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1 office 1 /*
2 * Copyright (C) 2018 Jigsaw Operations LLC
3 * Copyright (C) 2019 Ambroz Bizjak (modifications)
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 * 3. Neither the name of the author nor the
13 * names of its contributors may be used to endorse or promote products
14 * derived from this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
18 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
19 * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
20 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
21 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
22 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
23 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
25 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 */
27  
28 #ifndef BADVPN_SOCKS_UDP_CLIENT_SOCKSUDPCLIENT_H
29 #define BADVPN_SOCKS_UDP_CLIENT_SOCKSUDPCLIENT_H
30  
31 #include <stddef.h>
32 #include <stdint.h>
33  
34 #include <base/BPending.h>
35 #include <base/DebugObject.h>
36 #include <flow/BufferWriter.h>
37 #include <flow/PacketBuffer.h>
38 #include <flow/SinglePacketBuffer.h>
39 #include <flow/PacketPassInterface.h>
40 #include <flowextra/PacketPassInactivityMonitor.h>
41 #include <socksclient/BSocksClient.h>
42 #include <structure/BAVL.h>
43 #include <system/BAddr.h>
44 #include <system/BDatagram.h>
45 #include <system/BReactor.h>
46 #include <system/BTime.h>
47  
48 typedef void (*SocksUdpClient_handler_received) (
49 void *user, BAddr local_addr, BAddr remote_addr, const uint8_t *data, int data_len);
50  
51 typedef struct {
52 BAddr server_addr;
53 const struct BSocksClient_auth_info *auth_info;
54 size_t num_auth_info;
55 int num_connections;
56 int max_connections;
57 int send_buf_size;
58 int udp_mtu;
59 int socks_mtu;
60 btime_t keepalive_time;
61 BReactor *reactor;
62 void *user;
63 SocksUdpClient_handler_received handler_received;
64 BAVL connections_tree; // By local_addr
65 DebugObject d_obj;
66 } SocksUdpClient;
67  
68 struct SocksUdpClient_connection {
69 SocksUdpClient *client;
70 BAddr local_addr;
71 BSocksClient socks;
72 BufferWriter send_writer;
73 PacketBuffer send_buffer;
74 PacketPassInactivityMonitor send_monitor;
75 PacketPassInterface send_if;
76 BDatagram socket;
77 PacketPassInterface recv_if;
78 SinglePacketBuffer recv_buffer;
79 // The first_* members represent the initial packet, which has to be stored so it can
80 // wait for send_writer to become ready.
81 uint8_t *first_data;
82 int first_data_len;
83 BAddr first_remote_addr;
84 // If all packets sent so far have been sent to the same IP, port 53, with the
85 // same DNS ID, then this is that ID. Otherwise, it is -1. This is used to
86 // close ephemeral DNS query connections once a response is received.
87 int dns_id;
88 BPending first_job;
89 BAVLNode connections_tree_node;
90 };
91  
92 /**
93 * Initializes the SOCKS5-UDP client object.
94 *
95 * This function only initialzies the object and does not perform network access.
96 *
97 * @param o the object
98 * @param udp_mtu the maximum size of packets that will be sent through the tunnel
99 * @param max_connections how many local ports to track before dropping packets
100 * @param send_buf_size maximum number of buffered outgoing packets per connection
101 * @param keepalive_time how long to track an idle local port before forgetting it
102 * @param server_addr SOCKS5 server address
103 * @param auth_info List of authentication info for BSocksClient. The pointer must remain
104 * valid while this object exists, the data is not copied.
105 * @param num_auth_info Number of the above.
106 * @param reactor reactor we live in
107 * @param user value passed to handler
108 * @param handler_received handler for incoming UDP packets
109 * @return 1 on success, 0 on failure
110 */
111 int SocksUdpClient_Init (SocksUdpClient *o, int udp_mtu, int max_connections,
112 int send_buf_size, btime_t keepalive_time, BAddr server_addr,
113 const struct BSocksClient_auth_info *auth_info, size_t num_auth_info,
114 BReactor *reactor, void *user, SocksUdpClient_handler_received handler_received);
115  
116 /**
117 * Frees the SOCKS5-UDP client object.
118 *
119 * @param o the object
120 */
121 void SocksUdpClient_Free (SocksUdpClient *o);
122  
123 /**
124 * Submit a packet to be sent through the proxy.
125 *
126 * This will reuse an existing connection for packets from local_addr, or create one if
127 * there is none. If the number of live connections exceeds max_connections, or if the
128 * number of buffered packets from this port exceeds a limit, packets will be dropped
129 * silently.
130 *
131 * As a resource optimization, if a connection has only been used to send one DNS query,
132 * then the connection will be closed and freed once the reply is received.
133 *
134 * @param o the object
135 * @param local_addr the UDP packet's source address, and the expected destination for
136 * replies
137 * @param remote_addr the destination of the packet after it exits the proxy
138 * @param data the packet contents. Caller retains ownership.
139 * @param data_len number of bytes in the data
140 */
141 void SocksUdpClient_SubmitPacket (SocksUdpClient *o,
142 BAddr local_addr, BAddr remote_addr, const uint8_t *data, int data_len);
143  
144 #endif