c++ 网络编程（五）TCP/IP LINUX下 socket编程 多种I/O函数 -以及readv和writev函数用法

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <signal.h>
#include <fcntl.h>

#define BUF_SIZE 30
void error_handling(char *message);
void urg_handler(int signo);

int acpt_sock;
int recv_sock;

int main(int argc, const char * argv[]) {
    struct sockaddr_in recv_adr, serv_adr;
    int str_len, state;
    socklen_t serv_adr_sz;
    struct sigaction act;
    char buf[BUF_SIZE];
    if (argc != 2) {
        printf("Usage: %s <port> \n", argv[0]);
        exit(1);
    }

    //Linux上的信号处理(事件驱动),Windows可以用select函数模拟
    act.sa_handler = urg_handler; //回调函数
    sigemptyset(&act.sa_mask); //初始化0
    act.sa_flags = 0;

    acpt_sock = socket(PF_INET, SOCK_STREAM, 0);
    memset(&recv_adr, 0, sizeof(recv_adr));
    recv_adr.sin_family = AF_INET;
    recv_adr.sin_addr.s_addr = htonl(INADDR_ANY);
    recv_adr.sin_port = htons(atoi(argv[1]));

    if(bind(acpt_sock, (struct sockaddr *) &recv_adr, sizeof(recv_adr)) == -1)
        error_handling("bind() error");
    if(listen(acpt_sock, 5) == -1)
        error_handling("listen() error");

    serv_adr_sz = sizeof(serv_adr);
    recv_sock = accept(acpt_sock, (struct sockaddr *)&serv_adr, &serv_adr_sz);

    //将引发信号事件的句柄recv_sock改为getpid()生成的ID，防止多进程中子进程也响应这个事件
    fcntl(recv_sock, F_SETOWN, getpid());
    state = sigaction(SIGURG, &act, 0); //注册信号事件

    //一般消息接收
    while ((str_len = recv(recv_sock, buf, sizeof(buf), 0)) != 0)
    {
        if (str_len == -1)
            continue;
        buf[str_len] = 0;
        puts(buf);

    }

    close(recv_sock);
    close(acpt_sock);
    return 0;
}

//紧急消息接收
void urg_handler(int signo)
{
    int str_len;
    char buf[BUF_SIZE];
    str_len = recv(recv_sock, buf, sizeof(buf) - 1, MSG_OOB);
    buf[str_len] = 0;
    printf("Urgent message : %s \n", buf);
}

void error_handling(char *message)
{
    fputs(message, stderr);
    fputc(‘\n‘, stderr);
    exit(1);
}

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/socket.h>

#define BUF_SIZE 30
void error_handling(char *message);

int main(int argc, const char * argv[]) {
    int sock;
    struct sockaddr_in recv_adr;

    if(argc != 3)
    {
        printf("Usage: %s <IP> <port> \n", argv[0]);
        exit(1);
    }

    sock = socket(PF_INET, SOCK_STREAM, 0);
    if(sock == -1)
        error_handling("socket() error");
    memset(&recv_adr, 0, sizeof(recv_adr));
    recv_adr.sin_family = AF_INET;
    recv_adr.sin_addr.s_addr = inet_addr(argv[1]);
    recv_adr.sin_port = htons(atoi(argv[2]));

    if (connect(sock, (struct sockaddr *) &recv_adr, sizeof(recv_adr)) == -1)
        error_handling("connect() error");

    //发送紧急消息,Lunix上是信号处理(事件驱动)，Windows上可以select函数模拟
    write(sock, "123", strlen("123"));
    send(sock, "4", strlen("4"), MSG_OOB);
    sleep(2); //os上紧急消息同时发送，下一条会替换上一条，同一时间只能保存一条(可能是一个变量保存的，不是缓冲数组)
    write(sock, "567", strlen("567"));
    send(sock, "890", strlen("890"), MSG_OOB);

    close(sock);
    return 0;
}

void error_handling(char *message)
{
    fputs(message, stderr);
    fputc(‘\n‘, stderr);
    exit(1);
}

#include <stdio.h>
#include <sys/uio.h>

int main(int argc, const char * argv[]) {
    struct iovec vec[2];
    char buf1[] = "ABCDEFG";
    char buf2[] = "1234567";
    int str_len;
    vec[0].iov_base = buf1;
    vec[0].iov_len = 3;
    vec[1].iov_base = buf2;
    vec[1].iov_len = 4;

    str_len = writev(1, vec, 2); //1是系统标准输出文件描述符
    puts("");
    printf("Write bytes: %d \n", str_len);

    return 0;
}

#include <stdio.h>
#include <sys/uio.h>
#define BUF_SIZE 100

int main(int argc, const char * argv[]) {
    struct iovec vec[2];
    char buf1[BUF_SIZE] = {};
    char buf2[BUF_SIZE] = {};
    int str_len;

    vec[0].iov_base = buf1;
    vec[0].iov_len = 5;
    vec[1].iov_base = buf2;
    vec[1].iov_len = BUF_SIZE;

    //把数据放到多个缓冲中储存
    str_len = readv(0, vec, 2);  //2是从标准输入接收数据
    printf("Read bytes: %d \n", str_len);
    printf("First message: %s \n", buf1);
    printf("Second message: %s \n", buf2);

    return 0;
}