73 lines
1.4 KiB
Go
73 lines
1.4 KiB
Go
package net
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import (
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"errors"
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"fmt"
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"net"
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"strconv"
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"strings"
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)
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// HostPort format addr and port suitable for dial
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func HostPort(addr string, port interface{}) string {
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host := addr
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if strings.Count(addr, ":") > 0 {
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host = fmt.Sprintf("[%s]", addr)
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}
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return fmt.Sprintf("%s:%v", host, port)
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}
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// Listen takes addr:portmin-portmax and binds to the first available port
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// Example: Listen("localhost:5000-6000", fn)
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func Listen(addr string, fn func(string) (net.Listener, error)) (net.Listener, error) {
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if strings.Count(addr, ":") == 1 && strings.Count(addr, "-") == 0 {
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return fn(addr)
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}
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// host:port || host:min-max
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host, ports, err := net.SplitHostPort(addr)
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if err != nil {
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return nil, err
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}
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// try to extract port range
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prange := strings.Split(ports, "-")
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// single port
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if len(prange) < 2 {
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return fn(addr)
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}
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// we have a port range
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// extract min port
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min, err := strconv.Atoi(prange[0])
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if err != nil {
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return nil, errors.New("unable to extract port range")
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}
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// extract max port
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max, err := strconv.Atoi(prange[1])
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if err != nil {
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return nil, errors.New("unable to extract port range")
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}
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// range the ports
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for port := min; port <= max; port++ {
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// try bind to host:port
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ln, err := fn(HostPort(host, port))
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if err == nil {
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return ln, nil
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}
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// hit max port
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if port == max {
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return nil, err
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}
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}
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// why are we here?
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return nil, fmt.Errorf("unable to bind to %s", addr)
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}
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