2 * Copyright (C) 2012-2013 Steven Barth <steven@midlink.org>
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License v2 as published by
6 * the Free Software Foundation.
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
23 #include <arpa/inet.h>
24 #include <net/route.h>
30 static void forward_router_solicitation(const struct interface
*iface
);
31 static void forward_router_advertisement(uint8_t *data
, size_t len
);
33 static void handle_icmpv6(void *addr
, void *data
, size_t len
,
34 struct interface
*iface
, void *dest
);
35 static void trigger_router_advert(struct uloop_timeout
*event
);
36 static void sigusr1_refresh(int signal
);
38 static struct odhcpd_event router_event
= {.uloop
= {.fd
= -1}, .handle_dgram
= handle_icmpv6
, };
40 static FILE *fp_route
= NULL
;
42 #define TIME_LEFT(t1, now) ((t1) != UINT32_MAX ? (t1) - (now) : UINT32_MAX)
47 int sock
= socket(AF_INET6
, SOCK_RAW
| SOCK_CLOEXEC
, IPPROTO_ICMPV6
);
48 if (sock
< 0 && errno
!= EAFNOSUPPORT
) {
49 syslog(LOG_ERR
, "Failed to open RAW-socket: %s", strerror(errno
));
53 // Let the kernel compute our checksums
55 setsockopt(sock
, IPPROTO_RAW
, IPV6_CHECKSUM
, &val
, sizeof(val
));
57 // This is required by RFC 4861
59 setsockopt(sock
, IPPROTO_IPV6
, IPV6_MULTICAST_HOPS
, &val
, sizeof(val
));
60 setsockopt(sock
, IPPROTO_IPV6
, IPV6_UNICAST_HOPS
, &val
, sizeof(val
));
62 // We need to know the source interface
64 setsockopt(sock
, IPPROTO_IPV6
, IPV6_RECVPKTINFO
, &val
, sizeof(val
));
65 setsockopt(sock
, IPPROTO_IPV6
, IPV6_RECVHOPLIMIT
, &val
, sizeof(val
));
69 setsockopt(sock
, IPPROTO_IPV6
, IPV6_MULTICAST_LOOP
, &val
, sizeof(val
));
71 // Filter ICMPv6 package types
72 struct icmp6_filter filt
;
73 ICMP6_FILTER_SETBLOCKALL(&filt
);
74 ICMP6_FILTER_SETPASS(ND_ROUTER_ADVERT
, &filt
);
75 ICMP6_FILTER_SETPASS(ND_ROUTER_SOLICIT
, &filt
);
76 setsockopt(sock
, IPPROTO_ICMPV6
, ICMP6_FILTER
, &filt
, sizeof(filt
));
79 router_event
.uloop
.fd
= sock
;
80 odhcpd_register(&router_event
);
82 if (!(fp_route
= fopen("/proc/net/ipv6_route", "r")))
83 syslog(LOG_ERR
, "Failed to open routing table: %s",
86 signal(SIGUSR1
, sigusr1_refresh
);
91 int setup_router_interface(struct interface
*iface
, bool enable
)
93 if (!fp_route
|| router_event
.uloop
.fd
< 0)
96 struct ipv6_mreq all_nodes
= {ALL_IPV6_NODES
, iface
->ifindex
};
97 struct ipv6_mreq all_routers
= {ALL_IPV6_ROUTERS
, iface
->ifindex
};
99 uloop_timeout_cancel(&iface
->timer_rs
);
100 iface
->timer_rs
.cb
= NULL
;
102 if (iface
->ifindex
<= 0)
105 setsockopt(router_event
.uloop
.fd
, IPPROTO_IPV6
, IPV6_DROP_MEMBERSHIP
,
106 &all_nodes
, sizeof(all_nodes
));
107 setsockopt(router_event
.uloop
.fd
, IPPROTO_IPV6
, IPV6_DROP_MEMBERSHIP
,
108 &all_routers
, sizeof(all_routers
));
112 trigger_router_advert(&iface
->timer_rs
);
114 void *mreq
= &all_routers
;
116 if (iface
->ra
== MODE_RELAY
&& iface
->master
) {
118 forward_router_solicitation(iface
);
119 } else if (iface
->ra
== MODE_SERVER
&& !iface
->master
) {
120 iface
->timer_rs
.cb
= trigger_router_advert
;
121 uloop_timeout_set(&iface
->timer_rs
, 1000);
124 if (iface
->ra
== MODE_RELAY
|| (iface
->ra
== MODE_SERVER
&& !iface
->master
))
125 setsockopt(router_event
.uloop
.fd
, IPPROTO_IPV6
,
126 IPV6_ADD_MEMBERSHIP
, mreq
, sizeof(all_nodes
));
132 // Signal handler to resend all RDs
133 static void sigusr1_refresh(_unused
int signal
)
135 struct interface
*iface
;
136 list_for_each_entry(iface
, &interfaces
, head
)
137 if (iface
->ra
== MODE_SERVER
&& !iface
->master
)
138 uloop_timeout_set(&iface
->timer_rs
, 1000);
141 static bool router_icmpv6_valid(struct sockaddr_in6
*source
, uint8_t *data
, size_t len
)
143 struct icmp6_hdr
*hdr
= (struct icmp6_hdr
*)data
;
144 struct icmpv6_opt
*opt
, *end
= (struct icmpv6_opt
*)&data
[len
];
146 /* Hoplimit is already checked in odhcpd_receive_packets */
147 if (len
< sizeof(*hdr
) || hdr
->icmp6_code
)
150 switch (hdr
->icmp6_type
) {
151 case ND_ROUTER_ADVERT
:
152 if (!IN6_IS_ADDR_LINKLOCAL(&source
->sin6_addr
))
155 opt
= (struct icmpv6_opt
*)((struct nd_router_advert
*)data
+ 1);
158 case ND_ROUTER_SOLICIT
:
159 opt
= (struct icmpv6_opt
*)((struct nd_router_solicit
*)data
+ 1);
166 icmpv6_for_each_option(opt
, opt
, end
)
167 if (opt
->type
== ND_OPT_SOURCE_LINKADDR
&&
168 IN6_IS_ADDR_UNSPECIFIED(&source
->sin6_addr
) &&
169 hdr
->icmp6_type
== ND_ROUTER_SOLICIT
)
172 // Check all options parsed successfully
177 // Detect whether a default route exists, also find the source prefixes
178 static bool parse_routes(struct odhcpd_ipaddr
*n
, ssize_t len
)
182 char line
[512], ifname
[16];
183 bool found_default
= false;
184 struct odhcpd_ipaddr p
= { .addr
.in6
= IN6ADDR_ANY_INIT
, .prefix
= 0,
185 .dprefix
= 0, .preferred
= 0, .valid
= 0};
187 while (fgets(line
, sizeof(line
), fp_route
)) {
189 if (sscanf(line
, "00000000000000000000000000000000 00 "
190 "%*s %*s %*s %*s %*s %*s %*s %15s", ifname
) &&
191 strcmp(ifname
, "lo")) {
192 found_default
= true;
193 } else if (sscanf(line
, "%8" SCNx32
"%8" SCNx32
"%*8" SCNx32
"%*8" SCNx32
" %hhx %*s "
194 "%*s 00000000000000000000000000000000 %*s %*s %*s %" SCNx32
" lo",
195 &p
.addr
.in6
.s6_addr32
[0], &p
.addr
.in6
.s6_addr32
[1], &p
.prefix
, &rflags
) &&
196 p
.prefix
> 0 && (rflags
& RTF_NONEXTHOP
) && (rflags
& RTF_REJECT
)) {
197 // Find source prefixes by scanning through unreachable-routes
198 p
.addr
.in6
.s6_addr32
[0] = htonl(p
.addr
.in6
.s6_addr32
[0]);
199 p
.addr
.in6
.s6_addr32
[1] = htonl(p
.addr
.in6
.s6_addr32
[1]);
201 for (ssize_t i
= 0; i
< len
; ++i
) {
202 if (n
[i
].prefix
<= 64 && n
[i
].prefix
>= p
.prefix
&&
203 !odhcpd_bmemcmp(&p
.addr
.in6
, &n
[i
].addr
.in6
, p
.prefix
)) {
204 n
[i
].dprefix
= p
.prefix
;
212 return found_default
;
215 static int calc_adv_interval(struct interface
*iface
, uint32_t minvalid
,
218 uint32_t minival
= iface
->ra_mininterval
;
221 *maxival
= iface
->ra_maxinterval
;
223 if (*maxival
> minvalid
/3)
224 *maxival
= minvalid
/3;
226 if (*maxival
> MaxRtrAdvInterval
)
227 *maxival
= MaxRtrAdvInterval
;
228 else if (*maxival
< 4)
231 if (minival
< MinRtrAdvInterval
)
232 minival
= MinRtrAdvInterval
;
233 else if (minival
> (*maxival
* 3)/4)
234 minival
= (*maxival
>= 9 ? *maxival
/3 : *maxival
);
236 odhcpd_urandom(&msecs
, sizeof(msecs
));
237 msecs
= (labs(msecs
) % ((*maxival
!= minival
) ? (*maxival
- minival
)*1000 : 500)) +
243 static uint16_t calc_ra_lifetime(struct interface
*iface
, uint32_t maxival
)
245 uint16_t lifetime
= 3*maxival
;
247 if (iface
->ra_lifetime
>= 0) {
248 lifetime
= iface
->ra_lifetime
;
249 if (lifetime
< maxival
)
251 else if (lifetime
> 9000)
269 // Router Advert server mode
270 static uint64_t send_router_advert(struct interface
*iface
, const struct in6_addr
*from
)
272 time_t now
= odhcpd_time();
273 int mtu
= iface
->ra_mtu
;
274 int hlim
= iface
->ra_hoplimit
;
277 mtu
= odhcpd_get_interface_config(iface
->ifname
, "mtu");
283 hlim
= odhcpd_get_interface_config(iface
->ifname
, "hop_limit");
286 struct nd_router_advert h
;
287 struct icmpv6_opt lladdr
;
288 struct nd_opt_mtu mtu
;
290 .h
= {{.icmp6_type
= ND_ROUTER_ADVERT
, .icmp6_code
= 0}, 0, 0},
291 .lladdr
= {ND_OPT_SOURCE_LINKADDR
, 1, {0}},
292 .mtu
= {ND_OPT_MTU
, 1, 0, htonl(mtu
)},
296 adv
.h
.nd_ra_curhoplimit
= hlim
;
299 adv
.h
.nd_ra_flags_reserved
= ND_RA_FLAG_OTHER
;
301 if (iface
->ra_managed
>= RA_MANAGED_MFLAG
)
302 adv
.h
.nd_ra_flags_reserved
|= ND_RA_FLAG_MANAGED
;
304 if (iface
->route_preference
< 0)
305 adv
.h
.nd_ra_flags_reserved
|= ND_RA_PREF_LOW
;
306 else if (iface
->route_preference
> 0)
307 adv
.h
.nd_ra_flags_reserved
|= ND_RA_PREF_HIGH
;
309 adv
.h
.nd_ra_reachable
= htonl(iface
->ra_reachabletime
);
310 adv
.h
.nd_ra_retransmit
= htonl(iface
->ra_retranstime
);
312 odhcpd_get_mac(iface
, adv
.lladdr
.data
);
314 // If not currently shutting down
315 struct odhcpd_ipaddr
*addrs
= NULL
;
317 uint32_t minvalid
= UINT32_MAX
;
318 bool default_route
= false;
319 bool valid_prefix
= false;
322 if (iface
->timer_rs
.cb
) {
323 size_t size
= sizeof(*addrs
) * iface
->ia_addr_len
;
324 addrs
= alloca(size
);
325 memcpy(addrs
, iface
->ia_addr
, size
);
327 ipcnt
= iface
->ia_addr_len
;
329 // Check default route
330 if (iface
->default_router
) {
331 default_route
= true;
333 if (iface
->default_router
> 1)
335 } else if (parse_routes(addrs
, ipcnt
))
336 default_route
= true;
340 struct in6_addr dns_pref
, *dns_addr
= &dns_pref
;
343 odhcpd_get_interface_dns_addr(iface
, &dns_pref
);
345 // Construct Prefix Information options
347 struct nd_opt_prefix_info
*pfxs
= NULL
;
349 for (ssize_t i
= 0; i
< ipcnt
; ++i
) {
350 struct odhcpd_ipaddr
*addr
= &addrs
[i
];
351 uint32_t preferred
= 0;
354 if (addr
->prefix
> 96 || addr
->valid
<= (uint32_t)now
) {
355 char namebuf
[INET6_ADDRSTRLEN
];
357 inet_ntop(AF_INET6
, &addr
->addr
.in6
, namebuf
, sizeof(namebuf
));
358 syslog(LOG_INFO
, "Address %s (prefix %d, valid %u) not suitable as RA prefix on %s",
359 namebuf
, addr
->prefix
, addr
->valid
, iface
->ifname
);
363 struct nd_opt_prefix_info
*p
= NULL
;
364 for (size_t i
= 0; i
< pfxs_cnt
; ++i
) {
365 if (addr
->prefix
== pfxs
[i
].nd_opt_pi_prefix_len
&&
366 !odhcpd_bmemcmp(&pfxs
[i
].nd_opt_pi_prefix
,
367 &addr
->addr
.in6
, addr
->prefix
))
372 struct nd_opt_prefix_info
*tmp
;
374 tmp
= realloc(pfxs
, sizeof(*pfxs
) * (pfxs_cnt
+ 1));
376 syslog(LOG_ERR
, "Realloc failed for RA prefix option on interface %s", iface
->ifname
);
381 p
= &pfxs
[pfxs_cnt
++];
382 memset(p
, 0, sizeof(*p
));
385 if (addr
->preferred
> (uint32_t)now
) {
386 preferred
= TIME_LEFT(addr
->preferred
, now
);
388 if (iface
->ra_useleasetime
&&
389 preferred
> iface
->dhcpv4_leasetime
)
390 preferred
= iface
->dhcpv4_leasetime
;
393 valid
= TIME_LEFT(addr
->valid
, now
);
394 if (iface
->ra_useleasetime
&& valid
> iface
->dhcpv4_leasetime
)
395 valid
= iface
->dhcpv4_leasetime
;
397 if (minvalid
> valid
)
400 if (!IN6_IS_ADDR_ULA(&addr
->addr
.in6
) || iface
->default_router
)
403 odhcpd_bmemcpy(&p
->nd_opt_pi_prefix
, &addr
->addr
.in6
,
404 (iface
->ra_advrouter
) ? 128 : addr
->prefix
);
405 p
->nd_opt_pi_type
= ND_OPT_PREFIX_INFORMATION
;
406 p
->nd_opt_pi_len
= 4;
407 p
->nd_opt_pi_prefix_len
= (addr
->prefix
< 64) ? 64 : addr
->prefix
;
408 p
->nd_opt_pi_flags_reserved
= 0;
409 if (!iface
->ra_not_onlink
)
410 p
->nd_opt_pi_flags_reserved
|= ND_OPT_PI_FLAG_ONLINK
;
411 if (iface
->ra_managed
< RA_MANAGED_NO_AFLAG
&& addr
->prefix
<= 64)
412 p
->nd_opt_pi_flags_reserved
|= ND_OPT_PI_FLAG_AUTO
;
413 if (iface
->ra_advrouter
)
414 p
->nd_opt_pi_flags_reserved
|= ND_OPT_PI_FLAG_RADDR
;
415 p
->nd_opt_pi_preferred_time
= htonl(preferred
);
416 p
->nd_opt_pi_valid_time
= htonl(valid
);
419 // Calculate periodic transmit
421 int msecs
= calc_adv_interval(iface
, minvalid
, &maxival
);
425 syslog(LOG_WARNING
, "A default route is present but there is no public prefix "
426 "on %s thus we don't announce a default route!", iface
->ifname
);
427 adv
.h
.nd_ra_router_lifetime
= 0;
429 adv
.h
.nd_ra_router_lifetime
= htons(calc_ra_lifetime(iface
, maxival
));
432 adv
.h
.nd_ra_router_lifetime
= 0;
434 syslog(LOG_INFO
, "Using a RA lifetime of %d seconds on %s", ntohs(adv
.h
.nd_ra_router_lifetime
), iface
->ifname
);
437 if (iface
->dns_cnt
> 0) {
438 dns_addr
= iface
->dns
;
439 dns_cnt
= iface
->dns_cnt
;
442 if (!dns_addr
|| IN6_IS_ADDR_UNSPECIFIED(dns_addr
))
451 } dns
= {ND_OPT_RECURSIVE_DNS
, (1 + (2 * dns_cnt
)), 0, 0, 0};
453 // DNS Search options
454 uint8_t search_buf
[256], *search_domain
= iface
->search
;
455 size_t search_len
= iface
->search_len
, search_padded
= 0;
457 if (!search_domain
&& !res_init() && _res
.dnsrch
[0] && _res
.dnsrch
[0][0]) {
458 int len
= dn_comp(_res
.dnsrch
[0], search_buf
,
459 sizeof(search_buf
), NULL
, NULL
);
461 search_domain
= search_buf
;
467 search_padded
= ((search_len
+ 7) & (~7)) + 8;
476 } *search
= alloca(sizeof(*search
) + search_padded
);
478 search
->type
= ND_OPT_DNS_SEARCH
;
479 search
->len
= search_len
? ((sizeof(*search
) + search_padded
) / 8) : 0;
482 memcpy(search
->name
, search_domain
, search_len
);
483 memset(&search
->name
[search_len
], 0, search_padded
- search_len
);
486 size_t routes_cnt
= 0;
494 } *tmp
, *routes
= NULL
;
496 for (ssize_t i
= 0; i
< ipcnt
; ++i
) {
497 struct odhcpd_ipaddr
*addr
= &addrs
[i
];
498 if (addr
->dprefix
> 64 || addr
->dprefix
== 0 || addr
->valid
<= (uint32_t)now
||
499 (addr
->dprefix
== 64 && addr
->prefix
== 64)) {
500 continue; // Address not suitable
501 } else if (addr
->dprefix
> 32) {
502 addr
->addr
.in6
.s6_addr32
[1] &= htonl(~((1U << (64 - addr
->dprefix
)) - 1));
503 } else if (addr
->dprefix
<= 32) {
504 addr
->addr
.in6
.s6_addr32
[0] &= htonl(~((1U << (32 - addr
->dprefix
)) - 1));
505 addr
->addr
.in6
.s6_addr32
[1] = 0;
508 tmp
= realloc(routes
, sizeof(*routes
) * (routes_cnt
+ 1));
510 syslog(LOG_ERR
, "Realloc failed for RA route option on interface %s", iface
->ifname
);
516 memset(&routes
[routes_cnt
], 0, sizeof(*routes
));
517 routes
[routes_cnt
].type
= ND_OPT_ROUTE_INFO
;
518 routes
[routes_cnt
].len
= sizeof(*routes
) / 8;
519 routes
[routes_cnt
].prefix
= addr
->dprefix
;
520 routes
[routes_cnt
].flags
= 0;
521 if (iface
->route_preference
< 0)
522 routes
[routes_cnt
].flags
|= ND_RA_PREF_LOW
;
523 else if (iface
->route_preference
> 0)
524 routes
[routes_cnt
].flags
|= ND_RA_PREF_HIGH
;
525 routes
[routes_cnt
].lifetime
= htonl(TIME_LEFT(addr
->valid
, now
));
526 routes
[routes_cnt
].addr
[0] = addr
->addr
.in6
.s6_addr32
[0];
527 routes
[routes_cnt
].addr
[1] = addr
->addr
.in6
.s6_addr32
[1];
528 routes
[routes_cnt
].addr
[2] = 0;
529 routes
[routes_cnt
].addr
[3] = 0;
534 search
->lifetime
= htonl(maxival
*10);
535 dns
.lifetime
= search
->lifetime
;
537 struct icmpv6_opt adv_interval
= {
538 .type
= ND_OPT_RTR_ADV_INTERVAL
,
540 .data
= {0, 0, (maxival
*1000) >> 24, (maxival
*1000) >> 16, (maxival
*1000) >> 8, maxival
*1000}
543 struct iovec iov
[IOV_RA_TOTAL
] = {
544 [IOV_RA_ADV
] = {&adv
, sizeof(adv
)},
545 [IOV_RA_PFXS
] = {pfxs
, pfxs_cnt
* sizeof(*pfxs
)},
546 [IOV_RA_ROUTES
] = {routes
, routes_cnt
* sizeof(*routes
)},
547 [IOV_RA_DNS
] = {&dns
, (dns_cnt
) ? sizeof(dns
) : 0},
548 [IOV_RA_DNS_ADDR
] = {dns_addr
, dns_cnt
* sizeof(*dns_addr
)},
549 [IOV_RA_SEARCH
] = {search
, search
->len
* 8},
550 [IOV_RA_ADV_INTERVAL
] = {&adv_interval
, adv_interval
.len
* 8}};
551 struct sockaddr_in6 dest
= {AF_INET6
, 0, 0, ALL_IPV6_NODES
, 0};
553 if (from
&& !IN6_IS_ADDR_UNSPECIFIED(from
))
554 dest
.sin6_addr
= *from
;
556 odhcpd_send(router_event
.uloop
.fd
,
557 &dest
, iov
, ARRAY_SIZE(iov
), iface
);
566 static void trigger_router_advert(struct uloop_timeout
*event
)
568 struct interface
*iface
= container_of(event
, struct interface
, timer_rs
);
569 int msecs
= send_router_advert(iface
, NULL
);
571 // Rearm timer if not shut down
573 uloop_timeout_set(event
, msecs
);
577 // Event handler for incoming ICMPv6 packets
578 static void handle_icmpv6(void *addr
, void *data
, size_t len
,
579 struct interface
*iface
, _unused
void *dest
)
581 struct icmp6_hdr
*hdr
= data
;
582 struct sockaddr_in6
*from
= addr
;
584 if (!router_icmpv6_valid(addr
, data
, len
))
587 if ((iface
->ra
== MODE_SERVER
&& !iface
->master
)) { // Server mode
588 if (hdr
->icmp6_type
== ND_ROUTER_SOLICIT
)
589 send_router_advert(iface
, &from
->sin6_addr
);
590 } else if (iface
->ra
== MODE_RELAY
) { // Relay mode
591 if (hdr
->icmp6_type
== ND_ROUTER_ADVERT
&& iface
->master
)
592 forward_router_advertisement(data
, len
);
593 else if (hdr
->icmp6_type
== ND_ROUTER_SOLICIT
&& !iface
->master
)
594 forward_router_solicitation(odhcpd_get_master_interface());
599 // Forward router solicitation
600 static void forward_router_solicitation(const struct interface
*iface
)
605 struct icmp6_hdr rs
= {ND_ROUTER_SOLICIT
, 0, 0, {{0}}};
606 struct iovec iov
= {&rs
, sizeof(rs
)};
607 struct sockaddr_in6 all_routers
=
608 {AF_INET6
, 0, 0, ALL_IPV6_ROUTERS
, iface
->ifindex
};
610 syslog(LOG_NOTICE
, "Sending RS to %s", iface
->ifname
);
611 odhcpd_send(router_event
.uloop
.fd
, &all_routers
, &iov
, 1, iface
);
615 // Handler for incoming router solicitations on slave interfaces
616 static void forward_router_advertisement(uint8_t *data
, size_t len
)
618 struct nd_router_advert
*adv
= (struct nd_router_advert
*)data
;
621 uint8_t *end
= data
+ len
;
622 uint8_t *mac_ptr
= NULL
;
623 struct in6_addr
*dns_ptr
= NULL
;
624 size_t dns_count
= 0;
626 struct icmpv6_opt
*opt
;
627 icmpv6_for_each_option(opt
, &adv
[1], end
) {
628 if (opt
->type
== ND_OPT_SOURCE_LINKADDR
) {
629 // Store address of source MAC-address
631 } else if (opt
->type
== ND_OPT_RECURSIVE_DNS
&& opt
->len
> 1) {
632 // Check if we have to rewrite DNS
633 dns_ptr
= (struct in6_addr
*)&opt
->data
[6];
634 dns_count
= (opt
->len
- 1) / 2;
638 syslog(LOG_NOTICE
, "Got a RA");
640 // Indicate a proxy, however we don't follow the rest of RFC 4389 yet
641 adv
->nd_ra_flags_reserved
|= ND_RA_FLAG_PROXY
;
643 // Forward advertisement to all slave interfaces
644 struct sockaddr_in6 all_nodes
= {AF_INET6
, 0, 0, ALL_IPV6_NODES
, 0};
645 struct iovec iov
= {data
, len
};
647 struct interface
*iface
;
648 list_for_each_entry(iface
, &interfaces
, head
) {
649 if (iface
->ra
!= MODE_RELAY
|| iface
->master
)
652 // Fixup source hardware address option
654 odhcpd_get_mac(iface
, mac_ptr
);
656 // If we have to rewrite DNS entries
657 if (iface
->always_rewrite_dns
&& dns_ptr
&& dns_count
> 0) {
658 const struct in6_addr
*rewrite
= iface
->dns
;
659 struct in6_addr addr
;
660 size_t rewrite_cnt
= iface
->dns_cnt
;
662 if (rewrite_cnt
== 0) {
663 if (odhcpd_get_interface_dns_addr(iface
, &addr
))
664 continue; // Unable to comply
670 // Copy over any other addresses
671 for (size_t i
= 0; i
< dns_count
; ++i
) {
672 size_t j
= (i
< rewrite_cnt
) ? i
: rewrite_cnt
- 1;
673 dns_ptr
[i
] = rewrite
[j
];
677 odhcpd_send(router_event
.uloop
.fd
, &all_nodes
, &iov
, 1, iface
);