1/*
2 * Dropbear - a SSH2 server
3 *
4 * Copyright (c) 2002,2003 Matt Johnston
5 * All rights reserved.
6 *
7 * Permission is hereby granted, free of charge, to any person obtaining a copy
8 * of this software and associated documentation files (the "Software"), to deal
9 * in the Software without restriction, including without limitation the rights
10 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
11 * copies of the Software, and to permit persons to whom the Software is
12 * furnished to do so, subject to the following conditions:
13 *
14 * The above copyright notice and this permission notice shall be included in
15 * all copies or substantial portions of the Software.
16 *
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
20 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
22 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
23 * SOFTWARE. */
24
25#ifndef _CHANNEL_H_
26#define _CHANNEL_H_
27
28#include "includes.h"
29#include "buffer.h"
30#include "circbuffer.h"
31
32/* channel->type values */
33#define CHANNEL_ID_NONE 0
34#define CHANNEL_ID_SESSION 1
35#define CHANNEL_ID_X11 2
36#define CHANNEL_ID_AGENT 3
37#define CHANNEL_ID_TCPDIRECT 4
38#define CHANNEL_ID_TCPFORWARDED 5
39
40#define SSH_OPEN_ADMINISTRATIVELY_PROHIBITED    1
41#define SSH_OPEN_CONNECT_FAILED                 2
42#define SSH_OPEN_UNKNOWN_CHANNEL_TYPE           3
43#define SSH_OPEN_RESOURCE_SHORTAGE              4
44
45/* Not a real type */
46#define SSH_OPEN_IN_PROGRESS					99
47
48#define MAX_CHANNELS 100 /* simple mem restriction, includes each tcp/x11
49							connection, so can't be _too_ small */
50
51#define CHAN_EXTEND_SIZE 3 /* how many extra slots to add when we need more */
52
53#define RECV_MAXWINDOW 8000 /* tweak */
54#define RECV_WINDOWEXTEND 1000 /* We send a "window extend" every
55								RECV_WINDOWEXTEND bytes */
56#define RECV_MAXPACKET RECV_MAXWINDOW /* tweak */
57
58struct ChanType;
59
60struct Channel {
61
62	unsigned int index; /* the local channel index */
63	unsigned int remotechan;
64	unsigned int recvwindow, transwindow;
65	unsigned int recvdonelen;
66	unsigned int recvmaxpacket, transmaxpacket;
67	void* typedata; /* a pointer to type specific data */
68	int writefd; /* read from wire, written to insecure side */
69	int readfd; /* read from insecure size, written to wire */
70	int errfd; /* used like writefd or readfd, depending if it's client or server.
71				  Doesn't exactly belong here, but is cleaner here */
72	circbuffer *writebuf; /* data from the wire, for local consumption */
73	circbuffer *extrabuf; /* extended-data for the program - used like writebuf
74					     but for stderr */
75
76	/* whether close/eof messages have been exchanged */
77	int sent_close, recv_close;
78	int recv_eof, sent_eof;
79
80	int initconn; /* used for TCP forwarding, whether the channel has been
81					 fully initialised */
82
83	int await_open; /* flag indicating whether we've sent an open request
84					   for this channel (and are awaiting a confirmation
85					   or failure). */
86
87	int flushing;
88
89	const struct ChanType* type;
90
91};
92
93struct ChanType {
94
95	int sepfds; /* Whether this channel has seperate pipes for in/out or not */
96	char *name;
97	int (*inithandler)(struct Channel*);
98	int (*check_close)(struct Channel*);
99	void (*reqhandler)(struct Channel*);
100	void (*closehandler)(struct Channel*);
101
102};
103
104void chaninitialise(const struct ChanType *chantypes[]);
105void chancleanup();
106void setchannelfds(fd_set *readfd, fd_set *writefd);
107void channelio(fd_set *readfd, fd_set *writefd);
108struct Channel* getchannel();
109struct Channel* newchannel(unsigned int remotechan,
110		const struct ChanType *type,
111		unsigned int transwindow, unsigned int transmaxpacket);
112
113void recv_msg_channel_open();
114void recv_msg_channel_request();
115void send_msg_channel_failure(struct Channel *channel);
116void send_msg_channel_success(struct Channel *channel);
117void recv_msg_channel_data();
118void recv_msg_channel_extended_data();
119void recv_msg_channel_window_adjust();
120void recv_msg_channel_close();
121void recv_msg_channel_eof();
122
123void common_recv_msg_channel_data(struct Channel *channel, int fd,
124		circbuffer * buf);
125
126#ifdef DROPBEAR_CLIENT
127extern const struct ChanType clichansess;
128#endif
129
130#if defined(USING_LISTENERS) || defined(DROPBEAR_CLIENT)
131int send_msg_channel_open_init(int fd, const struct ChanType *type);
132void recv_msg_channel_open_confirmation();
133void recv_msg_channel_open_failure();
134#endif
135
136#endif /* _CHANNEL_H_ */
137