added new option 'always_send_user_agent'

docs/manual.rst

@@ -4329,6 +4329,7 @@ session_settings
 		int alert_queue_size;
 		int max_metadata_size;
 		bool smooth_connects;
+		bool always_send_user_agent;
 	};
 
 ``version`` is automatically set to the libtorrent version you're using
@@ -5170,6 +5171,10 @@ we're close to bump up against the limit of number of connections. The intention
 of this setting is to more evenly distribute our connection attempts over time,
 instead of attempting to connectin in batches, and timing them out in batches.
 
+``always_send_user_agent`` defaults to false. When set to true, web connections
+will include a user-agent with every request, as opposed to just the first
+request in a connection.
+
 pe_settings
 ===========
 

include/libtorrent/session_settings.hpp

@@ -264,6 +264,7 @@ namespace libtorrent
 			, alert_queue_size(1000)
 			, max_metadata_size(1024*1024)
 			, smooth_connects(true)
+			, always_send_user_agent(false)
 		{}
 
 		// libtorrent version. Used for forward binary compatibility
@@ -1051,6 +1052,9 @@ namespace libtorrent
 		// attempt to smooth out connects to avoid getting spikes in
 		// opening connections and timing out connections
 		bool smooth_connects;
+
+		// always send user-agent
+		bool always_send_user_agent;
 	};
 
 #ifndef TORRENT_DISABLE_DHT

src/web_connection_base.cpp

@@ -126,7 +126,7 @@ namespace libtorrent
 	{
 		request += "Host: ";
 		request += m_host;
-		if (m_first_request) {
+		if (m_first_request || m_ses.settings().always_send_user_agent) {
 			request += "\r\nUser-Agent: ";
 			request += m_ses.settings().user_agent;
 		}