mirror of
https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake.git
synced 2025-10-13 11:11:30 -04:00
0780f2e809
The option controls what source address to use when dialing the (Ext)ORPort. Using a source address other than 127.0.0.1, or a range of addresses, can help with localhost ephemeral port exhaustion. https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/-/issues/40198
41 lines
1.1 KiB
Go
41 lines
1.1 KiB
Go
package main
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import (
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"crypto/rand"
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"fmt"
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"net"
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)
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// randIPAddr generates a random IP address within the network represented by
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// ipnet.
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func randIPAddr(ipnet *net.IPNet) (net.IP, error) {
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if len(ipnet.IP) != len(ipnet.Mask) {
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return nil, fmt.Errorf("IP and mask have unequal lengths (%v and %v)", len(ipnet.IP), len(ipnet.Mask))
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}
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ip := make(net.IP, len(ipnet.IP))
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_, err := rand.Read(ip)
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if err != nil {
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return nil, err
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}
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for i := 0; i < len(ipnet.IP); i++ {
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ip[i] = (ipnet.IP[i] & ipnet.Mask[i]) | (ip[i] & ^ipnet.Mask[i])
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}
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return ip, nil
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}
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// parseIPCIDR parses a CIDR-notation IP address and prefix length; or if that
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// fails, as a plain IP address (with the prefix length equal to the address
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// length).
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func parseIPCIDR(s string) (*net.IPNet, error) {
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_, ipnet, err := net.ParseCIDR(s)
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if err == nil {
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return ipnet, nil
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}
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// IP/mask failed; try just IP now, but remember err, to return it in
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// case that fails too.
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ip := net.ParseIP(s)
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if ip != nil {
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return &net.IPNet{IP: ip, Mask: net.CIDRMask(len(ip)*8, len(ip)*8)}, nil
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}
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return nil, err
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}
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