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@@ -1,8 +1,7 @@
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-/**
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- * @file udpgw.c
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- * @author Ambroz Bizjak <ambrop7@gmail.com>
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- *
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- * @section LICENSE
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+/*
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+ * Copyright (C) Ambroz Bizjak <ambrop7@gmail.com>
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+ * Contributions:
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+ * Transparent DNS: Copyright (C) Kerem Hadimli <kerem.hadimli@gmail.com>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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@@ -31,6 +30,7 @@
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#include <string.h>
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#include <stdarg.h>
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#include <stdlib.h>
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+#include <limits.h>
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#include <protocol/udpgw_proto.h>
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#include <misc/debug.h>
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@@ -60,6 +60,8 @@
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#ifndef BADVPN_USE_WINAPI
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#include <base/BLog_syslog.h>
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+#include <arpa/nameser.h>
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+#include <resolv.h>
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#endif
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#include <udpgw/udpgw.h>
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@@ -69,6 +71,8 @@
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#define LOGGER_STDOUT 1
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#define LOGGER_SYSLOG 2
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+#define DNS_UPDATE_TIME 2000
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+
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struct client {
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BConnection con;
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BAddr addr;
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@@ -88,6 +92,7 @@ struct connection {
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struct client *client;
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uint16_t conid;
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BAddr addr;
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+ BAddr orig_addr;
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const uint8_t *first_data;
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int first_data_len;
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btime_t last_use_time;
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@@ -146,6 +151,10 @@ int num_listen_addrs;
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// local UDP port range, if options.local_udp_num_ports>=0
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BAddr local_udp_addr;
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+// DNS forwarding
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+BAddr dns_addr;
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+btime_t last_dns_update_time;
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+
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// reactor
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BReactor ss;
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@@ -171,7 +180,7 @@ static void client_connection_handler (struct client *client, int event);
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static void client_decoder_handler_error (struct client *client);
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static void client_recv_if_handler_send (struct client *client, uint8_t *data, int data_len);
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static uint8_t * build_port_usage_array_and_find_least_used_connection (BAddr remote_addr, struct connection **out_con);
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-static void connection_init (struct client *client, uint16_t conid, BAddr addr, const uint8_t *data, int data_len);
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+static void connection_init (struct client *client, uint16_t conid, BAddr addr, BAddr orig_addr, const uint8_t *data, int data_len);
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static void connection_free (struct connection *con);
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static void connection_logfunc (struct connection *con);
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static void connection_log (struct connection *con, int level, const char *fmt, ...);
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@@ -185,6 +194,7 @@ static void connection_dgram_handler_event (struct connection *con, int event);
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static void connection_udp_recv_if_handler_send (struct connection *con, uint8_t *data, int data_len);
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static struct connection * find_connection (struct client *client, uint16_t conid);
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static int uint16_comparator (void *unused, uint16_t *v1, uint16_t *v2);
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+static void maybe_update_dns (void);
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int main (int argc, char **argv)
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{
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@@ -266,6 +276,11 @@ int main (int argc, char **argv)
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// init time
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BTime_Init();
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+ // init DNS forwarding
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+ BAddr_InitNone(&dns_addr);
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+ last_dns_update_time = INT64_MIN;
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+ maybe_update_dns();
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+
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// init reactor
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if (!BReactor_Init(&ss)) {
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BLog(BLOG_ERROR, "BReactor_Init failed");
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@@ -799,9 +814,8 @@ void client_recv_if_handler_send (struct client *client, uint8_t *data, int data
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ASSERT(!con || !con->closing)
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// if connection exists, close it if needed
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- if (con && ((flags & UDPGW_CLIENT_FLAG_REBIND) || con->addr.ipv4.ip != header.addr_ip || con->addr.ipv4.port != header.addr_port)) {
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+ if (con && ((flags & UDPGW_CLIENT_FLAG_REBIND) || con->orig_addr.ipv4.ip != header.addr_ip || con->orig_addr.ipv4.port != header.addr_port)) {
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connection_log(con, BLOG_DEBUG, "close old");
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-
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connection_close(con);
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con = NULL;
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}
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@@ -816,11 +830,23 @@ void client_recv_if_handler_send (struct client *client, uint8_t *data, int data
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}
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// read address
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- BAddr addr;
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- BAddr_InitIPv4(&addr, header.addr_ip, header.addr_port);
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+ BAddr orig_addr;
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+ BAddr_InitIPv4(&orig_addr, header.addr_ip, header.addr_port);
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+ BAddr addr = orig_addr;
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+
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+ // if this is DNS, replace actual address, but keep header.addr_ip header.addr_port intact
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+ if ((flags & UDPGW_CLIENT_FLAG_DNS)) {
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+ maybe_update_dns();
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+ if (dns_addr.type == BADDR_TYPE_NONE) {
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+ client_log(client, BLOG_WARNING, "received DNS packet, but no DNS server available");
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+ } else {
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+ client_log(client, BLOG_DEBUG, "received DNS");
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+ addr = dns_addr;
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+ }
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+ }
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// create new connection
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- connection_init(client, conid, addr, data, data_len);
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+ connection_init(client, conid, addr, orig_addr, data, data_len);
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} else {
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// submit packet to existing connection
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connection_send_to_udp(con, data, data_len);
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@@ -881,12 +907,13 @@ uint8_t * build_port_usage_array_and_find_least_used_connection (BAddr remote_ad
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return port_usage;
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}
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-void connection_init (struct client *client, uint16_t conid, BAddr addr, const uint8_t *data, int data_len)
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+void connection_init (struct client *client, uint16_t conid, BAddr addr, BAddr orig_addr, const uint8_t *data, int data_len)
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{
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ASSERT(client->num_connections < options.max_connections_for_client)
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ASSERT(!find_connection(client, conid))
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BAddr_Assert(&addr);
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ASSERT(addr.type == BADDR_TYPE_IPV4)
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+ ASSERT(orig_addr.type == BADDR_TYPE_IPV4)
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ASSERT(data_len >= 0)
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ASSERT(data_len <= options.udp_mtu)
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@@ -901,6 +928,7 @@ void connection_init (struct client *client, uint16_t conid, BAddr addr, const u
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con->client = client;
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con->conid = conid;
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con->addr = addr;
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+ con->orig_addr = orig_addr;
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con->first_data = data;
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con->first_data_len = data_len;
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@@ -1151,8 +1179,8 @@ int connection_send_to_client (struct connection *con, uint8_t flags, const uint
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struct udpgw_header header;
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header.flags = htol8(flags);
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header.conid = htol16(con->conid);
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- header.addr_ip = con->addr.ipv4.ip;
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- header.addr_port = con->addr.ipv4.port;
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+ header.addr_ip = con->orig_addr.ipv4.ip;
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+ header.addr_port = con->orig_addr.ipv4.port;
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memcpy(out, &header, sizeof(header));
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// write message
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@@ -1295,3 +1323,40 @@ int uint16_comparator (void *unused, uint16_t *v1, uint16_t *v2)
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{
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return B_COMPARE(*v1, *v2);
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}
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+
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+void maybe_update_dns (void)
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+{
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+#ifndef BADVPN_USE_WINAPI
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+ btime_t now = btime_gettime();
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+ if (now < btime_add(last_dns_update_time, DNS_UPDATE_TIME)) {
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+ return;
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+ }
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+ last_dns_update_time = now;
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+ BLog(BLOG_DEBUG, "update dns");
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+
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+ if (res_init() != 0) {
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+ BLog(BLOG_ERROR, "res_init failed");
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+ goto fail;
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+ }
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+
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+ if (_res.nscount == 0) {
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+ BLog(BLOG_ERROR, "no name servers available");
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+ goto fail;
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+ }
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+
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+ BAddr addr;
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+ BAddr_InitIPv4(&addr, _res.nsaddr_list[0].sin_addr.s_addr, hton16(53));
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+
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+ if (!BAddr_Compare(&addr, &dns_addr)) {
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+ char str[BADDR_MAX_PRINT_LEN];
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+ BAddr_Print(&addr, str);
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+ BLog(BLOG_INFO, "using DNS server %s", str);
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+ }
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+
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+ dns_addr = addr;
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+ return;
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+
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+fail:
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+ BAddr_InitNone(&dns_addr);
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+#endif
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+}
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ambrop7