chore(settings): refactor settings processing (#756)

- Better settings tree structure logged using `qdm12/gotree`
- Read settings from environment variables, then files, then secret files
- Settings methods to default them, merge them and override them
- `DNS_PLAINTEXT_ADDRESS` default changed to `127.0.0.1` to use DoT. Warning added if set to something else.
- `HTTPPROXY_LISTENING_ADDRESS` instead of `HTTPPROXY_PORT` (with retro-compatibility)

internal/configuration/settings/dnsblacklist.go

@@ -0,0 +1,138 @@
+package settings
+
+import (
+	"errors"
+	"fmt"
+	"regexp"
+
+	"github.com/qdm12/dns/pkg/blacklist"
+	"github.com/qdm12/gluetun/internal/configuration/settings/helpers"
+	"github.com/qdm12/gotree"
+	"inet.af/netaddr"
+)
+
+// DNSBlacklist is settings for the DNS blacklist building.
+type DNSBlacklist struct {
+	BlockMalicious       *bool
+	BlockAds             *bool
+	BlockSurveillance    *bool
+	AllowedHosts         []string
+	AddBlockedHosts      []string
+	AddBlockedIPs        []netaddr.IP
+	AddBlockedIPPrefixes []netaddr.IPPrefix
+}
+
+func (b *DNSBlacklist) setDefaults() {
+	b.BlockMalicious = helpers.DefaultBool(b.BlockMalicious, true)
+	b.BlockAds = helpers.DefaultBool(b.BlockAds, false)
+	b.BlockSurveillance = helpers.DefaultBool(b.BlockSurveillance, true)
+}
+
+var hostRegex = regexp.MustCompile(`^([a-zA-Z0-9]|[a-zA-Z0-9_][a-zA-Z0-9\-_]{0,61}[a-zA-Z0-9_])(\.([a-zA-Z0-9]|[a-zA-Z0-9_][a-zA-Z0-9\-_]{0,61}[a-zA-Z0-9]))*$`) //nolint:lll
+
+var (
+	ErrAllowedHostNotValid = errors.New("allowed host is not valid")
+	ErrBlockedHostNotValid = errors.New("blocked host is not valid")
+)
+
+func (b DNSBlacklist) validate() (err error) {
+	for _, host := range b.AllowedHosts {
+		if !hostRegex.MatchString(host) {
+			return fmt.Errorf("%w: %s", ErrAllowedHostNotValid, host)
+		}
+	}
+
+	for _, host := range b.AddBlockedHosts {
+		if !hostRegex.MatchString(host) {
+			return fmt.Errorf("%w: %s", ErrBlockedHostNotValid, host)
+		}
+	}
+
+	return nil
+}
+
+func (b DNSBlacklist) copy() (copied DNSBlacklist) {
+	return DNSBlacklist{
+		BlockMalicious:       helpers.CopyBoolPtr(b.BlockMalicious),
+		BlockAds:             helpers.CopyBoolPtr(b.BlockAds),
+		BlockSurveillance:    helpers.CopyBoolPtr(b.BlockSurveillance),
+		AllowedHosts:         helpers.CopyStringSlice(b.AllowedHosts),
+		AddBlockedHosts:      helpers.CopyStringSlice(b.AddBlockedHosts),
+		AddBlockedIPs:        helpers.CopyNetaddrIPsSlice(b.AddBlockedIPs),
+		AddBlockedIPPrefixes: helpers.CopyIPPrefixSlice(b.AddBlockedIPPrefixes),
+	}
+}
+
+func (b *DNSBlacklist) mergeWith(other DNSBlacklist) {
+	b.BlockMalicious = helpers.MergeWithBool(b.BlockMalicious, other.BlockMalicious)
+	b.BlockAds = helpers.MergeWithBool(b.BlockAds, other.BlockAds)
+	b.BlockSurveillance = helpers.MergeWithBool(b.BlockSurveillance, other.BlockSurveillance)
+	b.AllowedHosts = helpers.MergeStringSlices(b.AllowedHosts, other.AllowedHosts)
+	b.AddBlockedHosts = helpers.MergeStringSlices(b.AddBlockedHosts, other.AddBlockedHosts)
+	b.AddBlockedIPs = helpers.MergeNetaddrIPsSlices(b.AddBlockedIPs, other.AddBlockedIPs)
+	b.AddBlockedIPPrefixes = helpers.MergeIPPrefixesSlices(b.AddBlockedIPPrefixes, other.AddBlockedIPPrefixes)
+}
+
+func (b *DNSBlacklist) overrideWith(other DNSBlacklist) {
+	b.BlockMalicious = helpers.OverrideWithBool(b.BlockMalicious, other.BlockMalicious)
+	b.BlockAds = helpers.OverrideWithBool(b.BlockAds, other.BlockAds)
+	b.BlockSurveillance = helpers.OverrideWithBool(b.BlockSurveillance, other.BlockSurveillance)
+	b.AllowedHosts = helpers.OverrideWithStringSlice(b.AllowedHosts, other.AllowedHosts)
+	b.AddBlockedHosts = helpers.OverrideWithStringSlice(b.AddBlockedHosts, other.AddBlockedHosts)
+	b.AddBlockedIPs = helpers.OverrideWithNetaddrIPsSlice(b.AddBlockedIPs, other.AddBlockedIPs)
+	b.AddBlockedIPPrefixes = helpers.OverrideWithIPPrefixesSlice(b.AddBlockedIPPrefixes, other.AddBlockedIPPrefixes)
+}
+
+func (b DNSBlacklist) ToBlacklistFormat() (settings blacklist.BuilderSettings, err error) {
+	return blacklist.BuilderSettings{
+		BlockMalicious:       *b.BlockMalicious,
+		BlockAds:             *b.BlockAds,
+		BlockSurveillance:    *b.BlockSurveillance,
+		AllowedHosts:         b.AllowedHosts,
+		AddBlockedHosts:      b.AddBlockedHosts,
+		AddBlockedIPs:        b.AddBlockedIPs,
+		AddBlockedIPPrefixes: b.AddBlockedIPPrefixes,
+	}, nil
+}
+
+func (b DNSBlacklist) String() string {
+	return b.toLinesNode().String()
+}
+
+func (b DNSBlacklist) toLinesNode() (node *gotree.Node) {
+	node = gotree.New("DNS filtering settings:")
+
+	node.Appendf("Block malicious: %s", helpers.BoolPtrToYesNo(b.BlockMalicious))
+	node.Appendf("Block ads: %s", helpers.BoolPtrToYesNo(b.BlockAds))
+	node.Appendf("Block surveillance: %s", helpers.BoolPtrToYesNo(b.BlockSurveillance))
+
+	if len(b.AllowedHosts) > 0 {
+		allowedHostsNode := node.Appendf("Allowed hosts:")
+		for _, host := range b.AllowedHosts {
+			allowedHostsNode.Appendf(host)
+		}
+	}
+
+	if len(b.AddBlockedHosts) > 0 {
+		blockedHostsNode := node.Appendf("Blocked hosts:")
+		for _, host := range b.AddBlockedHosts {
+			blockedHostsNode.Appendf(host)
+		}
+	}
+
+	if len(b.AddBlockedIPs) > 0 {
+		blockedIPsNode := node.Appendf("Blocked IP addresses:")
+		for _, ip := range b.AddBlockedIPs {
+			blockedIPsNode.Appendf(ip.String())
+		}
+	}
+
+	if len(b.AddBlockedIPPrefixes) > 0 {
+		blockedIPPrefixesNode := node.Appendf("Blocked IP networks:")
+		for _, ipNetwork := range b.AddBlockedIPPrefixes {
+			blockedIPPrefixesNode.Appendf(ipNetwork.String())
+		}
+	}
+
+	return node
+}