libosmocore support for GSMTAP based logging

Dear all, when debugging Osmocom programs, one usually looks at either the pcap trace of one of the many interfaces (Um interface via GSMTAP or OsmocomBB, Abis, Gb, Gp or A interface via ethernet, ...) or at the log files of the various osmocom programs. Sometimes it can be hard to match the two different domains, and it is useful to see in sequence when a certain message was received and what kind of actions this triggered inside e.g. OsmoPCU or OSmoSGSN. One could have used the libosmocore 'syslog' log target for this and then configure the local syslog daemon to log to a remote syslog server via the network. However, as there is another local process and context switches involved, the messages were re-ordered. Also, syslog only receives the fully-formatted log string, and not the meta-data like the log level or sub-system. Hence, the idae of having a GSMTAP based log target was floating around the project for many years. I finally implemented this today. The advantage is that in our single-threaded osmocom programs the GSMTAP messages will leave in-sequence with the protocol messages received or transmitted, and there is only the limited chance of re-ordering by the local network stack and/or intermediate routers. Both shouldn't be much of a concern during local debugging. What do you need to use this? 1) The follwoing three libosmcoore commits from gerrit: https://gerrit.osmocom.org/#/c/1355 https://gerrit.osmocom.org/#/c/1356 https://gerrit.osmocom.org/#/c/1357 2) a "log gsmtap" configuration in your config file (or via vty), similar to how syslog logging is configured: === SNIP === log gsmtap localhost logging filter all 1 logging color 1 logging print category 0 logging timestamp 0 logging level all everything logging level rll notice [...] === SNIP === 3) a wireshark with my Change-ID I0de723445e5b5ce0199a4081808111240a9ed047 (can also be found in the laforge/gsmtap-log branch of git://git.osmocom.org/wireshark or http://git.osmocom.org/wireshark/commit/?h=laforge/gsmtap-log&id=3a2078… I will leave this in review for a few days and then plan to merge it into libosmocore. The wireshark patch will also be submitted at that time. A screenshot is attached for your reference. There is of course no coloring of the lines in wirshark, but you can set various wireshark filters (e.g. on log level, sub-system) and also use colorization rules to e.g. map sub-systems again to colors. Regards, Harald -- - Harald Welte <laforge(a)gnumonks.org> http://laforge.gnumonks.org/ ============================================================================ "Privacy in residential applications is a desirable marketing option." (ETSI EN 300 175-7 Ch. A6)