Added explicit parser support for zero-length DHCP options, such as

rapid-commit, via format code 'Z' [rt17355]

6 files changed, 48 insertions, 14 deletions

diff --git a/RELNOTES b/RELNOTES
index 20547e66..432ed4e0 100644
--- a/RELNOTES
+++ b/RELNOTES
@@ -55,6 +55,9 @@ suggested fixes to <dhcp-users@isc.org>.
 
 			Changes since 4.0.0
 
+- Added explicit parser support for zero-length DHCP options, such as
+  rapid-commit, via format code 'Z'
+
 - Exit with warning when DHCPv6-specific statements are used in the
   config file but -6 is not specified.
 
diff --git a/common/conflex.c b/common/conflex.c
index 5ac39d8d..27568d28 100644
--- a/common/conflex.c
+++ b/common/conflex.c
@@ -1422,6 +1422,8 @@ intern(char *atom, enum dhcp_token dfv) {
 			return NS_YXRRSET;
 		break;
 	      case 'z':
+		if (!strcasecmp (atom + 1, "erolen"))
+			return ZEROLEN;
 		if (!strcasecmp (atom + 1, "one"))
 			return ZONE;
 		break;
diff --git a/common/options.c b/common/options.c
index cb46b11f..dc8f86ab 100644
--- a/common/options.c
+++ b/common/options.c
@@ -2660,7 +2660,7 @@ append_option(struct data_string *dst, struct universe *universe,
 {
 	struct data_string tmp;
 
-	if (src->len == 0)
+	if (src->len == 0 && option->format[0] != 'Z')
 		return 0;
 
 	memset(&tmp, 0, sizeof(tmp));
diff --git a/common/parse.c b/common/parse.c
index f6bfa131..585a3578 100644
--- a/common/parse.c
+++ b/common/parse.c
@@ -1666,6 +1666,18 @@ int parse_option_code_definition (cfile, option)
 		has_encapsulation = 1;
 		break;
 
+	      case ZEROLEN:
+		type = 'Z';
+		if (arrayp) {
+			parse_warn (cfile, "array incompatible with zerolen.");
+			skip_to_rbrace (cfile, recordp);
+			if (recordp)
+				skip_to_semi (cfile);
+			return 0;
+		}
+		no_more_in_record = 1;
+		break;
+
 	      default:
 		parse_warn (cfile, "unknown data type %s", val);
 		skip_to_rbrace (cfile, recordp);
@@ -4902,7 +4914,7 @@ struct option *option;
 			fmt = option->format;
 
 		/* 'a' means always uniform */
-		if ((fmt[0] != '\0') && (tolower((int)fmt[1]) == 'a')) 
+		if ((fmt[0] != 'Z') && (tolower((int)fmt[1]) == 'a')) 
 			uniform = 1;
 
 		do {
@@ -4913,8 +4925,9 @@ struct option *option;
 
 			tmp = *expr;
 			*expr = NULL;
+
 			if (!parse_option_token(expr, cfile, &fmt, tmp,
-                                                uniform, lookups)) {
+						uniform, lookups)) {
 				if (fmt [1] != 'o') {
 					if (tmp)
 						expression_dereference (&tmp,
@@ -4924,12 +4937,10 @@ struct option *option;
 				*expr = tmp;
 				tmp = NULL;
 			}
-                        if (tmp)
+			if (tmp)
 				expression_dereference (&tmp, MDL);
 
-			if (*fmt != '\0')
-				fmt++;
-
+			fmt++;
 		} while (*fmt != '\0');
 
 		if ((*fmt == 'A') || (*fmt == 'a')) {
@@ -4975,7 +4986,7 @@ int parse_option_statement (result, cfile, lookups, option, op)
 	int lose;
 
 	token = peek_token (&val, (unsigned *)0, cfile);
-	if ((token == SEMI) && (option->format[0] != '\0')) {
+	if ((token == SEMI) && (option->format[0] != 'Z')) {
 		/* Eat the semicolon... */
 		/*
 		 * XXXSK: I'm not sure why we should ever get here, but we 
@@ -5261,8 +5272,13 @@ int parse_option_token (rv, cfile, fmt, expr, uniform, lookups)
 			return 0;
 		break;
 
-	      case '\0': /* Zero-length option. */
-	        buf[0] = '\0';
+	      case 'Z': /* Zero-length option. */
+		token = peek_token (&val, (unsigned *)0, cfile);
+		if (token != SEMI) {
+			parse_warn(cfile, "semicolon expected.");
+			skip_to_semi(cfile);
+		}
+		buf[0] = '\0';
 		if (!make_const_data(&t,        /* expression */
 				     buf,       /* buffer */ 
 				     0,         /* length */ 
@@ -5273,7 +5289,7 @@ int parse_option_token (rv, cfile, fmt, expr, uniform, lookups)
 		break;
 
 	      default:
-		parse_warn (cfile, "Bad format %c in parse_option_token.",
+		parse_warn (cfile, "Bad format '%c' in parse_option_token.",
 			    **fmt);
 		skip_to_semi (cfile);
 		return 0;
@@ -5511,6 +5527,17 @@ int parse_option_decl (oc, cfile)
 				dp = buf;
 				goto alloc;
 
+			      case 'Z':	/* Zero-length option */
+				token = next_token(&val, (unsigned *)0, cfile);
+				if (token != SEMI) {
+					parse_warn(cfile,
+						   "semicolon expected.");
+					goto parse_exit;
+				}
+				len = 0;
+				buf[0] = '\0';
+				break;
+
 			      default:
 				log_error ("parse_option_param: Bad format %c",
 				      *fmt);
diff --git a/common/tables.c b/common/tables.c
index 9259332d..27972835 100644
--- a/common/tables.c
+++ b/common/tables.c
@@ -92,6 +92,7 @@ HASH_FUNCTIONS (option_code, const unsigned *, struct option,
    d - Domain name (i.e., FOO or FOO.BAR).
    D - Domain list (i.e., example.com eng.example.com)
    c - When following a 'D' atom, enables compression pointers.
+   Z - Zero-length option
 */
 
 struct universe dhcp_universe;
@@ -341,7 +342,7 @@ static struct option dhcpv6_options[] = {
 #endif
 	{ "unicast", "6",			&dhcpv6_universe, 12, 1 },
 	{ "status-code", "Nstatus-codes.to",	&dhcpv6_universe, 13, 1 },
-	{ "rapid-commit", "",			&dhcpv6_universe, 14, 1 },
+	{ "rapid-commit", "Z",			&dhcpv6_universe, 14, 1 },
 #if 0
 	/* XXX: user-class contents are of the form "StA" where the
 	 * integer describes the length of the text field.  We don't have
@@ -354,7 +355,7 @@ static struct option dhcpv6_options[] = {
 	{ "vendor-opts", "Evsio.",		&dhcpv6_universe, 17, 1 },
 	{ "interface-id", "X",			&dhcpv6_universe, 18, 1 },
 	{ "reconf-msg", "Ndhcpv6-messages.",	&dhcpv6_universe, 19, 1 },
-	{ "reconf-accept", "",			&dhcpv6_universe, 20, 1 },
+	{ "reconf-accept", "Z",			&dhcpv6_universe, 20, 1 },
 
 				/* RFC3319 OPTIONS */
 
diff --git a/includes/dhctoken.h b/includes/dhctoken.h
index 568d4112..2a8fb3f1 100644
--- a/includes/dhctoken.h
+++ b/includes/dhctoken.h
@@ -348,7 +348,8 @@ enum dhcp_token {
 	RANGE6 = 651,
 	WHITESPACE = 652,
 	TOKEN_ALSO = 653,
-	AFTER = 654
+	AFTER = 654,
+        ZEROLEN = 655
 };
 
 #define is_identifier(x)	((x) >= FIRST_TOKEN &&	\