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package http3
import (
"net"
"strings"
)
// An addrList represents a list of network endpoint addresses.
// Copy from [net.addrList] and change type from [net.Addr] to [net.IPAddr]
type addrList []net.IPAddr
// isIPv4 reports whether addr contains an IPv4 address.
func isIPv4(addr net.IPAddr) bool {
return addr.IP.To4() != nil
}
// isNotIPv4 reports whether addr does not contain an IPv4 address.
func isNotIPv4(addr net.IPAddr) bool { return !isIPv4(addr) }
// forResolve returns the most appropriate address in address for
// a call to ResolveTCPAddr, ResolveUDPAddr, or ResolveIPAddr.
// IPv4 is preferred, unless addr contains an IPv6 literal.
func (addrs addrList) forResolve(network, addr string) net.IPAddr {
var want6 bool
switch network {
case "ip":
// IPv6 literal (addr does NOT contain a port)
want6 = strings.ContainsRune(addr, ':')
case "tcp", "udp":
// IPv6 literal. (addr contains a port, so look for '[')
want6 = strings.ContainsRune(addr, '[')
}
if want6 {
return addrs.first(isNotIPv4)
}
return addrs.first(isIPv4)
}
// first returns the first address which satisfies strategy, or if
// none do, then the first address of any kind.
func (addrs addrList) first(strategy func(net.IPAddr) bool) net.IPAddr {
for _, addr := range addrs {
if strategy(addr) {
return addr
}
}
return addrs[0]
}
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