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Pull request: all: imp dhcp client hostname normalization

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Updates #2952.
Updates #2978.

Squashed commit of the following:

commit 20e379b94ccf8140fd9056429315945c17f711a5
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Mon Apr 19 15:58:37 2021 +0300

    all: imp naming

commit ed300e0563fa37e161406a97991b26a89e23903a
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Mon Apr 19 15:43:09 2021 +0300

    all: imp dhcp client hostname normalization
This commit is contained in:
Ainar Garipov
2021-04-19 16:04:40 +03:00
parent 91304663b7
commit d707f8b1d1
6 changed files with 127 additions and 73 deletions
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66
internal/dhcpd/v4.go
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@@ -558,34 +558,45 @@ func (o *optFQDN) ToBytes() []byte {
return b
}
// normalizeHostname normalizes and validates a hostname sent by the client.
//
// TODO(a.garipov): Add client hostname uniqueness validations and rename the
// method to validateHostname.
func (s *v4Server) normalizeHostname(name string) (norm string, err error) {
// normalizeHostname normalizes a hostname sent by the client.
func normalizeHostname(name string) (norm string, err error) {
if name == "" {
return "", nil
}
// Some devices send hostnames with spaces, but we still want to accept
// them, so replace them with dashes and issue a warning.
//
// See https://github.com/AdguardTeam/AdGuardHome/issues/2946.
norm = strings.ReplaceAll(name, " ", "-")
state := "non-normalized"
if name != norm {
log.Debug("dhcpv4: normalized hostname %q into %q", name, norm)
state = "normalized"
parts := strings.FieldsFunc(name, func(c rune) (ok bool) {
return c != '.' && !aghnet.IsValidHostOuterRune(c)
})
if len(parts) == 0 {
return "", fmt.Errorf("normalizing hostname %q: no valid parts", name)
}
err = aghnet.ValidateDomainName(norm)
if err != nil {
return "", fmt.Errorf("validating %s hostname: %w", state, err)
}
norm = strings.Join(parts, "-")
norm = strings.TrimSuffix(norm, "-")
return norm, nil
}
// validateHostname validates a hostname sent by the client.
func (s *v4Server) validateHostname(name string) (err error) {
if name == "" {
return nil
}
err = aghnet.ValidateDomainName(name)
if err != nil {
return fmt.Errorf("validating hostname: %w", err)
}
// TODO(a.garipov): Add client hostname uniqueness validation either
// here or into method processRequest. This is not as easy as it might
// look like, because the process of adding and releasing a lease is
// currently non-straightforward.
return nil
}
// Process Request request and return lease
// Return false if we don't need to reply
func (s *v4Server) processRequest(req, resp *dhcpv4.DHCPv4) (lease *Lease, ok bool) {
@@ -634,16 +645,29 @@ func (s *v4Server) processRequest(req, resp *dhcpv4.DHCPv4) (lease *Lease, ok bo
}
if !lease.IsStatic() {
cliHostname := req.HostName()
var hostname string
hostname, err = s.normalizeHostname(req.HostName())
hostname, err = normalizeHostname(cliHostname)
if err != nil {
log.Error("dhcpv4: cannot normalize hostname for %s: %s", mac, err)
return nil, false
// Go on and assign a hostname made from the IP.
}
if hostname != "" && cliHostname != hostname {
log.Debug("dhcpv4: normalized hostname %q into %q", cliHostname, hostname)
}
err = s.validateHostname(hostname)
if err != nil {
log.Error("dhcpv4: validating hostname for %s: %s", mac, err)
// Go on and assign a hostname made from the IP.
}
if hostname == "" {
hostname = aghnet.GenerateHostName(reqIP)
hostname = aghnet.GenerateHostname(reqIP)
}
lease.Hostname = hostname