1. 介绍

服务器和 客户端1 和 客户端2通信。

2.server.c

/*
 * socket
 * bind
 * send/recv
 */

#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <string.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <signal.h>

#define SERVER_PORT    8888

int main(int argc, char **argv)
{
	int server;
	int client;
	struct sockaddr_in server_addr;
	struct sockaddr_in client_addr;
	int ret;
	int server_recv;
	int addr_len;
	unsigned char recvbuf[1000];
	int client_num = -1;


	server = socket(AF_INET, SOCK_DGRAM, 0);
	if (server == -1){
		printf("soket error!\n");	
		return -1;
	}

	server_addr.sin_family = AF_INET;
	server_addr.sin_port = htons(SERVER_PORT);
	server_addr.sin_addr.s_addr = INADDR_ANY;
	memset(server_addr.sin_zero, 0, 8);
	/* 将文件句柄绑定ip和端口*/
	ret = bind(server, (const struct sockaddr *)&server_addr, 
			    sizeof(struct sockaddr));
	if (ret == -1){
		printf("bind error!\n");
		return -1;
	}

	while (1) {
		addr_len = sizeof(struct sockaddr);
		server_recv = recvfrom(server, recvbuf, 999, 0,
                             (struct sockaddr *)&client_addr, &addr_len);
		if (server_recv > 0){
			client_num++; /* 统计客户端*/
			printf("get connect form client %d : %s \n", client_num, 
					inet_ntoa(client_addr.sin_addr));
			recvbuf[server_recv]= '\0';
			printf("get msg form %s : %s\n", inet_ntoa(client_addr.sin_addr), recvbuf);
		}
	}

	close(server);
	return 0;
}

2. client.c

/*
 * socket
 * connect
 * send/recv
 */

#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <string.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>

#define SERVER_PORT    8888

int main(int argc, char **argv)
{
    int client;
    struct sockaddr_in server_addr;
    int ret;
    unsigned char sendbuf[1000];
    int client_send;

    if (argc != 2){
        printf("Usage: %s <server_ip>\n", argv[0]);
        return -1;
    }

    client = socket(AF_INET, SOCK_DGRAM, 0);

    server_addr.sin_family = AF_INET;
	server_addr.sin_port = htons(SERVER_PORT);
    memset(server_addr.sin_zero, 0, 8);
    if (inet_aton(argv[1], &server_addr.sin_addr) == 0){
        printf("invalid server_ip\n");
        return -1;
    }
	
    /* 连接服务器 */
    ret = connect(client, (const struct sockaddr *)&server_addr,
                   sizeof(struct sockaddr));
    if (ret == -1){
        printf("connect error!\n");
        return -1;
    }

    while (1){
         if (fgets(sendbuf, 999, stdin)){
            /* 发送数据给服务器 */
            client_send = send(client, sendbuf, strlen(sendbuf), 0);
            if (client_send <= 0){
                close(client);
                return -1;
            }
         }
    }

    return 0;
}

实验截图

END