同时处理TCP和UDP服务

即使是同一个端口，如果服务器要同时处理该端口上的TCP和UDP请求，则也需要创建两个不同的socket：一个是流socket，另一个是数据包socket，并将他们都绑定到该端口上。

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

#define MAX_EVENT_NUMBER 1024
#define TCP_BUFFER_SIZE 512
#define UDP_BUFFER_SIZE 1024

int setnonblocking(int fd)
{
    int old_option = fcntl(fd, F_GETFL);
    int new_option = old_option | O_NONBLOCK;
    fcntl(fd, F_SETFL, new_option);
    return old_option;
}

void addfd(int epollfd, int fd)
{
    struct epoll_event event;
    event.data.fd = fd;
    event.events = EPOLLIN | EPOLLET;
    epoll_ctl(epollfd, EPOLL_CTL_ADD, fd, &event);
    setnonblocking(fd);
}

int main(int argc, char* argv[])
{
    if(argc <= 2)
    {
        printf("usage: %s ip_address port_number\n", basename(argv[0]));
        return 1;
    }
    const char* ip = argv[1];
    int port = atoi(argv[2]);

    int ret = 0;
    struct sockaddr_in address;
    bzero(&address, sizeof(address));
    address.sin_family = AF_INET;
    inet_pton(AF_INET, ip, &address.sin_addr);
    address.sin_port = htons(port);

    //创建tcp socket ， 并将其绑定到端口port上
    int listenfd = socket(PF_INET, SOCK_STREAM, 0);
    assert(listenfd >= 0);

    ret = bind(listenfd, (struct sockaddr*)&address, sizeof(address));
    assert(ret != -1);

    ret = listen(listenfd, 5);
    assert(ret != -1);

    //创建udp socket ， 并将其绑定到端口port上
    bzero(&address, sizeof(address));
    address.sin_family = AF_INET;
    inet_pton(AF_INET, ip, &address.sin_addr);
    address.sin_port = htons(port);
    int udpfd = socket(PF_INET, SOCK_DGRAM, 0);
    assert(udpfd >= 0);
    ret = bind(udpfd, (struct sockaddr*)&address, sizeof(address));
    assert(ret != -1);

    struct epoll_event events[MAX_EVENT_NUMBER];
    int epollfd = epoll_create(5);
    assert(epollfd != -1);
    //注册tcp socket和udp socket上的可读事件
    addfd(epollfd, listenfd);
    addfd(epollfd, udpfd);

    while(1)
    {
        int number = epoll_wait(epollfd, events, MAX_EVENT_NUMBER, -1);
        if(number < 0)
        {
            printf("epoll failure\n");
            break;
        }

        for(int i = 0; i < number; ++i)
        {
            int sockfd = events[i].data.fd;
            if(sockfd == listenfd)
            {
                struct sockaddr_in client_address;
                socklen_t client_addrlength = sizeof(client_address);
                int connfd = accept(listenfd, (struct sockaddr*)&client_address, &client_addrlength);
                addfd(epollfd, connfd);
            }
            else if(sockfd == udpfd)
            {
                char buf[UDP_BUFFER_SIZE];
                memset(buf, '\0',UDP_BUFFER_SIZE);
                struct sockaddr_in client_address;
                socklen_t client_addrlength = sizeof(client_address);
                ret = recvfrom(udpfd, buf, UDP_BUFFER_SIZE - 1, 0, (struct sockaddr*)&client_address, &client_addrlength);
                if(ret > 0)
                {
                    sendto(udpfd, buf, ret, 0, (struct sockaddr*)&client_address, client_addrlength);
                }
            }
            else if(events[i].events & EPOLLIN)
            {
                char buf[TCP_BUFFER_SIZE];
                while(1)
                {
                    memset(buf, '\0', TCP_BUFFER_SIZE);
                    ret = recv(sockfd, buf, TCP_BUFFER_SIZE - 1, 0);
                    if(ret < 0)
                    {
                        if((errno == EAGAIN) || (errno == EWOULDBLOCK))
                        {
                            break;
                        }
                        close(sockfd);
                        break;
                    }
                    else if(ret == 0)
                    {
                        close(sockfd);
                    }
                    else
                    {
                        send(sockfd, buf, ret, 0);
                    }
                }
            }
            else
            {
                printf("something else happened\n");
            }
        }
    }
    close(listenfd);
    return 0;
}