| 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 -------------------------------------------------*/ |