gdb/ser-tcp.c

   1 /* Serial interface for raw TCP connections on Un*x like systems.
   2
   3    Copyright (C) 1992-2019 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 #include "netstuff.h"
  29
  30 #include <sys/types.h>
  31
  32 #ifdef HAVE_SYS_FILIO_H
  33 #include <sys/filio.h>  /* For FIONBIO.  */
  34 #endif
  35 #ifdef HAVE_SYS_IOCTL_H
  36 #include <sys/ioctl.h>  /* For FIONBIO.  */
  37 #endif
  38
  39 #include "gdb_sys_time.h"
  40
  41 #ifdef USE_WIN32API
  42 #include <winsock2.h>
  43 #include <wspiapi.h>
  44 #ifndef ETIMEDOUT
  45 #define ETIMEDOUT WSAETIMEDOUT
  46 #endif
  47 /* Gnulib defines close too, but gnulib's replacement
  48    doesn't call closesocket unless we import the
  49    socketlib module.  */
  50 #undef close
  51 #define close(fd) closesocket (fd)
  52 #define ioctl ioctlsocket
  53 #else
  54 #include <netinet/in.h>
  55 #include <arpa/inet.h>
  56 #include <netdb.h>
  57 #include <sys/socket.h>
  58 #include <netinet/tcp.h>
  59 #endif
  60
  61 #include <signal.h>
  62 #include "gdb_select.h"
  63 #include <algorithm>
  64
  65 #ifndef HAVE_SOCKLEN_T
  66 typedef int socklen_t;
  67 #endif
  68
  69 /* For "set tcp" and "show tcp".  */
  70
  71 static struct cmd_list_element *tcp_set_cmdlist;
  72 static struct cmd_list_element *tcp_show_cmdlist;
  73
  74 /* Whether to auto-retry refused connections.  */
  75
  76 static int tcp_auto_retry = 1;
  77
  78 /* Timeout period for connections, in seconds.  */
  79
  80 static unsigned int tcp_retry_limit = 15;
  81
  82 /* How many times per second to poll deprecated_ui_loop_hook.  */
  83
  84 #define POLL_INTERVAL 5
  85
  86 /* Helper function to wait a while.  If SOCK is not -1, wait on its
  87    file descriptor.  Otherwise just wait on a timeout, updating
  88    *POLLS.  Returns -1 on timeout or interrupt, otherwise the value of
  89    select.  */
  90
  91 static int
  92 wait_for_connect (int sock, unsigned int *polls)
  93 {
  94   struct timeval t;
  95   int n;
  96
  97   /* While we wait for the connect to complete,
  98      poll the UI so it can update or the user can
  99      interrupt.  */
 100   if (deprecated_ui_loop_hook && deprecated_ui_loop_hook (0))
 101     {
 102       errno = EINTR;
 103       return -1;
 104     }
 105
 106   /* Check for timeout.  */
 107   if (*polls > tcp_retry_limit * POLL_INTERVAL)
 108     {
 109       errno = ETIMEDOUT;
 110       return -1;
 111     }
 112
 113   /* Back off to polling once per second after the first POLL_INTERVAL
 114      polls.  */
 115   if (*polls < POLL_INTERVAL)
 116     {
 117       t.tv_sec = 0;
 118       t.tv_usec = 1000000 / POLL_INTERVAL;
 119     }
 120   else
 121     {
 122       t.tv_sec = 1;
 123       t.tv_usec = 0;
 124     }
 125
 126   if (sock >= 0)
 127     {
 128       fd_set rset, wset, eset;
 129
 130       FD_ZERO (&rset);
 131       FD_SET (sock, &rset);
 132       wset = rset;
 133       eset = rset;
 134
 135       /* POSIX systems return connection success or failure by signalling
 136          wset.  Windows systems return success in wset and failure in
 137          eset.
 138
 139          We must call select here, rather than gdb_select, because
 140          the serial structure has not yet been initialized - the
 141          MinGW select wrapper will not know that this FD refers
 142          to a socket.  */
 143       n = select (sock + 1, &rset, &wset, &eset, &t);
 144     }
 145   else
 146     /* Use gdb_select here, since we have no file descriptors, and on
 147        Windows, plain select doesn't work in that case.  */
 148     n = gdb_select (0, NULL, NULL, NULL, &t);
 149
 150   /* If we didn't time out, only count it as one poll.  */
 151   if (n > 0 || *polls < POLL_INTERVAL)
 152     (*polls)++;
 153   else
 154     (*polls) += POLL_INTERVAL;
 155
 156   return n;
 157 }
 158
 159 /* Try to connect to the host represented by AINFO.  If the connection
 160    succeeds, return its socket.  Otherwise, return -1 and set ERRNO
 161    accordingly.  POLLS is used when 'connect' returns EINPROGRESS, and
 162    we need to invoke 'wait_for_connect' to obtain the status.  */
 163
 164 static int
 165 try_connect (const struct addrinfo *ainfo, unsigned int *polls)
 166 {
 167   int sock = gdb_socket_cloexec (ainfo->ai_family, ainfo->ai_socktype,
 168                                  ainfo->ai_protocol);
 169
 170   if (sock < 0)
 171     return -1;
 172
 173   /* Set socket nonblocking.  */
 174 #ifdef USE_WIN32API
 175   u_long ioarg = 1;
 176 #else
 177   int ioarg = 1;
 178 #endif
 179
 180   ioctl (sock, FIONBIO, &ioarg);
 181
 182   /* Use Non-blocking connect.  connect() will return 0 if connected
 183      already.  */
 184   if (connect (sock, ainfo->ai_addr, ainfo->ai_addrlen) < 0)
 185     {
 186 #ifdef USE_WIN32API
 187       int err = WSAGetLastError();
 188 #else
 189       int err = errno;
 190 #endif
 191
 192       /* If we've got a "connection refused" error, just return
 193          -1.  The caller will know what to do.  */
 194       if (
 195 #ifdef USE_WIN32API
 196           err == WSAECONNREFUSED
 197 #else
 198           err == ECONNREFUSED
 199 #endif
 200           )
 201         {
 202           close (sock);
 203           errno = err;
 204           return -1;
 205         }
 206
 207       if (
 208           /* Any other error (except EINPROGRESS) will be "swallowed"
 209              here.  We return without specifying a return value, and
 210              set errno if the caller wants to inspect what
 211              happened.  */
 212 #ifdef USE_WIN32API
 213           /* Under Windows, calling "connect" with a non-blocking socket
 214              results in WSAEWOULDBLOCK, not WSAEINPROGRESS.  */
 215           err != WSAEWOULDBLOCK
 216 #else
 217           err != EINPROGRESS
 218 #endif
 219           )
 220         {
 221           close (sock);
 222           errno = err;
 223           return -1;
 224         }
 225
 226       /* Looks like we need to wait for the connect.  */
 227       int n;
 228
 229       do
 230         n = wait_for_connect (sock, polls);
 231       while (n == 0);
 232
 233       if (n < 0)
 234         {
 235           int saved_errno = errno;
 236
 237           /* A negative value here means that we either timed out or
 238              got interrupted by the user.  Just return.  */
 239           close (sock);
 240           errno = saved_errno;
 241           return -1;
 242         }
 243     }
 244
 245   /* Got something.  Is it an error?  */
 246   int err;
 247   socklen_t len = sizeof (err);
 248
 249   /* On Windows, the fourth parameter to getsockopt is a "char *";
 250      on UNIX systems it is generally "void *".  The cast to "char *"
 251      is OK everywhere, since in C++ any data pointer type can be
 252      implicitly converted to "void *".  */
 253   int ret = getsockopt (sock, SOL_SOCKET, SO_ERROR, (char *) &err, &len);
 254
 255   if (ret < 0)
 256     {
 257       int saved_errno = errno;
 258
 259       close (sock);
 260       errno = saved_errno;
 261       return -1;
 262     }
 263   else if (ret == 0 && err != 0)
 264     {
 265       close (sock);
 266       errno = err;
 267       return -1;
 268     }
 269
 270   /* The connection succeeded.  Return the socket.  */
 271   return sock;
 272 }
 273
 274 /* Open a tcp socket.  */
 275
 276 int
 277 net_open (struct serial *scb, const char *name)
 278 {
 279   struct addrinfo hint;
 280   struct addrinfo *ainfo;
 281
 282   memset (&hint, 0, sizeof (hint));
 283   /* Assume no prefix will be passed, therefore we should use
 284      AF_UNSPEC.  */
 285   hint.ai_family = AF_UNSPEC;
 286   hint.ai_socktype = SOCK_STREAM;
 287   hint.ai_protocol = IPPROTO_TCP;
 288
 289   parsed_connection_spec parsed = parse_connection_spec (name, &hint);
 290
 291   if (parsed.port_str.empty ())
 292     error (_("Missing port on hostname '%s'"), name);
 293
 294   int r = getaddrinfo (parsed.host_str.c_str (),
 295                        parsed.port_str.c_str (),
 296                        &hint, &ainfo);
 297
 298   if (r != 0)
 299     {
 300       fprintf_unfiltered (gdb_stderr, _("%s: cannot resolve name: %s\n"),
 301                           name, gai_strerror (r));
 302       errno = ENOENT;
 303       return -1;
 304     }
 305
 306   scoped_free_addrinfo free_ainfo (ainfo);
 307
 308   /* Flag to indicate whether we've got a connection refused.  It will
 309      be true if any of the connections tried was refused.  */
 310   bool got_connrefused;
 311   /* If a connection succeeeds, SUCCESS_AINFO will point to the
 312      'struct addrinfo' that succeed.  */
 313   struct addrinfo *success_ainfo = NULL;
 314   unsigned int polls = 0;
 315
 316   /* Assume the worst.  */
 317   scb->fd = -1;
 318
 319   do
 320     {
 321       got_connrefused = false;
 322
 323       for (struct addrinfo *iter = ainfo; iter != NULL; iter = iter->ai_next)
 324         {
 325           /* Iterate over the list of possible addresses to connect
 326              to.  For each, we'll try to connect and see if it
 327              succeeds.  */
 328           int sock = try_connect (iter, &polls);
 329
 330           if (sock >= 0)
 331             {
 332               /* We've gotten a successful connection.  Save its
 333                  'struct addrinfo', the socket, and break.  */
 334               success_ainfo = iter;
 335               scb->fd = sock;
 336               break;
 337             }
 338           else if (
 339 #ifdef USE_WIN32API
 340           errno == WSAECONNREFUSED
 341 #else
 342           errno == ECONNREFUSED
 343 #endif
 344                    )
 345             got_connrefused = true;
 346         }
 347     }
 348   /* Just retry if:
 349
 350      - tcp_auto_retry is true, and
 351      - We haven't gotten a connection yet, and
 352      - Any of our connection attempts returned with ECONNREFUSED, and
 353      - wait_for_connect signals that we can keep going.  */
 354   while (tcp_auto_retry
 355          && success_ainfo == NULL
 356          && got_connrefused
 357          && wait_for_connect (-1, &polls) >= 0);
 358
 359   if (success_ainfo == NULL)
 360     {
 361       net_close (scb);
 362       return -1;
 363     }
 364
 365   /* Turn off nonblocking.  */
 366 #ifdef USE_WIN32API
 367   u_long ioarg = 0;
 368 #else
 369   int ioarg = 0;
 370 #endif
 371
 372   ioctl (scb->fd, FIONBIO, &ioarg);
 373
 374   if (success_ainfo->ai_protocol == IPPROTO_TCP)
 375     {
 376       /* Disable Nagle algorithm.  Needed in some cases.  */
 377       int tmp = 1;
 378
 379       setsockopt (scb->fd, IPPROTO_TCP, TCP_NODELAY,
 380                   (char *) &tmp, sizeof (tmp));
 381     }
 382
 383 #ifdef SIGPIPE
 384   /* If we don't do this, then GDB simply exits
 385      when the remote side dies.  */
 386   signal (SIGPIPE, SIG_IGN);
 387 #endif
 388
 389   return 0;
 390 }
 391
 392 void
 393 net_close (struct serial *scb)
 394 {
 395   if (scb->fd == -1)
 396     return;
 397
 398   close (scb->fd);
 399   scb->fd = -1;
 400 }
 401
 402 int
 403 net_read_prim (struct serial *scb, size_t count)
 404 {
 405   /* Need to cast to silence -Wpointer-sign on MinGW, as Winsock's
 406      'recv' takes 'char *' as second argument, while 'scb->buf' is
 407      'unsigned char *'.  */
 408   return recv (scb->fd, (char *) scb->buf, count, 0);
 409 }
 410
 411 int
 412 net_write_prim (struct serial *scb, const void *buf, size_t count)
 413 {
 414   /* On Windows, the second parameter to send is a "const char *"; on
 415      UNIX systems it is generally "const void *".  The cast to "const
 416      char *" is OK everywhere, since in C++ any data pointer type can
 417      be implicitly converted to "const void *".  */
 418   return send (scb->fd, (const char *) buf, count, 0);
 419 }
 420
 421 int
 422 ser_tcp_send_break (struct serial *scb)
 423 {
 424   /* Send telnet IAC and BREAK characters.  */
 425   return (serial_write (scb, "\377\363", 2));
 426 }
 427
 428 /* Support for "set tcp" and "show tcp" commands.  */
 429
 430 static void
 431 set_tcp_cmd (const char *args, int from_tty)
 432 {
 433   help_list (tcp_set_cmdlist, "set tcp ", all_commands, gdb_stdout);
 434 }
 435
 436 static void
 437 show_tcp_cmd (const char *args, int from_tty)
 438 {
 439   help_list (tcp_show_cmdlist, "show tcp ", all_commands, gdb_stdout);
 440 }
 441
 442 #ifndef USE_WIN32API
 443
 444 /* The TCP ops.  */
 445
 446 static const struct serial_ops tcp_ops =
 447 {
 448   "tcp",
 449   net_open,
 450   net_close,
 451   NULL,
 452   ser_base_readchar,
 453   ser_base_write,
 454   ser_base_flush_output,
 455   ser_base_flush_input,
 456   ser_tcp_send_break,
 457   ser_base_raw,
 458   ser_base_get_tty_state,
 459   ser_base_copy_tty_state,
 460   ser_base_set_tty_state,
 461   ser_base_print_tty_state,
 462   ser_base_setbaudrate,
 463   ser_base_setstopbits,
 464   ser_base_setparity,
 465   ser_base_drain_output,
 466   ser_base_async,
 467   net_read_prim,
 468   net_write_prim
 469 };
 470
 471 #endif /* USE_WIN32API */
 472
 473 void
 474 _initialize_ser_tcp (void)
 475 {
 476 #ifdef USE_WIN32API
 477   /* Do nothing; the TCP serial operations will be initialized in
 478      ser-mingw.c.  */
 479 #else
 480   serial_add_interface (&tcp_ops);
 481 #endif /* USE_WIN32API */
 482
 483   add_prefix_cmd ("tcp", class_maintenance, set_tcp_cmd, _("\
 484 TCP protocol specific variables\n\
 485 Configure variables specific to remote TCP connections"),
 486                   &tcp_set_cmdlist, "set tcp ",
 487                   0 /* allow-unknown */, &setlist);
 488   add_prefix_cmd ("tcp", class_maintenance, show_tcp_cmd, _("\
 489 TCP protocol specific variables\n\
 490 Configure variables specific to remote TCP connections"),
 491                   &tcp_show_cmdlist, "show tcp ",
 492                   0 /* allow-unknown */, &showlist);
 493
 494   add_setshow_boolean_cmd ("auto-retry", class_obscure,
 495                            &tcp_auto_retry, _("\
 496 Set auto-retry on socket connect"), _("\
 497 Show auto-retry on socket connect"),
 498                            NULL, NULL, NULL,
 499                            &tcp_set_cmdlist, &tcp_show_cmdlist);
 500
 501   add_setshow_uinteger_cmd ("connect-timeout", class_obscure,
 502                             &tcp_retry_limit, _("\
 503 Set timeout limit in seconds for socket connection"), _("\
 504 Show timeout limit in seconds for socket connection"), _("\
 505 If set to \"unlimited\", GDB will keep attempting to establish a\n\
 506 connection forever, unless interrupted with Ctrl-c.\n\
 507 The default is 15 seconds."),
 508                             NULL, NULL,
 509                             &tcp_set_cmdlist, &tcp_show_cmdlist);
 510 }