tcp.c

#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <netdb.h>
#include <netinet/in.h>
#include <arpa/inet.h>
int main() {
    struct sockaddr_in serveraAddr, clientAddr;
    socklen_t clientAddrLen;
    int nFd = 0, linkFd = 0;
    int nRet = 0;
    int nReadLen = 0;
    char szBuff[BUFSIZ] = {
        0
    };

    /* 创建一个socket描述符 */
    nFd = socket(AF_INET, SOCK_STREAM, 0);
    if (-1 == nFd) {
        perror("socket:");
        return -1;
    }

    /* 给本地的socket地址赋值 */
    memset( & serveraAddr, 0, sizeof(struct sockaddr_in));
    serveraAddr.sin_family = AF_INET; //以ipv4协议进行连接
    serveraAddr.sin_addr.s_addr = htonl(INADDR_ANY); //接收所有客户端ip的连接
    serveraAddr.sin_port = htons(1111); //接收8080端口发来的连接

    /* 当TCP的连接的状态是TCP_WAIT状态的时候， 可以通过设置SO_REUSEADDR
        选项来强制使用属于TIME_WAIT状态的连接的socket*/
    int isReuse = 1;
    setsockopt(nFd, SOL_SOCKET, SO_REUSEADDR, (const char * ) & isReuse, sizeof(isReuse));

    /* 将该socket的描述符和本地的套接字地址绑定起来 */
    nRet = bind(nFd, (struct sockaddr * ) & serveraAddr, sizeof(serveraAddr));
    if (-1 == nRet) {
        perror("bind:");
        return -1;
    }

    /* 设置该套接口在监听状态 */
    listen(nFd, 1);

    /* 等待客户端发来的tcp连接 ,当客户端连接进来之后，返回两个之间的唯一的socket连接，存放在linkFd之中*/
    clientAddrLen = sizeof(struct sockaddr_in);
    linkFd = accept(nFd, (struct sockaddr * ) & clientAddr, & clientAddrLen);
    if (-1 == linkFd) {
        perror("accept:");
        return -1;
    }

    /* 把连接进来的客户端地址和端口打印出来 */
    printf("connect %s %d successful\n", inet_ntoa(clientAddr.sin_addr), ntohs(clientAddr.sin_port));

    /* 循环的读取客户端发来的数据 */
    FILE * out;
    if ((out = fopen("app.data", "wt")) == NULL) {
        fprintf(stderr, "Cannot open output file./n");
        return 1;
    }
    while (1) {
        memset(szBuff, 0, BUFSIZ);
        nReadLen = read(linkFd, szBuff, BUFSIZ);
        if (nReadLen > 0) {
            printf("read data: %s\n", szBuff);
            fprintf(out, "%s\n", szBuff);
            fflush(out);
        }
    }
    fclose(out);
    return 0;
}