Ping incorrectly sets the TTL rather than the timeout - setting an http proxy fails

[Greg Brackley <greg.brackley-mythtv-trac-2014@…>]

The function:

  bool ping(const QString &host, int timeout) file mythmiscutil.cpp line 220

has a timeout parameter, but in both the win32 and other code paths it is passed as a TTL parameter.

This means attempts to ping a host more than one hop away will fail. If I run the command manually it fails as I would expect:

# ping -t 1 -c 1 proxy.lucidsolutions.co.nz
PING proxy.lucidsolutions.co.nz (10.20.5.3) 56(84) bytes of data.
From gbe-12.orange.lucidsolutions.co.nz (10.20.12.1) icmp_seq=1 Time to live exceeded

--- proxy.lucidsolutions.co.nz ping statistics ---
1 packets transmitted, 0 received, +1 errors, 100% packet loss, time 1ms

The function:

  void setHttpProxy(void), file mythmiscutil.cpp line 831

uses the ping function to check if the proxy is available. My proxy is on another network. When I run mythfilldatabase I get the error:

E  setHttpProxy() - cannot locate host proxy.lucidsolutions.co.nz
                        Please check HTTP_PROXY environment variable!

I am having this issue with 0.27. The code appears to be the same on master.

Fix

The non-WIN32 ping command is:

 QString cmd = QString("ping -t %1 -c 1 %2 >/dev/null 2>&1")
                  .arg(timeout).arg(host);

I think the '-t' option should be '-W'.

The WIN32 ping command is:

    QString cmd = QString("%systemroot%\\system32\\ping.exe -i %1 -n 1 %2>NUL")
                  .arg(timeout).arg(host);

I think it should use the '-w' switch instead of '-i' and convert the 1 second to 1000 milli-seconds.

I believe the current code will appear to work if the proxy is on the same network as the machine running the mythtv code. If the proxy is down, then the intended short timeout behaviour will not be observed.

Links

​https://github.com/MythTV/mythtv/blob/fixes/0.27/mythtv/libs/libmythbase/mythmiscutil.cpp ​https://github.com/MythTV/mythtv/blob/master/mythtv/libs/libmythbase/mythmiscutil.cpp

[Greg Brackley <greg.brackley-mythtv-trac-2014@…>]

FreeBSD seems to support the '-t' parameter.

CentOS 6 and Fedora

Usage: ping [-LRUbdfnqrvVaA] [-c count] [-i interval] [-w deadline]
            [-p pattern] [-s packetsize] [-t ttl] [-I interface or address]
            [-M mtu discovery hint] [-S sndbuf]
            [ -T timestamp option ] [ -Q tos ] [hop1 ...] destination

Windows 7

Usage: ping [-t] [-a] [-n count] [-l size] [-f] [-i TTL] [-v TOS]
            [-r count] [-s count] [[-j host-list] | [-k host-list]]
            [-w timeout] [-R] [-S srcaddr] [-4] [-6] target_name

Options:
    -t             Ping the specified host until stopped.
                   To see statistics and continue - type Control-Break;
                   To stop - type Control-C.
    -a             Resolve addresses to hostnames.
    -n count       Number of echo requests to send.
    -l size        Send buffer size.
    -f             Set Don't Fragment flag in packet (IPv4-only).
    -i TTL         Time To Live.
    -v TOS         Type Of Service (IPv4-only. This setting has been deprecated
                   and has no effect on the type of service field in the IP Header).
    -r count       Record route for count hops (IPv4-only).
    -s count       Timestamp for count hops (IPv4-only).
    -j host-list   Loose source route along host-list (IPv4-only).
    -k host-list   Strict source route along host-list (IPv4-only).
    -w timeout     Timeout in milliseconds to wait for each reply.
    -R             Use routing header to test reverse route also (IPv6-only).
    -S srcaddr     Source address to use.
    -4             Force using IPv4.
    -6             Force using IPv6.

FreeBSD 9

usage: ping [-AaDdfnoQqRrv] [-c count] [-G sweepmaxsize] [-g sweepminsize]
            [-h sweepincrsize] [-i wait] [-l preload] [-M mask | time] [-m ttl]
            [-P policy] [-p pattern] [-S src_addr] [-s packetsize] [-t timeout]
            [-W waittime] [-z tos] host
       ping [-AaDdfLnoQqRrv] [-c count] [-I iface] [-i wait] [-l preload]
            [-M mask | time] [-m ttl] [-P policy] [-p pattern] [-S src_addr]
            [-s packetsize] [-T ttl] [-t timeout] [-W waittime]
            [-z tos] mcast-group

[Karl Dietz <dekarl@…>]

In 48ee1ab672587525c09981558f907f7f6808ffba/mythtv:

use timeout instead of TTL for Windows ping test

Refs #12034

[David Hampton <mythtv@…>]

Added a patch at ​​​https://github.com/MythTV/mythtv/pull/145 to compile in the correct timeout flag for the operating system.

[David Hampton <mythtv@…>]

In e2d0c1693ddb2f7be9521eaa31c9cf212f64b08a/mythtv:

Use correct ping timeout parameter for the operating system.

The ping command on Linux based operating systems uses the -w
paremeter to specify the timeout in seconds. The ping command on
FreeBSD based operating systems uses the -t parameter. Use compile
time flags to generate the right ping command for the operating
system. This fixes #12034.

[Stuart Auchterlonie <stuarta@…>]

In e03bee0c7eb381f488d3d09c7d0bc66a663a820a/mythtv:

Merge remote-tracking branch 'dhampton/devel/dh/ping'

Fixes #12034 - Use correct ping timeout parameter for the OS.

[David Hampton <mythtv@…>]

In afb2a83edd5e6f94572e5550bd9ae47dbc6834db/mythtv:

Use correct ping timeout parameter for the operating system.

The ping command on Linux based operating systems uses the -w
paremeter to specify the timeout in seconds. The ping command on
FreeBSD based operating systems uses the -t parameter. Use compile
time flags to generate the right ping command for the operating
system. This fixes #12034.

Signed-off-by: Stuart Auchterlonie <stuarta@…>