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