From 7e6299e72feaaf7e8bd499614999ba8a07dd1a8a Mon Sep 17 00:00:00 2001

From: Pavel Zhukov <pzhukov@redhat.com>

Date: Thu, 21 Feb 2019 10:32:35 +0100

Subject: [PATCH 12/28] RFC 3442 - Classless Static Route Option for DHCPv4

 (#516325)

(Submitted to dhcp-bugs@isc.org - [ISC-Bugs #24572])

---

 client/clparse.c      | 13 ++++++++--

 common/dhcp-options.5 | 43 +++++++++++++++++++++++++++++++++

 common/inet.c         | 54 +++++++++++++++++++++++++++++++++++++++++

 common/options.c      | 49 ++++++++++++++++++++++++++++++++++++-

 common/parse.c        | 56 ++++++++++++++++++++++++++++++++++++++++++-

 common/tables.c       |  2 ++

 includes/dhcp.h       |  1 +

 includes/dhcpd.h      |  2 ++

 includes/dhctoken.h   |  3 ++-

 9 files changed, 218 insertions(+), 5 deletions(-)

diff --git a/client/clparse.c b/client/clparse.c

index 902b523..57f6456 100644

--- a/client/clparse.c

+++ b/client/clparse.c

@@ -31,7 +31,7 @@

 struct client_config top_level_config;

-#define NUM_DEFAULT_REQUESTED_OPTS	14

+#define NUM_DEFAULT_REQUESTED_OPTS	15

 /* There can be 2 extra requested options for DHCPv4-over-DHCPv6. */

 struct option *default_requested_options[NUM_DEFAULT_REQUESTED_OPTS + 2 + 1];

@@ -90,7 +90,11 @@ isc_result_t read_client_conf ()

 				dhcp_universe.code_hash, &code, 0, MDL);

 	/* 4 */

-	code = DHO_ROUTERS;

+	/* The Classless Static Routes option code MUST appear in the parameter

+     * request list prior to both the Router option code and the Static

+     * Routes option code, if present. (RFC3442)

+	 */

+	code = DHO_CLASSLESS_STATIC_ROUTES;

 	option_code_hash_lookup(&default_requested_options[3],

 				dhcp_universe.code_hash, &code, 0, MDL);

@@ -144,6 +148,11 @@ isc_result_t read_client_conf ()

 	option_code_hash_lookup(&default_requested_options[13],

 				dhcp_universe.code_hash, &code, 0, MDL);

+	/* 15 */

+	code = DHO_ROUTERS;

+	option_code_hash_lookup(&default_requested_options[14],

+				dhcp_universe.code_hash, &code, 0, MDL);

+

 	for (code = 0 ; code < NUM_DEFAULT_REQUESTED_OPTS ; code++) {

 		if (default_requested_options[code] == NULL)

 			log_fatal("Unable to find option definition for "

diff --git a/common/dhcp-options.5 b/common/dhcp-options.5

index a784b32..86f04ed 100644

--- a/common/dhcp-options.5

+++ b/common/dhcp-options.5

@@ -117,6 +117,26 @@ hexadecimal, separated by colons.  For example:

 or

   option dhcp-client-identifier 43:4c:49:45:54:2d:46:4f:4f;

 .fi

+.PP

+The

+.B destination-descriptor

+describe the IP subnet number and subnet mask

+of a particular destination using a compact encoding. This encoding

+consists of one octet describing the width of the subnet mask,

+followed by all the significant octets of the subnet number.

+The following table contains some examples of how various subnet

+number/mask combinations can be encoded:

+.nf

+.sp 1

+Subnet number   Subnet mask      Destination descriptor

+0               0                0

+10.0.0.0        255.0.0.0        8.10

+10.0.0.0        255.255.255.0    24.10.0.0

+10.17.0.0       255.255.0.0      16.10.17

+10.27.129.0     255.255.255.0    24.10.27.129

+10.229.0.128    255.255.255.128  25.10.229.0.128

+10.198.122.47   255.255.255.255  32.10.198.122.47

+.fi

 .SH SETTING OPTION VALUES USING EXPRESSIONS

 Sometimes it's helpful to be able to set the value of a DHCP option

 based on some value that the client has sent.  To do this, you can

@@ -1093,6 +1113,29 @@ dhclient-script will create routes:

 .RE

 .PP

 .nf

+.B option \fBclassless-static-routes\fR \fIdestination-descriptor ip-address\fR

+                            [\fB,\fR \fIdestination-descriptor ip-address\fR...]\fB;\fR

+.fi

+.RS 0.25i

+.PP

+This option (see RFC3442) specifies a list of classless static routes

+that the client should install in its routing cache.

+.PP

+This option can contain one or more static routes, each of which

+consists of a destination descriptor and the IP address of the router

+that should be used to reach that destination.

+.PP

+Many clients may not implement the Classless Static Routes option.

+DHCP server administrators should therefore configure their DHCP

+servers to send both a Router option and a Classless Static Routes

+option, and should specify the default router(s) both in the Router

+option and in the Classless Static Routes option.

+.PP

+If the DHCP server returns both a Classless Static Routes option and

+a Router option, the DHCP client ignores the Router option.

+.RE

+.PP

+.nf

 .B option \fBstreettalk-directory-assistance-server\fR \fIip-address\fR

                                            [\fB,\fR \fIip-address\fR...]\fB;\fR

 .fi

diff --git a/common/inet.c b/common/inet.c

index 0f7f168..7c446d4 100644

--- a/common/inet.c

+++ b/common/inet.c

@@ -519,6 +519,60 @@ free_iaddrcidrnetlist(struct iaddrcidrnetlist **result) {

 	return ISC_R_SUCCESS;

 }

+static const char *

+inet_ntopdd(const unsigned char *src, unsigned srclen, char *dst, size_t size)

+{

+	char tmp[sizeof("32.255.255.255.255")];

+	int len;

+

+	switch (srclen) {

+		case 2:

+			len = sprintf (tmp, "%u.%u", src[0], src[1]);

+			break;

+		case 3:

+			len = sprintf (tmp, "%u.%u.%u", src[0], src[1], src[2]);

+			break;

+		case 4:

+			len = sprintf (tmp, "%u.%u.%u.%u", src[0], src[1], src[2], src[3]);

+			break;

+		case 5:

+			len = sprintf (tmp, "%u.%u.%u.%u.%u", src[0], src[1], src[2], src[3], src[4]);

+			break;

+		default:

+			return NULL;

+	}

+	if (len < 0)

+		return NULL;

+

+	if (len > size) {

+		errno = ENOSPC;

+		return NULL;

+	}

+

+	return strcpy (dst, tmp);

+}

+

+/* pdestdesc() turns an iaddr structure into a printable dest. descriptor */

+const char *

+pdestdesc(const struct iaddr addr) {

+	static char pbuf[sizeof("255.255.255.255.255")];

+

+	if (addr.len == 0) {

+		return "<null destination descriptor>";

+	}

+	if (addr.len == 1) {

+		return "0";

+	}

+	if ((addr.len >= 2) && (addr.len <= 5)) {

+		return inet_ntopdd(addr.iabuf, addr.len, pbuf, sizeof(pbuf));

+	}

+

+	log_fatal("pdestdesc():%s:%d: Invalid destination descriptor length %d.",

+		  MDL, addr.len);

+	/* quell compiler warnings */

+	return NULL;

+}

+

 /* piaddr() turns an iaddr structure into a printable address. */

 /* XXX: should use a const pointer rather than passing the structure */

 const char *

diff --git a/common/options.c b/common/options.c

index 92c8fee..66433c4 100644

--- a/common/options.c

+++ b/common/options.c

@@ -734,7 +734,11 @@ cons_options(struct packet *inpacket, struct dhcp_packet *outpacket,

 		 * packet.

 		 */

 		priority_list[priority_len++] = DHO_SUBNET_MASK;

-		priority_list[priority_len++] = DHO_ROUTERS;

+		if (lookup_option(&dhcp_universe, cfg_options,

+							DHO_CLASSLESS_STATIC_ROUTES))

+			priority_list[priority_len++] = DHO_CLASSLESS_STATIC_ROUTES;

+		else

+			priority_list[priority_len++] = DHO_ROUTERS;

 		priority_list[priority_len++] = DHO_DOMAIN_NAME_SERVERS;

 		priority_list[priority_len++] = DHO_HOST_NAME;

 		priority_list[priority_len++] = DHO_FQDN;

@@ -1812,6 +1816,7 @@ const char *pretty_print_option (option, data, len, emit_commas, emit_quotes)

 	unsigned long tval;

 	isc_boolean_t a_array = ISC_FALSE;

 	int len_used;

+	unsigned int octets = 0;

 	if (emit_commas)

 		comma = ',';

@@ -1820,6 +1825,7 @@ const char *pretty_print_option (option, data, len, emit_commas, emit_quotes)

 	memset (enumbuf, 0, sizeof enumbuf);

+	if (option->format[0] != 'R') { /* see explanation lower */

 	/* Figure out the size of the data. */

 	for (l = i = 0; option -> format [i]; i++, l++) {

 		if (l >= sizeof(fmtbuf) - 1)

@@ -2029,6 +2035,33 @@ const char *pretty_print_option (option, data, len, emit_commas, emit_quotes)

 	if (numhunk < 0)

 		numhunk = 1;

+	} else { /* option->format[i] == 'R') */

+		/* R (destination descriptor) has variable length.

+		 * We can find it only in classless static route option,

+		 * so we are for sure parsing classless static route option now.

+		 * We go through whole the option to check whether there are no

+		 * missing/extra bytes.

+		 * I didn't find out how to improve the existing code and that's the

+		 * reason for this separate 'else' where I do my own checkings.

+		 * I know it's little bit unsystematic, but it works.

+		 */

+		numhunk = 0;

+		numelem = 2; /* RI */

+		fmtbuf[0]='R'; fmtbuf[1]='I'; fmtbuf[2]=0;

+		for (i =0; i < len; i = i + octets + 5) {

+			if (data[i] > 32) { /* subnet mask width */

+				log_error ("wrong subnet mask width in destination descriptor");

+				break;

+			}

+			numhunk++;

+			octets = ((data[i]+7) / 8);

+		}

+		if (i != len) {

+			log_error ("classless static routes option has wrong size or "

+					   "there's some garbage in format");

+		}

+	}

+

 	/* Cycle through the array (or hunk) printing the data. */

 	for (i = 0; i < numhunk; i++) {

 		if ((a_array == ISC_TRUE) && (i != 0) && (numelem > 0)) {

@@ -2197,6 +2230,20 @@ const char *pretty_print_option (option, data, len, emit_commas, emit_quotes)

 				strcpy(op, piaddr(iaddr));

 				dp += 4;

 				break;

+

+			      case 'R':

+				if (dp[0] <= 32)

+					iaddr.len = (((dp[0]+7)/8)+1);

+				else {

+					log_error ("wrong subnet mask width in destination descriptor");

+					return "<error>";

+				}

+

+				memcpy(iaddr.iabuf, dp, iaddr.len);

+				strcpy(op, pdestdesc(iaddr));

+				dp += iaddr.len;

+				break;

+

 			      case '6':

 				iaddr.len = 16;

 				memcpy(iaddr.iabuf, dp, 16);

diff --git a/common/parse.c b/common/parse.c

index b123a6c..7cf4f2a 100644

--- a/common/parse.c

+++ b/common/parse.c

@@ -344,6 +344,39 @@ int parse_ip_addr (cfile, addr)

 	return 0;

 }

+/*

+ * destination-descriptor :== NUMBER DOT NUMBER |

+ *                            NUMBER DOT NUMBER DOT NUMBER |

+ *                            NUMBER DOT NUMBER DOT NUMBER DOT NUMBER |

+ *                            NUMBER DOT NUMBER DOT NUMBER DOT NUMBER DOT NUMBER

+ */

+

+int parse_destination_descriptor (cfile, addr)

+	struct parse *cfile;

+	struct iaddr *addr;

+{

+		unsigned int mask_width, dest_dest_len;

+		addr -> len = 0;

+		if (parse_numeric_aggregate (cfile, addr -> iabuf,

+									 &addr -> len, DOT, 10, 8)) {

+			mask_width = (unsigned int)addr->iabuf[0];

+			dest_dest_len = (((mask_width+7)/8)+1);

+			if (mask_width > 32) {

+				parse_warn (cfile,

+				"subnet mask width (%u) greater than 32.", mask_width);

+			}

+			else if (dest_dest_len != addr->len) {

+				parse_warn (cfile,

+				"destination descriptor with subnet mask width %u "

+				"should have %u octets, but has %u octets.",

+				mask_width, dest_dest_len, addr->len);

+			}

+

+			return 1;

+		}

+		return 0;

+}

+

 /*

  * Return true if every character in the string is hexadecimal.

  */

@@ -724,8 +757,10 @@ unsigned char *parse_numeric_aggregate (cfile, buf,

 		if (count) {

 			token = peek_token (&val, (unsigned *)0, cfile);

 			if (token != separator) {

-				if (!*max)

+				if (!*max) {

+					*max = count;

 					break;

+				}

 				if (token != RBRACE && token != LBRACE)

 					token = next_token (&val,

 							    (unsigned *)0,

@@ -1672,6 +1707,9 @@ int parse_option_code_definition (cfile, option)

 	      case IP_ADDRESS:

 		type = 'I';

 		break;

+	      case DESTINATION_DESCRIPTOR:

+		type = 'R';

+		break;

 	      case IP6_ADDRESS:

 		type = '6';

 		break;

@@ -5124,6 +5162,15 @@ int parse_option_token (rv, cfile, fmt, expr, uniform, lookups)

 		}

 		break;

+	      case 'R': /* destination descriptor */

+		if (!parse_destination_descriptor (cfile, &addr)) {

+			return 0;

+		}

+		if (!make_const_data (&t, addr.iabuf, addr.len, 0, 1, MDL)) {

+			return 0;

+		}

+		break;

+

 	      case '6': /* IPv6 address. */

 		if (!parse_ip6_addr(cfile, &addr)) {

 			return 0;

@@ -5401,6 +5448,13 @@ int parse_option_decl (oc, cfile)

 					goto exit;

 				len = ip_addr.len;

 				dp = ip_addr.iabuf;

+				goto alloc;

+

+			      case 'R': /* destination descriptor */

+				if (!parse_destination_descriptor (cfile, &ip_addr))

+					goto exit;

+				len = ip_addr.len;

+				dp = ip_addr.iabuf;

 			      alloc:

 				if (hunkix + len > sizeof hunkbuf) {

diff --git a/common/tables.c b/common/tables.c

index ce12fcd..96521a6 100644

--- a/common/tables.c

+++ b/common/tables.c

@@ -45,6 +45,7 @@ HASH_FUNCTIONS (option_code, const unsigned *, struct option,

    Format codes:

    I - IPv4 address

+   R - destination descriptor (RFC3442)

    6 - IPv6 address

    l - 32-bit signed integer

    L - 32-bit unsigned integer

@@ -223,6 +224,7 @@ static struct option dhcp_options[] = {

 #endif

 	{ "subnet-selection", "I",		&dhcp_universe, 118, 1 },

 	{ "domain-search", "D",			&dhcp_universe, 119, 1 },

+	{ "classless-static-routes", "RIA",	&dhcp_universe, 121, 1 },

 	{ "vivco", "Evendor-class.",		&dhcp_universe, 124, 1 },

 	{ "vivso", "Evendor.",			&dhcp_universe, 125, 1 },

 #if 0

diff --git a/includes/dhcp.h b/includes/dhcp.h

index cafe172..5a73129 100644

--- a/includes/dhcp.h

+++ b/includes/dhcp.h

@@ -159,6 +159,7 @@ struct dhcp_packet {

 #define DHO_V6_ONLY_PREFERRED			108 /* RFC8925 */

 #define DHO_SUBNET_SELECTION			118 /* RFC3011! */

 #define DHO_DOMAIN_SEARCH			119 /* RFC3397 */

+#define DHO_CLASSLESS_STATIC_ROUTES		121 /* RFC3442 */

 #define DHO_VIVCO_SUBOPTIONS			124

 #define DHO_VIVSO_SUBOPTIONS			125

diff --git a/includes/dhcpd.h b/includes/dhcpd.h

index 4a57002..25e1c72 100644

--- a/includes/dhcpd.h

+++ b/includes/dhcpd.h

@@ -2967,6 +2967,7 @@ isc_result_t range2cidr(struct iaddrcidrnetlist **result,

 			const struct iaddr *lo, const struct iaddr *hi);

 isc_result_t free_iaddrcidrnetlist(struct iaddrcidrnetlist **result);

 const char *piaddr (struct iaddr);

+const char *pdestdesc (struct iaddr);

 char *piaddrmask(struct iaddr *, struct iaddr *);

 char *piaddrcidr(const struct iaddr *, unsigned int);

 u_int16_t validate_port(char *);

@@ -3189,6 +3190,7 @@ void parse_client_lease_declaration (struct parse *,

 int parse_option_decl (struct option_cache **, struct parse *);

 void parse_string_list (struct parse *, struct string_list **, int);

 int parse_ip_addr (struct parse *, struct iaddr *);

+int parse_destination_descriptor (struct parse *, struct iaddr *);

 int parse_ip_addr_with_subnet(struct parse *, struct iaddrmatch *);

 void parse_reject_statement (struct parse *, struct client_config *);

diff --git a/includes/dhctoken.h b/includes/dhctoken.h

index 6daa422..3f5334e 100644

--- a/includes/dhctoken.h

+++ b/includes/dhctoken.h

@@ -378,7 +378,8 @@ enum dhcp_token {

 	TOKEN_OCTAL = 678,

 	KEY_ALGORITHM = 679,

 	BOOTP_BROADCAST_ALWAYS = 680,

-	DISCONNECT = 681

+	DESTINATION_DESCRIPTOR = 681,

+	DISCONNECT = 682

 };

 #define is_identifier(x)	((x) >= FIRST_TOKEN &&	\

-- 

2.35.1