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package portallocator
import (
"bufio"
"fmt"
"os"
)
func getDynamicPortRange() (start int, end int, err error) {
const portRangeKernelParam = "/proc/sys/net/ipv4/ip_local_port_range"
portRangeFallback := fmt.Sprintf("using fallback port range %d-%d", defaultPortRangeStart, defaultPortRangeEnd)
file, err := os.Open(portRangeKernelParam)
if err != nil {
return 0, 0, fmt.Errorf("port allocator - %s due to error: %v", portRangeFallback, err)
}
defer file.Close()
n, err := fmt.Fscanf(bufio.NewReader(file), "%d\t%d", &start, &end)
if n != 2 || err != nil {
if err == nil {
err = fmt.Errorf("unexpected count of parsed numbers (%d)", n)
}
return 0, 0, fmt.Errorf("port allocator - failed to parse system ephemeral port range from %s - %s: %v", portRangeKernelParam, portRangeFallback, err)
}
return start, end, nil
}
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