3438. [bug] Don't accept unknown data escape in quotes. [RT #32031]

Squashed commit of the following:

commit 7ad3daade513c94a1c92ee7c91c112f161d13ef4
Author: Mark Andrews <marka@isc.org>
Date:   Mon Dec 3 15:03:44 2012 +1100

    look at the second token to determine if a TXT record in of unknown format or not

commit 7df32138462646f6aee84ffa56d02ac24ec8d672
Author: Mark Andrews <marka@isc.org>
Date:   Mon Dec 3 12:42:18 2012 +1100

    '"\#"' was incorrectly being treated as a unknown data escape sequence.

CHANGES

@@ -1,3 +1,5 @@
+3438.	[bug]		Don't accept unknown data escape in quotes. [RT #32031]
+
 3437.	[bug]		isc_buffer_init -> isc_buffer_constinit to initialise
 			buffers with constant data. [RT #32064]
 

bin/tests/system/unknown/ns1/example-in.db

@@ -53,6 +53,8 @@ txt4		CLASS1	TYPE16	"hello"
 txt5			TXT	\# 6 0568656C6C6F
 txt6			TYPE16	\# 6 0568656C6C6F
 txt7		IN	TXT	\# 6 0568656C6C6F
+txt8		IN	TXT	"\#" 2 0145
+txt9		IN	TXT	\# text
 
 unk1			TYPE123	\# 1 00
 unk2		CLASS1	TYPE123	\# 1 00

bin/tests/system/unknown/tests.sh

@@ -172,5 +172,19 @@ diff large.out dig.out > /dev/null || { ret=1 ; echo "I: diff failed"; }
 [ $ret = 0 ] || echo "I: failed"
 status=`expr $status + $ret`
 
+echo "I:check that '"'"\\#"'"' is not treated as the unknown escape sequence"
+ret=0
+DIG $DIGOPTS @10.53.0.1 +tcp +short txt8.example txt > dig.out
+echo '"#" "2" "0145"' | diff - dig.out || ret=1
+[ $ret = 0 ] || echo "I: failed"
+status=`expr $status + $ret`
+
+echo "I:check that '"'TXT \# text'"' is not treated as the unknown escape sequence"
+ret=0
+DIG $DIGOPTS @10.53.0.1 +tcp +short txt9.example txt > dig.out
+echo '"#" "text"' | diff - dig.out || ret=1
+[ $ret = 0 ] || echo "I: failed"
+status=`expr $status + $ret`
+
 echo "I:exit status: $status"
 exit $status

lib/dns/include/dns/rdata.h

@@ -177,6 +177,7 @@ struct dns_rdata {
 #define DNS_RDATA_CHECKREVERSE		DNS_NAME_CHECKREVERSE
 #define DNS_RDATA_CHECKMX		DNS_NAME_CHECKMX
 #define DNS_RDATA_CHECKMXFAIL		DNS_NAME_CHECKMXFAIL
+#define DNS_RDATA_UNKNOWNESCAPE		0x80000000
 
 /***
  *** Initialization

lib/dns/rdata.c

@@ -621,6 +621,7 @@ dns_rdata_fromtext(dns_rdata_t *rdata, dns_rdataclass_t rdclass,
 	void (*callback)(dns_rdatacallbacks_t *, const char *, ...);
 	isc_result_t tresult;
 	size_t length;
+	isc_boolean_t unknown;
 
 	REQUIRE(origin == NULL || dns_name_isabsolute(origin) == ISC_TRUE);
 	if (rdata != NULL) {
@@ -648,13 +649,33 @@ dns_rdata_fromtext(dns_rdata_t *rdata, dns_rdataclass_t rdclass,
 		return (result);
 	}
 
-	if (strcmp(DNS_AS_STR(token), "\\#") == 0)
-		result = unknown_fromtext(rdclass, type, lexer, mctx, target);
-	else {
+	unknown = ISC_FALSE;
+	if (token.type == isc_tokentype_string &&
+	    strcmp(DNS_AS_STR(token), "\\#") == 0) {
+		/*
+		 * If this is a TXT record '\#' could be a escaped '#'.
+		 * Look to see if the next token is a number and if so
+		 * treat it as a unknown record format.
+		 */
+		if (type == dns_rdatatype_txt) {
+			result = isc_lex_getmastertoken(lexer, &token,
+							isc_tokentype_number,
+							ISC_FALSE);
+			if (result == ISC_R_SUCCESS)
+				isc_lex_ungettoken(lexer, &token);
+		}
+
+		if (result == ISC_R_SUCCESS) {
+			unknown = ISC_TRUE;
+			result = unknown_fromtext(rdclass, type, lexer,
+						  mctx, target);
+		} else
+			options |= DNS_RDATA_UNKNOWNESCAPE;
+	} else 
 		isc_lex_ungettoken(lexer, &token);
 
+	if (!unknown)
 		FROMTEXTSWITCH
-	}
 
 	/*
 	 * Consume to end of line / file.

lib/dns/rdata/generic/txt_16.c

@@ -38,6 +38,13 @@ fromtext_txt(ARGS_FROMTEXT) {
 	UNUSED(callbacks);
 
 	strings = 0;
+	if ((options & DNS_RDATA_UNKNOWNESCAPE) != 0) {
+		isc_textregion_t r;
+		DE_CONST("#", r.base);
+		r.length = 1;
+		RETTOK(txt_fromtext(&r, target));
+		strings++;
+	}
 	for (;;) {
 		RETERR(isc_lex_getmastertoken(lexer, &token,
 					      isc_tokentype_qstring,