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92 lines
2.2 KiB
Go
92 lines
2.2 KiB
Go
// We handle the checking as a lexing program.
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// We use the lexer like Rob Pike lectures about in this
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// clip: http://www.youtube.com/watch?v=HxaD_trXwRE
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package main
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import (
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"dns"
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"fmt"
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)
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type itemType int
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type item struct {
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typ itemType
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val string
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}
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const (
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itemError itemType = iota
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itemSoftware // the name of the DNS server software
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itemVendor // vendor of the DNS software
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itemVersionMajor // the major version of the software (empty if not determined)
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itemVersionMinor // the minor version of the software (empty if not determined)
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itemVersionPatch // the patch level of the software (empty if not determined)
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)
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var itemString = map[itemType]string{
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itemError: "error",
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itemSoftware: "software",
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itemVendor: "vendor",
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itemVersionMajor: "major",
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itemVersionMinor: "minor",
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itemVersionPatch: "patch",
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}
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// stateFn represents the state of the scanner as a function that returns the next state.
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type stateFn func(*lexer) stateFn
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type lexer struct {
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client *dns.Client // client used.
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addr string // addr of the server being scanned.
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fp *fingerprint // fingerprint to test.
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q dns.Question // question to ask.
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items chan item // channel of scanned items.
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state stateFn // the next function to enter.
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verbose bool // if true, the fingerprints are printed.
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debugging bool // If true, print the function names.
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}
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func (l *lexer) probe() (*fingerprint, dns.Question) {
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f, q := sendProbe(l.client, l.addr, l.fp, l.q)
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if l.verbose {
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fmt.Printf("QR : %s\t-", f)
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fmt.Printf(" (%s)\n", q.String())
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}
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return f, q
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}
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func (l *lexer) emit(i *item) {
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l.items <- *i
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}
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func (l *lexer) setString(s string) {
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l.fp.setString(s)
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if l.verbose {
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fmt.Printf("Q : %s\t-", s)
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}
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}
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func (l *lexer) setQuestion(name string, t uint16, c uint16) {
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l.q = dns.Question{name, t, c}
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if l.verbose {
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fmt.Printf(" (%s)\n", l.q.String())
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}
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}
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func (l *lexer) run() {
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go func() {
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for l.state != nil {
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l.state = l.state(l)
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}
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close(l.items)
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}()
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}
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func (l *lexer) debug(s string) {
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if l.debugging {
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fmt.Printf(" dns%s\n", s)
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}
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}
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