e82f7154 |
1 | /* -*-c-*- |
2 | * |
3 | * $Id: forward.c,v 1.1 1999/07/01 08:56:23 mdw Exp $ |
4 | * |
5 | * Port forwarding |
6 | * |
7 | * (c) 1999 Mark Wooding |
8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
11 | * |
12 | * This file is part of the `fw' port forwarder. |
13 | * |
14 | * `fw' is free software; you can redistribute it and/or modify |
15 | * it under the terms of the GNU General Public License as published by |
16 | * the Free Software Foundation; either version 2 of the License, or |
17 | * (at your option) any later version. |
18 | * |
19 | * `fw' is distributed in the hope that it will be useful, |
20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
22 | * GNU General Public License for more details. |
23 | * |
24 | * You should have received a copy of the GNU General Public License |
25 | * along with `fw'; if not, write to the Free Software Foundation, |
26 | * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
27 | */ |
28 | |
29 | /*----- Revision history --------------------------------------------------* |
30 | * |
31 | * $Log: forward.c,v $ |
32 | * Revision 1.1 1999/07/01 08:56:23 mdw |
33 | * Initial revision |
34 | * |
35 | */ |
36 | |
37 | /*----- Header files ------------------------------------------------------*/ |
38 | |
39 | #include "config.h" |
40 | |
41 | #include <errno.h> |
42 | #include <stdio.h> |
43 | #include <stdlib.h> |
44 | #include <string.h> |
45 | |
46 | #include <sys/types.h> |
47 | #include <sys/time.h> |
48 | #include <unistd.h> |
49 | |
50 | #include <sys/socket.h> |
51 | #include <netinet/in.h> |
52 | #include <arpa/inet.h> |
53 | |
54 | #include <mLib/alloc.h> |
55 | #include <mLib/conn.h> |
56 | #include <mLib/sel.h> |
57 | |
58 | #include "chan.h" |
59 | #include "forward.h" |
60 | #include "fw.h" |
61 | |
62 | /*----- Data structures ---------------------------------------------------*/ |
63 | |
64 | /* --- Port forwarding data --- */ |
65 | |
66 | typedef struct fw { |
67 | int fd_a; /* Client's file descriptor */ |
68 | int fd_b; /* Server's file descriptor */ |
69 | unsigned state; /* Current state of the world */ |
70 | conn c; /* Nonblocking connect to server */ |
71 | chan ab; /* Channel from @a@ to @b@ */ |
72 | chan ba; /* Channel from @b@ to @a@ */ |
73 | } fw; |
74 | |
75 | #define S_AB 1u /* Channel from @a@ to @b@ open */ |
76 | #define S_BA 2u /* Channel from @b@ to @a@ open */ |
77 | #define S_NOTCONN 4u /* Not connected to @b@ yet */ |
78 | #define S_NOTID 8u /* Not finished identification */ |
79 | |
80 | /*----- Main code ---------------------------------------------------------*/ |
81 | |
82 | /* --- @done@ --- * |
83 | * |
84 | * Arguments: @fw *f@ = pointer to forwarder |
85 | * |
86 | * Returns: --- |
87 | * |
88 | * Use: Tidies up a forwarder that nobody wants any more. |
89 | */ |
90 | |
91 | static void done(fw *f) |
92 | { |
93 | close(f->fd_a); |
94 | close(f->fd_b); |
95 | free(f); |
96 | } |
97 | |
98 | /* --- @ident@ --- * |
99 | * |
100 | * Arguments: @void *vp@ = pointer to forwarder |
101 | * |
102 | * Returns: --- |
103 | * |
104 | * Use: Handles completion of client identification. |
105 | */ |
106 | |
107 | static void ident(void *vp) |
108 | { |
109 | fw *f = vp; |
110 | f->state &= ~S_NOTID; |
111 | if (!f->state) |
112 | done(f); |
113 | } |
114 | |
115 | /* --- @closeba@ --- * |
116 | * |
117 | * Arguments: @void *vp@ = pointer to forwarder |
118 | * |
119 | * Returns: --- |
120 | * |
121 | * Use: Handles the closing of the %$b \rightarrow a$% channel. |
122 | */ |
123 | |
124 | static void closeba(void *vp) |
125 | { |
126 | fw *f = vp; |
127 | f->state &= ~S_BA; |
128 | if (!f->state) |
129 | done(f); |
130 | } |
131 | |
132 | /* --- @closeab@ --- * |
133 | * |
134 | * Arguments: @void *vp@ = pointer to forwarder |
135 | * |
136 | * Returns: --- |
137 | * |
138 | * Use: Handles the closing of the %$a \rightarrow b$% channel. |
139 | */ |
140 | |
141 | static void closeab(void *vp) |
142 | { |
143 | fw *f = vp; |
144 | f->state &= ~S_AB; |
145 | if (!f->state) |
146 | done(f); |
147 | } |
148 | |
149 | /* --- @go@ --- * |
150 | * |
151 | * Arguments: @int fd@ = newly connected socket |
152 | * @void *vp@ = pointer to forwarder |
153 | * |
154 | * Returns: --- |
155 | * |
156 | * Use: Completes the forwarder once the outbound connection is set |
157 | * up. |
158 | */ |
159 | |
160 | static void go(int fd, void *vp) |
161 | { |
162 | fw *f = vp; |
163 | |
164 | /* --- If it all went tits-up, deal with that --- */ |
165 | |
166 | if (fd == -1) { |
167 | chan_close(&f->ab); |
168 | close(f->fd_a); |
169 | free(f); |
170 | return; |
171 | } |
172 | |
173 | /* --- OK, finish configuring the forwarder --- */ |
174 | |
175 | f->fd_b = fd; |
176 | chan_dest(&f->ab, fd); |
177 | chan_open(&f->ba, fd, f->fd_a, closeba, f); |
178 | f->state |= S_BA; |
179 | f->state &= ~S_NOTCONN; |
180 | } |
181 | |
182 | /* --- @forward@ --- * |
183 | * |
184 | * Arguments: @int fd@ = file descriptor attached to client |
185 | * @struct sockaddr_in *sin@ = pointer to destination address |
186 | * @const id_req *q@ = pointer to identification request block |
187 | * |
188 | * Returns: --- |
189 | * |
190 | * Use: Start a port forwarding job. |
191 | */ |
192 | |
193 | void forward(int fd, struct sockaddr_in *sin, const id_req *q) |
194 | { |
195 | fw *f; |
196 | int nfd; |
197 | |
198 | /* --- Set up the new socket --- */ |
199 | |
200 | if ((nfd = socket(PF_INET, SOCK_STREAM, 0)) < 0) |
201 | return; |
202 | |
203 | { |
204 | int opt = 1; |
205 | setsockopt(fd, SOL_SOCKET, SO_OOBINLINE, &opt, sizeof(opt)); |
206 | setsockopt(nfd, SOL_SOCKET, SO_OOBINLINE, &opt, sizeof(opt)); |
207 | } |
208 | |
209 | /* --- Initialize the easy bits --- */ |
210 | |
211 | f = xmalloc(sizeof(*f)); |
212 | f->fd_a = fd; |
213 | f->fd_b = -1; |
214 | f->state = S_NOTCONN | S_AB | S_NOTID; |
215 | |
216 | /* --- Open the %$a \rightarrow b$% channel --- */ |
217 | |
218 | chan_open(&f->ab, fd, -1, closeab, f); |
219 | conn_init(&f->c, sel, nfd, (struct sockaddr *)sin, sizeof(*sin), go, f); |
220 | identify(q, ident, f); |
221 | } |
222 | |
223 | /*----- That's all, folks -------------------------------------------------*/ |