb_policy_name);
+      }
+      lb_policy_name = "grpclb";
+    }
+  }
+  // Use pick_first if nothing was specified and we didn't select grpclb
+  // above.
+  if (lb_policy_name == nullptr) lb_policy_name = "pick_first";
+  lb_policy_name_.reset(gpr_strdup(lb_policy_name));
+}
+
+void ProcessedResolverResult::ParseServiceConfig(
+    const grpc_json* field, ProcessedResolverResult* parsing_state) {
+  parsing_state->ParseLbConfigFromServiceConfig(field);
+  if (parsing_state->server_name_ != nullptr) {
+    parsing_state->ParseRetryThrottleParamsFromServiceConfig(field);
+  }
+}
+
+void ProcessedResolverResult::ParseLbConfigFromServiceConfig(
+    const grpc_json* field) {
+  if (lb_policy_config_ != nullptr) return;  // Already found.
+  // Find the LB config global parameter.
+  if (field->key == nullptr || strcmp(field->key, "loadBalancingConfig") != 0 ||
+      field->type != GRPC_JSON_ARRAY) {
+    return;  // Not valid lb config array.
+  }
+  // Find the first LB policy that this client supports.
+  for (grpc_json* lb_config = field->child; lb_config != nullptr;
+       lb_config = lb_config->next) {
+    if (lb_config->type != GRPC_JSON_OBJECT) return;
+    // Find the policy object.
+    grpc_json* policy = nullptr;
+    for (grpc_json* field = lb_config->child; field != nullptr;
+         field = field->next) {
+      if (field->key == nullptr || strcmp(field->key, "policy") != 0 ||
+          field->type != GRPC_JSON_OBJECT) {
+        return;
+      }
+      if (policy != nullptr) return;  // Duplicate.
+      policy = field;
+    }
+    // Find the specific policy content since the policy object is of type
+    // "oneof".
+    grpc_json* policy_content = nullptr;
+    for (grpc_json* field = policy->child; field != nullptr;
+         field = field->next) {
+      if (field->key == nullptr || field->type != GRPC_JSON_OBJECT) return;
+      if (policy_content != nullptr) return;  // Violate "oneof" type.
+      policy_content = field;
+    }
+    grpc_core::UniquePtr<char> lb_policy_name =
+        ConvertCamelToSnake(policy_content->key);
+    if (!grpc_core::LoadBalancingPolicyRegistry::LoadBalancingPolicyExists(
+            lb_policy_name.get())) {
+      continue;
+    }
+    lb_policy_name_ = std::move(lb_policy_name);
+    lb_policy_config_ = policy_content->child;
+    return;
+  }
+}
+
+void ProcessedResolverResult::ParseRetryThrottleParamsFromServiceConfig(
+    const grpc_json* field) {
+  if (strcmp(field->key, "retryThrottling") == 0) {
+    if (retry_throttle_data_ != nullptr) return;  // Duplicate.
+    if (field->type != GRPC_JSON_OBJECT) return;
+    int max_milli_tokens = 0;
+    int milli_token_ratio = 0;
+    for (grpc_json* sub_field = field->child; sub_field != nullptr;
+         sub_field = sub_field->next) {
+      if (sub_field->key == nullptr) return;
+      if (strcmp(sub_field->key, "maxTokens") == 0) {
+        if (max_milli_tokens != 0) return;  // Duplicate.
+        if (sub_field->type != GRPC_JSON_NUMBER) return;
+        max_milli_tokens = gpr_parse_nonnegative_int(sub_field->value);
+        if (max_milli_tokens == -1) return;
+        max_milli_tokens *= 1000;
+      } else if (strcmp(sub_field->key, "tokenRatio") == 0) {
+        if (milli_token_ratio != 0) return;  // Duplicate.
+        if (sub_field->type != GRPC_JSON_NUMBER) return;
+        // We support up to 3 decimal digits.
+        size_t whole_len = strlen(sub_field->value);
+        uint32_t multiplier = 1;
+        uint32_t decimal_value = 0;
+        const char* decimal_point = strchr(sub_field->value, '.');
+        if (decimal_point != nullptr) {
+          whole_len = static_cast<size_t>(decimal_point - sub_field->value);
+          multiplier = 1000;
+          size_t decimal_len = strlen(decimal_point + 1);
+          if (decimal_len > 3) decimal_len = 3;
+          if (!gpr_parse_bytes_to_uint32(decimal_point + 1, decimal_len,
+                                         &decimal_value)) {
+            return;
+          }
+          uint32_t decimal_multiplier = 1;
+          for (size_t i = 0; i < (3 - decimal_len); ++i) {
+            decimal_multiplier *= 10;
+          }
+          decimal_value *= decimal_multiplier;
+        }
+        uint32_t whole_value;
+        if (!gpr_parse_bytes_to_uint32(sub_field->value, whole_len,
+                                       &whole_value)) {
+          return;
+        }
+        milli_token_ratio =
+            static_cast<int>((whole_value * multiplier) + decimal_value);
+        if (milli_token_ratio <= 0) return;
+      }
+    }
+    retry_throttle_data_ =
+        grpc_core::internal::ServerRetryThrottleMap::GetDataForServer(
+            server_name_, max_milli_tokens, milli_token_ratio);
+  }
+}
+
+namespace {
+
+bool ParseWaitForReady(
+    grpc_json* field, ClientChannelMethodParams::WaitForReady* wait_for_ready) {
+  if (field->type != GRPC_JSON_TRUE && field->type != GRPC_JSON_FALSE) {
+    return false;
+  }
+  *wait_for_ready = field->type == GRPC_JSON_TRUE
+                        ? ClientChannelMethodParams::WAIT_FOR_READY_TRUE
+                        : ClientChannelMethodParams::WAIT_FOR_READY_FALSE;
+  return true;
+}
+
+// Parses a JSON field of the form generated for a google.proto.Duration
+// proto message, as per:
+//   https://developers.google.com/protocol-buffers/docs/proto3#json
+bool ParseDuration(grpc_json* field, grpc_millis* duration) {
+  if (field->type != GRPC_JSON_STRING) return false;
+  size_t len = strlen(field->value);
+  if (field->value[len - 1] != 's') return false;
+  UniquePtr<char> buf(gpr_strdup(field->value));
+  *(buf.get() + len - 1) = '\0';  // Remove trailing 's'.
+  char* decimal_point = strchr(buf.get(), '.');
+  int nanos = 0;
+  if (decimal_point != nullptr) {
+    *decimal_point = '\0';
+    nanos = gpr_parse_nonnegative_int(decimal_point + 1);
+    if (nanos == -1) {
+      return false;
+    }
+    int num_digits = static_cast<int>(strlen(decimal_point + 1));
+    if (num_digits > 9) {  // We don't accept greater precision than nanos.
+      return false;
+    }
+    for (int i = 0; i < (9 - num_digits); ++i) {
+      nanos *= 10;
+    }
+  }
+  int seconds =
+      decimal_point == buf.get() ? 0 : gpr_parse_nonnegative_int(buf.get());
+  if (seconds == -1) return false;
+  *duration = seconds * GPR_MS_PER_SEC + nanos / GPR_NS_PER_MS;
+  return true;
+}
+
+UniquePtr<ClientChannelMethodParams::RetryPolicy> ParseRetryPolicy(
+    grpc_json* field) {
+  auto retry_policy = MakeUnique<ClientChannelMethodParams::RetryPolicy>();
+  if (field->type != GRPC_JSON_OBJECT) return nullptr;
+  for (grpc_json* sub_field = field->child; sub_field != nullptr;
+       sub_field = sub_field->next) {
+    if (sub_field->key == nullptr) return nullptr;
+    if (strcmp(sub_field->key, "maxAttempts") == 0) {
+      if (retry_policy->max_attempts != 0) return nullptr;  // Duplicate.
+      if (sub_field->type != GRPC_JSON_NUMBER) return nullptr;
+      retry_policy->max_attempts = gpr_parse_nonnegative_int(sub_field->value);
+      if (retry_policy->max_attempts <= 1) return nullptr;
+      if (retry_policy->max_attempts > MAX_MAX_RETRY_ATTEMPTS) {
+        gpr_log(GPR_ERROR,
+                "service config: clamped retryPolicy.maxAttempts at %d",
+                MAX_MAX_RETRY_ATTEMPTS);
+        retry_policy->max_attempts = MAX_MAX_RETRY_ATTEMPTS;
+      }
+    } else if (strcmp(sub_field->key, "initialBackoff") == 0) {
+      if (retry_policy->initial_backoff > 0) return nullptr;  // Duplicate.
+      if (!ParseDuration(sub_field, &retry_policy->initial_backoff)) {
+        return nullptr;
+      }
+      if (retry_policy->initial_backoff == 0) return nullptr;
+    } else if (strcmp(sub_field->key, "maxBackoff") == 0) {
+      if (retry_policy->max_backoff > 0) return nullptr;  // Duplicate.
+      if (!ParseDuration(sub_field, &retry_policy->max_backoff)) {
+        return nullptr;
+      }
+      if (retry_policy->max_backoff == 0) return nullptr;
+    } else if (strcmp(sub_field->key, "backoffMultiplier") == 0) {
+      if (retry_policy->backoff_multiplier != 0) return nullptr;  // Duplicate.
+      if (sub_field->type != GRPC_JSON_NUMBER) return nullptr;
+      if (sscanf(sub_field->value, "%f", &retry_policy->backoff_multiplier) !=
+          1) {
+        return nullptr;
+      }
+      if (retry_policy->backoff_multiplier <= 0) return nullptr;
+    } else if (strcmp(sub_field->key, "retryableStatusCodes") == 0) {
+      if (!retry_policy->retryable_status_codes.Empty()) {
+        return nullptr;  // Duplicate.
+      }
+      if (sub_field->type != GRPC_JSON_ARRAY) return nullptr;
+      for (grpc_json* element = sub_field->child; element != nullptr;
+           element = element->next) {
+        if (element->type != GRPC_JSON_STRING) return nullptr;
+        grpc_status_code status;
+        if (!grpc_status_code_from_string(element->value, &status)) {
+          return nullptr;
+        }
+        retry_policy->retryable_status_codes.Add(status);
+      }
+      if (retry_policy->retryable_status_codes.Empty()) return nullptr;
+    }
+  }
+  // Make sure required fields are set.
+  if (retry_policy->max_attempts == 0 || retry_policy->initial_backoff == 0 ||
+      retry_policy->max_backoff == 0 || retry_policy->backoff_multiplier == 0 ||
+      retry_policy->retryable_status_codes.Empty()) {
+    return nullptr;
+  }
+  return retry_policy;
+}
+
+}  // namespace
+
+RefCountedPtr<ClientChannelMethodParams>
+ClientChannelMethodParams::CreateFromJson(const grpc_json* json) {
+  RefCountedPtr<ClientChannelMethodParams> method_params =
+      MakeRefCounted<ClientChannelMethodParams>();
+  for (grpc_json* field = json->child; field != nullptr; field = field->next) {
+    if (field->key == nullptr) continue;
+    if (strcmp(field->key, "waitForReady") == 0) {
+      if (method_params->wait_for_ready_ != WAIT_FOR_READY_UNSET) {
+        return nullptr;  // Duplicate.
+      }
+      if (!ParseWaitForReady(field, &method_params->wait_for_ready_)) {
+        return nullptr;
+      }
+    } else if (strcmp(field->key, "timeout") == 0) {
+      if (method_params->timeout_ > 0) return nullptr;  // Duplicate.
+      if (!ParseDuration(field, &method_params->timeout_)) return nullptr;
+    } else if (strcmp(field->key, "retryPolicy") == 0) {
+      if (method_params->retry_policy_ != nullptr) {
+        return nullptr;  // Duplicate.
+      }
+      method_params->retry_policy_ = ParseRetryPolicy(field);
+      if (method_params->retry_policy_ == nullptr) return nullptr;
+    }
+  }
+  return method_params;
+}
+
+}  // namespace internal
+}  // namespace grpc_core