diff --git a/agent/agentssh/portinspection_supported.go b/agent/agentssh/portinspection_supported.go index d45847bd6f0b6..f8c379cecc73f 100644 --- a/agent/agentssh/portinspection_supported.go +++ b/agent/agentssh/portinspection_supported.go @@ -3,6 +3,7 @@ package agentssh import ( + "errors" "fmt" "os" @@ -11,24 +12,37 @@ import ( ) func getListeningPortProcessCmdline(port uint32) (string, error) { - tabs, err := netstat.TCPSocks(func(s *netstat.SockTabEntry) bool { + acceptFn := func(s *netstat.SockTabEntry) bool { return s.LocalAddr != nil && uint32(s.LocalAddr.Port) == port - }) - if err != nil { - return "", xerrors.Errorf("inspect port %d: %w", port, err) } - if len(tabs) == 0 { - return "", nil + tabs4, err4 := netstat.TCPSocks(acceptFn) + tabs6, err6 := netstat.TCP6Socks(acceptFn) + + // In the common case, we want to check ipv4 listening addresses. If this + // fails, we should return an error. We also need to check ipv6. The + // assumption is, if we have an err4, and 0 ipv6 addresses listed, then we are + // interested in the err4 (and vice versa). So return both errors (at least 1 + // is non-nil) if the other list is empty. + if (err4 != nil && len(tabs6) == 0) || (err6 != nil && len(tabs4) == 0) { + return "", xerrors.Errorf("inspect port %d: %w", port, errors.Join(err4, err6)) } - // Defensive check. - if tabs[0].Process == nil { + var proc *netstat.Process + if len(tabs4) > 0 { + proc = tabs4[0].Process + } else if len(tabs6) > 0 { + proc = tabs6[0].Process + } + if proc == nil { + // Either nothing is listening on this port or we were unable to read the + // process details (permission issues reading /proc/$pid/* potentially). + // Or, perhaps /proc/net/tcp{,6} is not listing the port for some reason. return "", nil } // The process name provided by go-netstat does not include the full command // line so grab that instead. - pid := tabs[0].Process.Pid + pid := proc.Pid data, err := os.ReadFile(fmt.Sprintf("/proc/%d/cmdline", pid)) if err != nil { return "", xerrors.Errorf("read /proc/%d/cmdline: %w", pid, err)