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// Copyright (C) 2019-2024 Algorand, Inc.
// This file is part of go-algorand
//
// go-algorand is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as
// published by the Free Software Foundation, either version 3 of the
// License, or (at your option) any later version.
//
// go-algorand is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with go-algorand. If not, see <https://www.gnu.org/licenses/>.
package network
import (
"context"
"net"
"time"
"github.com/algorand/go-algorand/tools/network/dnssec"
"github.com/algorand/go-algorand/util"
)
type netDialer interface {
DialContext(ctx context.Context, network, address string) (net.Conn, error)
}
// Dialer establish tcp-level connection with the destination
type Dialer struct {
phonebook Phonebook
innerDialer netDialer
resolver *net.Resolver
}
// makeRateLimitingDialer creates a rate limiting dialer that would limit the connections
// according to the entries in the phonebook.
func makeRateLimitingDialer(phonebook Phonebook, resolver dnssec.ResolverIf) Dialer {
var innerDialer netDialer = &net.Dialer{
Timeout: 30 * time.Second,
KeepAlive: 30 * time.Second,
DualStack: true,
}
// if a DNSSEC-aware resolver provided, use a wrapping dnssec.Dialer to parse addr, resolve it securely
// and call a regular net.Dialer
if resolver != nil {
innerDialer = &dnssec.Dialer{
InnerDialer: innerDialer.(*net.Dialer),
Resolver: resolver,
}
}
return Dialer{
phonebook: phonebook,
innerDialer: innerDialer,
}
}
// Dial connects to the address on the named network.
// It waits if needed not to exceed connectionsRateLimitingCount.
func (d *Dialer) Dial(network, address string) (net.Conn, error) {
return d.DialContext(context.Background(), network, address)
}
// DialContext connects to the address on the named network using the provided context.
// It waits if needed not to exceed connectionsRateLimitingCount.
func (d *Dialer) DialContext(ctx context.Context, network, address string) (net.Conn, error) {
var waitTime time.Duration
var provisionalTime time.Time
for {
_, waitTime, provisionalTime = d.phonebook.GetConnectionWaitTime(address)
if waitTime == 0 {
break // break out of the loop and proceed to the connection
}
select {
case <-ctx.Done():
return nil, ctx.Err()
case <-util.NanoAfter(waitTime):
}
}
conn, err := d.innerDialContext(ctx, network, address)
d.phonebook.UpdateConnectionTime(address, provisionalTime)
return conn, err
}
func (d *Dialer) innerDialContext(ctx context.Context, network, address string) (net.Conn, error) {
// this would be a good place to have the dnssec evaluated.
return d.innerDialer.DialContext(ctx, network, address)
}
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