dotcloud/docker

package portallocator

import (
    "bufio"
    "fmt"
    "os"
)

func getDynamicPortRange() (start int, end int, err error) {
    const portRangeKernelParam = "/proc/sys/net/ipv4/ip_local_port_range"
    file, err := os.Open(portRangeKernelParam)
    if err != nil {
        return 0, 0, 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: %v", portRangeKernelParam, err)
    }
    return start, end, nil
}