Added local-address6

RELNOTES

@@ -296,6 +296,14 @@ dhcp-users@lists.isc.org.
   [ISC-Bugs #34097]
   [ISC-Bugs #41054]
 
+- Added to the server (-6) a new statement, local-address6, which specifies
+  the source address of packets sent by the server. An additional flag,
+  bind-local-address6, disabled by default makes the service socket to
+  be bound to local-address6. Note as for local-address this does not
+  work with direct client: a relay has to forward packets to the server
+  using the local-address6 destination.
+  [ISC-Bugs #46084]
+
 			Changes since 4.3.6 (Bugs):
 
 - Corrected an issue where the server would return a client's previously

common/discover.c

@@ -55,6 +55,14 @@ struct in_addr limited_broadcast;
 int local_family = AF_INET;
 struct in_addr local_address;
 
+#ifdef DHCPv6
+/*
+ * Another clear abuse of the fact that undefined IP addresses are all zeroes.
+ */
+struct in6_addr local_address6;
+int bind_local_address6 = 0;
+#endif /* DHCPv6 */
+
 void (*bootp_packet_handler) (struct interface_info *,
 			      struct dhcp_packet *, unsigned,
 			      unsigned int,

common/socket.c

@@ -157,10 +157,19 @@ if_register_socket(struct interface_info *info, int family,
 		addr6 = (struct sockaddr_in6 *)&name; 
 		addr6->sin6_family = AF_INET6;
 		addr6->sin6_port = local_port;
+		/* A server feature */
+		if (bind_local_address6) {
+			memcpy(&addr6->sin6_addr,
+			       &local_address6,
+			       sizeof(addr6->sin6_addr));
+		}
+		/* A client feature */
 		if (linklocal6) {
 			memcpy(&addr6->sin6_addr,
 			       linklocal6,
 			       sizeof(addr6->sin6_addr));
+		}
+		if (IN6_IS_ADDR_LINKLOCAL(&addr6->sin6_addr)) {
 			addr6->sin6_scope_id = if_nametoindex(info->name);
 		}
 #ifdef HAVE_SA_LEN
@@ -497,8 +506,21 @@ if_register6(struct interface_info *info, int do_multicast) {
 			 * create a socket, this is just a sanity check.
 			 */
 			log_fatal("Impossible condition at %s:%d", MDL);
+		} else if (bind_local_address6) {
+			char addr6_str[INET6_ADDRSTRLEN];
+
+			if (inet_ntop(AF_INET6,
+				      &local_address6,
+				      addr6_str,
+				      sizeof(addr6_str)) == NULL) {
+				log_fatal("inet_ntop: unable to convert "
+					  "local-address6");
+			}
+			log_info("Bound to [%s]:%d",
+				 addr6_str,
+				 (int) ntohs(local_port));
 		} else {
-			log_info("Bound to *:%d", ntohs(local_port));
+			log_info("Bound to *:%d", (int) ntohs(local_port));
 		}
 	}
 		
@@ -828,6 +850,7 @@ ssize_t send_packet6(struct interface_info *interface,
 	cmsg->cmsg_len = CMSG_LEN(sizeof(*pktinfo));
 	pktinfo = (struct in6_pktinfo *)CMSG_DATA(cmsg);
 	memset(pktinfo, 0, sizeof(*pktinfo));
+	pktinfo->ipi6_addr = local_address6;
 	pktinfo->ipi6_ifindex = ifindex;
 
 	result = sendmsg(interface->wfdesc, &m, 0);

includes/dhcpd.h

@@ -810,6 +810,8 @@ struct lease_state {
 #define SV_DDNS_GUARD_ID_MUST_MATCH 	93
 #define SV_DDNS_OTHER_GUARD_IS_DYNAMIC	94
 #define SV_RELEASE_ON_ROAM		95
+#define SV_LOCAL_ADDRESS6		96
+#define SV_BIND_LOCAL_ADDRESS6		97
 
 #if !defined (DEFAULT_PING_TIMEOUT)
 # define DEFAULT_PING_TIMEOUT 1
@@ -2826,6 +2828,8 @@ void interface_trace_setup (void);
 extern struct in_addr limited_broadcast;
 extern int local_family;
 extern struct in_addr local_address;
+extern struct in6_addr local_address6;
+extern int bind_local_address6;
 
 extern u_int16_t local_port;
 extern u_int16_t remote_port;

server/dhcpd.c

@@ -1150,6 +1150,29 @@ void postconf_initialization (int quiet)
                         data_string_forget(&db, MDL);
                         path_dhcpd_pid = s;
                 }
+
+		oc = lookup_option(&server_universe, options,
+				   SV_LOCAL_ADDRESS6);
+		if (oc &&
+		    evaluate_option_cache(&db, NULL, NULL, NULL, options, NULL,
+					  &global_scope, oc, MDL)) {
+			if (db.len == 16) {
+				memcpy(&local_address6, db.data, 16);
+			} else
+				log_fatal("invalid local address "
+					  "data length");
+			data_string_forget(&db, MDL);
+		}
+
+		oc = lookup_option(&server_universe, options,
+				   SV_BIND_LOCAL_ADDRESS6);
+		if (oc &&
+		    evaluate_boolean_option_cache(NULL, NULL, NULL,
+						  NULL, options, NULL,
+						  &global_scope, oc, MDL)) {
+			bind_local_address6 = 1;
+		}
+
         }
 #endif /* DHCPv6 */
 

server/dhcpd.conf.5

@@ -2744,6 +2744,29 @@ time.
 .RE
 .PP
 The
+.I local-address6
+and
+.I bind-local-address6
+statements
+.RS 0.25i
+.PP
+.B local-address6 \fIaddress\fB;\fR
+.PP
+.B bind-local-address6 \fIflag\fB;\fR
+.PP
+The \fIlocal-address6\fR statement causes the DHCP server to send IPv6
+packets as originating from the specified IPv6 \fIaddress\fR, rather than
+leaving the kernel to fill in the source address field.
+.PP
+When \fIbind-local-address6\fR is present and has a value of true or on,
+service sockets are bound to \fIaddress\fR too.
+.PP
+By default \fIaddress\fR is the undefined address and the
+\fIbind-local-address6\fR is disabled, both may only be set at the global
+scope.
+.RE
+.PP
+The
 .I log-facility
 statement
 .RS 0.25i

server/stables.c

@@ -288,6 +288,8 @@ static struct option server_options[] = {
 	{ "ddns-guard-id-must-match", "f",		&server_universe,  SV_DDNS_GUARD_ID_MUST_MATCH, 1 },
 	{ "ddns-other-guard-is-dynamic", "f",		&server_universe,  SV_DDNS_OTHER_GUARD_IS_DYNAMIC, 1 },
 	{ "release-on-roam", "f",	&server_universe,  SV_RELEASE_ON_ROAM, 1 },
+	{ "local-address6", "6",	&server_universe,  SV_LOCAL_ADDRESS6, 1 },
+	{ "bind-local-address6", "f",	&server_universe,  SV_BIND_LOCAL_ADDRESS6, 1 },
 	{ NULL, NULL, NULL, 0, 0 }
 };