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authorGravatar Miek Gieben <miek@miek.nl> 2017-04-13 16:26:17 +0100
committerGravatar GitHub <noreply@github.com> 2017-04-13 16:26:17 +0100
commita83d97a5c446481da3b9efc8f017e6a6ea34b7b0 (patch)
treebb8c23fb67f57982428cef5e990d6f1c97a349ad
parentacbf522cebdcd53c26d153c1d9267d709ba75f64 (diff)
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middleware/erratic: add delaying queries (#614)
* middleware/erratic: add delying queries * Dont println
-rw-r--r--middleware/erratic/README.md33
-rw-r--r--middleware/erratic/erratic.go30
-rw-r--r--middleware/erratic/erratic_test.go2
-rw-r--r--middleware/erratic/setup.go37
-rw-r--r--middleware/erratic/setup_test.go50
5 files changed, 131 insertions, 21 deletions
diff --git a/middleware/erratic/README.md b/middleware/erratic/README.md
index c255e3150..fe5aa5338 100644
--- a/middleware/erratic/README.md
+++ b/middleware/erratic/README.md
@@ -4,10 +4,6 @@
queries, but the responses can be delayed by a random amount of time or dropped all together, i.e.
no answer at all.
-~~~ txt
-._<transport>.qname. 0 IN SRV 0 0 <port> .
-~~~
-
The *erratic* middleware will respond to every A or AAAA query. For any other type it will return
a SERVFAIL response. The reply for A will return 192.0.2.53 (see RFC 5737), for AAAA it returns
2001:DB8::53 (see RFC 3849).
@@ -16,11 +12,14 @@ a SERVFAIL response. The reply for A will return 192.0.2.53 (see RFC 5737), for
~~~ txt
erratic {
- drop AMOUNT
+ drop [AMOUNT]
+ delay [AMOUNT [DURATION]]
}
~~~
-* **AMOUNT** drop 1 per **AMOUNT** of the queries, the default is 2.
+* `drop`: drop 1 per **AMOUNT** of the queries, the default is 2.
+* `delay`: delay 1 per **AMOUNT** of queries for **DURATION**, the default for **AMOUNT** is 2 and
+ the default for **DURATION** is 100ms.
## Examples
@@ -32,7 +31,7 @@ erratic {
}
~~~
-Or even shorter if the defaults suits you:
+Or even shorter if the defaults suits you. Note this only drops queries, it does not delay them.
~~~ txt
. {
@@ -40,6 +39,22 @@ Or even shorter if the defaults suits you:
}
~~~
-## Bugs
+Delay 1 in 3 queries for 50ms, but also drop 1 in 2.
+
+~~~ txt
+. {
+ erratic {
+ delay 3 50ms
+ }
+}
+~~~
-Delaying answers is not implemented.
+To stop dropping you'll need to explicitally set that to 0:
+~~~ txt
+. {
+ erratic {
+ delay 3 50ms
+ drop 0
+ }
+}
+~~~
diff --git a/middleware/erratic/erratic.go b/middleware/erratic/erratic.go
index a3fbb2e8e..1f663a558 100644
--- a/middleware/erratic/erratic.go
+++ b/middleware/erratic/erratic.go
@@ -3,6 +3,7 @@ package erratic
import (
"sync/atomic"
+ "time"
"github.com/coredns/coredns/request"
@@ -12,7 +13,10 @@ import (
// Erratic is a middleware that returns erratic repsonses to each client.
type Erratic struct {
- amount uint64
+ drop uint64
+
+ delay uint64
+ duration time.Duration
q uint64 // counter of queries
}
@@ -20,16 +24,21 @@ type Erratic struct {
// ServeDNS implements the middleware.Handler interface.
func (e *Erratic) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
state := request.Request{W: w, Req: r}
-
drop := false
- if e.amount > 0 {
- queryNr := atomic.LoadUint64(&e.q)
+ delay := false
- if queryNr%e.amount == 0 {
+ queryNr := atomic.LoadUint64(&e.q)
+ atomic.AddUint64(&e.q, 1)
+
+ if e.drop > 0 {
+ if queryNr%e.drop == 0 {
drop = true
}
-
- atomic.AddUint64(&e.q, 1)
+ }
+ if e.delay > 0 {
+ if queryNr%e.delay == 0 {
+ delay = true
+ }
}
m := new(dns.Msg)
@@ -50,6 +59,9 @@ func (e *Erratic) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg
m.Answer = append(m.Answer, &rr)
default:
if !drop {
+ if delay {
+ time.Sleep(e.duration)
+ }
// coredns will return error.
return dns.RcodeServerFailure, nil
}
@@ -59,6 +71,10 @@ func (e *Erratic) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg
return 0, nil
}
+ if delay {
+ time.Sleep(e.duration)
+ }
+
state.SizeAndDo(m)
w.WriteMsg(m)
diff --git a/middleware/erratic/erratic_test.go b/middleware/erratic/erratic_test.go
index e63545b35..c99135bbd 100644
--- a/middleware/erratic/erratic_test.go
+++ b/middleware/erratic/erratic_test.go
@@ -11,7 +11,7 @@ import (
)
func TestErraticDrop(t *testing.T) {
- e := &Erratic{amount: 2} // 50% drops
+ e := &Erratic{drop: 2} // 50% drops
tests := []struct {
expectedCode int
diff --git a/middleware/erratic/setup.go b/middleware/erratic/setup.go
index ac40d24fb..a642b6ff3 100644
--- a/middleware/erratic/setup.go
+++ b/middleware/erratic/setup.go
@@ -3,6 +3,7 @@ package erratic
import (
"fmt"
"strconv"
+ "time"
"github.com/coredns/coredns/core/dnsserver"
"github.com/coredns/coredns/middleware"
@@ -31,7 +32,7 @@ func setupErratic(c *caddy.Controller) error {
}
func parseErratic(c *caddy.Controller) (*Erratic, error) {
- e := &Erratic{amount: 2}
+ e := &Erratic{drop: 2}
for c.Next() { // 'erratic'
for c.NextBlock() {
switch c.Val() {
@@ -42,8 +43,30 @@ func parseErratic(c *caddy.Controller) (*Erratic, error) {
}
if len(args) == 0 {
- return nil, nil
+ continue
}
+
+ amount, err := strconv.ParseInt(args[0], 10, 32)
+ if err != nil {
+ return nil, err
+ }
+ if amount < 0 {
+ return nil, fmt.Errorf("illegal amount value given %q", args[0])
+ }
+ e.drop = uint64(amount)
+ case "delay":
+ args := c.RemainingArgs()
+ if len(args) > 2 {
+ return nil, c.ArgErr()
+ }
+
+ // Defaults.
+ e.delay = 2
+ e.duration = time.Duration(100 * time.Millisecond)
+ if len(args) == 0 {
+ continue
+ }
+
amount, err := strconv.ParseInt(args[0], 10, 32)
if err != nil {
return nil, err
@@ -51,7 +74,15 @@ func parseErratic(c *caddy.Controller) (*Erratic, error) {
if amount < 0 {
return nil, fmt.Errorf("illegal amount value given %q", args[0])
}
- e.amount = uint64(amount)
+ e.delay = uint64(amount)
+
+ if len(args) > 1 {
+ duration, err := time.ParseDuration(args[1])
+ if err != nil {
+ return nil, err
+ }
+ e.duration = duration
+ }
}
}
}
diff --git a/middleware/erratic/setup_test.go b/middleware/erratic/setup_test.go
index 99b545f5e..218973457 100644
--- a/middleware/erratic/setup_test.go
+++ b/middleware/erratic/setup_test.go
@@ -6,7 +6,7 @@ import (
"github.com/mholt/caddy"
)
-func TestSetupWhoami(t *testing.T) {
+func TestSetupErratic(t *testing.T) {
c := caddy.NewTestController("dns", `erratic {
drop
}`)
@@ -26,3 +26,51 @@ func TestSetupWhoami(t *testing.T) {
t.Fatalf("Test 4, expected errors, but got: %q", err)
}
}
+
+func TestParseErratic(t *testing.T) {
+ tests := []struct {
+ input string
+ shouldErr bool
+ drop uint64
+ delay uint64
+ }{
+ // oks
+ {`erratic`, false, 2, 0},
+ {`erratic {
+ drop 2
+ delay 3 1ms
+
+ }`, false, 2, 3},
+ // fails
+ {`erratic {
+ drop -1
+ }`, true, 0, 0},
+ {`erraric {
+ drop 3
+ delay 3 bla
+ }`, true, 0, 0},
+ }
+ for i, test := range tests {
+ c := caddy.NewTestController("dns", test.input)
+ e, err := parseErratic(c)
+ if test.shouldErr && err == nil {
+ t.Errorf("Test %v: Expected error but found nil", i)
+ continue
+ } else if !test.shouldErr && err != nil {
+ t.Errorf("Test %v: Expected no error but found error: %v", i, err)
+ continue
+ }
+
+ if test.shouldErr {
+ continue
+ }
+
+ if test.delay != e.delay {
+ t.Errorf("Test %v: Expected delay %d but found: %d", i, test.delay, e.delay)
+ }
+
+ if test.drop != e.drop {
+ t.Errorf("Test %v: Expected drop %d but found: %d", i, test.drop, e.drop)
+ }
+ }
+}