handling tcp and udp services simultaneously
从 bind 系统调用的参数来看, 一个 socket 只能与一个 socket 地址绑定, 即一个 socket 只能用来监听一个端口. 因此, 服务器如果要同时监听多个端口, 就必须创建多个 socket 并将它们分别绑定到各自端口上. 即使是同一个端口, 如果服务器要同时监听该端口上的 tcp 和 udp 请求, 也必须分别创建流 socket 和数据报 socket 并绑定到该端口上. 对此, 可以使用 i/o 复用技术来管理这些 socket
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <assert.h>
#include <stdio.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <fcntl.h>
#include <stdlib.h>
#include <sys/epoll.h>
#include <pthread.h>
#define MAX_EVENT_NUMBER 1024
#define TCP_BUFFER_SIZE 512
#define UPD_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, char const *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);
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);
bzero(&address, sizeof(address));
address.sin_family = AF_INET;
inet_pton(AF_INET, ip, &address.sin_addr);
address.sin_port = htons(port);
int uppfd = socket(PF_INET, SOCK_DGRAM, 0);
assert(uppfd >= 0);
ret = bind(uppfd, (struct sockaddr*)&address, sizeof(address));
assert(ret != -1);
epoll_event events[MAX_EVENT_NUMBER];
int epollfd = epoll_create(5);
assert(epollfd != -1);
//
addfd(epollfd, listenfd);
addfd(epollfd, uppfd);
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 == uppfd) {
char buf[UPD_BUFFER_SIZE];
memset(buf, '\0', UPD_BUFFER_SIZE);
struct sockaddr_in client_address;
socklen_t client_addrlength = sizeof(client_address);
ret = recvfrom(uppfd, buf, UPD_BUFFER_SIZE - 1, 0, (struct sockaddr*)&client_address, &client_addrlength);
if(ret > 0) {
sendto(uppfd, buf, UPD_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 {
printf("something else happened\n");
}
}
}
close(listenfd);
return 0;
}