github.com/Prakhar-Agarwal-byte/moby@v0.0.0-20231027092010-a14e3e8ab87e/libnetwork/portallocator/portallocator_freebsd.go (about)

     1  package portallocator
     2  
     3  import (
     4  	"bytes"
     5  	"fmt"
     6  	"os/exec"
     7  )
     8  
     9  func getDynamicPortRange() (start int, end int, err error) {
    10  	portRangeKernelSysctl := []string{"net.inet.ip.portrange.hifirst", "net.ip.portrange.hilast"}
    11  	portRangeLowCmd := exec.Command("/sbin/sysctl", portRangeKernelSysctl[0])
    12  	var portRangeLowOut bytes.Buffer
    13  	portRangeLowCmd.Stdout = &portRangeLowOut
    14  	cmdErr := portRangeLowCmd.Run()
    15  	if cmdErr != nil {
    16  		return 0, 0, fmt.Errorf("port allocator - sysctl net.inet.ip.portrange.hifirst failed: %v", err)
    17  	}
    18  	n, err := fmt.Sscanf(portRangeLowOut.String(), "%d", &start)
    19  	if n != 1 || err != nil {
    20  		if err == nil {
    21  			err = fmt.Errorf("unexpected count of parsed numbers (%d)", n)
    22  		}
    23  		return 0, 0, fmt.Errorf("port allocator - failed to parse system ephemeral port range start from %s: %v", portRangeLowOut.String(), err)
    24  	}
    25  
    26  	portRangeHighCmd := exec.Command("/sbin/sysctl", portRangeKernelSysctl[1])
    27  	var portRangeHighOut bytes.Buffer
    28  	portRangeHighCmd.Stdout = &portRangeHighOut
    29  	cmdErr = portRangeHighCmd.Run()
    30  	if cmdErr != nil {
    31  		return 0, 0, fmt.Errorf("port allocator - sysctl net.inet.ip.portrange.hilast failed: %v", err)
    32  	}
    33  	n, err = fmt.Sscanf(portRangeHighOut.String(), "%d", &end)
    34  	if n != 1 || err != nil {
    35  		if err == nil {
    36  			err = fmt.Errorf("unexpected count of parsed numbers (%d)", n)
    37  		}
    38  		return 0, 0, fmt.Errorf("port allocator - failed to parse system ephemeral port range end from %s: %v", portRangeHighOut.String(), err)
    39  	}
    40  	return start, end, nil
    41  }