Merge remote-tracking branch 'remotes/theo/tobast/v6tethered-reimplem' into v4viav6

CREDITS

@@ -22,6 +22,7 @@ This file lists people who have contributed to babeld (in alphabetical order):
     Matthieu Boutier              <boutier at irif dot fr>
     Sawssen Hadded                <saw dot hadded at gmail dot com>
     Stephane Glondu               <steph at glondu dot net>
+    Théophile Bastian             <theophile dot bastian at ens dot fr>
     Thomas Petazzoni              <thomas dot petazzoni at free-electrons dot com>
     Toke Høiland-Jørgensen        <toke at toke dot dk>
     Vincent Gross                 <dermiste at screwball-coders dot net>

babeld.c

@@ -63,6 +63,7 @@ int debug = 0;
 int link_detect = 0;
 int all_wireless = 0;
 int has_ipv6_subtrees = 0;
+int has_v4ov6 = 0;
 int default_wireless_hello_interval = -1;
 int default_wired_hello_interval = -1;
 int resend_delay = -1;
@@ -151,6 +152,7 @@ main(int argc, char **argv)
     protocol_port = 6696;
     change_smoothing_half_life(4);
     has_ipv6_subtrees = kernel_has_ipv6_subtrees();
+    has_v4ov6 = kernel_has_v4ov6();
 
     while(1) {
         opt = getopt(argc, argv,

babeld.h

@@ -92,6 +92,7 @@ extern const char *logfile, *pidfile, *state_file;
 extern int link_detect;
 extern int all_wireless;
 extern int has_ipv6_subtrees;
+extern int has_v4ov6;
 
 extern unsigned char myid[8];
 extern int have_id;

babeld.man

@@ -200,6 +200,11 @@ This specifies whether to use native source-specific IPv6 forwarding
 rather than multiple routing tables.  The default is chosen automatically
 depending on the kernel version.
 .TP
+.BR v4-over-v6 " {" true | false }
+This specifies whether to use v4-over-v6 routes (IPv4 routes with an IPv6
+next-hop).  This should not be enabled unless your kernel supports it.  The
+default is chosen automatically depending on the kernel version.
+.TP
 .BI debug " level"
 This specifies the debugging level, and is equivalent to the command-line
 option

configuration.c

@@ -1029,6 +1029,7 @@ parse_option(int c, gnc_t gnc, void *closure, char *token)
               strcmp(token, "daemonise") == 0 ||
               strcmp(token, "skip-kernel-setup") == 0 ||
               strcmp(token, "ipv6-subtrees") == 0 ||
+              strcmp(token, "v4-over-v6") == 0 ||
               strcmp(token, "reflect-kernel-metric") == 0) {
         int b;
         c = getbool(c, &b, gnc, closure);
@@ -1045,6 +1046,8 @@ parse_option(int c, gnc_t gnc, void *closure, char *token)
             skip_kernel_setup = b;
         else if(strcmp(token, "ipv6-subtrees") == 0)
             has_ipv6_subtrees = b;
+        else if(strcmp(token, "v4-over-v6") == 0)
+            has_v4ov6 = b;
         else if(strcmp(token, "reflect-kernel-metric") == 0)
             reflect_kernel_metric = b;
         else

kernel.h

@@ -95,3 +95,10 @@ int gettime(struct timeval *tv);
 int read_random_bytes(void *buf, int len);
 int kernel_older_than(const char *sysname, int version, int sub_version);
 int kernel_has_ipv6_subtrees(void);
+int kernel_has_v4ov6(void);
+int add_rule(int prio, const unsigned char *src_prefix, int src_plen,
+             int table);
+int flush_rule(int prio, int family);
+int change_rule(int new_prio, int old_prio, const unsigned char *src, int plen,
+                int table);
+

kernel_netlink.c

@@ -943,6 +943,14 @@ kernel_has_ipv6_subtrees(void)
     return (kernel_older_than("Linux", 3, 11) == 0);
 }
 
+int
+kernel_has_v4ov6(void)
+{
+    /* v4-over-v6 was introduced in Linux by commit
+       d15662682db232da77136cd348f4c9df312ca6f9 first released as 5.2 */
+    return (kernel_older_than("Linux", 5, 2) == 0);
+}
+
 int
 kernel_route(int operation, int table,
              const unsigned char *dest, unsigned short plen,
@@ -956,7 +964,7 @@ kernel_route(int operation, int table,
     struct rtmsg *rtm;
     struct rtattr *rta;
     int len = sizeof(buf.raw);
-    int rc, ipv4, use_src = 0;
+    int rc, ipv4, is_v4_over_v6, use_src = 0;
 
     if(!nl_setup) {
         fprintf(stderr,"kernel_route: netlink not initialized.\n");
@@ -978,8 +986,7 @@ kernel_route(int operation, int table,
 
     /* Check that the protocol family is consistent. */
     if(plen >= 96 && v4mapped(dest)) {
-        if(!v4mapped(gate) ||
-           !v4mapped(src)) {
+        if(!v4mapped(src)) {
             errno = EINVAL;
             return -1;
         }
@@ -1018,7 +1025,8 @@ kernel_route(int operation, int table,
     }
 
 
-    ipv4 = v4mapped(gate);
+    ipv4 = v4mapped(dest);
+    is_v4_over_v6 = ipv4 && !v4mapped(gate);
     use_src = !is_default(src, src_plen);
     if(use_src) {
         if(ipv4 || !has_ipv6_subtrees) {
@@ -1095,22 +1103,31 @@ kernel_route(int operation, int table,
         *(int*)RTA_DATA(rta) = ifindex;
 
 #define ADD_IPARG(type, addr) \
-        do if(ipv4) {                                                   \
+        do { \
             rta = RTA_NEXT(rta, len); \
-            rta->rta_len = RTA_LENGTH(sizeof(struct in_addr));          \
             rta->rta_type = type; \
+            if(v4mapped(addr)) { \
+                rta->rta_len = RTA_LENGTH(sizeof(struct in_addr)); \
                 memcpy(RTA_DATA(rta), addr + 12, sizeof(struct in_addr)); \
             } else { \
-            rta = RTA_NEXT(rta, len);                                   \
+                if(type == RTA_VIA) { \
+                    rta->rta_len = RTA_LENGTH(sizeof(struct in6_addr) + 2); \
+                    *((sa_family_t*) RTA_DATA(rta)) = AF_INET6; \
+                    memcpy(RTA_DATA(rta) + 2, addr, sizeof(struct in6_addr)); \
+                } else { \
                     rta->rta_len = RTA_LENGTH(sizeof(struct in6_addr)); \
-            rta->rta_type = type;                                       \
                     memcpy(RTA_DATA(rta), addr, sizeof(struct in6_addr)); \
+                } \
+            } \
         } while (0)
 
+        if(is_v4_over_v6)
+            ADD_IPARG(RTA_VIA, gate);
+        else
             ADD_IPARG(RTA_GATEWAY, gate);
+
         if(pref_src)
             ADD_IPARG(RTA_PREFSRC, pref_src);
-
 #undef ADD_IPARG
     } else {
         *(int*)RTA_DATA(rta) = -1;

kernel_socket.c

@@ -395,6 +395,12 @@ kernel_has_ipv6_subtrees(void)
     return 0;
 }
 
+int
+kernel_has_v4ov6(void)
+{
+    return 0;
+}
+
 int
 kernel_route(int operation, int table,
              const unsigned char *dest, unsigned short plen,

message.c

@@ -56,7 +56,7 @@ struct timeval seqno_time = {0, 0};
 static int
 known_ae(int ae)
 {
-    return ae <= 3;
+    return ae <= AE_IPV6_LOCAL || ae == AE_V4OV6;
 }
 
 /* Parse a network prefix, encoded in the somewhat baroque compressed
@@ -83,10 +83,11 @@ network_prefix(int ae, int plen, unsigned int omitted,
     memset(prefix, 0, 16);
 
     switch(ae) {
-    case 0:
+    case AE_WILDCARD:
         ret = 0;
         break;
-    case 1:
+    case AE_IPV4:
+    case AE_V4OV6:
         if(omitted > 4 || pb > 4 || (pb > omitted && len < pb - omitted))
             return -1;
         memcpy(prefix, v4prefix, 12);
@@ -97,7 +98,7 @@ network_prefix(int ae, int plen, unsigned int omitted,
         if(pb > omitted) memcpy(prefix + 12 + omitted, p, pb - omitted);
         ret = pb - omitted;
         break;
-    case 2:
+    case AE_IPV6:
         if(omitted > 16 || (pb > omitted && len < pb - omitted)) return -1;
         if(omitted) {
             if(dp == NULL || v4mapped(dp)) return -1;
@@ -106,7 +107,7 @@ network_prefix(int ae, int plen, unsigned int omitted,
         if(pb > omitted) memcpy(prefix + omitted, p, pb - omitted);
         ret = pb - omitted;
         break;
-    case 3:
+    case AE_IPV6_LOCAL:
         if(pb > 8 && len < pb - 8) return -1;
         prefix[0] = 0xfe;
         prefix[1] = 0x80;
@@ -117,7 +118,8 @@ network_prefix(int ae, int plen, unsigned int omitted,
         return -1;
     }
 
-    normalize_prefix(p_r, prefix, plen < 0 ? 128 : ae == 1 ? plen + 96 : plen);
+    normalize_prefix(p_r, prefix,
+                     plen < 0 ? 128 : ae_is_v4(ae) ? plen + 96 : plen);
     return ret;
 }
 
@@ -175,7 +177,7 @@ parse_update_subtlv(struct interface *ifp, int metric, int ae,
                                 len - 1, src_prefix);
             if(rc < 0)
                 goto fail;
-            if(ae == 1)
+            if(ae_is_v4(ae))
                 *src_plen = a[i + 2] + 96;
             else
                 *src_plen = a[i + 2];
@@ -341,7 +343,7 @@ parse_request_subtlv(int ae, const unsigned char *a, int alen,
                                 len - 1, src_prefix);
             if(rc < 0)
                 goto fail;
-            if(ae == 1)
+            if(ae_is_v4(ae))
                 *src_plen = a[i + 2] + 96;
             else
                 *src_plen = a[i + 2];
@@ -392,7 +394,7 @@ parse_seqno_request_subtlv(int ae, const unsigned char *a, int alen,
                                 len - 1, src_prefix);
             if(rc < 0)
                 goto fail;
-            if(ae == 1)
+            if(ae_is_v4(ae))
                 (*src_plen) += 96;
         } else {
             debugf("Received unknown%s Route Request sub-TLV %d.\n",
@@ -591,9 +593,10 @@ parse_packet(const unsigned char *from, struct interface *ifp,
     int bodylen;
     struct neighbour *neigh = NULL;
     int have_router_id = 0, have_v4_prefix = 0, have_v6_prefix = 0,
+        have_v4ov6_prefix = 0,
         have_v4_nh = 0, have_v6_nh = 0;
     unsigned char router_id[8], v4_prefix[16], v6_prefix[16],
-        v4_nh[16], v6_nh[16];
+        v4ov6_prefix[16], v4_nh[16], v6_nh[16];
     int have_hello_rtt = 0;
     /* Content of the RTT sub-TLV on IHU messages. */
     unsigned int hello_send_us = 0, hello_rtt_receive_time = 0;
@@ -745,7 +748,8 @@ parse_packet(const unsigned char *from, struct interface *ifp,
                    txcost, interval,
                    format_address(from), ifp->name,
                    format_address(address));
-            if(message[2] == 0 || interface_ll_address(ifp, address)) {
+            if(message[2] == AE_WILDCARD ||
+                    interface_ll_address(ifp, address)) {
                 int changed;
                 rc = parse_ihu_subtlv(message + 8 + rc, len - 6 - rc,
                                       &hello_send_us, &hello_rtt_receive_time,
@@ -800,12 +804,21 @@ parse_packet(const unsigned char *from, struct interface *ifp,
             debugf("Received nh %s (%d) from %s on %s.\n",
                    format_address(nh), message[2],
                    format_address(from), ifp->name);
-            if(message[2] == 1) {
+            switch(message[2]) {
+            case AE_IPV4:
                 memcpy(v4_nh, nh, 16);
                 have_v4_nh = 1;
-            } else {
+                break;
+            case AE_IPV6:
+            case AE_IPV6_LOCAL:
                 memcpy(v6_nh, nh, 16);
                 have_v6_nh = 1;
+                break;
+            case AE_V4OV6:
+                goto done;
+            default:
+                /* We should have guards against this before this point. */
+                goto fail;
             }
             rc = parse_other_subtlv(message + 4 + rc, len - 2 - rc);
             if(rc < 0)
@@ -819,7 +832,7 @@ parse_packet(const unsigned char *from, struct interface *ifp,
             int rc, parsed_len, is_ss;
             if(len < 10) {
                 if(len < 2 || message[3] & 0x80)
-                    have_v4_prefix = have_v6_prefix = 0;
+                    have_v4_prefix = have_v6_prefix = have_v4ov6_prefix = 0;
                 goto fail;
             }
             if(!known_ae(message[2])) {
@@ -827,18 +840,31 @@ parse_packet(const unsigned char *from, struct interface *ifp,
                        message[2]);
                 goto done;
             }
+            if(message[2] == AE_V4OV6 && !has_v4ov6) {
+                /* We can safely ignore the prefix update that might come
+                   alongside with this TLV, since we ignore every v4-over-v6
+                   TLVs */
+                debugf("Ignoring v4-over-v6 route (unsupported).\n");
+                goto done;
+            }
             DO_NTOHS(interval, message + 6);
             DO_NTOHS(seqno, message + 8);
             DO_NTOHS(metric, message + 10);
             if(message[5] == 0 ||
-               (message[2] == 1 ? have_v4_prefix : have_v6_prefix))
+               (message[2] == AE_IPV4 ? have_v4_prefix :
+                message[2] == AE_IPV6 ? have_v6_prefix :
+                message[2] == AE_V4OV6 ? have_v4ov6_prefix :
+                0))
                 rc = network_prefix(message[2], message[4], message[5],
                                     message + 12,
-                                    message[2] == 1 ? v4_prefix : v6_prefix,
+                                    (message[2] == AE_IPV4 ? v4_prefix :
+                                     message[2] == AE_IPV6 ? v6_prefix :
+                                     message[2] == AE_V4OV6 ?  v4ov6_prefix :
+                                     NULL),
                                     len - 10, prefix);
             else
                 rc = -1;
-            if(message[2] == 1) {
+            if(ae_is_v4(message[2])) {
                 v4tov6(src_prefix, zeroes);
                 src_plen = 96;
             } else {
@@ -847,24 +873,36 @@ parse_packet(const unsigned char *from, struct interface *ifp,
             }
             if(rc < 0) {
                 if(message[3] & 0x80)
-                    have_v4_prefix = have_v6_prefix = 0;
+                    have_v4_prefix = have_v6_prefix = have_v4ov6_prefix = 0;
                 goto fail;
             }
             parsed_len = 10 + rc;
 
-            plen = message[4] + (message[2] == 1 ? 96 : 0);
+            plen = message[4] + (ae_is_v4(message[2]) ? 96 : 0);
 
             if(message[3] & 0x80) {
-                if(message[2] == 1) {
+                switch(message[2]) {
+                case AE_IPV4:
                     memcpy(v4_prefix, prefix, 16);
                     have_v4_prefix = 1;
-                } else {
+                    break;
+                case AE_IPV6:
                     memcpy(v6_prefix, prefix, 16);
                     have_v6_prefix = 1;
+                    break;
+                case AE_V4OV6:
+                    memcpy(v4ov6_prefix, prefix, 16);
+                    have_v4ov6_prefix = 1;
+                    break;
+                default:
+                    debugf("Received default prefix update with invalid "
+                           "AE %d.\n",
+                           message[2]);
+                    break;
                 }
             }
             if(message[3] & 0x40) {
-                if(message[2] == 1) {
+                if(ae_is_v4(message[2])) {
                     memset(router_id, 0, 4);
                     memcpy(router_id + 4, prefix + 12, 4);
                 } else {
@@ -872,7 +910,9 @@ parse_packet(const unsigned char *from, struct interface *ifp,
                 }
                 have_router_id = 1;
             }
-            if(metric < INFINITY && !have_router_id && message[2] != 0) {
+            if(metric < INFINITY &&
+               !have_router_id &&
+               message[2] != AE_WILDCARD) {
                 fprintf(stderr, "Received prefix with no router id.\n");
                 goto fail;
             }
@@ -881,7 +921,7 @@ parse_packet(const unsigned char *from, struct interface *ifp,
                    (message[3] & 0x40) ? "/id" : "",
                    format_prefix(prefix, plen),
                    format_address(from), ifp->name);
-            if(message[2] == 1) {
+            if(message[2] == AE_IPV4) {
                 if(have_v4_nh) {
                     nh = v4_nh;
                 } else {
@@ -902,7 +942,7 @@ parse_packet(const unsigned char *from, struct interface *ifp,
             if(rc < 0)
                 goto done;
 
-            if(message[2] == 0) {
+            if(message[2] == AE_WILDCARD) {
                 if(metric < 0xFFFF) {
                     fprintf(stderr,
                             "Received wildcard update with finite metric.\n");
@@ -926,7 +966,7 @@ parse_packet(const unsigned char *from, struct interface *ifp,
                    is_ss ? format_prefix(src_prefix, src_plen) : "",
                    format_address(from), ifp->name);
 
-            if(message[2] == 1) {
+            if(message[2] == AE_IPV4) {
                 if(!ifp->ipv4)
                     goto done;
             }
@@ -947,8 +987,8 @@ parse_packet(const unsigned char *from, struct interface *ifp,
             rc = network_prefix(message[2], message[3], 0,
                                 message + 4, NULL, len - 2, prefix);
             if(rc < 0) goto fail;
-            plen = message[3] + (message[2] == 1 ? 96 : 0);
-            if(message[2] == 1) {
+            plen = message[3] + (ae_is_v4(message[2]) ? 96 : 0);
+            if(ae_is_v4(message[2])) {
                 v4tov6(src_prefix, zeroes);
                 src_plen = 96;
             } else {
@@ -960,7 +1000,7 @@ parse_packet(const unsigned char *from, struct interface *ifp,
             if(rc < 0)
                 goto done;
             is_ss = !is_default(src_prefix, src_plen);
-            if(message[2] == 0) {
+            if(message[2] == AE_WILDCARD) {
                 if(is_ss) {
                     /* Wildcard requests don't carry a source prefix. */
                     fprintf(stderr,
@@ -982,7 +1022,8 @@ parse_packet(const unsigned char *from, struct interface *ifp,
                 }
             } else {
                 debugf("Received request for dst %s%s%s from %s on %s.\n",
-                       message[2] == 0 ? "" : format_prefix(prefix, plen),
+                       message[2] == AE_WILDCARD ?
+                                     "" : format_prefix(prefix, plen),
                        is_ss ? " src " : "",
                        is_ss ? format_prefix(src_prefix, src_plen) : "",
                        format_address(from), ifp->name);
@@ -1002,7 +1043,7 @@ parse_packet(const unsigned char *from, struct interface *ifp,
             rc = network_prefix(message[2], message[3], 0,
                                 message + 16, NULL, len - 14, prefix);
             if(rc < 0) goto fail;
-            if(message[2] == 1) {
+            if(ae_is_v4(message[2])) {
                 v4tov6(src_prefix, zeroes);
                 src_plen = 96;
             } else {
@@ -1015,7 +1056,7 @@ parse_packet(const unsigned char *from, struct interface *ifp,
             if(rc < 0)
                 goto done;
             is_ss = !is_default(src_prefix, src_plen);
-            plen = message[3] + (message[2] == 1 ? 96 : 0);
+            plen = message[3] + (ae_is_v4(message[2]) ? 96 : 0);
             debugf("Received request (%d) for dst %s%s%s from %s on "
                    "%s (%s, %d).\n",
                    message[6],
@@ -1400,7 +1441,7 @@ really_buffer_update(struct buffered *buf, struct interface *ifp,
                      unsigned char *channels, int channels_len)
 {
     int add_metric, v4, real_plen, real_src_plen;
-    int omit, spb, channels_size, len;
+    int ae, omit, spb, channels_size, len;
     const unsigned char *real_prefix, *real_src_prefix;
     unsigned short flags = 0;
     int is_ss = !is_default(src_prefix, src_plen);
@@ -1424,24 +1465,28 @@ really_buffer_update(struct buffered *buf, struct interface *ifp,
     v4 = plen >= 96 && v4mapped(prefix);
 
     if(v4) {
-        if(!ifp->ipv4)
-            return;
-        omit = 0;
+        if(!ifp->ipv4) {
+            ae = AE_V4OV6;
+        } else {
+            ae = AE_IPV4;
             if(!buf->have_nh ||
                memcmp(buf->nh, ifp->ipv4, 4) != 0) {
                 start_message(buf, ifp, MESSAGE_NH, 6);
-            accumulate_byte(buf, 1);
+                accumulate_byte(buf, AE_IPV4);
                 accumulate_byte(buf, 0);
                 accumulate_bytes(buf, ifp->ipv4, 4);
                 end_message(buf, MESSAGE_NH, 6);
                 memcpy(&buf->nh, ifp->ipv4, 4);
                 buf->have_nh = 1;
             }
+        }
+        omit = 0;
         real_prefix = prefix + 12;
         real_plen = plen - 96;
         real_src_prefix = src_prefix + 12;
         real_src_plen = src_plen - 96;
     } else {
+        ae = AE_IPV6;
         omit = 0;
         if(buf->have_prefix) {
             while(omit < plen / 8 &&
@@ -1477,7 +1522,7 @@ really_buffer_update(struct buffered *buf, struct interface *ifp,
         len += 3 + spb;
 
     start_message(buf, ifp, MESSAGE_UPDATE, len);
-    accumulate_byte(buf, v4 ? 1 : 2);
+    accumulate_byte(buf, ae);
     accumulate_byte(buf, flags);
     accumulate_byte(buf, real_plen);
     accumulate_byte(buf, omit);
@@ -1856,7 +1901,7 @@ void
 buffer_wildcard_retraction(struct buffered *buf, struct interface *ifp)
 {
     start_message(buf, ifp, MESSAGE_UPDATE, 10);
-    accumulate_byte(buf, 0);
+    accumulate_byte(buf, AE_WILDCARD);
     accumulate_byte(buf, 0);
     accumulate_byte(buf, 0);
     accumulate_byte(buf, 0);
@@ -1941,7 +1986,7 @@ buffer_ihu(struct buffered *buf, struct interface *ifp, unsigned short rxcost,
     msglen = (ll ? 14 : 22) + (rtt_data ? 10 : 0);
 
     start_message(buf, ifp, MESSAGE_IHU, msglen);
-    accumulate_byte(buf, ll ? 3 : 2);
+    accumulate_byte(buf, ll ? AE_IPV6_LOCAL : AE_IPV6);
     accumulate_byte(buf, 0);
     accumulate_short(buf, rxcost);
     accumulate_short(buf, interval);
@@ -2061,7 +2106,7 @@ send_request(struct buffered *buf, struct interface *ifp,
         assert(!src_prefix);
         debugf("sending request for any.\n");
         start_message(buf, ifp, MESSAGE_REQUEST, 2);
-        accumulate_byte(buf, 0);
+        accumulate_byte(buf, AE_WILDCARD);
         accumulate_byte(buf, 0);
         end_message(buf, MESSAGE_REQUEST, 2);
         return;
@@ -2077,7 +2122,7 @@ send_request(struct buffered *buf, struct interface *ifp,
     len = 2 + pb + (is_ss ? 3 + spb : 0);
 
     start_message(buf, ifp, MESSAGE_REQUEST, len);
-    accumulate_byte(buf, v4 ? 1 : 2);
+    accumulate_byte(buf, v4 ? AE_IPV4 : AE_IPV6);
     accumulate_byte(buf, v4 ? plen - 96 : plen);
     if(v4)
         accumulate_bytes(buf, prefix + 12, pb);
@@ -2164,7 +2209,7 @@ send_multihop_request(struct buffered *buf, struct interface *ifp,
     len = 6 + 8 + pb + (is_ss ? 3 + spb : 0);
 
     start_message(buf, ifp, MESSAGE_MH_REQUEST, len);
-    accumulate_byte(buf, v4 ? 1 : 2);
+    accumulate_byte(buf, v4 ? AE_IPV4 : AE_IPV6);
     accumulate_byte(buf, v4 ? plen - 96 : plen);
     accumulate_short(buf, seqno);
     accumulate_byte(buf, hop_count);

message.h

@@ -47,6 +47,13 @@ THE SOFTWARE.
 #define SUBTLV_TIMESTAMP 3       /* Used to compute RTT. */
 #define SUBTLV_SOURCE_PREFIX 128 /* Source-specific routing. */
 
+/* Address encodings */
+#define AE_WILDCARD 0
+#define AE_IPV4 1
+#define AE_IPV6 2
+#define AE_IPV6_LOCAL 3
+#define AE_V4OV6 4
+
 extern unsigned short myseqno;
 extern struct timeval seqno_time;
 

util.c

@@ -502,6 +502,12 @@ v4tov6(unsigned char *dst, const unsigned char *src)
     memcpy(dst + 12, src, 4);
 }
 
+int
+ae_is_v4(int ae)
+{
+    return ae == 1 || ae == 4;
+}
+
 int
 daemonise()
 {

util.h

@@ -100,6 +100,7 @@ int wait_for_fd(int direction, int fd, int msecs);
 int martian_prefix(const unsigned char *prefix, int plen) ATTRIBUTE ((pure));
 int linklocal(const unsigned char *address) ATTRIBUTE ((pure));
 int v4mapped(const unsigned char *address) ATTRIBUTE ((pure));
+int ae_is_v4(int ae) ATTRIBUTE ((pure));
 void v4tov6(unsigned char *dst, const unsigned char *src);
 int daemonise(void);
 int set_src_prefix(unsigned char *src_addr, unsigned char *src_plen);