Hi DRC,
I overcame my laziness and launched vncpasswd with gdb. The result was
pretty much the same of what strace and printfs have shown. The problem
really seems to be in the communication with the Xvnc server...
Cheers,
Rafael
Reading symbols from /opt/TurboVNC/bin/vncpasswd...Reading symbols from
/usr/lib/debug/opt/TurboVNC/bin/vncpasswd.debug...done.
done.
(gdb) r -o -display :13
Starting program: /opt/TurboVNC/bin/vncpasswd -o -display :13
Program received signal SIGINT, Interrupt.
0x000000371f6cc30f in poll () from /lib64/libc.so.6
(gdb) bt
#0 0x000000371f6cc30f in poll () from /lib64/libc.so.6
#1 0x000000372124a9f0 in ?? () from /usr/lib64/libX11.so.6
#2 0x000000372124ae19 in _XRead () from /usr/lib64/libX11.so.6
#3 0x00000037212378c9 in XOpenDisplay () from /usr/lib64/libX11.so.6
#4 0x000000000040187c in DoOTP () at vncpasswd.c:81
#5 0x0000000000402187 in main (argc=4, argv=0x7fffffffe748) at
vncpasswd.c:293
(gdb)
2013/10/24 Rafael Guimaraes <rgu...@gmail.com>
> Hi DRC,
>
> I have followed the best debugging practice there is (don't worry, I'm
> being ironic :)), putting printfs around the possible problem and I figured
> out that the vncpasswd hangs when calling XOpenDisplay. When executing the
> code below, it prints "Opening display :13" and nothing else. If I run it
> with strace, I get the trace below.
>
> I didn't do the gdb test just because I am not very familiar with doing it
> by gdb (I've already done it before, but there has been centuries). If the
> following information is not enough and gdb would help, I am sure I can
> handle it, no problem. I am just trying to make thing easier for me! A
> little bit egocentric, I know, but I just can't help it... :)
>
> If you check the strace output, it hangs on the last line, when I seems to
> be trying to communicate through a socket "/tmp/.X11-unix/X13". I imagine
> it is trying to reach Xvnc on display 13 and it is getting no response, so
> it keeps waiting forever... Am I right? What should I do if this is the
> case?
>
> Cheers,
>
> Rafael
>
> VNCPASSWD CODE WITH PRINTFS:
>
> int DoOTP()
> {
> unsigned int full;
> unsigned int view = 0;
> Display* dpy;
> Atom prop;
> int len;
> char buf[MAXPWLEN + 1];
> char bytes[MAXPWLEN * 2];
> #ifdef UseDevUrandom
> int fd;
> #endif
>
> *printf("Opening display %s\n",displayname);*
> if ((dpy = XOpenDisplay(displayname)) == NULL) {
> fprintf(stderr, "unable to open display \"%s\"\n",
> XDisplayName(displayname));
> return(1);
> }
> *printf("Display opened\n");*
>
>
> STRACE:
>
> write(1, "Opening display :13\n", 20Opening display :13
> ) = 20
> brk(0) = 0x59f3000
> brk(0x5a14000) = 0x5a14000
> uname({sys="Linux", node="server03", ...}) = 0
> socket(PF_FILE, SOCK_STREAM, 0) = 3
> uname({sys="Linux", node="server03", ...}) = 0
> uname({sys="Linux", node="server03", ...}) = 0
> connect(3, {sa_family=AF_FILE, path="/tmp/.X11-unix/X13"...}, 20) = 0
> uname({sys="Linux", node="server03", ...}) = 0
> fcntl(3, F_SETFD, FD_CLOEXEC) = 0
> access("/u/cnhu/.Xauthority", R_OK) = 0
> open("/u/cnhu/.Xauthority", O_RDONLY) = 4
> fstat(4, {st_mode=S_IFREG|0600, st_size=13139, ...}) = 0
> mmap(NULL, 32768, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0)
> = 0x2b34aa97f000
> read(4, "\1\0\0\10mi080113\0\00210\0\22MIT-MAGIC-COOK"..., 32768) = 13139
> read(4, "", 32768) = 0
> close(4) = 0
> munmap(0x2b34aa97f000, 32768) = 0
> writev(3, [{"l\0\v\0\0\0\22\0\20\0\0\0", 12}, {"MIT-MAGIC-COOKIE-1", 18},
> {"\0\0", 2}, {"e\30\226A>\316@\17Y8\365+V\21\365\f", 16}], 4) = 48
> fcntl(3, F_GETFL) = 0x2 (flags O_RDWR)
> fcntl(3, F_SETFL, O_RDWR|O_NONBLOCK) = 0
> read(3, 0x7fff865304b0, 8) = -1 EAGAIN (Resource temporarily
> unavailable)
> poll([{fd=3, events=POLLIN}], 1, -1 <unfinished ...>
>
>
>
>
> 2013/10/24 DRC <dcomman...@users.sourceforge.net>
>
>> Can you figure out where in the vncpasswd code it's locking up? That
>> would help diagnose the issue. If you're using an RPM-based system, you
>> can install the turbovnc-debuginfo RPM and get a stack trace from gdb
>> when it locks up. Otherwise, you'll have to build vncpasswd from
>> source, but it's straightforward.
>>
>> This is a complete shot in the dark, but I'm wondering if maybe the
>> /dev/urandom device is somehow giving you problems on some of your
>> machines. vncpasswd will read from /dev/urandom when it generates an
>> OTP. If that is the problem, then adding
>>
>> #undef UseDevUrandom
>>
>> to the top of vncpasswd.c should temporarily work around it, and it
>> would be easy to add a more permanent workaround (a command line switch
>> that avoids using /dev/urandom.)
>>
>>
>> On 10/23/13 1:36 PM, Rafael Guimaraes wrote:
>> > Hi,
>> >
>> > I have created a VNC session and after using it for sometime, it seems
>> > to be "locked". It is configured to use one-time-passwords and I just
>> > can't generate a new otp for access the session, vncpasswd hangs
>> > indefinitely when trying to get a new password.
>> >
>> > The session was created by the following command line:
>> > /opt/TurboVNC/bin/Xvnc :13 -desktop X -httpd
>> > /opt/TurboVNC/bin/../vnc/classes -auth /u/cnhu/.Xauthority
>> > -dontdisconnect -geometry 3192x1046 -depth 24 -rfbwait 120000 -otpauth
>> > -rfbport 5913 -fp
>> >
>> /usr/share/X11/fonts/misc,/usr/share/X11/fonts/75dpi,/usr/share/X11/fonts/100dpi,/usr/share/X11/fonts/Type1,/usr/share/fonts/default/Type1
>> > -co /usr/share/X11/rgb -deferupdate 1
>> >
>> > When trying to launch a "vncpasswd -otp -display :13", I get no response
>> > and eventually I have to press Ctrl+C. I have runned the vncpasswd
>> > command line with strace and it seems to hang while trying to connect to
>> > Xvnc through the "/tmp/.X11-unix/X13" socket (not sure if I've got it
>> > right). Below you may check the end of the strace (until it hangs).
>> >
>> > What may the problem be? The same happened twice in two different
>> > machines. I have several other VNC sessions where this does not happen.
>> > Can I collect information from anywhere else that could help me trying
>> > to figure out what happened?
>> >
>> > uname({sys="Linux", node="server03", ...}) = 0
>> > socket(PF_FILE, SOCK_STREAM, 0) = 3
>> > uname({sys="Linux", node="server03", ...}) = 0
>> > uname({sys="Linux", node="server03", ...}) = 0
>> > connect(3, {sa_family=AF_FILE, path="/tmp/.X11-unix/X13"...}, 20) = 0
>> > uname({sys="Linux", node="server03", ...}) = 0
>> > fcntl(3, F_SETFD, FD_CLOEXEC) = 0
>> > access("/u/cnhu/.Xauthority", R_OK) = 0
>> > open("/u/cnhu/.Xauthority", O_RDONLY) = 4
>> > fstat(4, {st_mode=S_IFREG|0600, st_size=13139, ...}) = 0
>> > mmap(NULL, 32768, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1,
>> > 0) = 0x2ab9583b5000
>> > read(4, "\1\0\0\10mi080113\0\00210\0\22MIT-MAGIC-COOK"..., 32768) =
>> 13139
>> > read(4, "", 32768) = 0
>> > close(4) = 0
>> > munmap(0x2ab9583b5000, 32768) = 0
>> > writev(3, [{"l\0\v\0\0\0\22\0\20\0\0\0", 12}, {"MIT-MAGIC-COOKIE-1",
>> > 18}, {"\0\0", 2}, {"e\30\226A>\316@\17Y8\365+V\21\365\f", 16}], 4) = 48
>> > fcntl(3, F_GETFL) = 0x2 (flags O_RDWR)
>> > fcntl(3, F_SETFL, O_RDWR|O_NONBLOCK) = 0
>> > read(3, 0x7fff0b98aab0, 8) = -1 EAGAIN (Resource
>> > temporarily unavailable)
>> > poll([{fd=3, events=POLLIN}], 1, -1 <unfinished ...>
>>
>>
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