[patch 0/3][NETNS45][V2] remove timewait sockets at namespace exit

[Daniel Lezcano]

Denis Lunev spotted that using a reference to the network namespace
with the timewait sockets will be a waste of time because they
are pointless while we will remove the network stack at network
namespace exit.

The following patches do the following:
	- fix missing network namespace reference in timewait 
	socket
	- do some changes in timewait socket code to prepare 
	the next patch, especially split code taking a lock
	- do the effective timewait socket cleanup at network
	namespace exit.

The following code is a test program which creates 100 timewait
sockets.

#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/poll.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
#include <arpa/inet.h>

#include <unistd.h>

#define MAXCONN 100

int client(int *fds)
{
        int i;
        struct sockaddr_in addr;

        close(fds[1]);

        memset(&addr, 0, sizeof(addr));

        addr.sin_family = AF_INET;
        addr.sin_port =  htons(10000);
        addr.sin_addr.s_addr = inet_addr("127.0.0.1");

        if (read(fds[0], &i, sizeof(i)) == -1) {
                perror("read");
                return 1;
        }

        for (i = 0; i < MAXCONN; i++) {
                int fd = socket(PF_INET, SOCK_STREAM, 0);
                if (fd == -1) {
                        perror("socket");
                        return 1;
                }

                if (connect(fd, (const struct sockaddr *)&addr, sizeof(addr))) {
                        perror("connect");
                        return 1;
                }
        }

        return 0;
}

int server(int *fds)
{
        int i, fd, fdpoll[MAXCONN];
        struct sockaddr_in addr;
        socklen_t socklen = sizeof(addr);

        close(fds[0]);

        fd = socket(PF_INET, SOCK_STREAM, 0);
        if (fd == -1) {
                perror("socket");
                return 1;
        }

        memset(&addr, 0, sizeof(addr));

        addr.sin_family = AF_INET;
        addr.sin_port = htons(10000);
        addr.sin_addr.s_addr = inet_addr("127.0.0.1");

        if (bind(fd, (const struct sockaddr *)&addr, sizeof(addr))) {
                perror("bind");
                return 1;
        }

        if (listen(fd, MAXCONN)) {
                perror("listen");
                return 1;
        }

        if (write(fds[1], &i, sizeof(i)) == -1) {
                perror("write");
                return 1;
        }

        for (i = 0; i < MAXCONN; i++) {
                int f = accept(fd, (struct sockaddr *)&addr, &socklen);
                if (f == -1) {
                        perror("accept");
                        return 1;
                }
                fdpoll[i] = f;
        }

        return 0;
}

int main(int argc, char *argv[])
{
        int fds[2];
        int pid;

        if (pipe(fds)) {
                perror("pipe");
                return 1;
        }

        pid = fork();
        if (pid == -1) {
                perror("fork");
                return 1;
        }

        if (!pid)
                return client(fds);
        else
                return server(fds);
}

--