網絡部分補充說明:
負責傳送網間封包Sys_SendPacket()函數,調用了sendto這個Win socket API,它的作用是:
The sendto function is normally used on a connectionless socket to send a datagram to a specific peer socket identified by the to parameter. Even if the connectionless socket has been previously connected to a specific address, the to parameter overrides the destination address for that particular datagram only. On a connection-oriented socket, the to and tolen parameters are ignored, making sendto equivalent to send.
所以很明顯,使用sendto並不需要建立可靠的連接,也就是不必先調用connect,直接能夠發送datagram.
客戶端連接服務器端的步驟:
1. 客戶端執行CL_Connect_f()
如果客戶端連接的服務器不是本地機器,需要多执行SVC_GetChallenge这一步
cls.state置為CA_CONNECTING.
判斷語句如下:
cls.state=NET_IsLocalAddress(&clc.server_address)?CA_CHALLENGING: CA_CONNECTING;
2. 如果客戶端變量cls.state = CA_CONNECTING,那麼當系統執行到
CL_CheckForResend()時就會啟動
NET_OutOfBandPrint( NS_CLIENT, &clc.server_address, "getchallenge" );
發送”getchallenge”消息給服務器端
3. 服務器端接收到”getchallenge”消息就會調用SVC_GetChallenge()à
NET_OutOfBandPrint(NS_SERVER,address,"challengeResponse %i", challenge );
發送”challengeResponse”消息給客戶端
4. 客戶端接受到”challengeResponse”消息:
cls.state = CA_CHALLENGING;
5. 如果客戶端變量cls.state = CA_CHALLENGING,那麼當系統執行到
CL_CheckForResend()時就會啟動
NET_OutOfBandPrint(NS_CLIENT, &clc.server_address, "connect \"%s\"", info );
發送”connect”消息給服務器端
6. 服務器端接受收到”connect”消息啟動SVC_DirectConnect(),如果客戶身分被確認,那麼就調用函數NET_OutOfBandPrint( NS_SERVER, address, "connectResponse" );
發送”connectResponse”消息給客戶端
否則NET_OutOfBandPrint( NS_SERVER, address, "disconnect" );
發送” disconnect”消息給客戶端
7. 客戶端接收到”connectResponse”,啟動Netchan_Setup,然後調用函數CL_WritePacket()寫入一條空白消息給服務器端.