src/core/resolv.c

   1 /*
   2  * Copyright (C) 2007 Michael Brown <mbrown@fensystems.co.uk>.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License as
   6  * published by the Free Software Foundation; either version 2 of the
   7  * License, or any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  17  * 02110-1301, USA.
  18  *
  19  * You can also choose to distribute this program under the terms of
  20  * the Unmodified Binary Distribution Licence (as given in the file
  21  * COPYING.UBDL), provided that you have satisfied its requirements.
  22  */
  23
  24 FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
  25
  26 #include <stdint.h>
  27 #include <stdlib.h>
  28 #include <string.h>
  29 #include <errno.h>
  30 #include <ipxe/xfer.h>
  31 #include <ipxe/open.h>
  32 #include <ipxe/process.h>
  33 #include <ipxe/socket.h>
  34 #include <ipxe/resolv.h>
  35
  36 /** @file
  37  *
  38  * Name resolution
  39  *
  40  */
  41
  42 /***************************************************************************
  43  *
  44  * Name resolution interfaces
  45  *
  46  ***************************************************************************
  47  */
  48
  49 /**
  50  * Name resolved
  51  *
  52  * @v intf              Object interface
  53  * @v sa                Completed socket address (if successful)
  54  */
  55 void resolv_done ( struct interface *intf, struct sockaddr *sa ) {
  56         struct interface *dest;
  57         resolv_done_TYPE ( void * ) *op =
  58                 intf_get_dest_op ( intf, resolv_done, &dest );
  59         void *object = intf_object ( dest );
  60
  61         DBGC ( INTF_COL ( intf ), "INTF " INTF_INTF_FMT " resolv_done\n",
  62                INTF_INTF_DBG ( intf, dest ) );
  63
  64         if ( op ) {
  65                 op ( object, sa );
  66         } else {
  67                 /* Default is to ignore resolutions */
  68         }
  69
  70         intf_put ( dest );
  71 }
  72
  73 /***************************************************************************
  74  *
  75  * Numeric name resolver
  76  *
  77  ***************************************************************************
  78  */
  79
  80 /** A numeric name resolver */
  81 struct numeric_resolv {
  82         /** Reference counter */
  83         struct refcnt refcnt;
  84         /** Name resolution interface */
  85         struct interface resolv;
  86         /** Process */
  87         struct process process;
  88         /** Completed socket address */
  89         struct sockaddr sa;
  90         /** Overall status code */
  91         int rc;
  92 };
  93
  94 static void numeric_step ( struct numeric_resolv *numeric ) {
  95
  96         if ( numeric->rc == 0 )
  97                 resolv_done ( &numeric->resolv, &numeric->sa );
  98         intf_shutdown ( &numeric->resolv, numeric->rc );
  99 }
 100
 101 static struct process_descriptor numeric_process_desc =
 102         PROC_DESC_ONCE ( struct numeric_resolv, process, numeric_step );
 103
 104 static int numeric_resolv ( struct interface *resolv,
 105                             const char *name, struct sockaddr *sa ) {
 106         struct numeric_resolv *numeric;
 107
 108         /* Allocate and initialise structure */
 109         numeric = zalloc ( sizeof ( *numeric ) );
 110         if ( ! numeric )
 111                 return -ENOMEM;
 112         ref_init ( &numeric->refcnt, NULL );
 113         intf_init ( &numeric->resolv, &null_intf_desc, &numeric->refcnt );
 114         process_init ( &numeric->process, &numeric_process_desc,
 115                        &numeric->refcnt );
 116         memcpy ( &numeric->sa, sa, sizeof ( numeric->sa ) );
 117
 118         /* Attempt to resolve name */
 119         numeric->rc = sock_aton ( name, &numeric->sa );
 120
 121         /* Attach to parent interface, mortalise self, and return */
 122         intf_plug_plug ( &numeric->resolv, resolv );
 123         ref_put ( &numeric->refcnt );
 124         return 0;
 125 }
 126
 127 struct resolver numeric_resolver __resolver ( RESOLV_NUMERIC ) = {
 128         .name = "NUMERIC",
 129         .resolv = numeric_resolv,
 130 };
 131
 132 /***************************************************************************
 133  *
 134  * Name resolution multiplexer
 135  *
 136  ***************************************************************************
 137  */
 138
 139 /** A name resolution multiplexer */
 140 struct resolv_mux {
 141         /** Reference counter */
 142         struct refcnt refcnt;
 143         /** Parent name resolution interface */
 144         struct interface parent;
 145
 146         /** Child name resolution interface */
 147         struct interface child;
 148         /** Current child resolver */
 149         struct resolver *resolver;
 150
 151         /** Socket address to complete */
 152         struct sockaddr sa;
 153         /** Name to be resolved
 154          *
 155          * Must be at end of structure
 156          */
 157         char name[0];
 158 };
 159
 160 /**
 161  * Try current child name resolver
 162  *
 163  * @v mux               Name resolution multiplexer
 164  * @ret rc              Return status code
 165  */
 166 static int resmux_try ( struct resolv_mux *mux ) {
 167         struct resolver *resolver = mux->resolver;
 168         int rc;
 169
 170         DBGC ( mux, "RESOLV %p trying method %s\n", mux, resolver->name );
 171
 172         if ( ( rc = resolver->resolv ( &mux->child, mux->name,
 173                                        &mux->sa ) ) != 0 ) {
 174                 DBGC ( mux, "RESOLV %p could not use method %s: %s\n",
 175                        mux, resolver->name, strerror ( rc ) );
 176                 return rc;
 177         }
 178
 179         return 0;
 180 }
 181
 182 /**
 183  * Child resolved name
 184  *
 185  * @v mux               Name resolution multiplexer
 186  * @v sa                Completed socket address
 187  */
 188 static void resmux_child_resolv_done ( struct resolv_mux *mux,
 189                                        struct sockaddr *sa ) {
 190
 191         DBGC ( mux, "RESOLV %p resolved \"%s\" to %s using method %s\n",
 192                mux, mux->name, sock_ntoa ( sa ), mux->resolver->name );
 193
 194         /* Pass resolution to parent */
 195         resolv_done ( &mux->parent, sa );
 196 }
 197
 198 /**
 199  * Child finished resolution
 200  *
 201  * @v mux               Name resolution multiplexer
 202  * @v rc                Return status code
 203  */
 204 static void resmux_child_close ( struct resolv_mux *mux, int rc ) {
 205
 206         /* Restart child interface */
 207         intf_restart ( &mux->child, rc );
 208
 209         /* If this resolution succeeded, stop now */
 210         if ( rc == 0 ) {
 211                 DBGC ( mux, "RESOLV %p succeeded using method %s\n",
 212                        mux, mux->resolver->name );
 213                 goto finished;
 214         }
 215
 216         /* Attempt next child resolver, if possible */
 217         mux->resolver++;
 218         if ( mux->resolver >= table_end ( RESOLVERS ) ) {
 219                 DBGC ( mux, "RESOLV %p failed to resolve name\n", mux );
 220                 goto finished;
 221         }
 222         if ( ( rc = resmux_try ( mux ) ) != 0 )
 223                 goto finished;
 224
 225         /* Next resolver is now running */
 226         return;
 227
 228  finished:
 229         intf_shutdown ( &mux->parent, rc );
 230 }
 231
 232 /** Name resolution multiplexer child interface operations */
 233 static struct interface_operation resmux_child_op[] = {
 234         INTF_OP ( resolv_done, struct resolv_mux *, resmux_child_resolv_done ),
 235         INTF_OP ( intf_close, struct resolv_mux *, resmux_child_close ),
 236 };
 237
 238 /** Name resolution multiplexer child interface descriptor */
 239 static struct interface_descriptor resmux_child_desc =
 240         INTF_DESC ( struct resolv_mux, child, resmux_child_op );
 241
 242 /**
 243  * Start name resolution
 244  *
 245  * @v resolv            Name resolution interface
 246  * @v name              Name to resolve
 247  * @v sa                Socket address to complete
 248  * @ret rc              Return status code
 249  */
 250 int resolv ( struct interface *resolv, const char *name,
 251              struct sockaddr *sa ) {
 252         struct resolv_mux *mux;
 253         size_t name_len = ( strlen ( name ) + 1 );
 254         int rc;
 255
 256         /* Allocate and initialise structure */
 257         mux = zalloc ( sizeof ( *mux ) + name_len );
 258         if ( ! mux )
 259                 return -ENOMEM;
 260         ref_init ( &mux->refcnt, NULL );
 261         intf_init ( &mux->parent, &null_intf_desc, &mux->refcnt );
 262         intf_init ( &mux->child, &resmux_child_desc, &mux->refcnt );
 263         mux->resolver = table_start ( RESOLVERS );
 264         if ( sa )
 265                 memcpy ( &mux->sa, sa, sizeof ( mux->sa ) );
 266         memcpy ( mux->name, name, name_len );
 267
 268         DBGC ( mux, "RESOLV %p attempting to resolve \"%s\"\n", mux, name );
 269
 270         /* Start first resolver in chain.  There will always be at
 271          * least one resolver (the numeric resolver), so no need to
 272          * check for the zero-resolvers-available case.
 273          */
 274         if ( ( rc = resmux_try ( mux ) ) != 0 )
 275                 goto err;
 276
 277         /* Attach parent interface, mortalise self, and return */
 278         intf_plug_plug ( &mux->parent, resolv );
 279         ref_put ( &mux->refcnt );
 280         return 0;
 281
 282  err:
 283         ref_put ( &mux->refcnt );
 284         return rc;
 285 }
 286
 287 /***************************************************************************
 288  *
 289  * Named socket opening
 290  *
 291  ***************************************************************************
 292  */
 293
 294 /** A named socket */
 295 struct named_socket {
 296         /** Reference counter */
 297         struct refcnt refcnt;
 298         /** Data transfer interface */
 299         struct interface xfer;
 300         /** Name resolution interface */
 301         struct interface resolv;
 302         /** Communication semantics (e.g. SOCK_STREAM) */
 303         int semantics;
 304         /** Stored local socket address, if applicable */
 305         struct sockaddr local;
 306         /** Stored local socket address exists */
 307         int have_local;
 308 };
 309
 310 /**
 311  * Terminate named socket opener
 312  *
 313  * @v named             Named socket
 314  * @v rc                Reason for termination
 315  */
 316 static void named_close ( struct named_socket *named, int rc ) {
 317         /* Shut down interfaces */
 318         intf_shutdown ( &named->resolv, rc );
 319         intf_shutdown ( &named->xfer, rc );
 320 }
 321
 322 /**
 323  * Check flow control window
 324  *
 325  * @v named             Named socket
 326  * @ret len             Length of window
 327  */
 328 static size_t named_window ( struct named_socket *named __unused ) {
 329         /* Not ready for data until we have redirected away */
 330         return 0;
 331 }
 332
 333 /** Named socket opener data transfer interface operations */
 334 static struct interface_operation named_xfer_ops[] = {
 335         INTF_OP ( xfer_window, struct named_socket *, named_window ),
 336         INTF_OP ( intf_close, struct named_socket *, named_close ),
 337 };
 338
 339 /** Named socket opener data transfer interface descriptor */
 340 static struct interface_descriptor named_xfer_desc =
 341         INTF_DESC ( struct named_socket, xfer, named_xfer_ops );
 342
 343 /**
 344  * Name resolved
 345  *
 346  * @v named             Named socket
 347  * @v sa                Completed socket address
 348  */
 349 static void named_resolv_done ( struct named_socket *named,
 350                                 struct sockaddr *sa ) {
 351         int rc;
 352
 353         /* Nullify data transfer interface */
 354         intf_nullify ( &named->xfer );
 355
 356         /* Redirect data-xfer interface */
 357         if ( ( rc = xfer_redirect ( &named->xfer, LOCATION_SOCKET,
 358                                     named->semantics, sa,
 359                                     ( named->have_local ?
 360                                       &named->local : NULL ) ) ) != 0 ) {
 361                 /* Redirection failed - do not unplug data-xfer interface */
 362                 DBGC ( named, "NAMED %p could not redirect: %s\n",
 363                        named, strerror ( rc ) );
 364         } else {
 365                 /* Redirection succeeded - unplug data-xfer interface */
 366                 DBGC ( named, "NAMED %p redirected successfully\n", named );
 367                 intf_unplug ( &named->xfer );
 368         }
 369
 370         /* Terminate named socket opener */
 371         named_close ( named, rc );
 372 }
 373
 374 /** Named socket opener resolver interface operations */
 375 static struct interface_operation named_resolv_op[] = {
 376         INTF_OP ( intf_close, struct named_socket *, named_close ),
 377         INTF_OP ( resolv_done, struct named_socket *, named_resolv_done ),
 378 };
 379
 380 /** Named socket opener resolver interface descriptor */
 381 static struct interface_descriptor named_resolv_desc =
 382         INTF_DESC ( struct named_socket, resolv, named_resolv_op );
 383
 384 /**
 385  * Open named socket
 386  *
 387  * @v semantics         Communication semantics (e.g. SOCK_STREAM)
 388  * @v peer              Peer socket address to complete
 389  * @v name              Name to resolve
 390  * @v local             Local socket address, or NULL
 391  * @ret rc              Return status code
 392  */
 393 int xfer_open_named_socket ( struct interface *xfer, int semantics,
 394                              struct sockaddr *peer, const char *name,
 395                              struct sockaddr *local ) {
 396         struct named_socket *named;
 397         int rc;
 398
 399         /* Allocate and initialise structure */
 400         named = zalloc ( sizeof ( *named ) );
 401         if ( ! named )
 402                 return -ENOMEM;
 403         ref_init ( &named->refcnt, NULL );
 404         intf_init ( &named->xfer, &named_xfer_desc, &named->refcnt );
 405         intf_init ( &named->resolv, &named_resolv_desc, &named->refcnt );
 406         named->semantics = semantics;
 407         if ( local ) {
 408                 memcpy ( &named->local, local, sizeof ( named->local ) );
 409                 named->have_local = 1;
 410         }
 411
 412         DBGC ( named, "NAMED %p opening \"%s\"\n",
 413                named, name );
 414
 415         /* Start name resolution */
 416         if ( ( rc = resolv ( &named->resolv, name, peer ) ) != 0 )
 417                 goto err;
 418
 419         /* Attach parent interface, mortalise self, and return */
 420         intf_plug_plug ( &named->xfer, xfer );
 421         ref_put ( &named->refcnt );
 422         return 0;
 423
 424  err:
 425         ref_put ( &named->refcnt );
 426         return rc;
 427 }