1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
|
package rewrite
import (
"context"
"fmt"
"strings"
"github.com/coredns/coredns/plugin"
"github.com/miekg/dns"
)
// Result is the result of a rewrite
type Result int
const (
// RewriteIgnored is returned when rewrite is not done on request.
RewriteIgnored Result = iota
// RewriteDone is returned when rewrite is done on request.
RewriteDone
// RewriteStatus is returned when rewrite is not needed and status code should be set
// for the request.
RewriteStatus
)
// These are defined processing mode.
const (
// Processing should stop after completing this rule
Stop = "stop"
// Processing should continue to next rule
Continue = "continue"
)
// Rewrite is plugin to rewrite requests internally before being handled.
type Rewrite struct {
Next plugin.Handler
Rules []Rule
noRevert bool
}
// ServeDNS implements the plugin.Handler interface.
func (rw Rewrite) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
wr := NewResponseReverter(w, r)
for _, rule := range rw.Rules {
switch result := rule.Rewrite(w, r); result {
case RewriteDone:
respRule := rule.GetResponseRule()
if respRule.Active == true {
wr.ResponseRewrite = true
wr.ResponseRules = append(wr.ResponseRules, respRule)
}
if rule.Mode() == Stop {
if rw.noRevert {
return plugin.NextOrFailure(rw.Name(), rw.Next, ctx, w, r)
}
return plugin.NextOrFailure(rw.Name(), rw.Next, ctx, wr, r)
}
case RewriteIgnored:
break
case RewriteStatus:
// only valid for complex rules.
// if cRule, ok := rule.(*ComplexRule); ok && cRule.Status != 0 {
// return cRule.Status, nil
// }
}
}
return plugin.NextOrFailure(rw.Name(), rw.Next, ctx, w, r)
}
// Name implements the Handler interface.
func (rw Rewrite) Name() string { return "rewrite" }
// Rule describes a rewrite rule.
type Rule interface {
// Rewrite rewrites the current request.
Rewrite(dns.ResponseWriter, *dns.Msg) Result
// Mode returns the processing mode stop or continue.
Mode() string
// GetResponseRule returns the rule to rewrite response with, if any.
GetResponseRule() ResponseRule
}
func newRule(args ...string) (Rule, error) {
if len(args) == 0 {
return nil, fmt.Errorf("no rule type specified for rewrite")
}
arg0 := strings.ToLower(args[0])
var ruleType string
var expectNumArgs, startArg int
mode := Stop
switch arg0 {
case Continue:
mode = arg0
ruleType = strings.ToLower(args[1])
expectNumArgs = len(args) - 1
startArg = 2
case Stop:
ruleType = strings.ToLower(args[1])
expectNumArgs = len(args) - 1
startArg = 2
default:
// for backward compatibility
ruleType = arg0
expectNumArgs = len(args)
startArg = 1
}
if ruleType != "edns0" && ruleType != "name" && expectNumArgs != 3 {
return nil, fmt.Errorf("%s rules must have exactly two arguments", ruleType)
}
switch ruleType {
case "name":
return newNameRule(mode, args[startArg:]...)
case "class":
return newClassRule(mode, args[startArg:]...)
case "type":
return newTypeRule(mode, args[startArg:]...)
case "edns0":
return newEdns0Rule(mode, args[startArg:]...)
default:
return nil, fmt.Errorf("invalid rule type %q", args[0])
}
}
|
