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//+build linux
package freeport
import (
"fmt"
"os/exec"
"regexp"
"strconv"
)
const ephemeralPortRangeSysctlKey = "net.ipv4.ip_local_port_range"
var ephemeralPortRangePatt = regexp.MustCompile(`^\s*(\d+)\s+(\d+)\s*$`)
func getEphemeralPortRange() (int, int, error) {
cmd := exec.Command("/sbin/sysctl", "-n", ephemeralPortRangeSysctlKey)
out, err := cmd.Output()
if err != nil {
return 0, 0, err
}
val := string(out)
m := ephemeralPortRangePatt.FindStringSubmatch(val)
if m != nil {
min, err1 := strconv.Atoi(m[1])
max, err2 := strconv.Atoi(m[2])
if err1 == nil && err2 == nil {
return min, max, nil
}
}
return 0, 0, fmt.Errorf("unexpected sysctl value %q for key %q", val, ephemeralPortRangeSysctlKey)
}
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