[master] Added --prefix-len-hint command line argument to dhclient

Merges in rt43792

RELNOTES

@@ -183,6 +183,11 @@ dhcp-users@lists.isc.org.
   they are received.
   [ISC-Bugs #39669]
 
+- Added a new dhclient command line parameter, --prefix-len-hint <length>.
+  When used in conjunction with -P, it directs dhclient to use the given
+  length as the prefix length hint when requesting prefixes.
+  [ISC-Bugs #43792]
+
 			Changes since 4.3.0 (bug fixes)
 
 - Tidy up several small tickets.

client/dhc6.c

@@ -146,6 +146,8 @@ static int dhc6_score_lease(struct client_state *client,
 
 extern int onetry;
 extern int stateless;
+extern int prefix_len_hint;
+
 
 /*
  * Assign DHCPv6 port numbers as a client.
@@ -1708,7 +1710,7 @@ dhc6_create_iaid(struct client_state *client,
 	int start_idx, copy_len;
 
 	memset(ia, 0, sizeof(*ia));
-	if (!buffer_allocate(&ia->buffer, 12, MDL)) {
+	if (!buffer_allocate(&ia->buffer, len, MDL)) {
 		return (ISC_R_NOMEMORY);
 	}
 	ia->data = ia->buffer->data;
@@ -1771,18 +1773,22 @@ dhc6_bare_ia_xx(struct client_state *client,
 	      case D6O_IA_NA:
 		type_string = "IA_NA";
 		type_option = ia_na_option;
-		len = 12;
+		len = IA_NA_OFFSET;
 		break;
 	      case D6O_IA_TA:
 		type_string = "IA_TA";
 		type_option = ia_ta_option;
-		len = 4;
+		len = IA_TA_OFFSET;
 		break;
 	      case D6O_IA_PD:
 		type_string = "IA_PD";
 		type_option = ia_pd_option;
-		len = 12;
+		len = IA_PD_OFFSET;
+		if (prefix_len_hint > 0) {
+			len += IASUBOPT_PD_LEN;
+		}
 		break;
+
 	      default:
 		return (ISC_R_FAILURE);
 	}
@@ -1811,7 +1817,7 @@ dhc6_bare_ia_xx(struct client_state *client,
 		/* If we are requesting an NA or a PD we also want to add
 		 * the renew and rebind times we are requesting.
 		 */
-		if (len == 12) {
+		if (ia_type != D6O_IA_TA) {
 			t1 = client->config->requested_lease / 2;
 			t2 = t1 + (t1 / 2);
 			putULong(ia.buffer->data + 4, t1);
@@ -1823,6 +1829,18 @@ dhc6_bare_ia_xx(struct client_state *client,
 				  (unsigned)t2);
 		}
 
+		if (ia_type == D6O_IA_PD && prefix_len_hint > 0) {
+			unsigned char *ptr = ia.buffer->data + IA_NA_OFFSET;
+			putUShort(ptr, D6O_IAPREFIX);
+			ptr += 2;
+			putUShort(ptr, IASUBOPT_PD_LEN);
+			ptr += 2;
+			putUChar(ptr + IASUBOPT_PD_PREFLEN_OFFSET,
+				 prefix_len_hint);
+			log_debug("XMT:  | | X-- Request prefix ::/%u.",
+				  prefix_len_hint);
+		}
+
 		/* and append it to the packet */
 		append_option(packet, &dhcpv6_universe, type_option, &ia);
 		data_string_forget(&ia, MDL);
@@ -2128,6 +2146,25 @@ do_init6(void *input)
 
 				data_string_forget(&addr, MDL);
 			}
+		} else if (prefix_len_hint > 0) {
+			memset(&addr, 0, sizeof(addr));
+			if (!buffer_allocate(&addr.buffer, 25, MDL)) {
+				log_error("Unable to allocate memory "
+					  "for IAPREFIX.");
+				data_string_forget(&ia, MDL);
+				data_string_forget(&ds, MDL);
+				return;
+			}
+
+			addr.data = addr.buffer->data;
+			addr.len = 25;
+
+			putUChar(addr.buffer->data + 8, prefix_len_hint);
+			log_debug("XMT:  | | X-- Request prefix ::/%u.",
+				  prefix_len_hint);
+			append_option(&ia, &dhcpv6_universe, iaprefix_option,
+				      &addr);
+			data_string_forget(&addr, MDL);
 		}
 
 		append_option(&ds, &dhcpv6_universe, ia_pd_option, &ia);

client/dhclient.8

@@ -138,6 +138,10 @@ dhclient - Dynamic Host Configuration Protocol Client
 .I seconds
 ]
 [
+.B --prefix-len-hint
+.I length
+]
+[
 .B -v
 ]
 [
@@ -423,6 +427,11 @@ variable. If any of the IPv6 addresses on the interface are tentative
 seconds for DAD to complete. If the script ignores this variable the
 parameter has no effect.
 .PP
+.TP
+.BI \--prefix-len-hint \ length
+When used in conjunction with -P, it directs the client to use the given
+length to use a prefix hint of, "::/length", when requesting new prefixes.
+.PP
 .I Modifying default file locations:
 The following options can be used to modify the locations a client uses
 for its files.  They can be particularly useful if, for example,

client/dhclient.c

@@ -98,7 +98,11 @@ int wanted_ia_pd = 0;
 int require_all_ias = 0;	/* If the user requires all of the IAs to
 				   be available before accepting a lease
 				   0 = no, 1 = requries */
+#if defined(DHCPv6)
 int dad_wait_time = 0;
+int prefix_len_hint = 0;
+#endif
+
 char *mockup_relay = NULL;
 
 char *progname = NULL;
@@ -156,11 +160,12 @@ static const char use_v6command[] = "Command not used for DHCPv4: %s";
 #ifdef DHCP4o6
 #define DHCLIENT_USAGE0 \
 "[-4|-6] [-SNTPRI1dvrxi] [-nw] -4o6 <port>] [-p <port>]\n" \
-"                [-D LL|LLT] [--dad-wait-time seconds]\n"
+"                [-D LL|LLT] [--dad-wait-time seconds]\n" \
+"                [--prefix-len-hint length]\n"
 #else /* DHCP4o6 */
 #define DHCLIENT_USAGE0 \
 "[-4|-6] [-SNTPRI1dvrxi] [-nw] [-p <port>] [-D LL|LLT]\n" \
-"                [--dad-wait-time seconds]\n"
+"                [--dad-wait-time seconds] [--prefix-len-hint length]\n"
 #endif
 #else /* DHCPv6 */
 #define DHCLIENT_USAGE0 \
@@ -490,7 +495,17 @@ main(int argc, char **argv) {
 			if (errno || (*s != '\0') || (dad_wait_time < 0)) {
 				usage("Invalid value for --dad-wait-time: %s", argv[i]);
 			}
+		} else if (!strcmp(argv[i], "--prefix-len-hint")) {
+			if (++i == argc) {
+				usage(use_noarg, argv[i-1]);
+			}
 
+			errno = 0;
+			prefix_len_hint = (int)strtol(argv[i], &s, 10);
+			if (errno || (*s != '\0') || (prefix_len_hint < 0)) {
+				usage("Invalid value for --prefix-len-hint: %s",
+				      argv[i]);
+			}
 #endif /* DHCPv6 */
 		} else if (!strcmp(argv[i], "-D")) {
 			duid_v4 = 1;

includes/dhcp6.h

@@ -280,3 +280,15 @@ struct dhcpv4_over_dhcpv6_packet {
 #define EUI_64_ID_LEN 12  /* 2 for duid-type, 2 for hardware type, 8 for ID */
 #define IAID_LEN 4
 
+/* Offsets with iasubopt wire data of data values for IA_NA and TA */
+#define IASUBOPT_NA_ADDR_OFFSET         0
+#define IASUBOPT_NA_PREF_OFFSET         16
+#define IASUBOPT_NA_VALID_OFFSET        20
+#define IASUBOPT_NA_LEN                 24
+
+/* Offsets with iasubopt wire data of data values for PD */
+#define IASUBOPT_PD_PREF_OFFSET         0
+#define IASUBOPT_PD_VALID_OFFSET        4
+#define IASUBOPT_PD_PREFLEN_OFFSET      8
+#define IASUBOPT_PD_PREFIX_OFFSET       9
+#define IASUBOPT_PD_LEN                 25