diff --git a/mobile/library/cc/BUILD b/mobile/library/cc/BUILD
index fce829345778..e09ff75df02b 100644
--- a/mobile/library/cc/BUILD
+++ b/mobile/library/cc/BUILD
@@ -6,6 +6,12 @@ envoy_package()
 
 envoy_cc_library(
     name = "envoy_engine_cc_lib",
+    srcs = [
+        "log_level.cc",
+        "request_method.cc",
+        "retry_policy.cc",
+        "upstream_http_protocol.h",
+    ],
     hdrs = [
         "bridge_utility.h",
         "engine.h",
diff --git a/mobile/library/cc/log_level.cc b/mobile/library/cc/log_level.cc
new file mode 100644
index 000000000000..737b463183d2
--- /dev/null
+++ b/mobile/library/cc/log_level.cc
@@ -0,0 +1,35 @@
+#include "log_level.h"
+
+#include <stdexcept>
+
+namespace Envoy {
+namespace Platform {
+
+static const std::pair<LogLevel, std::string> LOG_LEVEL_LOOKUP[]{
+    {LogLevel::trace, "trace"}, {LogLevel::debug, "debug"}, {LogLevel::info, "info"},
+    {LogLevel::warn, "warn"},   {LogLevel::error, "error"}, {LogLevel::critical, "critical"},
+    {LogLevel::off, "off"},
+};
+
+std::string log_level_to_string(LogLevel method) {
+  for (const auto& pair : LOG_LEVEL_LOOKUP) {
+    if (pair.first == method) {
+      return pair.second;
+    }
+  }
+
+  throw std::out_of_range("unknown log level type");
+}
+
+LogLevel log_level_from_string(const std::string& str) {
+  for (const auto& pair : LOG_LEVEL_LOOKUP) {
+    if (pair.second == str) {
+      return pair.first;
+    }
+  }
+
+  throw std::out_of_range("unknown log level type");
+}
+
+} // namespace Platform
+} // namespace Envoy
diff --git a/mobile/library/cc/request_method.cc b/mobile/library/cc/request_method.cc
new file mode 100644
index 000000000000..108dc5f433be
--- /dev/null
+++ b/mobile/library/cc/request_method.cc
@@ -0,0 +1,37 @@
+#include "request_method.h"
+
+#include <stdexcept>
+#include <vector>
+
+namespace Envoy {
+namespace Platform {
+
+static const std::pair<RequestMethod, std::string> REQUEST_METHOD_LOOKUP[]{
+    {RequestMethod::DELETE, "DELETE"}, {RequestMethod::GET, "GET"},
+    {RequestMethod::HEAD, "HEAD"},     {RequestMethod::OPTIONS, "OPTIONS"},
+    {RequestMethod::PATCH, "PATCH"},   {RequestMethod::POST, "POST"},
+    {RequestMethod::PUT, "PUT"},       {RequestMethod::TRACE, "TRACE"},
+};
+
+std::string request_method_to_string(RequestMethod method) {
+  for (const auto& pair : REQUEST_METHOD_LOOKUP) {
+    if (pair.first == method) {
+      return pair.second;
+    }
+  }
+
+  throw std::out_of_range("unknown request method type");
+}
+
+RequestMethod request_method_from_string(const std::string& str) {
+  for (const auto& pair : REQUEST_METHOD_LOOKUP) {
+    if (pair.second == str) {
+      return pair.first;
+    }
+  }
+
+  throw std::out_of_range("unknown request method type");
+}
+
+} // namespace Platform
+} // namespace Envoy
diff --git a/mobile/library/cc/retry_policy.cc b/mobile/library/cc/retry_policy.cc
new file mode 100644
index 000000000000..17a9b96f98c9
--- /dev/null
+++ b/mobile/library/cc/retry_policy.cc
@@ -0,0 +1,105 @@
+#include "retry_policy.h"
+
+namespace Envoy {
+namespace Platform {
+
+static const std::pair<RetryRule, std::string> RETRY_RULE_LOOKUP[]{
+    {RetryRule::Status5xx, "5xx"},
+    {RetryRule::GatewayError, "gateway-error"},
+    {RetryRule::ConnectFailure, "connect-failure"},
+    {RetryRule::RefusedStream, "refused-stream"},
+    {RetryRule::Retriable4xx, "retriable-4xx"},
+    {RetryRule::RetriableHeaders, "retriable-headers"},
+    {RetryRule::Reset, "reset"},
+};
+
+std::string retry_rule_to_string(RetryRule retry_rule) {
+  for (const auto& pair : RETRY_RULE_LOOKUP) {
+    if (pair.first == retry_rule) {
+      return pair.second;
+    }
+  }
+  throw std::invalid_argument("invalid retry rule");
+}
+
+RetryRule retry_rule_from_string(const std::string& str) {
+  for (const auto& pair : RETRY_RULE_LOOKUP) {
+    if (pair.second == str) {
+      return pair.first;
+    }
+  }
+  throw std::invalid_argument("invalid retry rule");
+}
+
+RawHeaderMap RetryPolicy::as_raw_header_map() const {
+  RawHeaderMap outbound_headers{
+      {"x-envoy-max-retries", {std::to_string(this->max_retry_count)}},
+      {"x-envoy-upstream-rq-timeout-ms",
+       {std::to_string(this->total_upstream_timeout_ms.value_or(0))}},
+  };
+
+  if (this->per_try_timeout_ms.has_value()) {
+    outbound_headers["x-envoy-upstream-rq-per-try-timeout-ms"] =
+        std::vector<std::string>{std::to_string(this->per_try_timeout_ms.value())};
+  }
+
+  std::vector<std::string> retry_on;
+  for (const auto& retry_rule : this->retry_on) {
+    retry_on.push_back(retry_rule_to_string(retry_rule));
+  }
+
+  if (this->retry_status_codes.size() > 0) {
+    retry_on.push_back("retriable-status-codes");
+    std::vector<std::string> retry_status_codes;
+    for (const auto& status_code : this->retry_status_codes) {
+      retry_status_codes.push_back(std::to_string(status_code));
+    }
+    outbound_headers["x-envoy-retriable-status-codes"] = retry_status_codes;
+  }
+
+  if (retry_on.size() > 0) {
+    outbound_headers["x-envoy-retry-on"] = retry_on;
+  }
+
+  return outbound_headers;
+}
+
+RetryPolicy RetryPolicy::from_raw_header_map(const RawHeaderMap& headers) {
+  RetryPolicy retry_policy;
+
+  if (headers.contains("x-envoy-max-retries")) {
+    retry_policy.max_retry_count = std::stoi(headers.at("x-envoy-max-retries")[0]);
+  }
+
+  if (headers.contains("x-envoy-upstream-rq-timeout-ms")) {
+    retry_policy.total_upstream_timeout_ms =
+        std::stoi(headers.at("x-envoy-upstream-rq-timeout-ms")[0]);
+  }
+
+  if (headers.contains("x-envoy-upstream-rq-per-try-timeout-ms")) {
+    retry_policy.per_try_timeout_ms =
+        std::stoi(headers.at("x-envoy-upstream-rq-per-try-timeout-ms")[0]);
+  }
+
+  bool has_retriable_status_codes = false;
+  if (headers.contains("x-envoy-retry-on")) {
+    for (const auto& retry_rule_str : headers.at("x-envoy-retry-on")) {
+      if (retry_rule_str == "retriable-status_codes") {
+        has_retriable_status_codes = true;
+        continue;
+      }
+      retry_policy.retry_on.push_back(retry_rule_from_string(retry_rule_str));
+    }
+  }
+
+  if (has_retriable_status_codes && headers.contains("x-envoy-retriable-status-codes")) {
+    for (const auto& status_code_str : headers.at("x-envoy-retriable-status-codes")) {
+      retry_policy.retry_status_codes.push_back(std::stoi(status_code_str));
+    }
+  }
+
+  return retry_policy;
+}
+
+} // namespace Platform
+} // namespace Envoy
diff --git a/mobile/library/cc/upstream_http_protocol.cc b/mobile/library/cc/upstream_http_protocol.cc
new file mode 100644
index 000000000000..8ca0af5a5061
--- /dev/null
+++ b/mobile/library/cc/upstream_http_protocol.cc
@@ -0,0 +1,32 @@
+#include "upstream_http_protocol.h"
+
+#include <stdexcept>
+
+namespace Envoy {
+namespace Platform {
+
+static const std::pair<UpstreamHttpProtocol, std::string> UPSTREAM_HTTP_PROTOCOL_LOOKUP[]{
+    {UpstreamHttpProtocol::HTTP1, "http1"},
+    {UpstreamHttpProtocol::HTTP2, "http2"},
+};
+
+std::string upstream_http_protocol_to_string(UpstreamHttpProtocol protocol) {
+  for (const auto& pair : UPSTREAM_HTTP_PROTOCOL_LOOKUP) {
+    if (pair.first == protocol) {
+      return pair.second;
+    }
+  }
+  throw std::invalid_argument("invalid upstream http protocol");
+}
+
+UpstreamHttpProtocol upstream_http_protocol_from_string(const std::string& str) {
+  for (const auto& pair : UPSTREAM_HTTP_PROTOCOL_LOOKUP) {
+    if (pair.second == str) {
+      return pair.first;
+    }
+  }
+  throw std::invalid_argument("invalid upstream http protocol");
+}
+
+} // namespace Platform
+} // namespace Envoy