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

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

internal/net/config.go

@@ -0,0 +1,68 @@
+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
+	EventHandler  multinet.EventHandler
+}
+
+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(),
+		EventHandler:  c.EventHandler,
+	}, 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
+}