一个简单的UDP接收例子

一个简单的UDP Server例程：将UDP接收的数据显示出来，配合线程使用，更接近实际应用场景。（可自行在适当的地方添加数据发送函数）

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http://blog.csdn.net/a99778800/article/details/53659458

测试环境： ubuntu + gcc;

udp_server.c

gcc -o udp_server udp_server.c -lpthread

/* author: ljf
* udp_server.c
*/
#include <stdio.h>
#include <string.h>
#include <strings.h>
#include <unistd.h>

#include <sys/types.h>          /* See NOTES */
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <pthread.h>

int isRecvData = 0;

int g_size = 0;
unsigned char g_buffer[1024] = {0};

void *thread_udp_recv(void *arg)
{
int fd = *(int *)arg;

int recvLen = 0;
unsigned char recvDataBuff[1024] = {0}; // 逻辑上区别不同缓冲区，可直接使用g_buffer；

struct sockaddr_in from;
int fromlen = sizeof(from);

printf("thread: begin;\r\n");

while(1)
{
recvLen = recvfrom(fd, recvDataBuff, 1024, 0, (struct sockaddr *)&from, &fromlen);
if(-1 == recvLen)
{
g_size = -1;
perror("recvfrom");
break;
}

while(1 == isRecvData); // wait for show data;

if(recvLen > 0){
memcpy(g_buffer, recvDataBuff, recvLen);
g_size = recvLen;
isRecvData = 1;
printf("thread: %d byte data from %s:%d;\r\n", recvLen, inet_ntoa(from.sin_addr), ntohs(from.sin_port));
}
}

return NULL;
}

int main(int argc, char **argv)
{

int sockfd = 0;
struct sockaddr_in local_addr;
pthread_t tid_udp_recv; // 线程ID;

// 1. 创建套接字；
sockfd = socket(AF_INET, SOCK_DGRAM, 0);    // IPv4以太网协议/数据包套接字；
if(-1 == sockfd)
{
perror("socket");
return -1;
}
printf("sockfd = %d\n", sockfd);

// 2. 绑定服务器端口号；(也可以不绑定，由系统分配可用端口号)
local_addr.sin_family = AF_INET;
local_addr.sin_port = htons(9000);
local_addr.sin_addr.s_addr = INADDR_ANY; // 任意地址；
bzero(&local_addr.sin_zero, 8);
if(-1 == bind(sockfd, (struct sockaddr*)&local_addr, sizeof(local_addr)))
{
perror("bind");
close(sockfd);
return -1;
}

// 3. 启动接收线程；
pthread_create(&tid_udp_recv, NULL, thread_udp_recv, &sockfd);

while(g_size >= 0)
{
if(isRecvData){
// show data;
printf("main: new data\r\n");
for(int temp = 0; temp < g_size; temp++){
printf("%02x ", g_buffer[temp]);
}
printf("\n");
isRecvData = 0;
}
}

pthread_join(tid_udp_recv, NULL);
close(sockfd);

return 0;
}