Re: [2.6.22-rc4] UDP's local port assignment not working correctly.

From: Eric Dumazet
Date: Thu Jun 07 2007 - 09:18:52 EST


On Thu, 7 Jun 2007 20:40:39 +0900
Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> wrote:

> Hello.
>
> Same local ports are assigned to multiple sockets.
> The following program should print different local port number.
>
> ----- Start of program -----
> #include <stdio.h>
> #include <unistd.h>
> #include <sys/socket.h>
> #include <sys/types.h>
> #include <netinet/in.h>
>
> int main(int argc, char *argv[]) {
> struct sockaddr_in addr;
> socklen_t size = sizeof(addr);
> int server = socket(PF_INET, SOCK_DGRAM, 0), client = socket(PF_INET, SOCK_DGRAM, 0);
> addr.sin_family = AF_INET;
> addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
> addr.sin_port = htons(0);
>
> printf("Server: Binding UDP 127.0.0.1 0 ... ");
> bind(server, (struct sockaddr *) &addr, sizeof(addr));
> getsockname(server, (struct sockaddr *) &addr, &size);
> printf("bound to port %d\n", ntohs(addr.sin_port));
>
> printf("Client: Connecting UDP 127.0.0.1 %d ... ", ntohs(addr.sin_port));
> connect(client, (struct sockaddr *) &addr, sizeof(addr));
> getsockname(client, (struct sockaddr *) &addr, &size);
> printf("bound to port %d\n", ntohs(addr.sin_port));
>
> return 0;
> }
> ----- End of program -----
>
> I told YOSHIFUJI Hideaki and he answered me that
> this is a regression caused by changing UDP's hash search algorithm to 2-pass.
>
> Thanks.

CC netdev

Yes, this was discovered two days ago and David reverted four commits.

http://git.kernel.org/?p=linux/kernel/git/davem/net-2.6.git;a=commitdiff;h=82c5fde20031375cd93fa5a247cf15603ea1f152

So it should probably be included in Linus tree very very soon.

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