33package agentssh
44
55import (
6+ "errors"
67"fmt"
78"os"
89
@@ -11,24 +12,33 @@ import (
1112)
1213
1314func getListeningPortProcessCmdline (port uint32 ) (string ,error ) {
14- tabs , err := netstat . TCPSocks ( func (s * netstat.SockTabEntry )bool {
15+ acceptFn := func (s * netstat.SockTabEntry )bool {
1516return s .LocalAddr != nil && uint32 (s .LocalAddr .Port )== port
16- })
17- if err != nil {
18- return "" ,xerrors .Errorf ("inspect port %d: %w" ,port ,err )
1917}
20- if len (tabs )== 0 {
21- return "" ,nil
18+ tabs ,err := netstat .TCPSocks (acceptFn )
19+ tabs6 ,err6 := netstat .TCP6Socks (acceptFn )
20+
21+ // Only return the error if the other method found nothing.
22+ if (err != nil && len (tabs6 )== 0 )|| (err6 != nil && len (tabs )== 0 ) {
23+ return "" ,xerrors .Errorf ("inspect port %d: %w" ,port ,errors .Join (err ,err6 ))
2224}
2325
24- // Defensive check.
25- if tabs [0 ].Process == nil {
26+ var proc * netstat.Process
27+ if len (tabs )> 0 {
28+ proc = tabs [0 ].Process
29+ }else if len (tabs6 )> 0 {
30+ proc = tabs6 [0 ].Process
31+ }
32+ if proc == nil {
33+ // Either nothing is listening on this port or we were unable to read the
34+ // process details (permission issues reading /proc/$pid/* potentially).
35+ // Or, perhaps /proc/net/tcp{,6} is not listing the port for some reason.
2636return "" ,nil
2737}
2838
2939// The process name provided by go-netstat does not include the full command
3040// line so grab that instead.
31- pid := tabs [ 0 ]. Process .Pid
41+ pid := proc .Pid
3242data ,err := os .ReadFile (fmt .Sprintf ("/proc/%d/cmdline" ,pid ))
3343if err != nil {
3444return "" ,xerrors .Errorf ("read /proc/%d/cmdline: %w" ,pid ,err )