syncthing/lib/connections/util.go

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// Copyright (C) 2016 The Syncthing Authors.
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this file,
// You can obtain one at http://mozilla.org/MPL/2.0/.
package connections
import (
"net"
"net/url"
"strconv"
"strings"
"github.com/syncthing/syncthing/lib/osutil"
)
func fixupPort(uri *url.URL, defaultPort int) *url.URL {
copyURI := *uri
host, port, err := net.SplitHostPort(uri.Host)
if err != nil && strings.Contains(err.Error(), "missing port") {
// addr is on the form "1.2.3.4" or "[fe80::1]"
host = uri.Host
if strings.HasPrefix(host, "[") && strings.HasSuffix(host, "]") {
// net.JoinHostPort will add the brackets again
host = host[1 : len(host)-1]
}
copyURI.Host = net.JoinHostPort(host, strconv.Itoa(defaultPort))
} else if err == nil && port == "" {
// addr is on the form "1.2.3.4:" or "[fe80::1]:"
copyURI.Host = net.JoinHostPort(host, strconv.Itoa(defaultPort))
}
return &copyURI
}
func getURLsForAllAdaptersIfUnspecified(network string, uri *url.URL) []*url.URL {
ip, port, err := resolve(network, uri.Host)
// Failed to resolve
if err != nil || port == 0 {
return nil
}
// Not an unspecified address, so no point of substituting with local
// interface addresses as it's listening on a specific adapter anyway.
if len(ip) != 0 && !ip.IsUnspecified() {
return nil
}
hostPorts := getHostPortsForAllAdapters(port)
addrs := make([]*url.URL, 0, len(hostPorts))
for _, hostPort := range hostPorts {
newUri := *uri
newUri.Host = hostPort
addrs = append(addrs, &newUri)
}
return addrs
}
func getHostPortsForAllAdapters(port int) []string {
nets, err := osutil.GetLans()
if err != nil {
// Ignore failure.
return nil
}
hostPorts := make([]string, 0, len(nets))
portStr := strconv.Itoa(port)
for _, network := range nets {
// Only IPv4 addresses, as v6 link local require an interface identifiers to work correctly
// And non link local in theory are globally routable anyway.
if network.IP.To4() == nil {
continue
}
if network.IP.IsLinkLocalUnicast() || (isV4Local(network.IP) && network.IP.IsGlobalUnicast()) {
hostPorts = append(hostPorts, net.JoinHostPort(network.IP.String(), portStr))
}
}
return hostPorts
}
func resolve(network, hostPort string) (net.IP, int, error) {
switch network {
case "tcp", "tcp4", "tcp6":
if addr, err := net.ResolveTCPAddr(network, hostPort); err != nil {
return net.IPv4zero, 0, err
} else {
return addr.IP, addr.Port, nil
}
case "udp", "udp4", "udp6":
if addr, err := net.ResolveUDPAddr(network, hostPort); err != nil {
return net.IPv4zero, 0, err
} else {
return addr.IP, addr.Port, nil
}
case "ip", "ip4", "ip6":
if addr, err := net.ResolveIPAddr(network, hostPort); err != nil {
return net.IPv4zero, 0, err
} else {
return addr.IP, 0, nil
}
}
return net.IPv4zero, 0, net.UnknownNetworkError(network)
}
func isV4Local(ip net.IP) bool {
// See https://go-review.googlesource.com/c/go/+/162998/
// We only take the V4 part of that.
if ip4 := ip.To4(); ip4 != nil {
return ip4[0] == 10 ||
(ip4[0] == 172 && ip4[1]&0xf0 == 16) ||
(ip4[0] == 192 && ip4[1] == 168)
}
return false
}
func maybeReplacePort(uri *url.URL, laddr net.Addr) *url.URL {
if laddr == nil {
return uri
}
host, portStr, err := net.SplitHostPort(uri.Host)
if err != nil {
return uri
}
port, err := strconv.Atoi(portStr)
if err != nil {
return uri
}
if port != 0 {
return uri
}
_, lportStr, err := net.SplitHostPort(laddr.String())
if err != nil {
return uri
}
uriCopy := *uri
uriCopy.Host = net.JoinHostPort(host, lportStr)
return &uriCopy
}