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msg_test.go
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msg_test.go
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package dns
import (
"fmt"
"regexp"
"strconv"
"strings"
"testing"
)
const (
maxPrintableLabel = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789x"
tooLongLabel = maxPrintableLabel + "x"
)
var (
longDomain = maxPrintableLabel[:53] + strings.TrimSuffix(
strings.Join([]string{".", ".", ".", ".", "."}, maxPrintableLabel[:49]), ".")
reChar = regexp.MustCompile(`.`)
i = -1
maxUnprintableLabel = reChar.ReplaceAllStringFunc(maxPrintableLabel, func(ch string) string {
if i++; i >= 32 {
i = 0
}
return fmt.Sprintf("\\%03d", i)
})
)
func TestUnpackDomainName(t *testing.T) {
var cases = []struct {
label string
input string
expectedOutput string
expectedError string
}{
{"empty domain",
"\x00",
".",
""},
{"long label",
string(63) + maxPrintableLabel + "\x00",
maxPrintableLabel + ".",
""},
{"unprintable label",
string(63) + regexp.MustCompile(`\\[0-9]+`).ReplaceAllStringFunc(maxUnprintableLabel,
func(escape string) string {
n, _ := strconv.ParseInt(escape[1:], 10, 8)
return string(n)
}) + "\x00",
maxUnprintableLabel + ".",
""},
{"long domain",
string(53) + strings.Replace(longDomain, ".", string(49), -1) + "\x00",
longDomain + ".",
""},
{"compression pointer",
// an unrealistic but functional test referencing an offset _inside_ a label
"\x03foo" + "\x05\x03com\x00" + "\x07example" + "\xC0\x05",
"foo.\\003com\\000.example.com.",
""},
{"too long domain",
string(54) + "x" + strings.Replace(longDomain, ".", string(49), -1) + "\x00",
"x" + longDomain + ".",
ErrLongDomain.Error()},
{"too long by pointer",
// a matryoshka doll name to get over 255 octets after expansion via internal pointers
string([]byte{
// 11 length values, first to last
40, 37, 34, 31, 28, 25, 22, 19, 16, 13, 0,
// 12 filler values
120, 120, 120, 120, 120, 120, 120, 120, 120, 120, 120, 120,
// 10 pointers, last to first
192, 10, 192, 9, 192, 8, 192, 7, 192, 6, 192, 5, 192, 4, 192, 3, 192, 2, 192, 1,
}),
"",
ErrLongDomain.Error()},
{"long by pointer",
// a matryoshka doll name _not_ exceeding 255 octets after expansion
string([]byte{
// 11 length values, first to last
37, 34, 31, 28, 25, 22, 19, 16, 13, 10, 0,
// 9 filler values
120, 120, 120, 120, 120, 120, 120, 120, 120,
// 10 pointers, last to first
192, 10, 192, 9, 192, 8, 192, 7, 192, 6, 192, 5, 192, 4, 192, 3, 192, 2, 192, 1,
}),
"" +
(`\"\031\028\025\022\019\016\013\010\000xxxxxxxxx` +
`\192\010\192\009\192\008\192\007\192\006\192\005\192\004\192\003\192\002.`) +
(`\031\028\025\022\019\016\013\010\000xxxxxxxxx` +
`\192\010\192\009\192\008\192\007\192\006\192\005\192\004\192\003.`) +
(`\028\025\022\019\016\013\010\000xxxxxxxxx` +
`\192\010\192\009\192\008\192\007\192\006\192\005\192\004.`) +
(`\025\022\019\016\013\010\000xxxxxxxxx` +
`\192\010\192\009\192\008\192\007\192\006\192\005.`) +
`\022\019\016\013\010\000xxxxxxxxx\192\010\192\009\192\008\192\007\192\006.` +
`\019\016\013\010\000xxxxxxxxx\192\010\192\009\192\008\192\007.` +
`\016\013\010\000xxxxxxxxx\192\010\192\009\192\008.` +
`\013\010\000xxxxxxxxx\192\010\192\009.` +
`\010\000xxxxxxxxx\192\010.` +
`\000xxxxxxxxx.`,
""},
{"truncated name", "\x07example\x03", "", "dns: buffer size too small"},
{"non-absolute name", "\x07example\x03com", "", "dns: buffer size too small"},
{"compression pointer cycle",
"\x03foo" + "\x03bar" + "\x07example" + "\xC0\x04",
"",
"dns: too many compression pointers"},
{"reserved compression pointer 0b10", "\x07example\x80", "", "dns: bad rdata"},
{"reserved compression pointer 0b01", "\x07example\x40", "", "dns: bad rdata"},
}
for _, test := range cases {
output, idx, err := UnpackDomainName([]byte(test.input), 0)
if test.expectedOutput != "" && output != test.expectedOutput {
t.Errorf("%s: expected %s, got %s", test.label, test.expectedOutput, output)
}
if test.expectedError == "" && err != nil {
t.Errorf("%s: expected no error, got %d %v", test.label, idx, err)
} else if test.expectedError != "" && (err == nil || err.Error() != test.expectedError) {
t.Errorf("%s: expected error %s, got %d %v", test.label, test.expectedError, idx, err)
}
}
}