[#521] Add internal/net package with multinet dialer source

Code is taken from frostfs-node#1422
Author: Dmitrii Stepanov (dstepanov-yadro)

Signed-off-by: Alex Vanin <a.vanin@yadro.com>

go.mod

@@ -7,6 +7,7 @@ require (
 	git.frostfs.info/TrueCloudLab/frostfs-contract v0.20.1-0.20241022094040-5f956751d48b
 	git.frostfs.info/TrueCloudLab/frostfs-observability v0.0.0-20240909114314-666d326cc573
 	git.frostfs.info/TrueCloudLab/frostfs-sdk-go v0.0.0-20241022124111-5361f0ecebd3
+	git.frostfs.info/TrueCloudLab/multinet v0.0.0-20241015075604-6cb0d80e0972
 	git.frostfs.info/TrueCloudLab/policy-engine v0.0.0-20240822104152-a3bc3099bd5b
 	git.frostfs.info/TrueCloudLab/zapjournald v0.0.0-20240124114243-cb2e66427d02
 	github.com/aws/aws-sdk-go v1.44.6
@@ -34,6 +35,7 @@ require (
 	golang.org/x/crypto v0.24.0
 	golang.org/x/exp v0.0.0-20240506185415-9bf2ced13842
 	golang.org/x/net v0.26.0
+	golang.org/x/sys v0.22.0
 	golang.org/x/text v0.16.0
 	google.golang.org/grpc v1.66.2
 	google.golang.org/protobuf v1.34.2
@@ -94,7 +96,6 @@ require (
 	go.opentelemetry.io/proto/otlp v1.3.1 // indirect
 	go.uber.org/multierr v1.11.0 // indirect
 	golang.org/x/sync v0.7.0 // indirect
-	golang.org/x/sys v0.22.0 // indirect
 	golang.org/x/term v0.21.0 // indirect
 	google.golang.org/genproto/googleapis/api v0.0.0-20240701130421-f6361c86f094 // indirect
 	google.golang.org/genproto/googleapis/rpc v0.0.0-20240701130421-f6361c86f094 // indirect

go.sum

@@ -48,6 +48,8 @@ git.frostfs.info/TrueCloudLab/frostfs-sdk-go v0.0.0-20241022124111-5361f0ecebd3
 git.frostfs.info/TrueCloudLab/frostfs-sdk-go v0.0.0-20241022124111-5361f0ecebd3/go.mod h1:3txOjFJ8M/JFs01h7xOrnQHVn6hZgDNA16ivyUlu1iU=
 git.frostfs.info/TrueCloudLab/hrw v1.2.1 h1:ccBRK21rFvY5R1WotI6LNoPlizk7qSvdfD8lNIRudVc=
 git.frostfs.info/TrueCloudLab/hrw v1.2.1/go.mod h1:C1Ygde2n843yTZEQ0FP69jYiuaYV0kriLvP4zm8JuvM=
+git.frostfs.info/TrueCloudLab/multinet v0.0.0-20241015075604-6cb0d80e0972 h1:/960fWeyn2AFHwQUwDsWB3sbP6lTEnFnMzLMM6tx6N8=
+git.frostfs.info/TrueCloudLab/multinet v0.0.0-20241015075604-6cb0d80e0972/go.mod h1:2hM42MBrlhvN6XToaW6OWNk5ZLcu1FhaukGgxtfpDDI=
 git.frostfs.info/TrueCloudLab/policy-engine v0.0.0-20240822104152-a3bc3099bd5b h1:M50kdfrf/h8c3cz0bJ2AEUcbXvAlPFVC1Wp1WkfZ/8E=
 git.frostfs.info/TrueCloudLab/policy-engine v0.0.0-20240822104152-a3bc3099bd5b/go.mod h1:GZTk55RI4dKzsK6BCn5h2xxE28UHNfgoq/NJxW/LQ6A=
 git.frostfs.info/TrueCloudLab/rfc6979 v0.4.0 h1:M2KR3iBj7WpY3hP10IevfIB9MURr4O9mwVfJ+SjT3HA=

internal/net/config.go

@@ -0,0 +1,66 @@
+package net
+
+import (
+	"errors"
+	"fmt"
+	"net/netip"
+	"slices"
+	"time"
+
+	"git.frostfs.info/TrueCloudLab/multinet"
+)
+
+var errEmptySourceIPList = errors.New("empty source IP list")
+
+type Subnet struct {
+	Prefix    string
+	SourceIPs []string
+}
+
+type Config struct {
+	Enabled       bool
+	Subnets       []Subnet
+	Balancer      string
+	Restrict      bool
+	FallbackDelay time.Duration
+}
+
+func (c Config) toMultinetConfig() (multinet.Config, error) {
+	var subnets []multinet.Subnet
+	for _, s := range c.Subnets {
+		var ms multinet.Subnet
+		p, err := netip.ParsePrefix(s.Prefix)
+		if err != nil {
+			return multinet.Config{}, fmt.Errorf("parse IP prefix '%s': %w", s.Prefix, err)
+		}
+		ms.Prefix = p
+		for _, ip := range s.SourceIPs {
+			addr, err := netip.ParseAddr(ip)
+			if err != nil {
+				return multinet.Config{}, fmt.Errorf("parse IP address '%s': %w", ip, err)
+			}
+			ms.SourceIPs = append(ms.SourceIPs, addr)
+		}
+		if len(ms.SourceIPs) == 0 {
+			return multinet.Config{}, errEmptySourceIPList
+		}
+		subnets = append(subnets, ms)
+	}
+	return multinet.Config{
+		Subnets:       subnets,
+		Balancer:      multinet.BalancerType(c.Balancer),
+		Restrict:      c.Restrict,
+		FallbackDelay: c.FallbackDelay,
+		Dialer:        newDefaultDialer(),
+	}, nil
+}
+
+func (c Config) equals(other Config) bool {
+	return c.Enabled == other.Enabled &&
+		slices.EqualFunc(c.Subnets, other.Subnets, func(lhs, rhs Subnet) bool {
+			return lhs.Prefix == rhs.Prefix && slices.Equal(lhs.SourceIPs, rhs.SourceIPs)
+		}) &&
+		c.Balancer == other.Balancer &&
+		c.Restrict == other.Restrict &&
+		c.FallbackDelay == other.FallbackDelay
+}

internal/net/dial_target.go

@@ -0,0 +1,54 @@
+// NOTE: code is taken from https://github.com/grpc/grpc-go/blob/v1.68.x/internal/transport/http_util.go
+
+/*
+ *
+ * Copyright 2014 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package net
+
+import (
+	"net/url"
+	"strings"
+)
+
+// parseDialTarget returns the network and address to pass to dialer.
+func parseDialTarget(target string) (string, string) {
+	net := "tcp"
+	m1 := strings.Index(target, ":")
+	m2 := strings.Index(target, ":/")
+	// handle unix:addr which will fail with url.Parse
+	if m1 >= 0 && m2 < 0 {
+		if n := target[0:m1]; n == "unix" {
+			return n, target[m1+1:]
+		}
+	}
+	if m2 >= 0 {
+		t, err := url.Parse(target)
+		if err != nil {
+			return net, target
+		}
+		scheme := t.Scheme
+		addr := t.Path
+		if scheme == "unix" {
+			if addr == "" {
+				addr = t.Host
+			}
+			return scheme, addr
+		}
+	}
+	return net, target
+}

internal/net/dialer.go

@@ -0,0 +1,36 @@
+package net
+
+import (
+	"net"
+	"syscall"
+	"time"
+
+	"golang.org/x/sys/unix"
+)
+
+func newDefaultDialer() net.Dialer {
+	// From `grpc.WithContextDialer` comment:
+	//
+	// Note: All supported releases of Go (as of December 2023) override the OS
+	// defaults for TCP keepalive time and interval to 15s. To enable TCP keepalive
+	// with OS defaults for keepalive time and interval, use a net.Dialer that sets
+	// the KeepAlive field to a negative value, and sets the SO_KEEPALIVE socket
+	// option to true from the Control field. For a concrete example of how to do
+	// this, see internal.NetDialerWithTCPKeepalive().
+	//
+	// https://github.com/grpc/grpc-go/blob/830135e6c5a351abf75f0c9cfdf978e5df8daeba/dialoptions.go#L432
+	//
+	// From `internal.NetDialerWithTCPKeepalive` comment:
+	//
+	// TODO: Once https://github.com/golang/go/issues/62254 lands, and the
+	// appropriate Go version becomes less than our least supported Go version, we
+	// should look into using the new API to make things more straightforward.
+	return net.Dialer{
+		KeepAlive: time.Duration(-1),
+		Control: func(_, _ string, c syscall.RawConn) error {
+			return c.Control(func(fd uintptr) {
+				_ = unix.SetsockoptInt(int(fd), unix.SOL_SOCKET, unix.SO_KEEPALIVE, 1)
+			})
+		},
+	}
+}

internal/net/dialer_source.go

@@ -0,0 +1,69 @@
+package net
+
+import (
+	"context"
+	"net"
+	"sync"
+
+	"git.frostfs.info/TrueCloudLab/multinet"
+)
+
+type DialerSource struct {
+	guard sync.RWMutex
+
+	c Config
+
+	md multinet.Dialer
+}
+
+func NewDialerSource(c Config) (*DialerSource, error) {
+	result := &DialerSource{}
+	if err := result.build(c); err != nil {
+		return nil, err
+	}
+	return result, nil
+}
+
+func (s *DialerSource) build(c Config) error {
+	if c.Enabled {
+		mc, err := c.toMultinetConfig()
+		if err != nil {
+			return err
+		}
+		md, err := multinet.NewDialer(mc)
+		if err != nil {
+			return err
+		}
+		s.md = md
+		s.c = c
+		return nil
+	}
+	s.md = nil
+	s.c = c
+	return nil
+}
+
+// GrpcContextDialer returns grpc.WithContextDialer func.
+// Returns nil if multinet disabled.
+func (s *DialerSource) GrpcContextDialer() func(context.Context, string) (net.Conn, error) {
+	s.guard.RLock()
+	defer s.guard.RUnlock()
+
+	if s.c.Enabled {
+		return func(ctx context.Context, address string) (net.Conn, error) {
+			network, address := parseDialTarget(address)
+			return s.md.DialContext(ctx, network, address)
+		}
+	}
+	return nil
+}
+
+func (s *DialerSource) Update(c Config) error {
+	s.guard.Lock()
+	defer s.guard.Unlock()
+
+	if s.c.equals(c) {
+		return nil
+	}
+	return s.build(c)
+}