overwrite user-agent for outproxy requests

libi2pd_client/HTTPProxy.cpp

@@ -390,6 +390,10 @@ namespace proxy {
 		std::string origURI = m_ClientRequest.uri; // TODO: what do we need to change uri for?
 		m_ClientRequest.uri = m_ClientRequestURL.to_string();
 
+		// update User-Agent to ESR version of Firefox, same as Tor Browser below version 8, for non-HTTPS connections
+		if(m_ClientRequest.method != "CONNECT")
+			m_ClientRequest.UpdateHeader("User-Agent", "Mozilla/5.0 (Windows NT 6.1; rv:52.0) Gecko/20100101 Firefox/52.0");
+
 		m_ClientRequest.write(m_ClientRequestBuffer);
 		m_ClientRequestBuffer << m_recv_buf.substr(m_req_len);