Added `set_address_family`

httplib.h

@@ -663,6 +663,7 @@ public:
   Server &set_expect_100_continue_handler(Expect100ContinueHandler handler);
   Server &set_logger(Logger logger);
 
+  Server &set_address_family(int family);
   Server &set_tcp_nodelay(bool on);
   Server &set_socket_options(SocketOptions socket_options);
 
@@ -782,6 +783,7 @@ private:
   Logger logger_;
   Expect100ContinueHandler expect_100_continue_handler_;
 
+  int address_family_ = AF_UNSPEC;
   bool tcp_nodelay_ = CPPHTTPLIB_TCP_NODELAY;
   SocketOptions socket_options_ = default_socket_options;
 };
@@ -971,6 +973,7 @@ public:
 
   void set_default_headers(Headers headers);
 
+  void set_address_family(int family);
   void set_tcp_nodelay(bool on);
   void set_socket_options(SocketOptions socket_options);
 
@@ -1092,6 +1095,7 @@ protected:
   bool keep_alive_ = false;
   bool follow_location_ = false;
 
+  int address_family_ = AF_UNSPEC;
   bool tcp_nodelay_ = CPPHTTPLIB_TCP_NODELAY;
   SocketOptions socket_options_ = nullptr;
 
@@ -1282,6 +1286,7 @@ public:
 
   void set_default_headers(Headers headers);
 
+  void set_address_family(int family);
   void set_tcp_nodelay(bool on);
   void set_socket_options(SocketOptions socket_options);
 
@@ -2060,7 +2065,7 @@ inline int shutdown_socket(socket_t sock) {
 }
 
 template <typename BindOrConnect>
-socket_t create_socket(const char *host, int port, int socket_flags,
+socket_t create_socket(const char *host, int port, int address_family, int socket_flags,
                        bool tcp_nodelay, SocketOptions socket_options,
                        BindOrConnect bind_or_connect) {
   // Get address info
@@ -2068,7 +2073,7 @@ socket_t create_socket(const char *host, int port, int socket_flags,
   struct addrinfo *result;
 
   memset(&hints, 0, sizeof(struct addrinfo));
-  hints.ai_family = AF_UNSPEC;
+  hints.ai_family = address_family;
   hints.ai_socktype = SOCK_STREAM;
   hints.ai_flags = socket_flags;
   hints.ai_protocol = 0;
@@ -2209,12 +2214,13 @@ inline std::string if2ip(const std::string &ifn) {
 #endif
 
 inline socket_t create_client_socket(const char *host, int port,
+    int address_family,
                                      bool tcp_nodelay,
                                      SocketOptions socket_options,
                                      time_t timeout_sec, time_t timeout_usec,
                                      const std::string &intf, Error &error) {
   auto sock = create_socket(
-      host, port, 0, tcp_nodelay, std::move(socket_options),
+      host, port, address_family, 0, tcp_nodelay, std::move(socket_options),
       [&](socket_t sock, struct addrinfo &ai) -> bool {
         if (!intf.empty()) {
 #ifdef USE_IF2IP
@@ -4381,6 +4387,11 @@ Server::set_expect_100_continue_handler(Expect100ContinueHandler handler) {
   return *this;
 }
 
+inline Server &Server::set_address_family(int family) {
+  address_family_ = family;
+  return *this;
+}
+
 inline Server &Server::set_tcp_nodelay(bool on) {
   tcp_nodelay_ = on;
   return *this;
@@ -4760,7 +4771,7 @@ inline socket_t
 Server::create_server_socket(const char *host, int port, int socket_flags,
                              SocketOptions socket_options) const {
   return detail::create_socket(
-      host, port, socket_flags, tcp_nodelay_, std::move(socket_options),
+      host, port, address_family_, socket_flags, tcp_nodelay_, std::move(socket_options),
       [](socket_t sock, struct addrinfo &ai) -> bool {
         if (::bind(sock, ai.ai_addr, static_cast<socklen_t>(ai.ai_addrlen))) {
           return false;
@@ -5249,11 +5260,11 @@ inline void ClientImpl::copy_settings(const ClientImpl &rhs) {
 inline socket_t ClientImpl::create_client_socket(Error &error) const {
   if (!proxy_host_.empty() && proxy_port_ != -1) {
     return detail::create_client_socket(
-        proxy_host_.c_str(), proxy_port_, tcp_nodelay_, socket_options_,
+        proxy_host_.c_str(), proxy_port_, address_family_, tcp_nodelay_, socket_options_,
         connection_timeout_sec_, connection_timeout_usec_, interface_, error);
   }
   return detail::create_client_socket(
-      host_.c_str(), port_, tcp_nodelay_, socket_options_,
+      host_.c_str(), port_, address_family_, tcp_nodelay_, socket_options_,
       connection_timeout_sec_, connection_timeout_usec_, interface_, error);
 }
 
@@ -6381,6 +6392,8 @@ inline void ClientImpl::set_default_headers(Headers headers) {
   default_headers_ = std::move(headers);
 }
 
+inline void ClientImpl::set_address_family(int family) { address_family_ = family; }
+
 inline void ClientImpl::set_tcp_nodelay(bool on) { tcp_nodelay_ = on; }
 
 inline void ClientImpl::set_socket_options(SocketOptions socket_options) {
@@ -7443,6 +7456,8 @@ inline void Client::set_default_headers(Headers headers) {
   cli_->set_default_headers(std::move(headers));
 }
 
+inline void Client::set_address_family(int family) { cli_->set_address_family(family); }
+
 inline void Client::set_tcp_nodelay(bool on) { cli_->set_tcp_nodelay(on); }
 
 inline void Client::set_socket_options(SocketOptions socket_options) {

test/test.cc

@@ -3137,7 +3137,7 @@ static bool send_request(time_t read_timeout_sec, const std::string &req,
   auto error = Error::Success;
 
   auto client_sock =
-      detail::create_client_socket(HOST, PORT, false, nullptr,
+      detail::create_client_socket(HOST, PORT, AF_UNSPEC, false, nullptr,
                                    /*timeout_sec=*/5, 0, std::string(), error);
 
   if (client_sock == INVALID_SOCKET) { return false; }