/usr/share/gocode/src/github.com/miekg/dns/generate.go is in golang-github-miekg-dns-dev 0.0~git20161018.0.58f52c5-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 | package dns
import (
"bytes"
"errors"
"fmt"
"strconv"
"strings"
)
// Parse the $GENERATE statement as used in BIND9 zones.
// See http://www.zytrax.com/books/dns/ch8/generate.html for instance.
// We are called after '$GENERATE '. After which we expect:
// * the range (12-24/2)
// * lhs (ownername)
// * [[ttl][class]]
// * type
// * rhs (rdata)
// But we are lazy here, only the range is parsed *all* occurrences
// of $ after that are interpreted.
// Any error are returned as a string value, the empty string signals
// "no error".
func generate(l lex, c chan lex, t chan *Token, o string) string {
step := 1
if i := strings.IndexAny(l.token, "/"); i != -1 {
if i+1 == len(l.token) {
return "bad step in $GENERATE range"
}
if s, err := strconv.Atoi(l.token[i+1:]); err == nil {
if s < 0 {
return "bad step in $GENERATE range"
}
step = s
} else {
return "bad step in $GENERATE range"
}
l.token = l.token[:i]
}
sx := strings.SplitN(l.token, "-", 2)
if len(sx) != 2 {
return "bad start-stop in $GENERATE range"
}
start, err := strconv.Atoi(sx[0])
if err != nil {
return "bad start in $GENERATE range"
}
end, err := strconv.Atoi(sx[1])
if err != nil {
return "bad stop in $GENERATE range"
}
if end < 0 || start < 0 || end < start {
return "bad range in $GENERATE range"
}
<-c // _BLANK
// Create a complete new string, which we then parse again.
s := ""
BuildRR:
l = <-c
if l.value != zNewline && l.value != zEOF {
s += l.token
goto BuildRR
}
for i := start; i <= end; i += step {
var (
escape bool
dom bytes.Buffer
mod string
err error
offset int
)
for j := 0; j < len(s); j++ { // No 'range' because we need to jump around
switch s[j] {
case '\\':
if escape {
dom.WriteByte('\\')
escape = false
continue
}
escape = true
case '$':
mod = "%d"
offset = 0
if escape {
dom.WriteByte('$')
escape = false
continue
}
escape = false
if j+1 >= len(s) { // End of the string
dom.WriteString(fmt.Sprintf(mod, i+offset))
continue
} else {
if s[j+1] == '$' {
dom.WriteByte('$')
j++
continue
}
}
// Search for { and }
if s[j+1] == '{' { // Modifier block
sep := strings.Index(s[j+2:], "}")
if sep == -1 {
return "bad modifier in $GENERATE"
}
mod, offset, err = modToPrintf(s[j+2 : j+2+sep])
if err != nil {
return err.Error()
}
j += 2 + sep // Jump to it
}
dom.WriteString(fmt.Sprintf(mod, i+offset))
default:
if escape { // Pretty useless here
escape = false
continue
}
dom.WriteByte(s[j])
}
}
// Re-parse the RR and send it on the current channel t
rx, err := NewRR("$ORIGIN " + o + "\n" + dom.String())
if err != nil {
return err.Error()
}
t <- &Token{RR: rx}
// Its more efficient to first built the rrlist and then parse it in
// one go! But is this a problem?
}
return ""
}
// Convert a $GENERATE modifier 0,0,d to something Printf can deal with.
func modToPrintf(s string) (string, int, error) {
xs := strings.SplitN(s, ",", 3)
if len(xs) != 3 {
return "", 0, errors.New("bad modifier in $GENERATE")
}
// xs[0] is offset, xs[1] is width, xs[2] is base
if xs[2] != "o" && xs[2] != "d" && xs[2] != "x" && xs[2] != "X" {
return "", 0, errors.New("bad base in $GENERATE")
}
offset, err := strconv.Atoi(xs[0])
if err != nil || offset > 255 {
return "", 0, errors.New("bad offset in $GENERATE")
}
width, err := strconv.Atoi(xs[1])
if err != nil || width > 255 {
return "", offset, errors.New("bad width in $GENERATE")
}
switch {
case width < 0:
return "", offset, errors.New("bad width in $GENERATE")
case width == 0:
return "%" + xs[1] + xs[2], offset, nil
}
return "%0" + xs[1] + xs[2], offset, nil
}
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