1、背景

工作中经常有创建TCP和UDP客户端程序的时候，因此在将创建客户端的TCP和UDP的代码记录一下。

• socket创建

static int OpenSocket(char *svrIP, uint16_t svrPort, int mode)
{
	int sockfd = -1;
	int transport;			// 默认使用UDP
	struct sockaddr_in addr = {0, };
	
	if (!svrIP)
	{
		GB_PrintError("svrIP is invalid.\n");
		return -1;
	}

	transport = mode?SOCK_STREAM:SOCK_DGRAM;
	sockfd = socket(AF_INET, transport, 0);
	if (sockfd < 0)
	{
		GB_PrintError("create sock failed.\n");
		return -1;
	}

	int opt = 1;
	if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, (char *)&opt, sizeof(opt)) < 0)
	{
		close(sockfd);
		GB_PrintError("SOL_SOCKET SO_REUSEADDR failed.\n");
		return -1;
	}

	// 如果是TCP 需要连接服务器
	if (mode)
	{
		memset(&addr, 0, sizeof(struct sockaddr_in));
		addr.sin_family = AF_INET;
		addr.sin_port = htons(svrPort);
		addr.sin_addr.s_addr = inet_addr(svrIP);
		if (connect(sockfd, (struct sockaddr *)&addr, sizeof(struct sockaddr_in)) < 0) 
		{
			close(sockfd);
			GB_PrintError("connet svr failed. stream svrip:%s, stream svrPort:%d. error code:%d\n", svrIP, svrPort, errno);
			return -1;
		}
	}
	
	return sockfd;
}

• 数据发送

static int sendStreamData(PreviewParam_t *handle, char *streamData, int streamLen, int mode)
{
	int w = 0;
	struct sockaddr_in addr = {0, };
	

	if (!handle || !streamData || streamLen<= 0 || handle->scokfd < 0)
	{
		GB_PrintError("handle error.\n");
		return -1;
	}

	
	// 如果是TCP方式
	if (mode)
	{
		w = send(handle->scokfd, streamData, streamLen, 0);
	}
	else 
	{
		addr.sin_family = AF_INET;
		addr.sin_port = htons(handle->svrPort);
		addr.sin_addr.s_addr = inet_addr(handle->svrIP);
		w = sendto(handle->scokfd, streamData, streamLen, 0, (struct sockaddr *)&addr, sizeof(struct sockaddr));
	}

	return w;
}

• 创建TCP服务端程序：

static int CreateTcpServer(uint16_t port)
{
	int sockfd = -1;
	struct sockaddr_in serveraddr = {0, };
	

	sockfd = socket(AF_INET, SOCK_STREAM, 0);
 	if (sockfd < 0) 
 	{
		return -1;
 	}

 	int opt = 1;
	if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, (char *)&opt, sizeof(opt)) < 0)
	{
		close(sockfd);
		return -1;
	}

	bzero((char *) &serveraddr, sizeof(serveraddr));
	serveraddr.sin_family = AF_INET;
	serveraddr.sin_addr.s_addr = htonl(INADDR_ANY);
	serveraddr.sin_port = htons(port);
	if (bind(sockfd, (struct sockaddr *) &serveraddr, sizeof(serveraddr)) < 0) 
	{
		close(sockfd);
		return -1;
	}

	if (listen(sockfd, 5) < 0) /* allow 5 requests to queue up */ 
	{
		close(sockfd);
		return -1;
	}

 	return sockfd;
}

• 保存监听的句柄

int StreamServerProcess(void)
{
	int socket = -1;
	int clientLen = 0; 
	struct sockaddr_in clientAddr;
	StreamSvrHandle_t *pStreamHanle = NULL;

	
	pStreamHanle = GetStreamSvrHandle();
	if (!pStreamHanle)
	{
		return -1;
	}

	if (pStreamHanle->svrSocket == -1)
	{
		pStreamHanle->svrSocket = CreateTcpServer(STREAM_SERVER_PORT);
	}
	
	clientLen = sizeof(clientAddr);
	socket = accept(pStreamHanle->svrSocket, (struct sockaddr *) &clientAddr, &clientLen);
    if (socket < 0) 
    {
    	close(pStreamHanle->svrSocket);
    	pStreamHanle->svrSocket = -1;
		return -1;
    }
    else 
    {
		if (AddStreamHandle(socket, &clientAddr))
		{
			return -1;
		}
    }
	
	return 0;
}

参考资料：
网络基础–TCP/IP网络基础