Pull request: * all: move internal Go packages to internal/

Merge in DNS/adguard-home from 2234-move-to-internal to master

Squashed commit of the following:

commit d26a288cabeac86f9483fab307677b1027c78524
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Fri Oct 30 12:44:18 2020 +0300

    * all: move internal Go packages to internal/

    Closes #2234.

internal/dnsforward/ipset.go

@@ -0,0 +1,142 @@
+package dnsforward
+
+import (
+	"net"
+	"strings"
+	"sync"
+
+	"github.com/AdguardTeam/AdGuardHome/internal/util"
+	"github.com/AdguardTeam/golibs/log"
+	"github.com/miekg/dns"
+)
+
+type ipsetCtx struct {
+	ipsetList   map[string][]string // domain -> []ipset_name
+	ipsetCache  map[[4]byte]bool    // cache for IP[] to prevent duplicate calls to ipset program
+	ipsetMutex  *sync.Mutex
+	ipset6Cache map[[16]byte]bool // cache for IP[] to prevent duplicate calls to ipset program
+	ipset6Mutex *sync.Mutex
+}
+
+// Convert configuration settings to an internal map
+// DOMAIN[,DOMAIN].../IPSET1_NAME[,IPSET2_NAME]...
+func (c *ipsetCtx) init(ipsetConfig []string) {
+	c.ipsetList = make(map[string][]string)
+	c.ipsetCache = make(map[[4]byte]bool)
+	c.ipsetMutex = &sync.Mutex{}
+	c.ipset6Cache = make(map[[16]byte]bool)
+	c.ipset6Mutex = &sync.Mutex{}
+
+	for _, it := range ipsetConfig {
+		it = strings.TrimSpace(it)
+		hostsAndNames := strings.Split(it, "/")
+		if len(hostsAndNames) != 2 {
+			log.Debug("IPSET: invalid value '%s'", it)
+			continue
+		}
+
+		ipsetNames := strings.Split(hostsAndNames[1], ",")
+		if len(ipsetNames) == 0 {
+			log.Debug("IPSET: invalid value '%s'", it)
+			continue
+		}
+		bad := false
+		for i := range ipsetNames {
+			ipsetNames[i] = strings.TrimSpace(ipsetNames[i])
+			if len(ipsetNames[i]) == 0 {
+				bad = true
+				break
+			}
+		}
+		if bad {
+			log.Debug("IPSET: invalid value '%s'", it)
+			continue
+		}
+
+		hosts := strings.Split(hostsAndNames[0], ",")
+		for _, host := range hosts {
+			host = strings.TrimSpace(host)
+			host = strings.ToLower(host)
+			if len(host) == 0 {
+				log.Debug("IPSET: invalid value '%s'", it)
+				continue
+			}
+			c.ipsetList[host] = ipsetNames
+		}
+	}
+	log.Debug("IPSET: added %d hosts", len(c.ipsetList))
+}
+
+func (c *ipsetCtx) getIP(rr dns.RR) net.IP {
+	switch a := rr.(type) {
+	case *dns.A:
+		var ip4 [4]byte
+		copy(ip4[:], a.A.To4())
+		c.ipsetMutex.Lock()
+		defer c.ipsetMutex.Unlock()
+		_, found := c.ipsetCache[ip4]
+		if found {
+			return nil // this IP was added before
+		}
+		c.ipsetCache[ip4] = false
+		return a.A
+
+	case *dns.AAAA:
+		var ip6 [16]byte
+		copy(ip6[:], a.AAAA)
+		c.ipset6Mutex.Lock()
+		defer c.ipset6Mutex.Unlock()
+		_, found := c.ipset6Cache[ip6]
+		if found {
+			return nil // this IP was added before
+		}
+		c.ipset6Cache[ip6] = false
+		return a.AAAA
+
+	default:
+		return nil
+	}
+}
+
+// Add IP addresses of the specified in configuration domain names to an ipset list
+func (c *ipsetCtx) process(ctx *dnsContext) int {
+	req := ctx.proxyCtx.Req
+	if !(req.Question[0].Qtype == dns.TypeA ||
+		req.Question[0].Qtype == dns.TypeAAAA) ||
+		!ctx.responseFromUpstream {
+		return resultDone
+	}
+
+	host := req.Question[0].Name
+	host = strings.TrimSuffix(host, ".")
+	host = strings.ToLower(host)
+	ipsetNames, found := c.ipsetList[host]
+	if !found {
+		return resultDone
+	}
+
+	log.Debug("IPSET: found ipsets %v for host %s", ipsetNames, host)
+
+	for _, it := range ctx.proxyCtx.Res.Answer {
+		ip := c.getIP(it)
+		if ip == nil {
+			continue
+		}
+
+		ipStr := ip.String()
+		for _, name := range ipsetNames {
+			code, out, err := util.RunCommand("ipset", "add", name, ipStr)
+			if err != nil {
+				log.Info("IPSET: %s(%s) -> %s: %s", host, ipStr, name, err)
+				continue
+			}
+			if code != 0 {
+				log.Info("IPSET: ipset add:  code:%d  output:'%s'", code, out)
+				continue
+			}
+			log.Debug("IPSET: added %s(%s) -> %s", host, ipStr, name)
+		}
+	}
+
+	return resultDone
+}