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plugin/rewrite: streamline the ResponseRule handling. (#4473)

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* plugin/rewrite: streamline the ResponseRule handling.

The functionality of a response rule is now completely encapsulated behind
a `ResponseRule` interface. This significantly simplifies the complete
processing flow, it enables more flexible response handling and it is possible
to eliminate lots of state flags, ifs and switches.

Based on the new flexibility the pull request also enables to support a
response name rewrite for all name rewrite types.
To be compatible, an explicit `answer auto` option is added to support
a best effort response rewrite (name and value).
Additionally now all name rewrite rules support additional name and value
reponse rewrite options.

Using this feature it is also possible now to rewrite a complete sub domain
hierarchy to a single domain name combined with a correct rewrite (#2389).

Signed-off-by: Uwe Krueger <uwe.krueger@sap.com>

* revert policy

Signed-off-by: Uwe Krueger <uwe.krueger@sap.com>

Co-authored-by: Miek Gieben <miek@miek.nl>
This commit is contained in:
Uwe Krueger
2021-05-04 10:05:45 +02:00
committed by GitHub
parent 696c8731d6
commit 40edf1e566
13 changed files with 889 additions and 521 deletions
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50
plugin/rewrite/edns0.go
View File

@@ -49,14 +49,14 @@ func setupEdns0Opt(r *dns.Msg) *dns.OPT {
}
// Rewrite will alter the request EDNS0 NSID option
func (rule *edns0NsidRule) Rewrite(ctx context.Context, state request.Request) Result {
func (rule *edns0NsidRule) Rewrite(ctx context.Context, state request.Request) (ResponseRules, Result) {
o := setupEdns0Opt(state.Req)
for _, s := range o.Option {
if e, ok := s.(*dns.EDNS0_NSID); ok {
if rule.action == Replace || rule.action == Set {
e.Nsid = "" // make sure it is empty for request
return RewriteDone
return nil, RewriteDone
}
}
}
@@ -64,20 +64,17 @@ func (rule *edns0NsidRule) Rewrite(ctx context.Context, state request.Request) R
// add option if not found
if rule.action == Append || rule.action == Set {
o.Option = append(o.Option, &dns.EDNS0_NSID{Code: dns.EDNS0NSID, Nsid: ""})
return RewriteDone
return nil, RewriteDone
}
return RewriteIgnored
return nil, RewriteIgnored
}
// Mode returns the processing mode.
func (rule *edns0NsidRule) Mode() string { return rule.mode }
// GetResponseRules returns rules to rewrite the response with. Currently not implemented.
func (rule *edns0NsidRule) GetResponseRules() []ResponseRule { return []ResponseRule{} }
// Rewrite will alter the request EDNS0 local options.
func (rule *edns0LocalRule) Rewrite(ctx context.Context, state request.Request) Result {
func (rule *edns0LocalRule) Rewrite(ctx context.Context, state request.Request) (ResponseRules, Result) {
o := setupEdns0Opt(state.Req)
for _, s := range o.Option {
@@ -85,7 +82,7 @@ func (rule *edns0LocalRule) Rewrite(ctx context.Context, state request.Request)
if rule.code == e.Code {
if rule.action == Replace || rule.action == Set {
e.Data = rule.data
return RewriteDone
return nil, RewriteDone
}
}
}
@@ -94,18 +91,15 @@ func (rule *edns0LocalRule) Rewrite(ctx context.Context, state request.Request)
// add option if not found
if rule.action == Append || rule.action == Set {
o.Option = append(o.Option, &dns.EDNS0_LOCAL{Code: rule.code, Data: rule.data})
return RewriteDone
return nil, RewriteDone
}
return RewriteIgnored
return nil, RewriteIgnored
}
// Mode returns the processing mode.
func (rule *edns0LocalRule) Mode() string { return rule.mode }
// GetResponseRules returns a rule to rewrite the response with. Currently not implemented.
func (rule *edns0LocalRule) GetResponseRules() []ResponseRule { return []ResponseRule{} }
// newEdns0Rule creates an EDNS0 rule of the appropriate type based on the args
func newEdns0Rule(mode string, args ...string) (Rule, error) {
if len(args) < 2 {
@@ -222,10 +216,10 @@ func (rule *edns0VariableRule) ruleData(ctx context.Context, state request.Reque
}
// Rewrite will alter the request EDNS0 local options with specified variables.
func (rule *edns0VariableRule) Rewrite(ctx context.Context, state request.Request) Result {
func (rule *edns0VariableRule) Rewrite(ctx context.Context, state request.Request) (ResponseRules, Result) {
data, err := rule.ruleData(ctx, state)
if err != nil || data == nil {
return RewriteIgnored
return nil, RewriteIgnored
}
o := setupEdns0Opt(state.Req)
@@ -234,9 +228,9 @@ func (rule *edns0VariableRule) Rewrite(ctx context.Context, state request.Reques
if rule.code == e.Code {
if rule.action == Replace || rule.action == Set {
e.Data = data
return RewriteDone
return nil, RewriteDone
}
return RewriteIgnored
return nil, RewriteIgnored
}
}
}
@@ -244,18 +238,15 @@ func (rule *edns0VariableRule) Rewrite(ctx context.Context, state request.Reques
// add option if not found
if rule.action == Append || rule.action == Set {
o.Option = append(o.Option, &dns.EDNS0_LOCAL{Code: rule.code, Data: data})
return RewriteDone
return nil, RewriteDone
}
return RewriteIgnored
return nil, RewriteIgnored
}
// Mode returns the processing mode.
func (rule *edns0VariableRule) Mode() string { return rule.mode }
// GetResponseRules returns rules to rewrite the response with. Currently not implemented.
func (rule *edns0VariableRule) GetResponseRules() []ResponseRule { return []ResponseRule{} }
func isValidVariable(variable string) bool {
switch variable {
case
@@ -333,17 +324,17 @@ func (rule *edns0SubnetRule) fillEcsData(state request.Request, ecs *dns.EDNS0_S
}
// Rewrite will alter the request EDNS0 subnet option.
func (rule *edns0SubnetRule) Rewrite(ctx context.Context, state request.Request) Result {
func (rule *edns0SubnetRule) Rewrite(ctx context.Context, state request.Request) (ResponseRules, Result) {
o := setupEdns0Opt(state.Req)
for _, s := range o.Option {
if e, ok := s.(*dns.EDNS0_SUBNET); ok {
if rule.action == Replace || rule.action == Set {
if rule.fillEcsData(state, e) == nil {
return RewriteDone
return nil, RewriteDone
}
}
return RewriteIgnored
return nil, RewriteIgnored
}
}
@@ -352,19 +343,16 @@ func (rule *edns0SubnetRule) Rewrite(ctx context.Context, state request.Request)
opt := &dns.EDNS0_SUBNET{Code: dns.EDNS0SUBNET}
if rule.fillEcsData(state, opt) == nil {
o.Option = append(o.Option, opt)
return RewriteDone
return nil, RewriteDone
}
}
return RewriteIgnored
return nil, RewriteIgnored
}
// Mode returns the processing mode
func (rule *edns0SubnetRule) Mode() string { return rule.mode }
// GetResponseRules return rules to rewrite the response with. Currently not implemented.
func (rule *edns0SubnetRule) GetResponseRules() []ResponseRule { return []ResponseRule{} }
// These are all defined actions.
const (
Replace = "replace"