rclone/vendor/storj.io/common/rpc/lookup.go
2020-05-12 15:56:50 +00:00

49 lines
1.5 KiB
Go

// Copyright (C) 2020 Storj Labs, Inc.
// See LICENSE for copying information.
package rpc
import (
"context"
"net"
)
// LookupNodeAddress resolves a storage node address to the first IP address resolved.
// If an IP address is accidentally provided it is returned back. This function
// is used to resolve storage node IP addresses so that uplinks can use
// IP addresses directly without resolving many hosts.
func LookupNodeAddress(ctx context.Context, nodeAddress string) string {
host, port, err := net.SplitHostPort(nodeAddress)
if err != nil {
// If there was an error parsing out the port we just use a plain host.
host = nodeAddress
port = ""
}
// We check if the address is an IP address to decide if we need to resolve it or not.
ip := net.ParseIP(host)
// nodeAddress is already an IP, so we can use that.
if ip != nil {
return nodeAddress
}
// We have a hostname not an IP address so we should resolve the IP address
// to give back to the uplink client.
addresses, err := net.DefaultResolver.LookupHost(ctx, host)
if err != nil || len(addresses) == 0 {
// We ignore the error because if this fails for some reason we can just
// re-use the hostname, it just won't be as fast for the uplink to dial.
return nodeAddress
}
// We return the first address found because some DNS servers already do
// round robin load balancing and we would be messing with their behaviour
// if we tried to get smart here.
first := addresses[0]
if port == "" {
return first
}
return net.JoinHostPort(first, port)
}