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plugin/rewrite: Add "revert" parameter for EDNS0 options (#6893)

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* plugin/rewrite: Add "revert" parameter for EDNS0 options

Signed-off-by: Nikita Usatov <nikitakosatka@yandex.ru>

* Update README

Signed-off-by: Nikita Usatov <nikitakosatka@yandex.ru>

* plugin/rewrite: Update tests

Signed-off-by: Nikita Usatov <nikitakosatka@yandex.ru>

* plugin/rewrite: Revert change to improve coverage

Signed-off-by: Nikita Usatov <nikitakosatka@yandex.ru>

---------

Signed-off-by: Nikita Usatov <nikitakosatka@yandex.ru>
This commit is contained in:
Nikita Usatov
2024-10-07 20:47:56 +03:00
committed by GitHub
parent 5100feebd3
commit 92724349dc
3 changed files with 436 additions and 37 deletions
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118
plugin/rewrite/edns0.go
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@@ -22,6 +22,7 @@ type edns0LocalRule struct {
action string
code uint16
data []byte
revert bool
}
// edns0VariableRule is a rewrite rule for EDNS0_LOCAL options with variable.
@@ -30,12 +31,43 @@ type edns0VariableRule struct {
action string
code uint16
variable string
revert bool
}
// ends0NsidRule is a rewrite rule for EDNS0_NSID options.
type edns0NsidRule struct {
mode string
action string
revert bool
}
type edns0SetResponseRule struct {
code uint16
}
func (r *edns0SetResponseRule) RewriteResponse(res *dns.Msg, _ dns.RR) {
ednsOpt := res.IsEdns0()
for idx, opt := range ednsOpt.Option {
if opt.Option() == r.code {
ednsOpt.Option = append(ednsOpt.Option[:idx], ednsOpt.Option[idx+1:]...)
return
}
}
}
type edns0ReplaceResponseRule[T dns.EDNS0] struct {
code uint16
source T
}
func (r *edns0ReplaceResponseRule[T]) RewriteResponse(res *dns.Msg, _ dns.RR) {
ednsOpt := res.IsEdns0()
for idx, opt := range ednsOpt.Option {
if opt.Option() == r.code {
ednsOpt.Option[idx] = r.source
return
}
}
}
// setupEdns0Opt will retrieve the EDNS0 OPT or create it if it does not exist.
@@ -52,11 +84,17 @@ func setupEdns0Opt(r *dns.Msg) *dns.OPT {
func (rule *edns0NsidRule) Rewrite(ctx context.Context, state request.Request) (ResponseRules, Result) {
o := setupEdns0Opt(state.Req)
var resp ResponseRules
for _, s := range o.Option {
if e, ok := s.(*dns.EDNS0_NSID); ok {
if rule.action == Replace || rule.action == Set {
if rule.revert {
old := *e
resp = append(resp, &edns0ReplaceResponseRule[*dns.EDNS0_NSID]{code: e.Code, source: &old})
}
e.Nsid = "" // make sure it is empty for request
return nil, RewriteDone
return resp, RewriteDone
}
}
}
@@ -64,7 +102,10 @@ func (rule *edns0NsidRule) 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_NSID{Code: dns.EDNS0NSID, Nsid: ""})
return nil, RewriteDone
if rule.revert {
resp = append(resp, &edns0SetResponseRule{code: dns.EDNS0NSID})
}
return resp, RewriteDone
}
return nil, RewriteIgnored
@@ -77,12 +118,18 @@ func (rule *edns0NsidRule) Mode() string { return rule.mode }
func (rule *edns0LocalRule) Rewrite(ctx context.Context, state request.Request) (ResponseRules, Result) {
o := setupEdns0Opt(state.Req)
var resp ResponseRules
for _, s := range o.Option {
if e, ok := s.(*dns.EDNS0_LOCAL); ok {
if rule.code == e.Code {
if rule.action == Replace || rule.action == Set {
if rule.revert {
old := *e
resp = append(resp, &edns0ReplaceResponseRule[*dns.EDNS0_LOCAL]{code: rule.code, source: &old})
}
e.Data = rule.data
return nil, RewriteDone
return resp, RewriteDone
}
}
}
@@ -91,7 +138,10 @@ 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 nil, RewriteDone
if rule.revert {
resp = append(resp, &edns0SetResponseRule{code: rule.code})
}
return resp, RewriteDone
}
return nil, RewriteIgnored
@@ -116,32 +166,39 @@ func newEdns0Rule(mode string, args ...string) (Rule, error) {
return nil, fmt.Errorf("invalid action: %q", action)
}
// Extract "revert" parameter.
var revert bool
if args[len(args)-1] == "revert" {
revert = true
args = args[:len(args)-1]
}
switch ruleType {
case "local":
if len(args) != 4 {
return nil, fmt.Errorf("EDNS0 local rules require exactly three args")
return nil, fmt.Errorf("EDNS0 local rules require three or four args")
}
// Check for variable option.
if strings.HasPrefix(args[3], "{") && strings.HasSuffix(args[3], "}") {
return newEdns0VariableRule(mode, action, args[2], args[3])
return newEdns0VariableRule(mode, action, args[2], args[3], revert)
}
return newEdns0LocalRule(mode, action, args[2], args[3])
return newEdns0LocalRule(mode, action, args[2], args[3], revert)
case "nsid":
if len(args) != 2 {
return nil, fmt.Errorf("EDNS0 NSID rules do not accept args")
return nil, fmt.Errorf("EDNS0 NSID rules can accept no more than one arg")
}
return &edns0NsidRule{mode: mode, action: action}, nil
return &edns0NsidRule{mode: mode, action: action, revert: revert}, nil
case "subnet":
if len(args) != 4 {
return nil, fmt.Errorf("EDNS0 subnet rules require exactly three args")
return nil, fmt.Errorf("EDNS0 subnet rules require three or four args")
}
return newEdns0SubnetRule(mode, action, args[2], args[3])
return newEdns0SubnetRule(mode, action, args[2], args[3], revert)
default:
return nil, fmt.Errorf("invalid rule type %q", ruleType)
}
}
func newEdns0LocalRule(mode, action, code, data string) (*edns0LocalRule, error) {
func newEdns0LocalRule(mode, action, code, data string, revert bool) (*edns0LocalRule, error) {
c, err := strconv.ParseUint(code, 0, 16)
if err != nil {
return nil, err
@@ -158,11 +215,11 @@ func newEdns0LocalRule(mode, action, code, data string) (*edns0LocalRule, error)
// Add this code to the ones the server supports.
edns.SetSupportedOption(uint16(c))
return &edns0LocalRule{mode: mode, action: action, code: uint16(c), data: decoded}, nil
return &edns0LocalRule{mode: mode, action: action, code: uint16(c), data: decoded, revert: revert}, nil
}
// newEdns0VariableRule creates an EDNS0 rule that handles variable substitution
func newEdns0VariableRule(mode, action, code, variable string) (*edns0VariableRule, error) {
func newEdns0VariableRule(mode, action, code, variable string, revert bool) (*edns0VariableRule, error) {
c, err := strconv.ParseUint(code, 0, 16)
if err != nil {
return nil, err
@@ -175,7 +232,7 @@ func newEdns0VariableRule(mode, action, code, variable string) (*edns0VariableRu
// Add this code to the ones the server supports.
edns.SetSupportedOption(uint16(c))
return &edns0VariableRule{mode: mode, action: action, code: uint16(c), variable: variable}, nil
return &edns0VariableRule{mode: mode, action: action, code: uint16(c), variable: variable, revert: revert}, nil
}
// ruleData returns the data specified by the variable.
@@ -221,13 +278,19 @@ func (rule *edns0VariableRule) Rewrite(ctx context.Context, state request.Reques
return nil, RewriteIgnored
}
var resp ResponseRules
o := setupEdns0Opt(state.Req)
for _, s := range o.Option {
if e, ok := s.(*dns.EDNS0_LOCAL); ok {
if rule.code == e.Code {
if rule.action == Replace || rule.action == Set {
if rule.revert {
old := *e
resp = append(resp, &edns0ReplaceResponseRule[*dns.EDNS0_LOCAL]{code: rule.code, source: &old})
}
e.Data = data
return nil, RewriteDone
return resp, RewriteDone
}
return nil, RewriteIgnored
}
@@ -237,7 +300,10 @@ 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 nil, RewriteDone
if rule.revert {
resp = append(resp, &edns0SetResponseRule{code: rule.code})
}
return resp, RewriteDone
}
return nil, RewriteIgnored
@@ -271,9 +337,10 @@ type edns0SubnetRule struct {
v4BitMaskLen uint8
v6BitMaskLen uint8
action string
revert bool
}
func newEdns0SubnetRule(mode, action, v4BitMaskLen, v6BitMaskLen string) (*edns0SubnetRule, error) {
func newEdns0SubnetRule(mode, action, v4BitMaskLen, v6BitMaskLen string, revert bool) (*edns0SubnetRule, error) {
v4Len, err := strconv.ParseUint(v4BitMaskLen, 0, 16)
if err != nil {
return nil, err
@@ -293,7 +360,7 @@ func newEdns0SubnetRule(mode, action, v4BitMaskLen, v6BitMaskLen string) (*edns0
}
return &edns0SubnetRule{mode: mode, action: action,
v4BitMaskLen: uint8(v4Len), v6BitMaskLen: uint8(v6Len)}, nil
v4BitMaskLen: uint8(v4Len), v6BitMaskLen: uint8(v6Len), revert: revert}, nil
}
// fillEcsData sets the subnet data into the ecs option
@@ -326,11 +393,17 @@ func (rule *edns0SubnetRule) fillEcsData(state request.Request, ecs *dns.EDNS0_S
func (rule *edns0SubnetRule) Rewrite(ctx context.Context, state request.Request) (ResponseRules, Result) {
o := setupEdns0Opt(state.Req)
var resp ResponseRules
for _, s := range o.Option {
if e, ok := s.(*dns.EDNS0_SUBNET); ok {
if rule.action == Replace || rule.action == Set {
if rule.revert {
old := *e
resp = append(resp, &edns0ReplaceResponseRule[*dns.EDNS0_SUBNET]{code: e.Code, source: &old})
}
if rule.fillEcsData(state, e) == nil {
return nil, RewriteDone
return resp, RewriteDone
}
}
return nil, RewriteIgnored
@@ -342,7 +415,10 @@ 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 nil, RewriteDone
if rule.revert {
resp = append(resp, &edns0SetResponseRule{code: dns.EDNS0SUBNET})
}
return resp, RewriteDone
}
}