AdGuardHome/internal/dnsforward/ipset.go

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package dnsforward
import (
"fmt"
"net"
"os"
"strings"
"github.com/AdguardTeam/AdGuardHome/internal/aghos"
"github.com/AdguardTeam/AdGuardHome/internal/ipset"
"github.com/AdguardTeam/golibs/errors"
"github.com/AdguardTeam/golibs/log"
"github.com/miekg/dns"
)
// ipsetCtx is the ipset context. ipsetMgr can be nil.
type ipsetCtx struct {
ipsetMgr ipset.Manager
}
// init initializes the ipset context. It is not safe for concurrent use.
//
// TODO(a.garipov): Rewrite into a simple constructor?
func (c *ipsetCtx) init(ipsetConf []string) (err error) {
c.ipsetMgr, err = ipset.NewManager(ipsetConf)
if errors.Is(err, os.ErrInvalid) || errors.Is(err, os.ErrPermission) {
// ipset cannot currently be initialized if the server was installed
// from Snap or when the user or the binary doesn't have the required
// permissions, or when the kernel doesn't support netfilter.
//
// Log and go on.
//
// TODO(a.garipov): The Snap problem can probably be solved if we add
// the netlink-connector interface plug.
log.Info("ipset: warning: cannot initialize: %s", err)
return nil
} else if unsupErr := (&aghos.UnsupportedError{}); errors.As(err, &unsupErr) {
log.Info("ipset: warning: %s", err)
return nil
} else if err != nil {
return fmt.Errorf("initializing ipset: %w", err)
}
return nil
}
// close closes the Linux Netfilter connections.
func (c *ipsetCtx) close() (err error) {
if c.ipsetMgr != nil {
return c.ipsetMgr.Close()
}
return nil
}
func (c *ipsetCtx) dctxIsfilled(dctx *dnsContext) (ok bool) {
return dctx != nil &&
dctx.responseFromUpstream &&
dctx.proxyCtx != nil &&
dctx.proxyCtx.Res != nil &&
dctx.proxyCtx.Req != nil &&
len(dctx.proxyCtx.Req.Question) > 0
}
// skipIpsetProcessing returns true when the ipset processing can be skipped for
// this request.
func (c *ipsetCtx) skipIpsetProcessing(dctx *dnsContext) (ok bool) {
if c == nil || c.ipsetMgr == nil || !c.dctxIsfilled(dctx) {
return true
}
qtype := dctx.proxyCtx.Req.Question[0].Qtype
return qtype != dns.TypeA && qtype != dns.TypeAAAA && qtype != dns.TypeANY
}
// ipFromRR returns an IP address from a DNS resource record.
func ipFromRR(rr dns.RR) (ip net.IP) {
switch a := rr.(type) {
case *dns.A:
return a.A
case *dns.AAAA:
return a.AAAA
default:
return nil
}
}
// ipsFromAnswer returns IPv4 and IPv6 addresses from a DNS answer.
func ipsFromAnswer(ans []dns.RR) (ip4s, ip6s []net.IP) {
for _, rr := range ans {
ip := ipFromRR(rr)
if ip == nil {
continue
}
if ip.To4() == nil {
ip6s = append(ip6s, ip)
continue
}
ip4s = append(ip4s, ip)
}
return ip4s, ip6s
}
// process adds the resolved IP addresses to the domain's ipsets, if any.
func (c *ipsetCtx) process(dctx *dnsContext) (rc resultCode) {
log.Debug("dnsforward: ipset: started processing")
defer log.Debug("dnsforward: ipset: finished processing")
if c.skipIpsetProcessing(dctx) {
return resultCodeSuccess
}
log.Debug("ipset: starting processing")
req := dctx.proxyCtx.Req
host := req.Question[0].Name
host = strings.TrimSuffix(host, ".")
host = strings.ToLower(host)
ip4s, ip6s := ipsFromAnswer(dctx.proxyCtx.Res.Answer)
n, err := c.ipsetMgr.Add(host, ip4s, ip6s)
if err != nil {
// Consider ipset errors non-critical to the request.
log.Error("dnsforward: ipset: adding host ips: %s", err)
return resultCodeSuccess
}
log.Debug("dnsforward: ipset: added %d new ipset entries", n)
return resultCodeSuccess
}