[Problem]: number of open sockets keep growing indefinitly

[lstrojny]

What happened?

When a client connects to shairport-sync and then eventually disconnects, the socket stays open and will eventually exhaust the nofiles limit on the system.

Here is how to trigger the issue (use lsof | grep shairport | wc -l to count the number of open files on the server).

telnet dodecaphonism 7000
Trying 10.1.25.10...
Connected to dodecaphonism.
Escape character is '^]'.
OPTIONS rtsp://localhost RTSP/1.0

RTSP/1.0 200 OK
Server: AirTunes/366.0
Public: ANNOUNCE, SETUP, RECORD, PAUSE, FLUSH, FLUSHBUFFERED, TEARDOWN, OPTIONS, POST, GET, PUT

TEARDOWN rtsp://localhost RTSP/1.0

RTSP/1.0 451 Unavailable
Server: AirTunes/366.0
Connection: close

^]
telnet>

This is what the state of the connections is shortly after quitting telnet:

[...]
shairport  5040  5047 shairport shairport-sync   24u     IPv4    1090080       0t0        TCP raspberrypi.local:bbs->MacBook-Pro:59346 (CLOSE_WAIT)
shairport  5040  5047 shairport shairport-sync   25u     IPv4    1094833       0t0        TCP raspberrypi.local:bbs->MacBook-Pro:60095 (CLOSE_WAIT)

Expectation would be that once telnet disconnects the socket on the server side is closed as well.

Relevant log output

shairport  5040  5047 shairport shairport-sync    9u     sock        0,8       0t0    1078272 protocol: TCP
shairport  5040  5047 shairport shairport-sync   10u     sock        0,8       0t0    1083393 protocol: TCP
shairport  5040  5047 shairport shairport-sync   11u     sock        0,8       0t0    1083394 protocol: TCP
shairport  5040  5047 shairport shairport-sync   12u     sock        0,8       0t0    1083590 protocol: TCP
shairport  5040  5047 shairport shairport-sync   13u     sock        0,8       0t0    1083672 protocol: TCP
shairport  5040  5047 shairport shairport-sync   14u     sock        0,8       0t0    1083673 protocol: TCP
shairport  5040  5047 shairport shairport-sync   15u     sock        0,8       0t0    1083687 protocol: TCP
shairport  5040  5047 shairport shairport-sync   16u     sock        0,8       0t0    1083927 protocol: TCP
shairport  5040  5047 shairport shairport-sync   17u     sock        0,8       0t0    1083931 protocol: TCP
shairport  5040  5047 shairport shairport-sync   18u     sock        0,8       0t0    1083945 protocol: TCP
shairport  5040  5047 shairport shairport-sync   19u     sock        0,8       0t0    1084015 protocol: TCP
shairport  5040  5047 shairport shairport-sync   20u     sock        0,8       0t0    1084092 protocol: TCP

Configuration Information.

     0.001043125 "shairport.c:2057" >> Display Config Start.
     0.004572552 "shairport.c:2057"
     0.000074271 "shairport.c:2057" From "uname -a":
     0.000024948 "shairport.c:2057"  Linux dodecaphonism 5.15.76-v7+ #1596 SMP Mon Oct 31 17:08:20 GMT 2022 armv7l GNU/Linux
     0.010415989 "shairport.c:2057"
     0.000077813 "shairport.c:2057" From /etc/os-release:
     0.000026146 "shairport.c:2057"  Raspbian GNU/Linux 11 (bullseye)
     0.006834844 "shairport.c:2057"
     0.000078854 "shairport.c:2057" From /sys/firmware/devicetree/base/model:
     0.000025104 "shairport.c:2057"  Raspberry Pi 3 Model B Rev 1.2
     0.000090833 "shairport.c:2057"
     0.000024219 "shairport.c:2057" Shairport Sync Version String:
     0.000022604 "shairport.c:2057"  4.1-4-g99e76fdf-AirPlay2-OpenSSL-Avahi-ALSA-soxr-metadata-sysconfdir:/etc
     0.000025573 "shairport.c:2057"
     0.000020313 "shairport.c:2057" Command Line:
     0.000020937 "shairport.c:2057"  shairport-sync --displayConfig
     0.000080990 "shairport.c:2057"
     0.000023333 "shairport.c:2057" Configuration File:
     0.000021771 "shairport.c:2057"  /etc/shairport-sync.conf
     0.000021927 "shairport.c:2057"
     0.000183125 "shairport.c:2057" Configuration File Settings:
     0.000026094 "shairport.c:2057"  general :
     0.000022135 "shairport.c:2057"  {
     0.000021354 "shairport.c:2057"    name = "Lautsprecher im Büro";
     0.000022084 "shairport.c:2057"    interpolation = "soxr";
     0.000021875 "shairport.c:2057"    output_backend = "alsa";
     0.000021770 "shairport.c:2057"    mdns_backend = "avahi";
     0.000021511 "shairport.c:2057"  };
     0.000021250 "shairport.c:2057"  diagnostics :
     0.000020989 "shairport.c:2057"  {
     0.000020990 "shairport.c:2057"    statistics = "yes";
     0.000112500 "shairport.c:2057"    log_verbosity = 1;
     0.000025156 "shairport.c:2057"  };
     0.000022136 "shairport.c:2057"
     0.000020520 "shairport.c:2057" >> Display Config End.
     0.000021875 "shairport.c:2059" >> Goodbye!
     0.000051459 "shairport.c:1670" normal exit

How did you install Shairport Sync?

Built from source

Check previous issues

• [X] Confirm

[mikebrady]

Thanks for the interesting report.

I can reproduce the issue, thanks.

[mikebrady]

Thanks again for the report. An update with that bug fixed (I believe) has been pushed into the development branch.

If you got a chance to check it out, that would be great. That bug has been there for a long time!

[lstrojny]

Fix looks good to me. Tried running the latest development version and despite shairport being hammered by monitoring probes, number of open files stay constant. Thank you for looking into a somewhat esoteric issue and thank you very much for shairport in general.