Linux: is there a read or recv from socket with timeout?

How can I try to read data from socket with timeout? I know, select, pselect, poll, has a timeout field, but using of them disables "tcp fast-path" in tcp reno stack.

The only idea I have is to use recv(fd, ..., MSG_DONTWAIT) in a loop

You can use the setsockopt function to set a timeout on receive operations:

> SO_RCVTIMEO > > Sets the timeout value that specifies > the maximum amount of time an input > function waits until it completes. It > accepts a timeval structure with the > number of seconds and microseconds > specifying the limit on how long to > wait for an input operation to > complete. If a receive operation has > blocked for this much time without > receiving additional data, it shall > return with a partial count or errno > set to [EAGAIN] or [EWOULDBLOCK] if no > data is received. The default for this > option is zero, which indicates that a > receive operation shall not time out. > This option takes a timeval structure. > Note that not all implementations > allow this option to be set.

// LINUX
struct timeval tv;
tv.tv_sec = timeout_in_seconds;
tv.tv_usec = 0;
setsockopt(sockfd, SOL_SOCKET, SO_RCVTIMEO, (const char*)&tv, sizeof tv);
    
// WINDOWS
DWORD timeout = timeout_in_seconds * 1000;
setsockopt(socket, SOL_SOCKET, SO_RCVTIMEO, (const char*)&timeout, sizeof timeout);

// MAC OS X (identical to Linux)
struct timeval tv;
tv.tv_sec = timeout_in_seconds;
tv.tv_usec = 0;
setsockopt(sockfd, SOL_SOCKET, SO_RCVTIMEO, (const char*)&tv, sizeof tv);

Reportedly on Windows this should be done before calling bind. I have verified by experiment that it can be done either before or after bind on Linux and OS X.

Here's some simple code to add a time out to your recv function using poll in C:

struct pollfd fd;
int ret;

fd.fd = mySocket; // your socket handler 
fd.events = POLLIN;
ret = poll(&fd, 1, 1000); // 1 second for timeout
switch (ret) {
	case -1:
	    // Error
        break;
	case 0:
        // Timeout 
        break;
    default:
        recv(mySocket,buf,sizeof(buf), 0); // get your data
        break;
}

// works also after bind operation for WINDOWS

DWORD timeout = timeout_in_seconds * 1000;
setsockopt(socket, SOL_SOCKET, SO_RCVTIMEO, (const char*)&timeout, sizeof timeout);

Install a handler for SIGALRM, then use alarm() or ualarm() before a regular blocking recv(). If the alarm goes off, the recv() will return an error with errno set to EINTR.

LINUX

struct timeval tv;
tv.tv_sec = 30;        // 30 Secs Timeout
tv.tv_usec = 0;        // Not init'ing this can cause strange errors
setsockopt(sockfd, SOL_SOCKET, SO_RCVTIMEO, (const char*)&tv,sizeof(struct timeval));

WINDOWS

DWORD timeout = SOCKET_READ_TIMEOUT_SEC * 1000;
setsockopt(socket, SOL_SOCKET, SO_RCVTIMEO, (const char*)&timeout, sizeof(timeout));

NOTE: You have put this setting before bind() function call for proper run