3d5750f31c
additionally optimize for IP only setups, avoid doing unnecessary lookups if the Dial addr is an IP. allow support for multiple listeners on same socket, this is mainly meant for future purposes.
72 lines
2.2 KiB
Go
72 lines
2.2 KiB
Go
// Copyright (c) 2015-2021 MinIO, Inc.
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//
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// This file is part of MinIO Object Storage stack
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Affero General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Affero General Public License for more details.
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//
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// You should have received a copy of the GNU Affero General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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package http
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import (
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"context"
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"net"
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"time"
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"github.com/rs/dnscache"
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)
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// DialContextWithDNSCache is a helper function which returns `net.DialContext` function.
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// It randomly fetches an IP from the DNS cache and dials it by the given dial
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// function. It dials one by one and returns first connected `net.Conn`.
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// If it fails to dial all IPs from cache it returns first error. If no baseDialFunc
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// is given, it sets default dial function.
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//
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// You can use returned dial function for `http.Transport.DialContext`.
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//
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// In this function, it uses functions from `rand` package. To make it really random,
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// you MUST call `rand.Seed` and change the value from the default in your application
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func DialContextWithDNSCache(resolver *dnscache.Resolver, baseDialCtx DialContext) DialContext {
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if baseDialCtx == nil {
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// This is same as which `http.DefaultTransport` uses.
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baseDialCtx = (&net.Dialer{
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Timeout: 30 * time.Second,
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KeepAlive: 30 * time.Second,
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}).DialContext
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}
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return func(ctx context.Context, network, addr string) (conn net.Conn, err error) {
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host, port, 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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if net.ParseIP(host) != nil {
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// For IP only setups there is no need for DNS lookups.
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return baseDialCtx(ctx, "tcp", addr)
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}
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ips, err := resolver.LookupHost(ctx, host)
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if err != nil {
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return nil, err
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}
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for _, ip := range ips {
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conn, err = baseDialCtx(ctx, "tcp", net.JoinHostPort(ip, port))
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if err == nil {
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break
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}
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}
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return
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}
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}
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