git.distorted.org.uk Git - u/mdw/putty/blob - unix/uxproxy.c

   1 /*
   2  * uxproxy.c: Unix implementation of platform_new_connection(),
   3  * supporting an OpenSSH-like proxy command.
   4  */
   5
   6 #include <stdio.h>
   7 #include <assert.h>
   8 #include <errno.h>
   9 #include <unistd.h>
  10 #include <fcntl.h>
  11
  12 #define DEFINE_PLUG_METHOD_MACROS
  13 #include "tree234.h"
  14 #include "putty.h"
  15 #include "network.h"
  16 #include "proxy.h"
  17
  18 typedef struct Socket_localproxy_tag * Local_Proxy_Socket;
  19
  20 struct Socket_localproxy_tag {
  21     const struct socket_function_table *fn;
  22     /* the above variable absolutely *must* be the first in this structure */
  23
  24     int to_cmd, from_cmd;              /* fds */
  25
  26     char *error;
  27
  28     Plug plug;
  29
  30     bufchain pending_output_data;
  31     bufchain pending_input_data;
  32     enum { EOF_NO, EOF_PENDING, EOF_SENT } outgoingeof;
  33
  34     void *privptr;
  35 };
  36
  37 static int localproxy_select_result(int fd, int event);
  38
  39 /*
  40  * Trees to look up the pipe fds in.
  41  */
  42 static tree234 *localproxy_by_fromfd, *localproxy_by_tofd;
  43 static int localproxy_fromfd_cmp(void *av, void *bv)
  44 {
  45     Local_Proxy_Socket a = (Local_Proxy_Socket)av;
  46     Local_Proxy_Socket b = (Local_Proxy_Socket)bv;
  47     if (a->from_cmd < b->from_cmd)
  48         return -1;
  49     if (a->from_cmd > b->from_cmd)
  50         return +1;
  51     return 0;
  52 }
  53 static int localproxy_fromfd_find(void *av, void *bv)
  54 {
  55     int a = *(int *)av;
  56     Local_Proxy_Socket b = (Local_Proxy_Socket)bv;
  57     if (a < b->from_cmd)
  58         return -1;
  59     if (a > b->from_cmd)
  60         return +1;
  61     return 0;
  62 }
  63 static int localproxy_tofd_cmp(void *av, void *bv)
  64 {
  65     Local_Proxy_Socket a = (Local_Proxy_Socket)av;
  66     Local_Proxy_Socket b = (Local_Proxy_Socket)bv;
  67     if (a->to_cmd < b->to_cmd)
  68         return -1;
  69     if (a->to_cmd > b->to_cmd)
  70         return +1;
  71     return 0;
  72 }
  73 static int localproxy_tofd_find(void *av, void *bv)
  74 {
  75     int a = *(int *)av;
  76     Local_Proxy_Socket b = (Local_Proxy_Socket)bv;
  77     if (a < b->to_cmd)
  78         return -1;
  79     if (a > b->to_cmd)
  80         return +1;
  81     return 0;
  82 }
  83
  84 /* basic proxy socket functions */
  85
  86 static Plug sk_localproxy_plug (Socket s, Plug p)
  87 {
  88     Local_Proxy_Socket ps = (Local_Proxy_Socket) s;
  89     Plug ret = ps->plug;
  90     if (p)
  91         ps->plug = p;
  92     return ret;
  93 }
  94
  95 static void sk_localproxy_close (Socket s)
  96 {
  97     Local_Proxy_Socket ps = (Local_Proxy_Socket) s;
  98
  99     if (ps->to_cmd >= 0) {
 100         del234(localproxy_by_tofd, ps);
 101         uxsel_del(ps->to_cmd);
 102         close(ps->to_cmd);
 103     }
 104
 105     del234(localproxy_by_fromfd, ps);
 106     uxsel_del(ps->from_cmd);
 107     close(ps->from_cmd);
 108
 109     sfree(ps);
 110 }
 111
 112 static int localproxy_try_send(Local_Proxy_Socket ps)
 113 {
 114     int sent = 0;
 115
 116     while (bufchain_size(&ps->pending_output_data) > 0) {
 117         void *data;
 118         int len, ret;
 119
 120         bufchain_prefix(&ps->pending_output_data, &data, &len);
 121         ret = write(ps->to_cmd, data, len);
 122         if (ret < 0 && errno != EWOULDBLOCK) {
 123             /* We're inside the Unix frontend here, so we know
 124              * that the frontend handle is unnecessary. */
 125             logevent(NULL, strerror(errno));
 126             fatalbox("%s", strerror(errno));
 127         } else if (ret <= 0) {
 128             break;
 129         } else {
 130             bufchain_consume(&ps->pending_output_data, ret);
 131             sent += ret;
 132         }
 133     }
 134
 135     if (ps->outgoingeof == EOF_PENDING) {
 136         del234(localproxy_by_tofd, ps);
 137         close(ps->to_cmd);
 138         uxsel_del(ps->to_cmd);
 139         ps->to_cmd = -1;
 140         ps->outgoingeof = EOF_SENT;
 141     }
 142
 143     if (bufchain_size(&ps->pending_output_data) == 0)
 144         uxsel_del(ps->to_cmd);
 145     else
 146         uxsel_set(ps->to_cmd, 2, localproxy_select_result);
 147
 148     return sent;
 149 }
 150
 151 static int sk_localproxy_write (Socket s, const char *data, int len)
 152 {
 153     Local_Proxy_Socket ps = (Local_Proxy_Socket) s;
 154
 155     assert(ps->outgoingeof == EOF_NO);
 156
 157     bufchain_add(&ps->pending_output_data, data, len);
 158
 159     localproxy_try_send(ps);
 160
 161     return bufchain_size(&ps->pending_output_data);
 162 }
 163
 164 static int sk_localproxy_write_oob (Socket s, const char *data, int len)
 165 {
 166     /*
 167      * oob data is treated as inband; nasty, but nothing really
 168      * better we can do
 169      */
 170     return sk_localproxy_write(s, data, len);
 171 }
 172
 173 static void sk_localproxy_write_eof (Socket s)
 174 {
 175     Local_Proxy_Socket ps = (Local_Proxy_Socket) s;
 176
 177     assert(ps->outgoingeof == EOF_NO);
 178     ps->outgoingeof = EOF_PENDING;
 179
 180     localproxy_try_send(ps);
 181 }
 182
 183 static void sk_localproxy_flush (Socket s)
 184 {
 185     /* Local_Proxy_Socket ps = (Local_Proxy_Socket) s; */
 186     /* do nothing */
 187 }
 188
 189 static void sk_localproxy_set_private_ptr (Socket s, void *ptr)
 190 {
 191     Local_Proxy_Socket ps = (Local_Proxy_Socket) s;
 192     ps->privptr = ptr;
 193 }
 194
 195 static void * sk_localproxy_get_private_ptr (Socket s)
 196 {
 197     Local_Proxy_Socket ps = (Local_Proxy_Socket) s;
 198     return ps->privptr;
 199 }
 200
 201 static void sk_localproxy_set_frozen (Socket s, int is_frozen)
 202 {
 203     Local_Proxy_Socket ps = (Local_Proxy_Socket) s;
 204
 205     if (is_frozen)
 206         uxsel_del(ps->from_cmd);
 207     else
 208         uxsel_set(ps->from_cmd, 1, localproxy_select_result);
 209 }
 210
 211 static const char * sk_localproxy_socket_error (Socket s)
 212 {
 213     Local_Proxy_Socket ps = (Local_Proxy_Socket) s;
 214     return ps->error;
 215 }
 216
 217 static int localproxy_select_result(int fd, int event)
 218 {
 219     Local_Proxy_Socket s;
 220     char buf[20480];
 221     int ret;
 222
 223     if (!(s = find234(localproxy_by_fromfd, &fd, localproxy_fromfd_find)) &&
 224         !(s = find234(localproxy_by_tofd, &fd, localproxy_tofd_find)) )
 225         return 1;                      /* boggle */
 226
 227     if (event == 1) {
 228         assert(fd == s->from_cmd);
 229         ret = read(fd, buf, sizeof(buf));
 230         if (ret < 0) {
 231             return plug_closing(s->plug, strerror(errno), errno, 0);
 232         } else if (ret == 0) {
 233             return plug_closing(s->plug, NULL, 0, 0);
 234         } else {
 235             return plug_receive(s->plug, 0, buf, ret);
 236         }
 237     } else if (event == 2) {
 238         assert(fd == s->to_cmd);
 239         if (localproxy_try_send(s))
 240             plug_sent(s->plug, bufchain_size(&s->pending_output_data));
 241         return 1;
 242     }
 243
 244     return 1;
 245 }
 246
 247 Socket platform_new_connection(SockAddr addr, char *hostname,
 248                                int port, int privport,
 249                                int oobinline, int nodelay, int keepalive,
 250                                Plug plug, Conf *conf)
 251 {
 252     char *cmd;
 253
 254     static const struct socket_function_table socket_fn_table = {
 255         sk_localproxy_plug,
 256         sk_localproxy_close,
 257         sk_localproxy_write,
 258         sk_localproxy_write_oob,
 259         sk_localproxy_write_eof,
 260         sk_localproxy_flush,
 261         sk_localproxy_set_private_ptr,
 262         sk_localproxy_get_private_ptr,
 263         sk_localproxy_set_frozen,
 264         sk_localproxy_socket_error
 265     };
 266
 267     Local_Proxy_Socket ret;
 268     int to_cmd_pipe[2], from_cmd_pipe[2], pid;
 269
 270     if (conf_get_int(conf, CONF_proxy_type) != PROXY_CMD)
 271         return NULL;
 272
 273     cmd = format_telnet_command(addr, port, conf);
 274
 275     ret = snew(struct Socket_localproxy_tag);
 276     ret->fn = &socket_fn_table;
 277     ret->plug = plug;
 278     ret->error = NULL;
 279     ret->outgoingeof = EOF_NO;
 280
 281     bufchain_init(&ret->pending_input_data);
 282     bufchain_init(&ret->pending_output_data);
 283
 284     /*
 285      * Create the pipes to the proxy command, and spawn the proxy
 286      * command process.
 287      */
 288     if (pipe(to_cmd_pipe) < 0 ||
 289         pipe(from_cmd_pipe) < 0) {
 290         ret->error = dupprintf("pipe: %s", strerror(errno));
 291         sfree(cmd);
 292         return (Socket)ret;
 293     }
 294     cloexec(to_cmd_pipe[1]);
 295     cloexec(from_cmd_pipe[0]);
 296
 297     pid = fork();
 298
 299     if (pid < 0) {
 300         ret->error = dupprintf("fork: %s", strerror(errno));
 301         sfree(cmd);
 302         return (Socket)ret;
 303     } else if (pid == 0) {
 304         close(0);
 305         close(1);
 306         dup2(to_cmd_pipe[0], 0);
 307         dup2(from_cmd_pipe[1], 1);
 308         close(to_cmd_pipe[0]);
 309         close(from_cmd_pipe[1]);
 310         noncloexec(0);
 311         noncloexec(1);
 312         execl("/bin/sh", "sh", "-c", cmd, (void *)NULL);
 313         _exit(255);
 314     }
 315
 316     sfree(cmd);
 317
 318     close(to_cmd_pipe[0]);
 319     close(from_cmd_pipe[1]);
 320
 321     ret->to_cmd = to_cmd_pipe[1];
 322     ret->from_cmd = from_cmd_pipe[0];
 323
 324     if (!localproxy_by_fromfd)
 325         localproxy_by_fromfd = newtree234(localproxy_fromfd_cmp);
 326     if (!localproxy_by_tofd)
 327         localproxy_by_tofd = newtree234(localproxy_tofd_cmp);
 328
 329     add234(localproxy_by_fromfd, ret);
 330     add234(localproxy_by_tofd, ret);
 331
 332     uxsel_set(ret->from_cmd, 1, localproxy_select_result);
 333
 334     /* We are responsible for this and don't need it any more */
 335     sk_addr_free(addr);
 336
 337     return (Socket) ret;
 338 }