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Pull request: dhcpd: normalize hostnames of invalid static leases 

Updates #3027.

Squashed commit of the following:

commit 171ebaecb4b96ebeb2d0fa350460c65f244e94ae
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Thu Apr 29 14:45:04 2021 +0300

    all: imp docs

commit 48b13ed5b435042a0622a66b60407116ae5aa288
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Thu Apr 29 14:34:28 2021 +0300

    dhcpd: normalize hostnames of invalid static leases
This commit is contained in:
Ainar Garipov 2021-04-29 14:52:22 +03:00
parent f5adf15c8c
commit c8092fe34d
2 changed files with 46 additions and 37 deletions
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2
CHANGELOG.md
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@ -19,9 +19,11 @@ and this project adheres to
### Fixed
- Normalization of perviously-saved invalid static DHCP leases ([#3027]).
- Validation of IPv6 addresses with zones in system resolvers ([#3022]).
[#3022]: https://github.com/AdguardTeam/AdGuardHome/issues/3022
[#3027]: https://github.com/AdguardTeam/AdGuardHome/issues/3027

81
internal/dhcpd/v4.go
View File

@ -51,6 +51,8 @@ func (s *v4Server) WriteDiskConfig6(c *V6ServerConf) {
// ResetLeases - reset leases
func (s *v4Server) ResetLeases(leases []*Lease) {
var err error
if !s.conf.Enabled {
return
}
@ -60,9 +62,14 @@ func (s *v4Server) ResetLeases(leases []*Lease) {
s.leases = nil
for _, l := range leases {
err := s.addLease(l)
l.Hostname, err = s.validHostnameForClient(l.Hostname, l.IP)
if err != nil {
// TODO(a.garipov): Better error handling.
log.Info("dhcpv4: warning: previous hostname %q is invalid: %s", l.Hostname, err)
}
err = s.addLease(l)
if err != nil {
// TODO(a.garipov): Wrap and bubble up the error.
log.Error(
"dhcpv4: reset: re-adding a lease for %s (%s): %s",
l.IP,
@ -562,7 +569,8 @@ func (o *optFQDN) ToBytes() []byte {
return b
}
// normalizeHostname normalizes a hostname sent by the client.
// normalizeHostname normalizes a hostname sent by the client. If err is not
// nil, norm is an empty string.
func normalizeHostname(name string) (norm string, err error) {
if name == "" {
return "", nil
@ -603,6 +611,37 @@ func (s *v4Server) validateHostname(name string) (err error) {
return nil
}
// validHostnameForClient accepts the hostname sent by the client and returns
// either a normalized version of that hostname or a new hostname generated from
// the client's IP address.
//
// hostname is always a non-empty valid hostname. If err is not nil, it
// describes the issues encountered when normalizing cliHostname.
func (s *v4Server) validHostnameForClient(
cliHostname string,
ip net.IP,
) (hostname string, err error) {
hostname, err = normalizeHostname(cliHostname)
if err == nil {
err = s.validateHostname(hostname)
if err != nil {
// Go on and assign a hostname made from the IP below,
// returning the error that we've got.
hostname = ""
}
}
if hostname == "" {
hostname = aghnet.GenerateHostname(ip)
}
if hostname != cliHostname {
log.Info("dhcpv4: normalized hostname %q into %q", cliHostname, hostname)
}
return hostname, err
}
// validateLease returns an error if the lease is invalid.
func (s *v4Server) validateLease(l *Lease) (err error) {
defer agherr.Annotate("validating lease: %s", &err)
@ -682,43 +721,11 @@ func (s *v4Server) processRequest(req, resp *dhcpv4.DHCPv4) (lease *Lease, ok bo
if !lease.IsStatic() {
cliHostname := req.HostName()
var hostname string
hostname, err = normalizeHostname(cliHostname)
lease.Hostname, err = s.validHostnameForClient(cliHostname, reqIP)
if err != nil {
log.Error("dhcpv4: cannot normalize hostname for %s: %s", mac, err)
// Go on and assign a hostname made from the IP.
log.Info("dhcpv4: warning: client hostname %q is invalid: %s", cliHostname, err)
}
if hostname != "" {
if cliHostname != hostname {
log.Debug(
"dhcpv4: normalized hostname %q into %q",
cliHostname,
hostname,
)
}
if lease.Hostname != hostname {
// Either a new lease or an old lease with a new
// hostname, so validate.
err = s.validateHostname(hostname)
if err != nil {
log.Error("dhcpv4: validating %s: %s", mac, err)
// Go on and assign a hostname made from
// the IP below.
hostname = ""
}
}
}
if hostname == "" {
hostname = aghnet.GenerateHostname(reqIP)
}
lease.Hostname = hostname
s.commitLease(lease)
} else if len(lease.Hostname) != 0 {
o := &optFQDN{