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relay: forward message if dns rewriting is impossible #231

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relay: forward message if dns rewriting is impossible #231

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49 changes: 27 additions & 22 deletions src/dhcpv6.c
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Original file line number Diff line number Diff line change
Expand Up @@ -761,6 +761,31 @@ static void handle_dhcpv6(void *addr, void *data, size_t len,
}
}

static void rewrite_dns(struct interface *iface, struct in6_addr *dns_ptr, size_t dns_count)
{
if (!dns_ptr || dns_count == 0)
return;

const struct in6_addr *rewrite = iface->dns;
struct in6_addr addr;
size_t rewrite_cnt = iface->dns_cnt;

if (rewrite_cnt == 0) {
if (odhcpd_get_interface_dns_addr(iface, &addr)) {
syslog(LOG_ERR, "Unable to get interface address");
return;
}

rewrite = &addr;
rewrite_cnt = 1;
}

/* Copy over any other addresses */
for (size_t i = 0; i < dns_count; ++i) {
size_t j = (i < rewrite_cnt) ? i : rewrite_cnt - 1;
memcpy(&dns_ptr[i], &rewrite[j], sizeof(*rewrite));
}
}

/* Relay server response (regular relay server handling) */
static void relay_server_response(uint8_t *data, size_t len)
Expand Down Expand Up @@ -821,28 +846,8 @@ static void relay_server_response(uint8_t *data, size_t len)
}

/* Rewrite DNS servers if requested */
if (iface->always_rewrite_dns && dns_ptr && dns_count > 0) {
if (is_authenticated)
return; /* Impossible to rewrite */

const struct in6_addr *rewrite = iface->dns;
struct in6_addr addr;
size_t rewrite_cnt = iface->dns_cnt;

if (rewrite_cnt == 0) {
if (odhcpd_get_interface_dns_addr(iface, &addr))
return; /* Unable to get interface address */

rewrite = &addr;
rewrite_cnt = 1;
}

/* Copy over any other addresses */
for (size_t i = 0; i < dns_count; ++i) {
size_t j = (i < rewrite_cnt) ? i : rewrite_cnt - 1;
memcpy(&dns_ptr[i], &rewrite[j], sizeof(*rewrite));
}
}
if (iface->always_rewrite_dns && !is_authenticated)
rewrite_dns(iface, dns_ptr, dns_count);

struct iovec iov = {payload_data, payload_len};

Expand Down