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
@@ -604,8 +604,8 @@ running on the
 .Xr resolvconf 8
 .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 3633, RFC 3396, RFC 3397, RFC 3442, RFC 3927, RFC 4361, RFC 4390, RFC 4702,
+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