Add DHPCv6 FQDN support (RFC4704)

Improve hostname support in general, so we are aware of hostname changes.
When setting the hostname, prefer the FQDN name or append a domain.

common.c

@@ -60,6 +60,7 @@
 #  define _PATH_DEVNULL "/dev/null"
 #endif
 
+static char hostname_buffer[HOSTNAME_MAX_LEN];
 int clock_monotonic;
 static char *lbuf;
 static size_t lbuf_len;
@@ -134,6 +135,19 @@ set_nonblock(int fd)
 	return 0;
 }
 
+const char *
+get_hostname(void)
+{
+
+	gethostname(hostname_buffer, sizeof(hostname_buffer));
+	if (strcmp(hostname_buffer, "(none)") == 0 ||
+	    strcmp(hostname_buffer, "localhost") == 0 ||
+	    strncmp(hostname_buffer, "localhost.", strlen("localhost.")) == 0 ||
+	    hostname_buffer[0] == '.')
+		return NULL;
+	return hostname_buffer;
+}
+
 /* Handy function to get the time.
  * We only care about time advancements, not the actual time itself
  * Which is why we use CLOCK_MONOTONIC, but it is not available on all

common.h

@@ -34,6 +34,10 @@
 #include "config.h"
 #include "defs.h"
 
+#ifndef HOSTNAME_MAX_LEN
+#define HOSTNAME_MAX_LEN	250	/* 255 - 3 (FQDN) - 2 (DNS enc) */
+#endif
+
 #define UNCONST(a)		((void *)(unsigned long)(const void *)(a))
 
 #define timeval_to_double(tv) ((tv)->tv_sec * 1.0 + (tv)->tv_usec * 1.0e-6)
@@ -96,6 +100,7 @@
 int set_cloexec(int);
 int set_nonblock(int);
 char *get_line(FILE * __restrict);
+const char *get_hostname(void);
 extern int clock_monotonic;
 int get_monotonic(struct timeval *);
 ssize_t setvar(char ***, const char *, const char *, const char *);

dhcp-common.c

@@ -89,6 +89,50 @@ int make_option_mask(const struct dhcp_opt *dopts,
 	return 0;
 }
 
+size_t
+encode_rfc1035(const char *src, uint8_t *dst)
+{
+	uint8_t *p;
+	uint8_t *lp;
+	size_t len;
+	uint8_t has_dot;
+
+	if (src == NULL || *src == '\0')
+		return 0;
+	if (dst) {
+		p = dst;
+		lp = p++;
+	}
+	len = 1;
+	has_dot = 0;
+	for (; *src; src++) {
+		if (*src == '\0')
+			break;
+		if (*src == '.') {
+			/* Skip the trailing . */
+			if (src[1] == '\0')
+				break;
+			has_dot = 1;
+			if (dst) {
+				*lp = p - lp - 1;
+				if (*lp == '\0')
+					return len;
+				lp = p++;
+			}
+		} else if (dst)
+			*p++ = (uint8_t)*src;
+		len++;
+	}
+	if (dst) {
+		*lp = p - lp - 1;
+		if (has_dot)
+			*p++ = '\0';
+	}
+	if (has_dot)
+		len++;
+	return len;
+}
+
 /* Decode an RFC3397 DNS search order option into a space
  * separated string. Returns length of string (including
  * terminating zero) or zero on error. out may be NULL

dhcp-common.h

@@ -67,6 +67,7 @@ struct dhcp_opt {
 #define del_option_mask(var, val) (var[val >> 3] &= ~(1 << (val & 7)))
 #define has_option_mask(var, val) (var[val >> 3] & (1 << (val & 7)))
 int make_option_mask(const struct dhcp_opt *,uint8_t *, const char *, int);
+size_t encode_rfc1035(const char *src, uint8_t *dst);
 ssize_t decode_rfc3397(char *, ssize_t, int, const uint8_t *);
 ssize_t print_string(char *, ssize_t, int, const uint8_t *);
 ssize_t print_option(char *, ssize_t, int, int, const uint8_t *, const char *);

dhcp.c

@@ -801,33 +801,6 @@ get_option_routes(struct interface *ifp, const struct dhcp_message *dhcp)
 	return routes;
 }
 
-static size_t
-encode_rfc1035(const char *src, uint8_t *dst)
-{
-	uint8_t *p = dst;
-	uint8_t *lp = p++;
-
-	if (*src == '\0')
-		return 0;
-	for (; *src; src++) {
-		if (*src == '\0')
-			break;
-		if (*src == '.') {
-			/* Skip the trailing . */
-			if (src[1] == '\0')
-				break;
-			*lp = p - lp - 1;
-			if (*lp == '\0')
-				return p - dst;
-			lp = p++;
-		} else
-			*p++ = (uint8_t)*src;
-	}
-	*lp = p - lp - 1;
-	*p++ = '\0';
-	return p - dst;
-}
-
 #define PUTADDR(_type, _val)						      \
 	{								      \
 		*p++ = _type;						      \
@@ -877,6 +850,7 @@ make_message(struct dhcp_message **message,
 	const struct dhcp_state *state = D_CSTATE(iface);
 	const struct dhcp_lease *lease = &state->lease;
 	time_t up = uptime() - state->start_uptime;
+	const char *hostname;
 
 	dhcp = calloc(1, sizeof (*dhcp));
 	if (dhcp == NULL)
@@ -1006,18 +980,22 @@ make_message(struct dhcp_message **message,
 		 * upto the first dot (the short hostname) as otherwise
 		 * confuses some DHCP servers when updating DNS.
 		 * The FQDN option should be used if a FQDN is required. */
-		if (ifo->options & DHCPCD_HOSTNAME && ifo->hostname[0]) {
+		if (ifo->hostname[0] == '\0')
+			hostname = get_hostname();
+		else
+			hostname = ifo->hostname;
+		if (ifo->options & DHCPCD_HOSTNAME && hostname) {
 			*p++ = DHO_HOSTNAME;
-			hp = strchr(ifo->hostname, '.');
+			hp = strchr(hostname, '.');
 			if (hp)
-				len = hp - ifo->hostname;
+				len = hp - hostname;
 			else
-				len = strlen(ifo->hostname);
+				len = strlen(hostname);
 			*p++ = len;
-			memcpy(p, ifo->hostname, len);
+			memcpy(p, hostname, len);
 			p += len;
 		}
-		if (ifo->fqdn != FQDN_DISABLE && ifo->hostname[0]) {
+		if (ifo->fqdn != FQDN_DISABLE) {
 			/* IETF DHC-FQDN option (81), RFC4702 */
 			*p++ = DHO_FQDN;
 			lp = p;
@@ -1032,12 +1010,17 @@ make_message(struct dhcp_message **message,
 			 * N: 1 => Client requests Server to not
 			 *         update DNS
 			 */
-			*p++ = (ifo->fqdn & 0x09) | 0x04;
+			if (hostname)
+				*p++ = (ifo->fqdn & 0x09) | 0x04;
+			else
+				*p++ = (FQDN_NONE & 0x09) | 0x04;
 			*p++ = 0; /* from server for PTR RR */
 			*p++ = 0; /* from server for A RR if S=1 */
-			ul = encode_rfc1035(ifo->hostname, p);
-			*lp += ul;
-			p += ul;
+			if (hostname) {
+				ul = encode_rfc1035(hostname, p);
+				*lp += ul;
+				p += ul;
+			}
 		}
 
 		/* vendor is already encoded correctly, so just add it */

dhcp6.c

@@ -126,6 +126,7 @@ const struct dhcp_opt dhcp6_opts[] = {
 	{ D6_OPTION_BCMS_SERVER_A,	IPV6A,		"bcms_server_a" },
 	{ D6_OPTION_POSIX_TIMEZONE,	STRING,		"posix_timezone" },
 	{ D6_OPTION_TZDB_TIMEZONE,	STRING,		"tzdb_timezone" },
+	{ D6_OPTION_FQDN,		RFC3397,	"fqdn" },
 	{ 0, 0, NULL }
 };
 
@@ -361,6 +362,7 @@ dhcp6_makemessage(struct interface *ifp)
 	uint8_t IA, *p;
 	uint32_t u32;
 	const struct ipv6_addr *ap;
+	const char *hostname;
 
 	state = D6_STATE(ifp);
 	if (state->send) {
@@ -379,8 +381,16 @@ dhcp6_makemessage(struct interface *ifp)
 				len += sizeof(*u16);
 		}
 		if (len == 0)
-			len = sizeof(*u16) * 3;
+			len = sizeof(*u16) * 4;
 		len += sizeof(*o);
+
+		if (ifo->fqdn != FQDN_DISABLE) {
+			if (ifo->hostname[0] == '\0')
+				hostname = get_hostname();
+			else
+				hostname = ifo->hostname;
+			len += sizeof(*o) + 1 + encode_rfc1035(hostname, NULL);
+		}
 	}
 
 	len += sizeof(*state->send);
@@ -568,6 +578,26 @@ dhcp6_makemessage(struct interface *ifp)
 	}
 
 	if (state->send->type !=  DHCP6_RELEASE) {
+		if (ifo->fqdn != FQDN_DISABLE) {
+			o = D6_NEXT_OPTION(o);
+			o->code = htons(D6_OPTION_FQDN);
+			p = D6_OPTION_DATA(o);
+			switch (ifo->fqdn) {
+			case FQDN_BOTH:
+				*p = 0x01;
+				break;
+			case FQDN_PTR:
+				*p = 0x00;
+				break;
+			default:
+				*p = 0x04;
+				break;
+			}
+			o->len = encode_rfc1035(hostname, p + 1);
+			if (o->len == 0)
+				*p = 0x04;
+			o->len = htons(++o->len);
+		}
 		o = D6_NEXT_OPTION(o);
 		o->code = htons(D6_OPTION_ORO);
 		o->len = 0;
@@ -581,10 +611,11 @@ dhcp6_makemessage(struct interface *ifp)
 			}
 		}
 		if (o->len == 0) {
+			*u16++ = htons(D6_OPTION_UNICAST);
 			*u16++ = htons(D6_OPTION_DNS_SERVERS);
 			*u16++ = htons(D6_OPTION_DOMAIN_LIST);
-			*u16++ = htons(D6_OPTION_UNICAST);
-			o->len = sizeof(*u16) * 3;
+			*u16++ = htons(D6_OPTION_FQDN);
+			o->len = sizeof(*u16) * 4;
 		}
 		o->len = htons(o->len);
 	}

dhcp6.h

@@ -79,6 +79,7 @@
 #define D6_OPTION_INFO_REFRESH_TIME	32
 #define D6_OPTION_BCMS_SERVER_D		33
 #define D6_OPTION_BCMS_SERVER_A		34
+#define D6_OPTION_FQDN			39
 #define D6_OPTION_POSIX_TIMEZONE	41
 #define D6_OPTION_TZDB_TIMEZONE		42
 

dhcpcd-hooks/30-hostname

@@ -65,15 +65,27 @@ try_hostname()
 
 set_hostname()
 {
-	if need_hostname; then
-		if [ -n "$new_host_name" ]; then
+
+	need_hostname || return
+
+	if [ -n "$new_fqdn_name" ]; then
+		try_hostname "$new_fqdn_name"
+	elif [ -n "$new_host_name" ]; then
+		if [ -n "$new_domain_name" ]; then
+			try_hostname "$new_host_name.$new_domain_name"
+		else
 			try_hostname "$new_host_name"
-		elif [ -n "$new_fqdn_name" ]; then
-			try_hostname "$new_fqdn_name"
 		fi
 	fi
 }
 
+# For ease of use, map DHCP6 names onto our DHCP4 names
+case "$reason" in
+BOUND6|RENEW6|REBIND6|REBOOT6|INFORM6)
+	new_fqdn_name="$new_dhcp6_fqdn"
+	;;
+esac
+
 if $if_up; then
 	set_hostname
 fi

dhcpcd.8.in

@@ -22,7 +22,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd May 3, 2013
+.Dd June 5, 2013
 .Dt DHCPCD 8
 .Os
 .Sh NAME
@@ -605,7 +605,7 @@ running on the
 .Sh STANDARDS
 RFC 951, RFC 1534, RFC 2131, RFC 2132, RFC 2855, RFC 3004, RFC 3315,RFC 3361,
 RFC 3633, RFC 3396, RFC 3397, RFC 3442, RFC 3927, RFC 4361, RFC 4390, RFC 4702,
-RFC 4861, RFC 4833, RFC 5227, RFC 5969, RFC 6106.
+RFC 4704, RFC 4861, RFC 4833, RFC 5227, RFC 5969, RFC 6106.
 .Sh AUTHORS
 .An Roy Marples Aq roy@marples.name
 .Sh BUGS

dhcpcd.conf.5.in

@@ -180,9 +180,11 @@ IPv6RS should be disabled globally when requesting a Prefix Delegation like so:
 Only configure IPv4.
 .It Ic ipv6only
 Only confgiure IPv6.
-.It Ic fqdn Op none | ptr | both
-none disables FQDN encoding, ptr just asks the DHCP server to update the PTR
+.It Ic fqdn Op disable | ptr | both
+ptr just asks the DHCP server to update the PTR
 record of the host in DNS whereas both also updates the A record.
+disable will disable the FQDN option.
+The default is both.
 .Nm dhcpcd
 itself never does any DNS updates.
 .Nm dhcpcd

if-options.c

@@ -459,20 +459,20 @@ parse_option(struct if_options *ifo, int opt, const char *arg)
 		add_environ(ifo, arg, 1);
 		break;
 	case 'h':
-		if (arg) {
-			s = parse_string(ifo->hostname,
-			    HOSTNAME_MAX_LEN, arg);
-			if (s == -1) {
-				syslog(LOG_ERR, "hostname: %m");
-				return -1;
-			}
-			if (s != 0 && ifo->hostname[0] == '.') {
-				syslog(LOG_ERR,
-				    "hostname cannot begin with .");
-				return -1;
-			}
-			ifo->hostname[s] = '\0';
+		if (!arg) {
+			ifo->options |= DHCPCD_HOSTNAME;
+			break;
 		}
+		s = parse_string(ifo->hostname, HOSTNAME_MAX_LEN, arg);
+		if (s == -1) {
+			syslog(LOG_ERR, "hostname: %m");
+			return -1;
+		}
+		if (s != 0 && ifo->hostname[0] == '.') {
+			syslog(LOG_ERR, "hostname cannot begin with .");
+			return -1;
+		}
+		ifo->hostname[s] = '\0';
 		if (ifo->hostname[0] == '\0')
 			ifo->options &= ~DHCPCD_HOSTNAME;
 		else
@@ -1131,12 +1131,6 @@ read_config(const char *file,
 	ifo->reboot = DEFAULT_REBOOT;
 	ifo->metric = -1;
 	strlcpy(ifo->script, SCRIPT, sizeof(ifo->script));
-	gethostname(ifo->hostname, HOSTNAME_MAX_LEN);
-	/* Ensure that the hostname is NULL terminated */
-	ifo->hostname[HOSTNAME_MAX_LEN] = '\0';
-	if (strcmp(ifo->hostname, "(none)") == 0 ||
-	    strcmp(ifo->hostname, "localhost") == 0)
-		ifo->hostname[0] = '\0';
 
 	ifo->vendorclassid[0] = strlen(vendor);
 	memcpy(ifo->vendorclassid + 1, vendor, ifo->vendorclassid[0]);

if-options.h

@@ -45,7 +45,9 @@
 #define DEFAULT_TIMEOUT		30
 #define DEFAULT_REBOOT		5
 
+#ifndef HOSTNAME_MAX_LEN
 #define HOSTNAME_MAX_LEN	250	/* 255 - 3 (FQDN) - 2 (DNS enc) */
+#endif
 #define VENDORCLASSID_MAX_LEN	255
 #define CLIENTID_MAX_LEN	48
 #define USERCLASS_MAX_LEN	255