gdb/ser-tcp.c

   1 /* Serial interface for raw TCP connections on Un*x like systems.
   2
   3    Copyright (C) 1992-2018 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #include "defs.h"
  21 #include "serial.h"
  22 #include "ser-base.h"
  23 #include "ser-tcp.h"
  24 #include "gdbcmd.h"
  25 #include "cli/cli-decode.h"
  26 #include "cli/cli-setshow.h"
  27 #include "filestuff.h"
  28
  29 #include <sys/types.h>
  30
  31 #ifdef HAVE_SYS_FILIO_H
  32 #include <sys/filio.h>  /* For FIONBIO.  */
  33 #endif
  34 #ifdef HAVE_SYS_IOCTL_H
  35 #include <sys/ioctl.h>  /* For FIONBIO.  */
  36 #endif
  37
  38 #include "gdb_sys_time.h"
  39
  40 #ifdef USE_WIN32API
  41 #include <winsock2.h>
  42 #ifndef ETIMEDOUT
  43 #define ETIMEDOUT WSAETIMEDOUT
  44 #endif
  45 /* Gnulib defines close too, but gnulib's replacement
  46    doesn't call closesocket unless we import the
  47    socketlib module.  */
  48 #undef close
  49 #define close(fd) closesocket (fd)
  50 #define ioctl ioctlsocket
  51 #else
  52 #include <netinet/in.h>
  53 #include <arpa/inet.h>
  54 #include <netdb.h>
  55 #include <sys/socket.h>
  56 #include <netinet/tcp.h>
  57 #endif
  58
  59 #include <signal.h>
  60 #include "gdb_select.h"
  61 #include <algorithm>
  62
  63 #ifndef HAVE_SOCKLEN_T
  64 typedef int socklen_t;
  65 #endif
  66
  67 /* For "set tcp" and "show tcp".  */
  68
  69 static struct cmd_list_element *tcp_set_cmdlist;
  70 static struct cmd_list_element *tcp_show_cmdlist;
  71
  72 /* Whether to auto-retry refused connections.  */
  73
  74 static int tcp_auto_retry = 1;
  75
  76 /* Timeout period for connections, in seconds.  */
  77
  78 static unsigned int tcp_retry_limit = 15;
  79
  80 /* How many times per second to poll deprecated_ui_loop_hook.  */
  81
  82 #define POLL_INTERVAL 5
  83
  84 /* Helper function to wait a while.  If SCB is non-null, wait on its
  85    file descriptor.  Otherwise just wait on a timeout, updating *POLLS.
  86    Returns -1 on timeout or interrupt, otherwise the value of select.  */
  87
  88 static int
  89 wait_for_connect (struct serial *scb, unsigned int *polls)
  90 {
  91   struct timeval t;
  92   int n;
  93
  94   /* While we wait for the connect to complete,
  95      poll the UI so it can update or the user can
  96      interrupt.  */
  97   if (deprecated_ui_loop_hook && deprecated_ui_loop_hook (0))
  98     {
  99       errno = EINTR;
 100       return -1;
 101     }
 102
 103   /* Check for timeout.  */
 104   if (*polls > tcp_retry_limit * POLL_INTERVAL)
 105     {
 106       errno = ETIMEDOUT;
 107       return -1;
 108     }
 109
 110   /* Back off to polling once per second after the first POLL_INTERVAL
 111      polls.  */
 112   if (*polls < POLL_INTERVAL)
 113     {
 114       t.tv_sec = 0;
 115       t.tv_usec = 1000000 / POLL_INTERVAL;
 116     }
 117   else
 118     {
 119       t.tv_sec = 1;
 120       t.tv_usec = 0;
 121     }
 122
 123   if (scb)
 124     {
 125       fd_set rset, wset, eset;
 126
 127       FD_ZERO (&rset);
 128       FD_SET (scb->fd, &rset);
 129       wset = rset;
 130       eset = rset;
 131
 132       /* POSIX systems return connection success or failure by signalling
 133          wset.  Windows systems return success in wset and failure in
 134          eset.
 135
 136          We must call select here, rather than gdb_select, because
 137          the serial structure has not yet been initialized - the
 138          MinGW select wrapper will not know that this FD refers
 139          to a socket.  */
 140       n = select (scb->fd + 1, &rset, &wset, &eset, &t);
 141     }
 142   else
 143     /* Use gdb_select here, since we have no file descriptors, and on
 144        Windows, plain select doesn't work in that case.  */
 145     n = gdb_select (0, NULL, NULL, NULL, &t);
 146
 147   /* If we didn't time out, only count it as one poll.  */
 148   if (n > 0 || *polls < POLL_INTERVAL)
 149     (*polls)++;
 150   else
 151     (*polls) += POLL_INTERVAL;
 152
 153   return n;
 154 }
 155
 156 /* Open a tcp socket.  */
 157
 158 int
 159 net_open (struct serial *scb, const char *name)
 160 {
 161   char hostname[100];
 162   const char *port_str;
 163   int n, port, tmp;
 164   int use_udp;
 165   struct hostent *hostent;
 166   struct sockaddr_in sockaddr;
 167 #ifdef USE_WIN32API
 168   u_long ioarg;
 169 #else
 170   int ioarg;
 171 #endif
 172   unsigned int polls = 0;
 173
 174   use_udp = 0;
 175   if (startswith (name, "udp:"))
 176     {
 177       use_udp = 1;
 178       name = name + 4;
 179     }
 180   else if (startswith (name, "tcp:"))
 181     name = name + 4;
 182
 183   port_str = strchr (name, ':');
 184
 185   if (!port_str)
 186     error (_("net_open: No colon in host name!"));  /* Shouldn't ever
 187                                                        happen.  */
 188
 189   tmp = std::min (port_str - name, (ptrdiff_t) sizeof hostname - 1);
 190   strncpy (hostname, name, tmp);        /* Don't want colon.  */
 191   hostname[tmp] = '\000';       /* Tie off host name.  */
 192   port = atoi (port_str + 1);
 193
 194   /* Default hostname is localhost.  */
 195   if (!hostname[0])
 196     strcpy (hostname, "localhost");
 197
 198   hostent = gethostbyname (hostname);
 199   if (!hostent)
 200     {
 201       fprintf_unfiltered (gdb_stderr, "%s: unknown host\n", hostname);
 202       errno = ENOENT;
 203       return -1;
 204     }
 205
 206   sockaddr.sin_family = PF_INET;
 207   sockaddr.sin_port = htons (port);
 208   memcpy (&sockaddr.sin_addr.s_addr, hostent->h_addr,
 209           sizeof (struct in_addr));
 210
 211  retry:
 212
 213   if (use_udp)
 214     scb->fd = gdb_socket_cloexec (PF_INET, SOCK_DGRAM, 0);
 215   else
 216     scb->fd = gdb_socket_cloexec (PF_INET, SOCK_STREAM, 0);
 217
 218   if (scb->fd == -1)
 219     return -1;
 220
 221   /* Set socket nonblocking.  */
 222   ioarg = 1;
 223   ioctl (scb->fd, FIONBIO, &ioarg);
 224
 225   /* Use Non-blocking connect.  connect() will return 0 if connected
 226      already.  */
 227   n = connect (scb->fd, (struct sockaddr *) &sockaddr, sizeof (sockaddr));
 228
 229   if (n < 0)
 230     {
 231 #ifdef USE_WIN32API
 232       int err = WSAGetLastError();
 233 #else
 234       int err = errno;
 235 #endif
 236
 237       /* Maybe we're waiting for the remote target to become ready to
 238          accept connections.  */
 239       if (tcp_auto_retry
 240 #ifdef USE_WIN32API
 241           && err == WSAECONNREFUSED
 242 #else
 243           && err == ECONNREFUSED
 244 #endif
 245           && wait_for_connect (NULL, &polls) >= 0)
 246         {
 247           close (scb->fd);
 248           goto retry;
 249         }
 250
 251       if (
 252 #ifdef USE_WIN32API
 253           /* Under Windows, calling "connect" with a non-blocking socket
 254              results in WSAEWOULDBLOCK, not WSAEINPROGRESS.  */
 255           err != WSAEWOULDBLOCK
 256 #else
 257           err != EINPROGRESS
 258 #endif
 259           )
 260         {
 261           errno = err;
 262           net_close (scb);
 263           return -1;
 264         }
 265
 266       /* Looks like we need to wait for the connect.  */
 267       do
 268         {
 269           n = wait_for_connect (scb, &polls);
 270         }
 271       while (n == 0);
 272       if (n < 0)
 273         {
 274           net_close (scb);
 275           return -1;
 276         }
 277     }
 278
 279   /* Got something.  Is it an error?  */
 280   {
 281     int res, err;
 282     socklen_t len;
 283
 284     len = sizeof (err);
 285     /* On Windows, the fourth parameter to getsockopt is a "char *";
 286        on UNIX systems it is generally "void *".  The cast to "char *"
 287        is OK everywhere, since in C++ any data pointer type can be
 288        implicitly converted to "void *".  */
 289     res = getsockopt (scb->fd, SOL_SOCKET, SO_ERROR, (char *) &err, &len);
 290     if (res < 0 || err)
 291       {
 292         /* Maybe the target still isn't ready to accept the connection.  */
 293         if (tcp_auto_retry
 294 #ifdef USE_WIN32API
 295             && err == WSAECONNREFUSED
 296 #else
 297             && err == ECONNREFUSED
 298 #endif
 299             && wait_for_connect (NULL, &polls) >= 0)
 300           {
 301             close (scb->fd);
 302             goto retry;
 303           }
 304         if (err)
 305           errno = err;
 306         net_close (scb);
 307         return -1;
 308       }
 309   }
 310
 311   /* Turn off nonblocking.  */
 312   ioarg = 0;
 313   ioctl (scb->fd, FIONBIO, &ioarg);
 314
 315   if (use_udp == 0)
 316     {
 317       /* Disable Nagle algorithm.  Needed in some cases.  */
 318       tmp = 1;
 319       setsockopt (scb->fd, IPPROTO_TCP, TCP_NODELAY,
 320                   (char *)&tmp, sizeof (tmp));
 321     }
 322
 323 #ifdef SIGPIPE
 324   /* If we don't do this, then GDB simply exits
 325      when the remote side dies.  */
 326   signal (SIGPIPE, SIG_IGN);
 327 #endif
 328
 329   return 0;
 330 }
 331
 332 void
 333 net_close (struct serial *scb)
 334 {
 335   if (scb->fd == -1)
 336     return;
 337
 338   close (scb->fd);
 339   scb->fd = -1;
 340 }
 341
 342 int
 343 net_read_prim (struct serial *scb, size_t count)
 344 {
 345   /* Need to cast to silence -Wpointer-sign on MinGW, as Winsock's
 346      'recv' takes 'char *' as second argument, while 'scb->buf' is
 347      'unsigned char *'.  */
 348   return recv (scb->fd, (char *) scb->buf, count, 0);
 349 }
 350
 351 int
 352 net_write_prim (struct serial *scb, const void *buf, size_t count)
 353 {
 354   /* On Windows, the second parameter to send is a "const char *"; on
 355      UNIX systems it is generally "const void *".  The cast to "const
 356      char *" is OK everywhere, since in C++ any data pointer type can
 357      be implicitly converted to "const void *".  */
 358   return send (scb->fd, (const char *) buf, count, 0);
 359 }
 360
 361 int
 362 ser_tcp_send_break (struct serial *scb)
 363 {
 364   /* Send telnet IAC and BREAK characters.  */
 365   return (serial_write (scb, "\377\363", 2));
 366 }
 367
 368 /* Support for "set tcp" and "show tcp" commands.  */
 369
 370 static void
 371 set_tcp_cmd (const char *args, int from_tty)
 372 {
 373   help_list (tcp_set_cmdlist, "set tcp ", all_commands, gdb_stdout);
 374 }
 375
 376 static void
 377 show_tcp_cmd (const char *args, int from_tty)
 378 {
 379   help_list (tcp_show_cmdlist, "show tcp ", all_commands, gdb_stdout);
 380 }
 381
 382 #ifndef USE_WIN32API
 383
 384 /* The TCP ops.  */
 385
 386 static const struct serial_ops tcp_ops =
 387 {
 388   "tcp",
 389   net_open,
 390   net_close,
 391   NULL,
 392   ser_base_readchar,
 393   ser_base_write,
 394   ser_base_flush_output,
 395   ser_base_flush_input,
 396   ser_tcp_send_break,
 397   ser_base_raw,
 398   ser_base_get_tty_state,
 399   ser_base_copy_tty_state,
 400   ser_base_set_tty_state,
 401   ser_base_print_tty_state,
 402   ser_base_setbaudrate,
 403   ser_base_setstopbits,
 404   ser_base_setparity,
 405   ser_base_drain_output,
 406   ser_base_async,
 407   net_read_prim,
 408   net_write_prim
 409 };
 410
 411 #endif /* USE_WIN32API */
 412
 413 void
 414 _initialize_ser_tcp (void)
 415 {
 416 #ifdef USE_WIN32API
 417   /* Do nothing; the TCP serial operations will be initialized in
 418      ser-mingw.c.  */
 419 #else
 420   serial_add_interface (&tcp_ops);
 421 #endif /* USE_WIN32API */
 422
 423   add_prefix_cmd ("tcp", class_maintenance, set_tcp_cmd, _("\
 424 TCP protocol specific variables\n\
 425 Configure variables specific to remote TCP connections"),
 426                   &tcp_set_cmdlist, "set tcp ",
 427                   0 /* allow-unknown */, &setlist);
 428   add_prefix_cmd ("tcp", class_maintenance, show_tcp_cmd, _("\
 429 TCP protocol specific variables\n\
 430 Configure variables specific to remote TCP connections"),
 431                   &tcp_show_cmdlist, "show tcp ",
 432                   0 /* allow-unknown */, &showlist);
 433
 434   add_setshow_boolean_cmd ("auto-retry", class_obscure,
 435                            &tcp_auto_retry, _("\
 436 Set auto-retry on socket connect"), _("\
 437 Show auto-retry on socket connect"),
 438                            NULL, NULL, NULL,
 439                            &tcp_set_cmdlist, &tcp_show_cmdlist);
 440
 441   add_setshow_uinteger_cmd ("connect-timeout", class_obscure,
 442                             &tcp_retry_limit, _("\
 443 Set timeout limit in seconds for socket connection"), _("\
 444 Show timeout limit in seconds for socket connection"), _("\
 445 If set to \"unlimited\", GDB will keep attempting to establish a\n\
 446 connection forever, unless interrupted with Ctrl-c.\n\
 447 The default is 15 seconds."),
 448                             NULL, NULL,
 449                             &tcp_set_cmdlist, &tcp_show_cmdlist);
 450 }