UDP在多个端口上接收数据 [英] UDP receiving data on multiple ports

问题描述

是否可以在2个端口上使用recvfrom接收数据?我有一个用于用户请求的端口，另一个用于聊天消息的端口.是否可以通过一个recvfrom()绑定两个具有不同端口的套​​接字并接收数据?

致谢

编辑 这段代码有效吗?

int socket_fd,socket_fd2;
struct sockaddr_in addr, chat_addr;

addr.sin_family = AF_INET;
addr.sin_port = htons(1234);
addr.sin_addr.s_addr = inet_addr("127.0.0.1");

chat_addr.sin_family = AF_INET;
chat_addr.sin_port = htons(4321);
chat_addr.sin_addr.s_addr = inet_addr("127.0.0.1");

bind(socket_fd2, (struct sockaddr *) &chat_addr, sizeof(struct sockaddr_in));
bind(socket_fd, (struct sockaddr *) &addr, sizeof(struct sockaddr_in));

所以我想在两个不同的端口上接收数据.

解决方案

否，无法通过一次调用recvfrom从两个套接字读取，因为该函数仅需要一个套接字文件描述符参数.

您要么需要每个端口一个线程，要么需要一种机制(例如select，poll)来告诉哪个套接字有等待读取的数据.

在后一种情况下，一旦知道哪些套接字具有待处理的数据，就可以然后在该特定套接字上调用recvfrom以获取所需的数据，例如:

// set up select parameters
fd_set socks;
FD_ZERO(&socks);
FD_SET(socket_fd, &socks);
FD_SET(socket_fd2, &socks);

// find out which sockets are read - NB: it might be both!
int nsocks = max(socket_fd, socket_fd2) + 1;
if (select(nsocks, &socks, (fd_set *)0, (fd_set *)0, 0) >= 0) {
     if (FD_ISSET(socket_fd, &socks) {
          // handle socket 1
          recvfrom(socket_fd, ...);
     }
     if (FD_ISSET(socket_fd2, &socks) {
          // handle socket 2
          recvfrom(socket_fd2, ...);
     }
}

注意:这只是一个粗略而现成的示例-实际代码将进行错误检查等.

Is it possible to receive data with recvfrom on 2 ports? I have a port which I use for user requests and another port for chat messages. Is it possible to bind two sockets, with different ports and receive data with one recvfrom()?

Regards

EDIT Does this code work?

int socket_fd,socket_fd2;
struct sockaddr_in addr, chat_addr;

addr.sin_family = AF_INET;
addr.sin_port = htons(1234);
addr.sin_addr.s_addr = inet_addr("127.0.0.1");

chat_addr.sin_family = AF_INET;
chat_addr.sin_port = htons(4321);
chat_addr.sin_addr.s_addr = inet_addr("127.0.0.1");

bind(socket_fd2, (struct sockaddr *) &chat_addr, sizeof(struct sockaddr_in));
bind(socket_fd, (struct sockaddr *) &addr, sizeof(struct sockaddr_in));

So I want to receive data on two different ports.

解决方案

No, it's not possible to read from both sockets using a single call to recvfrom, since that function only takes a single socket file descriptor parameter.

You either need a thread per port, or a mechanism (e.g. select, poll) to tell which sockets have data waiting to be read.

In the latter case, once you know which sockets have pending data you can then call recvfrom on that specific socket to get the data you need, e.g.:

// set up select parameters
fd_set socks;
FD_ZERO(&socks);
FD_SET(socket_fd, &socks);
FD_SET(socket_fd2, &socks);

// find out which sockets are read - NB: it might be both!
int nsocks = max(socket_fd, socket_fd2) + 1;
if (select(nsocks, &socks, (fd_set *)0, (fd_set *)0, 0) >= 0) {
     if (FD_ISSET(socket_fd, &socks) {
          // handle socket 1
          recvfrom(socket_fd, ...);
     }
     if (FD_ISSET(socket_fd2, &socks) {
          // handle socket 2
          recvfrom(socket_fd2, ...);
     }
}

NB: this is just a rough and ready sample - real code would have error checking, etc.

这篇关于UDP在多个端口上接收数据的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！