TCP服务和UDP服务的同时处理

前言

在实际的生产环境中，我们的服务程序往往需要同时监听多个端口，从bind系统调用的参数我们知道，一个socket只能与一个socket地址相绑定，即一个socket只能用来监听一个端口。因此要监听多个端口就需要创建多个socket,并将它们分别绑定多个端口，通过IO复用进行监听多个socket.

引入

通过刚才的介绍我们可以知道，即使是同一个端口，如果服务器要同时监听TCP和UDP请求，则也需要创建两个不同的socket:一个流socket，一个数据包socket,并将他们绑定到同一个端口上，添加到我们IO多路复用要监控的集合中。

代码实现

#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_flag = fcntl(fd,F_GETFL);
    int new_flag = old_flag|O_NONBLOCK;
    fcntl(AF_INET,F_SETFL,new_flag);
    return old_flag;
}

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,char** argv)
{
    if(argc <= 2)
    {
        printf("usage:%s ip_address port_number\n",basename(argv[1]));
        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.s_addr);
    address.sin_port = htons(port);

    //创建TCPsocket将其绑定在端口port上
    int listenfd = socket(PF_INET,SOCK_STREAM,0);
    assert(listenfd >= 0);

    ret = bind(listenfd,(struct sockaddr*)&address,sizeof(address));
    assert(ret >= 0);

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

    //创建UDPsocket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.s_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);
    //注册TCP socket和UDP socket上的可读可写事件
    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)
                {
                    std::cout<<"a udp message"<

要点

• 如果udp服务的端口和ip 与 tcp服务的一致并不需要重置sockaddr_in结构体（亲自尝试过）。
• udp服务的收发包逻辑
  • recvfrom
  • sendto