Linux
如何找到 unix socket 連接的另一端?
我有一個程序(dbus-daemon),它通過 UNIX 套接字有許多打開的連接。這些連接之一是 fd #36:
=$ ps uw -p 23284 USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND depesz 23284 0.0 0.0 24680 1772 ? Ss 15:25 0:00 /bin/dbus-daemon --fork --print-pid 5 --print-address 7 --session =$ ls -l /proc/23284/fd/36 lrwx------ 1 depesz depesz 64 2011-03-28 15:32 /proc/23284/fd/36 -> socket:[1013410] =$ netstat -nxp | grep 1013410 (Not all processes could be identified, non-owned process info will not be shown, you would have to be root to see it all.) unix 3 [ ] STREAM CONNECTED 1013410 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD =$ netstat -nxp | grep dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1013953 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1013825 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1013726 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1013471 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1013410 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1012325 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1012302 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1012289 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1012151 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011957 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011937 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011900 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011775 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011771 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011769 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011766 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011663 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011635 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011627 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011540 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011480 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011349 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011312 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011284 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011250 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011231 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011155 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011061 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011049 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011035 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011013 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1010961 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1010945 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD
根據連接數,我假設 dbus-daemon 實際上是伺服器。這沒關係。但是我怎樣才能找到連接到它的程序 - 使用 dbus-launcher 中第 36 個文件句柄的連接?在 /proc/net/unix 上嘗試了 lsof 甚至 greps,但我找不到找到客戶端程序的方法。
最近我偶然發現了一個類似的問題。我震驚地發現在某些情況下這可能是不可能的。我從 lsof (Vic Abell) 的創建者那裡找到了一條評論,他指出這在很大程度上取決於 unix 套接字的實現。有時套接字的所謂“端點”資訊可用,有時不可用。不幸的是,正如他指出的那樣,在 Linux 中這是不可能的。
例如,在 Linux 上,lsof 必須使用 /proc/net/unix,所有 UNIX 域套接字都有一個綁定路徑,但沒有端點資訊。通常沒有綁定路徑。這通常使得無法確定另一個端點,但這是 Linux /proc 文件系統實現的結果。
如果您查看/proc/net/unix,您可以自己看到,(至少在我的系統上)他是絕對正確的。我仍然感到震驚,因為在跟踪伺服器問題時,我發現這樣的功能必不可少。