andreacavalli/xserver-multidpi
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

os/xdmcp: Just send XDMCP keepalive packets once every three minutes

Browse Source 
There was a complicated scheme to increase the time between keepalives
from 3 minutes up to as much as 24 hours in an attempt to reduce
network traffic from idle X terminals. X terminals receiving X
traffic, or receiving user input would use the 3 minute value; X
terminals without any network traffic would use a longer value.

However, this was actually broken -- any activity in the X server,
either client requests or user input, would end up resetting the
keepalive timeout, so a user mashing on the keyboard would never
discover that the XDMCP master had disappeared and have the session
terminated, which was precisely the design goal of the XDMCP keepalive
mechanism.

Instead of attempting to fix this, accept the cost of a pair of XDMCP
packets once every three minutes and just perform keepalives
regularly.

This will also make reworking the block and wakeup handler APIs to
eliminate select masks easier.

Reviewed-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Keith Packard <keithp@keithp.com>
This commit is contained in:
Keith Packard 2015-09-21 07:16:17 +01:00 committed by Adam Jackson
parent a3a4029133
commit db1089eafc
1 changed files with 2 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
os/xdmcp.c
View File

@ -84,8 +84,6 @@ static int req_socklen;
static CARD32 SessionID;
static CARD32 timeOutTime;
static int timeOutRtx;
static CARD32 defaultKeepaliveDormancy = XDM_DEF_DORMANCY;
static CARD32 keepaliveDormancy = XDM_DEF_DORMANCY;
static CARD16 DisplayNumber;
static xdmcp_states XDM_INIT_STATE = XDM_OFF;
@ -632,6 +630,7 @@ XdmcpOpenDisplay(int sock)
if (state != XDM_AWAIT_MANAGE_RESPONSE)
return;
state = XDM_RUN_SESSION;
timeOutTime = GetTimeInMillis() + XDM_DEF_DORMANCY * 1000;
sessionSocket = sock;
}
@ -689,7 +688,6 @@ XdmcpWakeupHandler(void *data, /* unused */
int i, void *pReadmask)
{
fd_set *last_select_mask = (fd_set *) pReadmask;
fd_set devicesReadable;
if (state == XDM_OFF)
return;
@ -704,13 +702,6 @@ XdmcpWakeupHandler(void *data, /* unused */
FD_CLR(xdmcpSocket6, last_select_mask);
}
#endif
XFD_ANDSET(&devicesReadable, last_select_mask, &EnabledDevices);
if (XFD_ANYSET(&devicesReadable)) {
if (state == XDM_RUN_SESSION)
keepaliveDormancy = defaultKeepaliveDormancy;
}
if (XFD_ANYSET(&AllClients) && state == XDM_RUN_SESSION)
timeOutTime = GetTimeInMillis() + keepaliveDormancy * 1000;
}
else if (timeOutTime && (int) (GetTimeInMillis() - timeOutTime) >= 0) {
if (state == XDM_RUN_SESSION) {
@ -1399,15 +1390,8 @@ recv_alive_msg(unsigned length)
if (XdmcpReadCARD8(&buffer, &SessionRunning) &&
XdmcpReadCARD32(&buffer, &AliveSessionID)) {
if (SessionRunning && AliveSessionID == SessionID) {
/* backoff dormancy period */
state = XDM_RUN_SESSION;
if ((GetTimeInMillis() - LastEventTime(XIAllDevices).milliseconds) >
keepaliveDormancy * 1000) {
keepaliveDormancy <<= 1;
if (keepaliveDormancy > XDM_MAX_DORMANCY)
keepaliveDormancy = XDM_MAX_DORMANCY;
}
timeOutTime = GetTimeInMillis() + keepaliveDormancy * 1000;
timeOutTime = GetTimeInMillis() + XDM_DEF_DORMANCY * 1000;
}
else {
XdmcpDeadSession("Alive response indicates session dead");