9-8-tcp-udp.c

#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <assert.h>
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/epoll.h>
#include <pthread.h>
#include <string.h>

#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)
{
    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, const char *argv[])
{
    if (argc < 2) 
    {
        fprintf(stderr, "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);
   
    /*  create tcp socket, and bind it to the port
     */
    fprintf(stdout, "create tcp socket -> bind port -> listen port\n");
    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);

    /*create udp socket, and bind it to the port
     */
    fprintf(stdout, "create udp socket -> bind port\n");
    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);

    epoll_event events[MAX_EVENT_NUMBER];
    int epollfd = epoll_create(5);
    assert(epollfd != -1);

    /* register tcp socket and udp socket's readable events */
    addfd(epollfd, listenfd);
    addfd(epollfd, udpfd);

    while(1)
    {
        int number  = epoll_wait(epollfd, events, MAX_EVENT_NUMBER, -1);
        if (number < 0) 
        {
            fprintf(stderr, "epoll_wait 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, UDP_BUFFER_SIZE-1, 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
            {
                fprintf(stderr, "something else happened\n");
            }
        }
    }

    close(listenfd);
    return 0;
}