Add GetDynamicPortRange api for Wifilan medium

PiperOrigin-RevId: 416669312

cpp/platform/api/wifi_lan.h

@@ -144,6 +144,10 @@ class WifiLanMedium {
   // On error, returns nullptr.
   virtual std::unique_ptr<WifiLanServerSocket> ListenForService(
       int port = 0) = 0;
+
+  // Returns the port range as a pair of min and max port.
+  virtual absl::optional<std::pair<std::int32_t, std::int32_t>>
+  GetDynamicPortRange() = 0;
 };
 
 }  // namespace api

cpp/platform/impl/g3/wifi_lan.h

@@ -233,6 +233,12 @@ class WifiLanMedium : public api::WifiLanMedium {
   std::unique_ptr<api::WifiLanServerSocket> ListenForService(int port) override
       ABSL_LOCKS_EXCLUDED(mutex_);
 
+  // Returns the port range as a pair of min and max port.
+  absl::optional<std::pair<std::int32_t, std::int32_t>> GetDynamicPortRange()
+      override {
+    return std::make_pair(49152, 65535);
+  }
+
  private:
   struct AdvertisingInfo {
     bool Empty() const { return service_types.empty(); }

cpp/platform/impl/ios/Source/Platform/wifi_lan.h

@@ -155,6 +155,10 @@ class WifiLanMedium : public api::WifiLanMedium {
   std::unique_ptr<api::WifiLanServerSocket> ListenForService(int port) override
       ABSL_LOCKS_EXCLUDED(mutex_);
 
+  absl::optional<std::pair<std::int32_t, std::int32_t>> GetDynamicPortRange() override {
+    return absl::nullopt;
+  }
+
  private:
   struct AdvertisingInfo {
     bool Empty() const { return services.empty(); }

cpp/platform/impl/windows/wifi_lan.h

@@ -30,6 +30,7 @@
 #include "absl/container/flat_hash_map.h"
 #include "absl/container/flat_hash_set.h"
 #include "absl/synchronization/mutex.h"
+#include "absl/types/optional.h"
 #include "platform/api/wifi_lan.h"
 #include "platform/base/exception.h"
 #include "platform/base/input_stream.h"
@@ -247,6 +248,11 @@ class WifiLanMedium : public api::WifiLanMedium {
   // continue.
   void NotifyDnsServiceUnregistered(DWORD status);
 
+  absl::optional<std::pair<std::int32_t, std::int32_t>> GetDynamicPortRange()
+      override {
+    return absl::nullopt;
+  }
+
  private:
   // mDNS text attributes
   static constexpr std::string_view KEY_ENDPOINT_INFO = "n";

cpp/platform/public/wifi_lan.h

@@ -187,6 +187,11 @@ class WifiLanMedium {
     return WifiLanServerSocket(impl_->ListenForService(port));
   }
 
+  // Returns the port range as a pair of min and max port.
+  absl::optional<std::pair<std::int32_t, std::int32_t>> GetDynamicPortRange() {
+    return impl_->GetDynamicPortRange();
+  }
+
   bool IsValid() const { return impl_ != nullptr; }
 
   api::WifiLanMedium& GetImpl() { return *impl_; }