网络编程常用函数的封装

这里整理一些C++网络编程常用函数的封装，方便使用，以后会慢慢添加完善

* 将Socket设置为非阻塞

#include <fcntl.h>

int setNonblock(int fd)
{
    int flag;
    if ((flag = fcntl(fd, F_GETFL, 0)) < 0 || fcntl(fd, F_SETFL, flag | O_NONBLOCK) < 0) {
        return -1;
    }
    return 0;
}

* 获取指定网卡的IP地址

#include <net/if.h>
#include <sys/ioctl.h>

int getIpOfNic(const string strNic, string & strIp)
{
    int fd;
    struct ifreq ifr;

    if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
        return -1;
    }

    strcpy(ifr.ifr_name, strNic.c_str());
    if (ioctl(fd, SIOCGIFADDR, &ifr) < 0) {
        close(fd);
        return -2;
    }

    strIp = inet_ntoa(((struct sockaddr_in*)&(ifr.ifr_addr))->sin_addr);
    return 0;
}

* 创建一个udpSocket句柄（tcpSocket类似）

#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>

int createUdpSocket(const string strIp, const uint32_t uPort, bool bBlock = false)
{
    int fd;
    struct sockaddr_in sSvrAddr;

    if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
        return -1;
    }

    if (bBlock) {
        if (setNonblock(fd) < 0) {
            close(fd);
            return -2;
        }
    }

    memset(&sSvrAddr, 0, sizeof(sSvrAddr));
    sSvrAddr.sin_family = AF_INET;
    sSvrAddr.sin_addr.s_addr = inet_addr(strIp.c_str());
    sSvrAddr.sin_port = htons(uPort);

    if (bind(fd, (struct sockaddr *)&sSvrAddr, sizeof(sSvrAddr)) <0) {
        close(fd);
        return -3;
    }

    return fd;
}