Merge pull request #179 from zajdee/add_pref64_support

Add pref64 support (RFC8781)

defaults.h

@@ -64,6 +64,9 @@
 #define DFLT_DeprecatePrefixFlag 0
 #define DFLT_DecrementLifetimesFlag 0
 
+/* RFC8781 section 4.1; this is the non-scaled value (8191 << 3) */
+#define DFLT_NAT64MaxValidLifetime 65528 /* seconds */
+
 /* Each route has an associated: */
 #define DFLT_AdvRouteLifetime(iface) (3 * (iface)->MaxRtrAdvInterval)
 

gram.y

@@ -52,6 +52,7 @@
 %token		T_LOWPANCO
 %token		T_ABRO
 %token		T_RASRCADDRESS
+%token		T_NAT64PREFIX
 
 %token	<str>	STRING
 %token	<num>	NUMBER
@@ -138,6 +139,7 @@
 %type   <abroinfo> abrodef
 %type   <num>	number_or_infinity
 %type	<rasrcaddressinfo> rasrcaddresslist v6addrlist_rasrcaddress
+%type	<nat64pinfo> nat64prefixdef
 
 %union {
 	unsigned int		num;
@@ -153,6 +155,7 @@
 	struct AdvLowpanCo	*lowpancoinfo;
 	struct AdvAbro		*abroinfo;
 	struct AdvRASrcAddress	*rasrcaddressinfo;
+	struct NAT64Prefix	*nat64pinfo;
 };
 
 %{
@@ -166,6 +169,7 @@ static struct AdvRDNSS *rdnss;
 static struct AdvDNSSL *dnssl;
 static struct AdvLowpanCo *lowpanco;
 static struct AdvAbro  *abro;
+static struct NAT64Prefix *nat64prefix;
 static void cleanup(void);
 #define ABORT	do { cleanup(); YYABORT; } while (0);
 static void yyerror(char const * msg);
@@ -237,6 +241,7 @@ ifaceparam 	: ifaceval
 		| lowpancodef   { ADD_TO_LL(struct AdvLowpanCo, AdvLowpanCoList, $1); }
 		| abrodef       { ADD_TO_LL(struct AdvAbro, AdvAbroList, $1); }
 		| rasrcaddresslist { ADD_TO_LL(struct AdvRASrcAddress, AdvRASrcAddressList, $1); }
+		| nat64prefixdef { ADD_TO_LL(struct NAT64Prefix, NAT64PrefixList, $1); }
 		;
 
 ifaceval	: T_MinRtrAdvInterval NUMBER ';'
@@ -478,6 +483,92 @@ v6addrlist_rasrcaddress	: IPV6ADDR ';'
 		}
 		;
 
+nat64prefixdef	: nat64prefixhead optional_nat64prefixplist ';'
+		{
+			if (nat64prefix) {
+
+				if (nat64prefix->AdvValidLifetime > DFLT_NAT64MaxValidLifetime)
+				{
+					flog(LOG_ERR, "AdvValidLifeTime must be "
+						"smaller or equal to %d in %s, line %d",
+						DFLT_NAT64MaxValidLifetime, filename, num_lines);
+					ABORT;
+				}
+				nat64prefix->curr_validlft = nat64prefix->AdvValidLifetime;
+			}
+			$$ = nat64prefix;
+			nat64prefix = NULL;
+		}
+		;
+
+nat64prefixhead	: T_NAT64PREFIX IPV6ADDR '/' NUMBER
+		{
+			struct in6_addr zeroaddr;
+			memset(&zeroaddr, 0, sizeof(zeroaddr));
+
+			if (!memcmp($2, &zeroaddr, sizeof(struct in6_addr))) {
+				flog(LOG_ERR, "invalid all-zeros nat64prefix in %s, line %d", filename, num_lines);
+				ABORT;
+			}
+
+			nat64prefix = malloc(sizeof(struct NAT64Prefix));
+
+			if (nat64prefix == NULL) {
+				flog(LOG_CRIT, "malloc failed: %s", strerror(errno));
+				ABORT;
+			}
+
+			nat64prefix_init_defaults(nat64prefix, iface);
+
+			if ($4 > MAX_PrefixLen)
+			{
+				flog(LOG_ERR, "invalid prefix length in %s, line %d", filename, num_lines);
+				ABORT;
+			}
+
+			/* RFC8781, section 4: only prefix lengths of 96, 64, 56, 48, 40, and 32 bits are valid */
+			switch ($4) {
+			case 32:
+			case 40:
+			case 48:
+			case 56:
+			case 64:
+			case 96:
+				break;
+			default:
+				flog(LOG_ERR, "only /96, /64, /56, /48, /40 and /32 are allowed for "
+						"nat64prefix in %s:%d", filename, num_lines);
+				ABORT;
+			}
+			nat64prefix->PrefixLen = $4;
+
+			memcpy(&nat64prefix->Prefix, $2, sizeof(struct in6_addr));
+		}
+		;
+
+optional_nat64prefixplist: /* empty */
+		| '{' /* somewhat empty */ '}'
+		| '{' nat64prefixplist '}'
+		;
+
+nat64prefixplist : nat64prefixplist nat64prefixparms
+		| nat64prefixparms
+		;
+
+nat64prefixparms : T_AdvValidLifetime NUMBER ';'
+		{
+			if ($2 > DFLT_NAT64MaxValidLifetime)
+			{
+				flog(LOG_ERR, "maximum for NAT64 AdvValidLifetime is %d (in %s, line %d)",
+					DFLT_NAT64MaxValidLifetime, filename, num_lines);
+				ABORT;
+			}
+			if (nat64prefix) {
+				nat64prefix->AdvValidLifetime = $2;
+			}
+		}
+		;
+
 prefixdef	: prefixhead optional_prefixplist ';'
 		{
 			if (prefix) {

interface.c

@@ -133,6 +133,15 @@ void prefix_init_defaults(struct AdvPrefix *prefix)
 	prefix->curr_preferredlft = prefix->AdvPreferredLifetime;
 }
 
+void nat64prefix_init_defaults(struct NAT64Prefix *prefix, struct Interface *iface)
+{
+	memset(prefix, 0, sizeof(struct NAT64Prefix));
+
+	prefix->AdvValidLifetime = min(DFLT_NAT64MaxValidLifetime, 3*(iface->MaxRtrAdvInterval));
+
+	prefix->curr_validlft = prefix->AdvValidLifetime;
+}
+
 void route_init_defaults(struct AdvRoute *route, struct Interface *iface)
 {
 	memset(route, 0, sizeof(struct AdvRoute));

process.c

@@ -412,6 +412,9 @@ static void process_ra(struct Interface *iface, unsigned char *msg, int len, str
 			}
 			break;
 		}
+		case ND_OPT_PREF64:
+			/* not checked */
+			break;
 		default:
 			dlog(LOG_DEBUG, 1, "unknown option %d in RA on %s from %s", (int)*opt_str, iface->props.name, addr_str);
 			break;

radvd.8.man

@@ -173,4 +173,5 @@ Reuben Hawkins  <reubenhwk@gmail.com>   - current maintainer
 Pierre Ossman   <pierre@ossman.eu>      - RFC6106 (DNSSL) support
 Varka Bhadram 	<varkabhadram@gmail.com> - 6LoWPAN-ND (RFC6775) support
 Robin H. Johnson	<robbat2@gentoo.org>	- RA splitting per RFC 6980 & RFC4861#6.2.3
+Radek Zajic	<radek@zajic.v.pytli.cz>	- NAT64 pref64 support (RFC8781)
 .fi

radvd.conf.5.man

@@ -32,6 +32,7 @@ The file contains one or more interface definitions of the form:
 	list of RDNSS definitions
 	list of DNSSL definitions
 	list of ABRO definitions
+	list of NAT64 pref64 definitions
 	list of acceptable RA source addresses
 .B };
 .fi
@@ -131,6 +132,18 @@ ABRO (Authoritative Border Router Option) definitions are of the form:
 .B };
 .fi
 
+NAT64 pref64 (the NAT64 prefix included in the router advertisements):
+
+.nf
+.BR "nat64prefix " prefix / "length " {
+	list of NAT64 prefix specific options
+.B };
+.fi
+
+The value of
+.B length
+can only be one of /32, /40, /48, /56, /64, or /96.
+
 .SH INTERFACE SPECIFIC OPTIONS
 
 .TP
@@ -627,6 +640,18 @@ A value of all zero bits assumes a default value of 10,000(~one week).
 .BR "AdvVersionLow, AdvVersionHigh " unsigned integer
 Both forms 32-bit unsigned version number corresponding to the set of information contained in RA message.
 
+.SH NAT64 PREF64 SPECIFIC OPTIONS
+
+.TP
+.BR "AdvValidLifetime " seconds ""
+
+The length of time in seconds (relative to the time the packet is
+sent) that the prefix is valid for the purpose of NAT64 existence
+determination. In case the value is not a multiple of 8, the validity
+is rounded up to the next multiple of 8. The maximum is 65528 seconds.
+
+Default: the lesser value of 3 * MaxRtrAdvInterval, or 65528
+
 .SH EXAMPLES
 
 .nf
@@ -746,6 +771,23 @@ interface lowpan0
 	};
 };
 
+The NAT64 pref64 support
+.nf
+interface eth0
+{
+	prefix 2001:db8:100::/64 {
+		AdvOnLink on;
+		AdvAutonomous on;
+		AdvRouterAddr on;
+	};
+	nat64prefix 64:ff9b::/96 {
+		AdvValidLifeTime 1800;
+	};
+	RDNSS 2001:db8:100::64 {
+		AdvRDNSSLifetime 1800;
+	};
+};
+
 .SH FILES
 
 .nf
@@ -798,6 +840,8 @@ RFC 7772, February 2016.
 .PP
 J. Jeong, S. Park, L. Beloeil, and S. Madanapalli, "IPv6 Router Advertisement Options for DNS Configuration",
 RFC 8106, March 2017.
+L. Colitti, and J. Linkova, "Discovering PREF64 in Router Advertisements",
+RFC 8781, April 2020.
 
 .SH "SEE ALSO"
 

radvd.h

@@ -29,6 +29,7 @@ extern int disableigmp6check;
 #define min(a, b) (((a) < (b)) ? (a) : (b))
 
 struct AdvPrefix;
+struct NAT64Prefix;
 struct Clients;
 
 #define HWADDR_MAX 16
@@ -104,6 +105,8 @@ struct Interface {
 	struct AdvRDNSS *AdvRDNSSList;
 	struct AdvDNSSL *AdvDNSSLList;
 
+	struct NAT64Prefix *NAT64PrefixList;
+
 	uint32_t AdvLinkMTU; /* XXX: sllao also has an if_maxmtu value...Why? */
 	uint32_t AdvRAMTU;   /* MTU used for RA */
 
@@ -166,6 +169,16 @@ struct AdvPrefix {
 	struct AdvPrefix *next;
 };
 
+struct NAT64Prefix {
+	struct in6_addr Prefix;
+	uint8_t PrefixLen;
+
+	uint32_t AdvValidLifetime;
+	uint32_t curr_validlft;
+
+	struct NAT64Prefix *next;
+};
+
 /* More-Specific Routes extensions */
 
 struct AdvRoute {
@@ -269,6 +282,18 @@ struct nd_opt_6co {
 	struct in6_addr nd_opt_6co_con_prefix;
 }; /*Added by Bhadram */
 
+/* Pref64 option type (RFC8781, section 4) */
+#ifndef ND_OPT_PREF64
+#define ND_OPT_PREF64 38
+#endif
+
+struct nd_opt_nat64prefix_info {
+	uint8_t nd_opt_pi_type;
+	uint8_t nd_opt_pi_len;
+	uint16_t nd_opt_pi_lifetime_preflen;
+	unsigned char nd_opt_pi_nat64prefix[12];
+};
+
 /* gram.y */
 struct Interface *readin_config(char const *fname);
 
@@ -308,6 +333,7 @@ struct Interface *find_iface_by_time(struct Interface *iface_list);
 void dnssl_init_defaults(struct AdvDNSSL *, struct Interface *);
 void for_each_iface(struct Interface *ifaces, void (*foo)(struct Interface *iface, void *), void *data);
 void free_ifaces(struct Interface *ifaces);
+void nat64prefix_init_defaults(struct NAT64Prefix *, struct Interface *);
 void iface_init_defaults(struct Interface *);
 void prefix_init_defaults(struct AdvPrefix *);
 void rdnss_init_defaults(struct AdvRDNSS *, struct Interface *);

radvdump.c

@@ -285,6 +285,8 @@ static void print_ff(unsigned char *msg, int len, struct sockaddr_in6 *addr, int
 			break;
 		case ND_OPT_DNSSL_INFORMATION:
 			break;
+		case ND_OPT_PREF64:
+			break;
 		default:
 			dlog(LOG_DEBUG, 1, "unknown option %d in RA", (int)*opt_str);
 			break;
@@ -466,6 +468,53 @@ static void print_ff(unsigned char *msg, int len, struct sockaddr_in6 *addr, int
 			printf("\t}; # End of DNSSL definition\n\n");
 			break;
 		}
+		case ND_OPT_PREF64: {
+			if (optlen != sizeof(struct nd_opt_nat64prefix_info)) {
+				flog(LOG_ERR, "incorrect pref64 option length in RA from %s, skipping", addr_str);
+				break;
+			}
+
+			struct nd_opt_nat64prefix_info *pinfo = (struct nd_opt_nat64prefix_info *)opt_str;
+			uint16_t lifetime_preflen = ntohs(pinfo->nd_opt_pi_lifetime_preflen);
+			uint8_t prefix_length_code = lifetime_preflen & 7;
+			uint16_t prefix_lifetime = lifetime_preflen & 0xFFF8;
+			int prefix_size = -1;
+			struct in6_addr nat64prefix;
+
+			/* The option only contains the first 96 bits of the prefix */
+			memset(&nat64prefix, 0, sizeof(nat64prefix));
+			memcpy(&nat64prefix, &pinfo->nd_opt_pi_nat64prefix, 12);
+			addrtostr(&nat64prefix, prefix_str, sizeof(prefix_str));
+
+			switch (prefix_length_code) {
+			case 0:
+				prefix_size = 96;
+				break;
+			case 1:
+				prefix_size = 64;
+				break;
+			case 2:
+				prefix_size = 56;
+				break;
+			case 3:
+				prefix_size = 48;
+				break;
+			case 4:
+				prefix_size = 40;
+				break;
+			case 5:
+				prefix_size = 32;
+				break;
+			default:
+				flog(LOG_ERR, "Invalid (reserved) nat64prefix length code %d received", prefix_length_code);
+			}
+
+			printf("\n\tnat64prefix %s/%d\n\t{\n", prefix_str, prefix_size);
+			printf("\t\tAdvValidLifetime %u;\n", prefix_lifetime);
+			printf("\t}; # End of nat64prefix definition\n\n");
+
+			break;
+		}
 		default:
 			break;
 		}

scanner.l

@@ -51,6 +51,8 @@ DNSSL			{ return T_DNSSL; }
 clients			{ return T_CLIENTS; }
 lowpanco		{ return T_LOWPANCO; }
 abro			{ return T_ABRO; }
+nat64prefix		{ return T_NAT64PREFIX; }
+
 AdvRASrcAddress	{ return T_RASRCADDRESS; }
 
 IgnoreIfMissing		{ return T_IgnoreIfMissing; }