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dhcp/SOURCES/0012-RFC-3442-Classless-Sta...

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From 01b1dcfef129a4eccfaf0f63a216774019f82dca Mon Sep 17 00:00:00 2001
From: Pavel Zhukov <pzhukov@redhat.com>
Date: Thu, 21 Feb 2019 10:32:35 +0100
Subject: [PATCH 12/26] RFC 3442 - Classless Static Route Option for DHCPv4
(#516325)
Cc: pzhukov@redhat.com
(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 | 5 +++--
9 files changed, 219 insertions(+), 6 deletions(-)
diff --git a/client/clparse.c b/client/clparse.c
index 44387ed..862e4f9 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];
@@ -87,7 +87,11 @@ 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);
@@ -141,6 +145,11 @@ 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 d9e1197..2343b19 100644
--- a/common/dhcp-options.5
+++ b/common/dhcp-options.5
@@ -110,6 +110,26 @@ 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
@@ -1086,6 +1106,29 @@ 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 c4da73c..981fb92 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 fc0e088..3034cf0 100644
--- a/common/options.c
+++ b/common/options.c
@@ -729,7 +729,11 @@ 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;
@@ -1804,6 +1808,7 @@ 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 = ',';
@@ -1812,6 +1817,7 @@ 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)
@@ -2004,6 +2010,33 @@ 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)) {
@@ -2159,6 +2192,20 @@ 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 3ac4ebf..f17bc0b 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;
@@ -5101,6 +5139,15 @@ 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;
@@ -5378,6 +5425,13 @@ 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 d2294c0..f1be07d 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
@@ -216,6 +217,7 @@ 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 0a74137..95bf539 100644
--- a/includes/dhcp.h
+++ b/includes/dhcp.h
@@ -158,6 +158,7 @@ struct dhcp_packet {
#define DHO_ASSOCIATED_IP 92
#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 3632a6b..2ac39ae 100644
--- a/includes/dhcpd.h
+++ b/includes/dhcpd.h
@@ -2951,6 +2951,7 @@ 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 *);
@@ -3169,6 +3170,7 @@ 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 7e7215a..b4d93ba 100644
--- a/includes/dhctoken.h
+++ b/includes/dhctoken.h
@@ -376,8 +376,9 @@ enum dhcp_token {
LEASE_ID_FORMAT = 676,
TOKEN_HEX = 677,
TOKEN_OCTAL = 678,
- KEY_ALGORITHM = 679
- BOOTP_BROADCAST_ALWAYS = 680
+ KEY_ALGORITHM = 679,
+ BOOTP_BROADCAST_ALWAYS = 680,
+ DESTINATION_DESCRIPTOR = 681
};
#define is_identifier(x) ((x) >= FIRST_TOKEN && \
--
2.14.5
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