FTP: Only issue EPSV command for non-IPv4 connections.

net/ftp/ftp_network_transaction.cc

Index: net/ftp/ftp_network_transaction.cc
diff --git a/net/ftp/ftp_network_transaction.cc b/net/ftp/ftp_network_transaction.cc
index 272f49fbee8ed9316ffc916dd40b0318d2906f0a..c4b2181b9b1e5ad26613649a26e8b40cf8f88f57 100644
--- a/net/ftp/ftp_network_transaction.cc
+++ b/net/ftp/ftp_network_transaction.cc
@@ -682,6 +682,15 @@ int FtpNetworkTransaction::DoCtrlConnectComplete(int result) {
     if (result == OK) {
       response_.socket_address = HostPortPair::FromIPEndPoint(ip_endpoint);
       next_state_ = STATE_CTRL_READ;
+
+      if (ip_endpoint.GetFamily() == AF_INET) {
+        // Do not use EPSV for IPv4 connections. Some servers become confused
+        // and we time out while waiting to connect. PASV is perfectly fine for
+        // IPv4. Note that this blacklists IPv4 not to use EPSV instead of
+        // whitelisting IPv6 to use it, to make the code more future-proof:
+        // all future protocols should just use EPSV.
+        use_epsv_ = false;
+      }
     }
   }
   return result;