From c8092fe34d62f00ee6c224c0eddbdb5a58ec3bcc Mon Sep 17 00:00:00 2001 From: Ainar Garipov Date: Thu, 29 Apr 2021 14:52:22 +0300 Subject: [PATCH] Pull request: dhcpd: normalize hostnames of invalid static leases Updates #3027. Squashed commit of the following: commit 171ebaecb4b96ebeb2d0fa350460c65f244e94ae Author: Ainar Garipov Date: Thu Apr 29 14:45:04 2021 +0300 all: imp docs commit 48b13ed5b435042a0622a66b60407116ae5aa288 Author: Ainar Garipov Date: Thu Apr 29 14:34:28 2021 +0300 dhcpd: normalize hostnames of invalid static leases --- CHANGELOG.md | 2 ++ internal/dhcpd/v4.go | 81 ++++++++++++++++++++++++-------------------- 2 files changed, 46 insertions(+), 37 deletions(-) diff --git a/CHANGELOG.md b/CHANGELOG.md index a6fc8a33..6d7d372d 100644 --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -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 diff --git a/internal/dhcpd/v4.go b/internal/dhcpd/v4.go index 5cbfc370..cb59fcb4 100644 --- a/internal/dhcpd/v4.go +++ b/internal/dhcpd/v4.go @@ -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{