fewer bind-to-device conditions in AsyncUDPSocket

Differential Revision: D28163554

fbshipit-source-id: 2167a39e88f7aa6053dea5119a30947d2f3304f3

folly/io/async/AsyncUDPServerSocket.h

@@ -127,14 +127,9 @@ class AsyncUDPServerSocket : private AsyncUDPSocket::ReadCallback,
         validateSocketOptions(
             options, addy.getFamily(), SocketOptionKey::ApplyPos::PRE_BIND),
         SocketOptionKey::ApplyPos::PRE_BIND);
-#ifdef FOLLY_HAVE_BIND_OPTIONS_IFNAME
     AsyncUDPSocket::BindOptions bindOptions;
     bindOptions.ifName = ifName;
     socket_->bind(addy, bindOptions);
-#else
-    (void)ifName;
-    socket_->bind(addy);
-#endif
     socket_->applyOptions(
         validateSocketOptions(
             options, addy.getFamily(), SocketOptionKey::ApplyPos::POST_BIND),

folly/io/async/AsyncUDPSocket.cpp

@@ -207,22 +207,23 @@ void AsyncUDPSocket::bind(
     const folly::SocketAddress& address, BindOptions bindOptions) {
   init(address.getFamily(), bindOptions);
 
-  // bind the socket to the interface
-#ifdef FOLLY_HAVE_BIND_OPTIONS_IFNAME
-  if (!bindOptions.ifName.empty() &&
-      netops::setsockopt(
-          fd_,
-          SOL_SOCKET,
-          SO_BINDTODEVICE,
-          bindOptions.ifName.c_str(),
-          bindOptions.ifName.length())) {
-    auto errnoCopy = errno;
-    throw AsyncSocketException(
-        AsyncSocketException::NOT_OPEN,
-        "failed to bind to device: " + bindOptions.ifName,
-        errnoCopy);
-  }
+  {
+    // bind the socket to the interface
+    int optname = 0;
+#if defined(SO_BINDTODEVICE)
+    optname = SO_BINDTODEVICE;
 #endif
+    auto& ifName = bindOptions.ifName;
+    if (optname && !ifName.empty() &&
+        netops::setsockopt(
+            fd_, SOL_SOCKET, optname, ifName.data(), ifName.length())) {
+      auto errnoCopy = errno;
+      throw AsyncSocketException(
+          AsyncSocketException::NOT_OPEN,
+          "failed to bind to device: " + ifName,
+          errnoCopy);
+    }
+  }
 
   // bind to the address
   sockaddr_storage addrStorage;

folly/io/async/AsyncUDPSocket.h

@@ -30,10 +30,6 @@
 #include <folly/net/NetOps.h>
 #include <folly/net/NetworkSocket.h>
 
-#if defined(__linux__) && !FOLLY_MOBILE
-#define FOLLY_HAVE_BIND_OPTIONS_IFNAME
-#endif
-
 namespace folly {
 
 /**
@@ -177,9 +173,7 @@ class AsyncUDPSocket : public EventHandler {
     BindOptions() noexcept {}
     // Whether IPV6_ONLY should be set on the socket.
     bool bindV6Only{true};
-#ifdef FOLLY_HAVE_BIND_OPTIONS_IFNAME
     std::string ifName;
-#endif
   };
 
   /**