On Fri, 2011-10-07 at 19:19 +0200, Johannes Berg wrote:
> This works similar to the existing TX timestamping
> in that it reflects the SKB back to the socket's
> error queue with a SCM_WIFI_STATUS cmsg that has
> an int indicating ACK status (0/1).
I should give you a test application. This is based on the code in
Documentation/networking/timestamping/timestamping.c and sends the same
frames, but to UDP port 1 to a peer you give on the command line.
E.g. if you save this file as ack.c, you can do
$ ./ack 192.168.100.2
SO_WIFI_STATUS 1
1318010597.494035: sent 124 bytes
1318010597.494084: select 2505916us
1318010597.513457: select returned: 1, success
ready for reading
1318010597.513668: received error data, 194 bytes from 69.0.0.152, 72 bytes control messages
cmsg len 20: SOL_SOCKET acked: 1
cmsg len 48: IPPROTO_IP IP_RECVERR ee_errno 'No message of desired type' ee_origin 4 => bounced packet => GOT OUR DATA BACK (HURRAY!)
1318010597.513860: select 2486140us
(not sure what's with the bogus RX IP, probably just not a valid field here)
johannes
/*
* This program demonstrates how the wifi ack status feature in
* the Linux kernel works. It sends some random packets and prints
* out whether it was acked.
*
* Copyright (C) 2009, 2011 Intel Corporation.
* Author: Patrick Ohly <patrick.ohly@xxxxxxxxx>
* Author: Johannes Berg <johannes.berg@xxxxxxxxx>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. * See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License along with
* this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <sys/time.h>
#include <sys/socket.h>
#include <sys/select.h>
#include <sys/ioctl.h>
#include <arpa/inet.h>
#include <net/if.h>
#include <asm/types.h>
#include <linux/net_tstamp.h>
#include <linux/errqueue.h>
#ifndef SO_WIFI_STATUS
# define SO_WIFI_STATUS 41
# define SCM_WIFI_STATUS SO_WIFI_STATUS
#endif
#ifndef SO_EE_ORIGIN_TXSTATUS
#define SO_EE_ORIGIN_TXSTATUS 4
#endif
static void bail(const char *error)
{
printf("%s: %s\n", error, strerror(errno));
exit(1);
}
static const unsigned char sync[] = {
0x00, 0x01, 0x00, 0x01,
0x5f, 0x44, 0x46, 0x4c,
0x54, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00,
0x01, 0x01,
/* fake uuid */
0x00, 0x01,
0x02, 0x03, 0x04, 0x05,
0x00, 0x01, 0x00, 0x37,
0x00, 0x00, 0x00, 0x08,
0x00, 0x00, 0x00, 0x00,
0x49, 0x05, 0xcd, 0x01,
0x29, 0xb1, 0x8d, 0xb0,
0x00, 0x00, 0x00, 0x00,
0x00, 0x01,
/* fake uuid */
0x00, 0x01,
0x02, 0x03, 0x04, 0x05,
0x00, 0x00, 0x00, 0x37,
0x00, 0x00, 0x00, 0x04,
0x44, 0x46, 0x4c, 0x54,
0x00, 0x00, 0xf0, 0x60,
0x00, 0x01, 0x00, 0x00,
0x00, 0x00, 0x00, 0x01,
0x00, 0x00, 0xf0, 0x60,
0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x04,
0x44, 0x46, 0x4c, 0x54,
0x00, 0x01,
/* fake uuid */
0x00, 0x01,
0x02, 0x03, 0x04, 0x05,
0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00
};
static void sendpacket(int sock, struct sockaddr *addr, socklen_t addr_len)
{
struct timeval now;
int res;
res = sendto(sock, sync, sizeof(sync), 0,
addr, addr_len);
gettimeofday(&now, 0);
if (res < 0)
printf("%s: %s\n", "send", strerror(errno));
else
printf("%ld.%06ld: sent %d bytes\n",
(long)now.tv_sec, (long)now.tv_usec,
res);
}
static void printpacket(struct msghdr *msg, int res,
char *data, int sock)
{
struct sockaddr_in *from_addr = (struct sockaddr_in *)msg->msg_name;
struct cmsghdr *cmsg;
struct timeval tv;
struct timespec ts;
struct timeval now;
gettimeofday(&now, 0);
printf("%ld.%06ld: received %s data, %d bytes from %s, %zu bytes control messages\n",
(long)now.tv_sec, (long)now.tv_usec, "error",
res,
inet_ntoa(from_addr->sin_addr),
msg->msg_controllen);
for (cmsg = CMSG_FIRSTHDR(msg);
cmsg;
cmsg = CMSG_NXTHDR(msg, cmsg)) {
printf(" cmsg len %zu: ", cmsg->cmsg_len);
switch (cmsg->cmsg_level) {
case SOL_SOCKET:
printf("SOL_SOCKET ");
switch (cmsg->cmsg_type) {
case SCM_WIFI_STATUS: {
int *ack = (void *)CMSG_DATA(cmsg);
printf("acked: %d", *ack);
break;
}
default:
printf("type %d", cmsg->cmsg_type);
break;
}
break;
case IPPROTO_IP:
printf("IPPROTO_IP ");
switch (cmsg->cmsg_type) {
case IP_RECVERR: {
struct sock_extended_err *err =
(struct sock_extended_err *)CMSG_DATA(cmsg);
printf("IP_RECVERR ee_errno '%s' ee_origin %d => %s",
strerror(err->ee_errno),
err->ee_origin,
err->ee_origin == SO_EE_ORIGIN_TXSTATUS ?
"bounced packet" : "unexpected origin"
);
if (res < sizeof(sync))
printf(" => truncated data?!");
else if (!memcmp(sync, data + res - sizeof(sync),
sizeof(sync)))
printf(" => GOT OUR DATA BACK (HURRAY!)");
break;
}
case IP_PKTINFO: {
struct in_pktinfo *pktinfo =
(struct in_pktinfo *)CMSG_DATA(cmsg);
printf("IP_PKTINFO interface index %u",
pktinfo->ipi_ifindex);
break;
}
default:
printf("type %d", cmsg->cmsg_type);
break;
}
break;
default:
printf("level %d type %d",
cmsg->cmsg_level,
cmsg->cmsg_type);
break;
}
printf("\n");
}
}
static void recvpacket(int sock)
{
char data[256];
struct msghdr msg;
struct iovec entry;
struct sockaddr_in from_addr;
struct {
struct cmsghdr cm;
char control[512];
} control;
int res;
memset(&msg, 0, sizeof(msg));
msg.msg_iov = &entry;
msg.msg_iovlen = 1;
entry.iov_base = data;
entry.iov_len = sizeof(data);
msg.msg_name = (caddr_t)&from_addr;
msg.msg_namelen = sizeof(from_addr);
msg.msg_control = &control;
msg.msg_controllen = sizeof(control);
res = recvmsg(sock, &msg, MSG_ERRQUEUE|MSG_DONTWAIT);
if (res < 0) {
printf("%s %s: %s\n",
"recvmsg", "error",
strerror(errno));
} else {
printpacket(&msg, res, data, sock);
}
}
int main(int argc, char **argv)
{
int i;
int enabled = 1;
int sock;
struct ifreq device;
struct ifreq hwtstamp;
struct sockaddr_in addr;
struct ip_mreq imr;
int val;
socklen_t len;
struct timeval next;
addr.sin_family = AF_INET;
addr.sin_port = htons(1);
if (argc != 2 || inet_aton(argv[1], &addr.sin_addr) == 0) {
printf("%s <ip addr>\n", argv[0]);
exit(1);
}
sock = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
if (sock < 0)
bail("socket");
/* set socket option for wifi status */
if (setsockopt(sock, SOL_SOCKET, SO_WIFI_STATUS,
&enabled, sizeof(enabled)) < 0) {
bail("enable ack status");
}
/* request IP_PKTINFO for debugging purposes */
if (setsockopt(sock, SOL_IP, IP_PKTINFO,
&enabled, sizeof(enabled)) < 0)
printf("%s: %s\n", "setsockopt IP_PKTINFO", strerror(errno));
/* verify socket options */
len = sizeof(val);
if (getsockopt(sock, SOL_SOCKET, SO_WIFI_STATUS, &val, &len) < 0)
printf("%s: %s\n", "getsockopt SO_TIMESTAMP", strerror(errno));
else
printf("SO_WIFI_STATUS %d\n", val);
/* send packets forever every five seconds */
gettimeofday(&next, 0);
next.tv_sec = (next.tv_sec + 1) / 5 * 5;
next.tv_usec = 0;
while (1) {
struct timeval now;
struct timeval delta;
long delta_us;
int res;
fd_set readfs, errorfs;
gettimeofday(&now, 0);
delta_us = (long)(next.tv_sec - now.tv_sec) * 1000000 +
(long)(next.tv_usec - now.tv_usec);
if (delta_us > 0) {
/* continue waiting for timeout or data */
delta.tv_sec = delta_us / 1000000;
delta.tv_usec = delta_us % 1000000;
FD_ZERO(&readfs);
FD_ZERO(&errorfs);
FD_SET(sock, &readfs);
FD_SET(sock, &errorfs);
printf("%ld.%06ld: select %ldus\n",
(long)now.tv_sec, (long)now.tv_usec,
delta_us);
res = select(sock + 1, &readfs, 0, &errorfs, &delta);
gettimeofday(&now, 0);
printf("%ld.%06ld: select returned: %d, %s\n",
(long)now.tv_sec, (long)now.tv_usec,
res,
res < 0 ? strerror(errno) : "success");
if (res > 0) {
if (FD_ISSET(sock, &readfs))
printf("ready for reading\n");
if (FD_ISSET(sock, &errorfs))
printf("has error\n");
recvpacket(sock);
}
} else {
/* write one packet */
sendpacket(sock,
(struct sockaddr *)&addr,
sizeof(addr));
next.tv_sec += 5;
continue;
}
}
return 0;
}
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