lib/liblwip/api/api_lib.c

   1 /**
   2  * @file
   3  * Sequential API External module
   4  *
   5  */
   6
   7 /*
   8  * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
   9  * All rights reserved.
  10  *
  11  * Redistribution and use in source and binary forms, with or without modification,
  12  * are permitted provided that the following conditions are met:
  13  *
  14  * 1. Redistributions of source code must retain the above copyright notice,
  15  *    this list of conditions and the following disclaimer.
  16  * 2. Redistributions in binary form must reproduce the above copyright notice,
  17  *    this list of conditions and the following disclaimer in the documentation
  18  *    and/or other materials provided with the distribution.
  19  * 3. The name of the author may not be used to endorse or promote products
  20  *    derived from this software without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
  23  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
  24  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
  25  * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  26  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
  27  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  28  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  29  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
  30  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
  31  * OF SUCH DAMAGE.
  32  *
  33  * This file is part of the lwIP TCP/IP stack.
  34  *
  35  * Author: Adam Dunkels <adam@sics.se>
  36  *
  37  */
  38
  39 /* This is the part of the API that is linked with
  40    the application */
  41
  42 #include "lwip/opt.h"
  43
  44 #if LWIP_NETCONN /* don't build if not configured for use in lwipopts.h */
  45
  46 #include "lwip/api.h"
  47 #include "lwip/tcpip.h"
  48 #include "lwip/memp.h"
  49
  50 #include "lwip/ip.h"
  51 #include "lwip/raw.h"
  52 #include "lwip/udp.h"
  53 #include "lwip/tcp.h"
  54
  55 #include <string.h>
  56
  57 /**
  58  * Create a new netconn (of a specific type) that has a callback function.
  59  * The corresponding pcb is also created.
  60  *
  61  * @param t the type of 'connection' to create (@see enum netconn_type)
  62  * @param proto the IP protocol for RAW IP pcbs
  63  * @param callback a function to call on status changes (RX available, TX'ed)
  64  * @return a newly allocated struct netconn or
  65  *         NULL on memory error
  66  */
  67 struct netconn*
  68 netconn_new_with_proto_and_callback(enum netconn_type t, u8_t proto, netconn_callback callback)
  69 {
  70   struct netconn *conn;
  71   struct api_msg msg;
  72
  73   conn = netconn_alloc(t, callback);
  74   if (conn != NULL) {
  75     msg.function = do_newconn;
  76     msg.msg.msg.n.proto = proto;
  77     msg.msg.conn = conn;
  78     if (TCPIP_APIMSG(&msg) != ERR_OK) {
  79       LWIP_ASSERT("freeing conn without freeing pcb", conn->pcb.tcp == NULL);
  80       LWIP_ASSERT("conn has no op_completed", sys_sem_valid(&conn->op_completed));
  81       LWIP_ASSERT("conn has no recvmbox", sys_mbox_valid(&conn->recvmbox));
  82 #if LWIP_TCP
  83       LWIP_ASSERT("conn->acceptmbox shouldn't exist", !sys_mbox_valid(&conn->acceptmbox));
  84 #endif /* LWIP_TCP */
  85       sys_sem_free(&conn->op_completed);
  86       sys_mbox_free(&conn->recvmbox);
  87       memp_free(MEMP_NETCONN, conn);
  88       return NULL;
  89     }
  90   }
  91   return conn;
  92 }
  93
  94 /**
  95  * Close a netconn 'connection' and free its resources.
  96  * UDP and RAW connection are completely closed, TCP pcbs might still be in a waitstate
  97  * after this returns.
  98  *
  99  * @param conn the netconn to delete
 100  * @return ERR_OK if the connection was deleted
 101  */
 102 err_t
 103 netconn_delete(struct netconn *conn)
 104 {
 105   struct api_msg msg;
 106
 107   /* No ASSERT here because possible to get a (conn == NULL) if we got an accept error */
 108   if (conn == NULL) {
 109     return ERR_OK;
 110   }
 111
 112   msg.function = do_delconn;
 113   msg.msg.conn = conn;
 114   tcpip_apimsg(&msg);
 115
 116   netconn_free(conn);
 117
 118   /* don't care for return value of do_delconn since it only calls void functions */
 119
 120   return ERR_OK;
 121 }
 122
 123 /**
 124  * Get the local or remote IP address and port of a netconn.
 125  * For RAW netconns, this returns the protocol instead of a port!
 126  *
 127  * @param conn the netconn to query
 128  * @param addr a pointer to which to save the IP address
 129  * @param port a pointer to which to save the port (or protocol for RAW)
 130  * @param local 1 to get the local IP address, 0 to get the remote one
 131  * @return ERR_CONN for invalid connections
 132  *         ERR_OK if the information was retrieved
 133  */
 134 err_t
 135 netconn_getaddr(struct netconn *conn, ip_addr_t *addr, u16_t *port, u8_t local)
 136 {
 137   struct api_msg msg;
 138   err_t err;
 139
 140   LWIP_ERROR("netconn_getaddr: invalid conn", (conn != NULL), return ERR_ARG;);
 141   LWIP_ERROR("netconn_getaddr: invalid addr", (addr != NULL), return ERR_ARG;);
 142   LWIP_ERROR("netconn_getaddr: invalid port", (port != NULL), return ERR_ARG;);
 143
 144   msg.function = do_getaddr;
 145   msg.msg.conn = conn;
 146   msg.msg.msg.ad.ipaddr = addr;
 147   msg.msg.msg.ad.port = port;
 148   msg.msg.msg.ad.local = local;
 149   err = TCPIP_APIMSG(&msg);
 150
 151   NETCONN_SET_SAFE_ERR(conn, err);
 152   return err;
 153 }
 154
 155 /**
 156  * Bind a netconn to a specific local IP address and port.
 157  * Binding one netconn twice might not always be checked correctly!
 158  *
 159  * @param conn the netconn to bind
 160  * @param addr the local IP address to bind the netconn to (use IP_ADDR_ANY
 161  *             to bind to all addresses)
 162  * @param port the local port to bind the netconn to (not used for RAW)
 163  * @return ERR_OK if bound, any other err_t on failure
 164  */
 165 err_t
 166 netconn_bind(struct netconn *conn, ip_addr_t *addr, u16_t port)
 167 {
 168   struct api_msg msg;
 169   err_t err;
 170
 171   LWIP_ERROR("netconn_bind: invalid conn", (conn != NULL), return ERR_ARG;);
 172
 173   msg.function = do_bind;
 174   msg.msg.conn = conn;
 175   msg.msg.msg.bc.ipaddr = addr;
 176   msg.msg.msg.bc.port = port;
 177   err = TCPIP_APIMSG(&msg);
 178
 179   NETCONN_SET_SAFE_ERR(conn, err);
 180   return err;
 181 }
 182
 183 /**
 184  * Connect a netconn to a specific remote IP address and port.
 185  *
 186  * @param conn the netconn to connect
 187  * @param addr the remote IP address to connect to
 188  * @param port the remote port to connect to (no used for RAW)
 189  * @return ERR_OK if connected, return value of tcp_/udp_/raw_connect otherwise
 190  */
 191 err_t
 192 netconn_connect(struct netconn *conn, ip_addr_t *addr, u16_t port)
 193 {
 194   struct api_msg msg;
 195   err_t err;
 196
 197   LWIP_ERROR("netconn_connect: invalid conn", (conn != NULL), return ERR_ARG;);
 198
 199   msg.function = do_connect;
 200   msg.msg.conn = conn;
 201   msg.msg.msg.bc.ipaddr = addr;
 202   msg.msg.msg.bc.port = port;
 203   /* This is the only function which need to not block tcpip_thread */
 204   err = tcpip_apimsg(&msg);
 205
 206   NETCONN_SET_SAFE_ERR(conn, err);
 207   return err;
 208 }
 209
 210 /**
 211  * Disconnect a netconn from its current peer (only valid for UDP netconns).
 212  *
 213  * @param conn the netconn to disconnect
 214  * @return TODO: return value is not set here...
 215  */
 216 err_t
 217 netconn_disconnect(struct netconn *conn)
 218 {
 219   struct api_msg msg;
 220   err_t err;
 221
 222   LWIP_ERROR("netconn_disconnect: invalid conn", (conn != NULL), return ERR_ARG;);
 223
 224   msg.function = do_disconnect;
 225   msg.msg.conn = conn;
 226   err = TCPIP_APIMSG(&msg);
 227
 228   NETCONN_SET_SAFE_ERR(conn, err);
 229   return err;
 230 }
 231
 232 /**
 233  * Set a TCP netconn into listen mode
 234  *
 235  * @param conn the tcp netconn to set to listen mode
 236  * @param backlog the listen backlog, only used if TCP_LISTEN_BACKLOG==1
 237  * @return ERR_OK if the netconn was set to listen (UDP and RAW netconns
 238  *         don't return any error (yet?))
 239  */
 240 err_t
 241 netconn_listen_with_backlog(struct netconn *conn, u8_t backlog)
 242 {
 243   struct api_msg msg;
 244   err_t err;
 245
 246   /* This does no harm. If TCP_LISTEN_BACKLOG is off, backlog is unused. */
 247   LWIP_UNUSED_ARG(backlog);
 248
 249   LWIP_ERROR("netconn_listen: invalid conn", (conn != NULL), return ERR_ARG;);
 250
 251   msg.function = do_listen;
 252   msg.msg.conn = conn;
 253 #if TCP_LISTEN_BACKLOG
 254   msg.msg.msg.lb.backlog = backlog;
 255 #endif /* TCP_LISTEN_BACKLOG */
 256   err = TCPIP_APIMSG(&msg);
 257
 258   NETCONN_SET_SAFE_ERR(conn, err);
 259   return err;
 260 }
 261
 262 /**
 263  * Accept a new connection on a TCP listening netconn.
 264  *
 265  * @param conn the TCP listen netconn
 266  * @param new_conn pointer where the new connection is stored
 267  * @return ERR_OK if a new connection has been received or an error
 268  *                code otherwise
 269  */
 270 err_t
 271 netconn_accept(struct netconn *conn, struct netconn **new_conn)
 272 {
 273 #if LWIP_TCP
 274   struct netconn *newconn;
 275   err_t err;
 276 #if TCP_LISTEN_BACKLOG
 277   struct api_msg msg;
 278 #endif /* TCP_LISTEN_BACKLOG */
 279
 280   LWIP_ERROR("netconn_accept: invalid pointer",    (new_conn != NULL),                  return ERR_ARG;);
 281   *new_conn = NULL;
 282   LWIP_ERROR("netconn_accept: invalid conn",       (conn != NULL),                      return ERR_ARG;);
 283   LWIP_ERROR("netconn_accept: invalid acceptmbox", sys_mbox_valid(&conn->acceptmbox),   return ERR_ARG;);
 284
 285   err = conn->last_err;
 286   if (ERR_IS_FATAL(err)) {
 287     /* don't recv on fatal errors: this might block the application task
 288        waiting on acceptmbox forever! */
 289     return err;
 290   }
 291
 292 #if LWIP_SO_RCVTIMEO
 293   if (sys_arch_mbox_fetch(&conn->acceptmbox, (void **)&newconn, conn->recv_timeout) == SYS_ARCH_TIMEOUT) {
 294     NETCONN_SET_SAFE_ERR(conn, ERR_TIMEOUT);
 295     return ERR_TIMEOUT;
 296   }
 297 #else
 298   sys_arch_mbox_fetch(&conn->acceptmbox, (void **)&newconn, 0);
 299 #endif /* LWIP_SO_RCVTIMEO*/
 300   /* Register event with callback */
 301   API_EVENT(conn, NETCONN_EVT_RCVMINUS, 0);
 302
 303   if (newconn == NULL) {
 304     /* connection has been closed */
 305     NETCONN_SET_SAFE_ERR(conn, ERR_CLSD);
 306     return ERR_CLSD;
 307   }
 308 #if TCP_LISTEN_BACKLOG
 309   /* Let the stack know that we have accepted the connection. */
 310   msg.function = do_recv;
 311   msg.msg.conn = conn;
 312   /* don't care for the return value of do_recv */
 313   TCPIP_APIMSG(&msg);
 314 #endif /* TCP_LISTEN_BACKLOG */
 315
 316   *new_conn = newconn;
 317   /* don't set conn->last_err: it's only ERR_OK, anyway */
 318   return ERR_OK;
 319 #else /* LWIP_TCP */
 320   LWIP_UNUSED_ARG(conn);
 321   LWIP_UNUSED_ARG(new_conn);
 322   return ERR_ARG;
 323 #endif /* LWIP_TCP */
 324 }
 325
 326 /**
 327  * Receive data: actual implementation that doesn't care whether pbuf or netbuf
 328  * is received
 329  *
 330  * @param conn the netconn from which to receive data
 331  * @param new_buf pointer where a new pbuf/netbuf is stored when received data
 332  * @return ERR_OK if data has been received, an error code otherwise (timeout,
 333  *                memory error or another error)
 334  */
 335 static err_t
 336 netconn_recv_data(struct netconn *conn, void **new_buf)
 337 {
 338   void *buf = NULL;
 339   u16_t len;
 340   err_t err;
 341 #if LWIP_TCP
 342   struct api_msg msg;
 343 #endif /* LWIP_TCP */
 344
 345   LWIP_ERROR("netconn_recv: invalid pointer", (new_buf != NULL), return ERR_ARG;);
 346   *new_buf = NULL;
 347   LWIP_ERROR("netconn_recv: invalid conn",    (conn != NULL),    return ERR_ARG;);
 348   LWIP_ERROR("netconn_accept: invalid recvmbox", sys_mbox_valid(&conn->recvmbox), return ERR_CONN;);
 349
 350   err = conn->last_err;
 351   if (ERR_IS_FATAL(err)) {
 352     /* don't recv on fatal errors: this might block the application task
 353        waiting on recvmbox forever! */
 354     /* @todo: this does not allow us to fetch data that has been put into recvmbox
 355        before the fatal error occurred - is that a problem? */
 356     return err;
 357   }
 358
 359 #if LWIP_SO_RCVTIMEO
 360   if (sys_arch_mbox_fetch(&conn->recvmbox, &buf, conn->recv_timeout) == SYS_ARCH_TIMEOUT) {
 361     NETCONN_SET_SAFE_ERR(conn, ERR_TIMEOUT);
 362     return ERR_TIMEOUT;
 363   }
 364 #else
 365   sys_arch_mbox_fetch(&conn->recvmbox, &buf, 0);
 366 #endif /* LWIP_SO_RCVTIMEO*/
 367
 368 #if LWIP_TCP
 369   if (conn->type == NETCONN_TCP) {
 370     if (!netconn_get_noautorecved(conn) || (buf == NULL)) {
 371       /* Let the stack know that we have taken the data. */
 372       /* TODO: Speedup: Don't block and wait for the answer here
 373          (to prevent multiple thread-switches). */
 374       msg.function = do_recv;
 375       msg.msg.conn = conn;
 376       if (buf != NULL) {
 377         msg.msg.msg.r.len = ((struct pbuf *)buf)->tot_len;
 378       } else {
 379         msg.msg.msg.r.len = 1;
 380       }
 381       /* don't care for the return value of do_recv */
 382       TCPIP_APIMSG(&msg);
 383     }
 384
 385     /* If we are closed, we indicate that we no longer wish to use the socket */
 386     if (buf == NULL) {
 387       API_EVENT(conn, NETCONN_EVT_RCVMINUS, 0);
 388       /* Avoid to lose any previous error code */
 389       NETCONN_SET_SAFE_ERR(conn, ERR_CLSD);
 390       return ERR_CLSD;
 391     }
 392     len = ((struct pbuf *)buf)->tot_len;
 393   }
 394 #endif /* LWIP_TCP */
 395 #if LWIP_TCP && (LWIP_UDP || LWIP_RAW)
 396   else
 397 #endif /* LWIP_TCP && (LWIP_UDP || LWIP_RAW) */
 398 #if (LWIP_UDP || LWIP_RAW)
 399   {
 400     LWIP_ASSERT("buf != NULL", buf != NULL);
 401     len = netbuf_len((struct netbuf *)buf);
 402   }
 403 #endif /* (LWIP_UDP || LWIP_RAW) */
 404
 405   SYS_ARCH_DEC(conn->recv_avail, len);
 406   /* Register event with callback */
 407   API_EVENT(conn, NETCONN_EVT_RCVMINUS, len);
 408
 409   LWIP_DEBUGF(API_LIB_DEBUG, ("netconn_recv_data: received %p, len=%"U16_F"\n", buf, len));
 410
 411   *new_buf = buf;
 412   /* don't set conn->last_err: it's only ERR_OK, anyway */
 413   return ERR_OK;
 414 }
 415
 416 /**
 417  * Receive data (in form of a pbuf) from a TCP netconn
 418  *
 419  * @param conn the netconn from which to receive data
 420  * @param new_buf pointer where a new pbuf is stored when received data
 421  * @return ERR_OK if data has been received, an error code otherwise (timeout,
 422  *                memory error or another error)
 423  *         ERR_ARG if conn is not a TCP netconn
 424  */
 425 err_t
 426 netconn_recv_tcp_pbuf(struct netconn *conn, struct pbuf **new_buf)
 427 {
 428   LWIP_ERROR("netconn_recv: invalid conn", (conn != NULL) &&
 429              netconn_type(conn) == NETCONN_TCP, return ERR_ARG;);
 430
 431   return netconn_recv_data(conn, (void **)new_buf);
 432 }
 433
 434 /**
 435  * Receive data (in form of a netbuf containing a packet buffer) from a netconn
 436  *
 437  * @param conn the netconn from which to receive data
 438  * @param new_buf pointer where a new netbuf is stored when received data
 439  * @return ERR_OK if data has been received, an error code otherwise (timeout,
 440  *                memory error or another error)
 441  */
 442 err_t
 443 netconn_recv(struct netconn *conn, struct netbuf **new_buf)
 444 {
 445 #if LWIP_TCP
 446   struct netbuf *buf = NULL;
 447   err_t err;
 448 #endif /* LWIP_TCP */
 449
 450   LWIP_ERROR("netconn_recv: invalid pointer", (new_buf != NULL), return ERR_ARG;);
 451   *new_buf = NULL;
 452   LWIP_ERROR("netconn_recv: invalid conn",    (conn != NULL),    return ERR_ARG;);
 453   LWIP_ERROR("netconn_accept: invalid recvmbox", sys_mbox_valid(&conn->recvmbox), return ERR_CONN;);
 454
 455 #if LWIP_TCP
 456   if (conn->type == NETCONN_TCP) {
 457     struct pbuf *p = NULL;
 458     /* This is not a listening netconn, since recvmbox is set */
 459
 460     buf = (struct netbuf *)memp_malloc(MEMP_NETBUF);
 461     if (buf == NULL) {
 462       NETCONN_SET_SAFE_ERR(conn, ERR_MEM);
 463       return ERR_MEM;
 464     }
 465
 466     err = netconn_recv_data(conn, (void **)&p);
 467     if (err != ERR_OK) {
 468       memp_free(MEMP_NETBUF, buf);
 469       return err;
 470     }
 471     LWIP_ASSERT("p != NULL", p != NULL);
 472
 473     buf->p = p;
 474     buf->ptr = p;
 475     buf->port = 0;
 476     ip_addr_set_any(&buf->addr);
 477     *new_buf = buf;
 478     /* don't set conn->last_err: it's only ERR_OK, anyway */
 479     return ERR_OK;
 480   } else
 481 #endif /* LWIP_TCP */
 482   {
 483 #if (LWIP_UDP || LWIP_RAW)
 484     return netconn_recv_data(conn, (void **)new_buf);
 485 #endif /* (LWIP_UDP || LWIP_RAW) */
 486   }
 487 }
 488
 489 /**
 490  * TCP: update the receive window: by calling this, the application
 491  * tells the stack that it has processed data and is able to accept
 492  * new data.
 493  * ATTENTION: use with care, this is mainly used for sockets!
 494  * Can only be used when calling netconn_set_noautorecved(conn, 1) before.
 495  *
 496  * @param conn the netconn for which to update the receive window
 497  * @param length amount of data processed (ATTENTION: this must be accurate!)
 498  */
 499 void
 500 netconn_recved(struct netconn *conn, u32_t length)
 501 {
 502   if ((conn != NULL) && (conn->type == NETCONN_TCP) &&
 503       (netconn_get_noautorecved(conn))) {
 504     struct api_msg msg;
 505     /* Let the stack know that we have taken the data. */
 506     /* TODO: Speedup: Don't block and wait for the answer here
 507        (to prevent multiple thread-switches). */
 508     msg.function = do_recv;
 509     msg.msg.conn = conn;
 510     msg.msg.msg.r.len = length;
 511     /* don't care for the return value of do_recv */
 512     TCPIP_APIMSG(&msg);
 513   }
 514 }
 515
 516 /**
 517  * Send data (in form of a netbuf) to a specific remote IP address and port.
 518  * Only to be used for UDP and RAW netconns (not TCP).
 519  *
 520  * @param conn the netconn over which to send data
 521  * @param buf a netbuf containing the data to send
 522  * @param addr the remote IP address to which to send the data
 523  * @param port the remote port to which to send the data
 524  * @return ERR_OK if data was sent, any other err_t on error
 525  */
 526 err_t
 527 netconn_sendto(struct netconn *conn, struct netbuf *buf, ip_addr_t *addr, u16_t port)
 528 {
 529   if (buf != NULL) {
 530     ip_addr_set(&buf->addr, addr);
 531     buf->port = port;
 532     return netconn_send(conn, buf);
 533   }
 534   return ERR_VAL;
 535 }
 536
 537 /**
 538  * Send data over a UDP or RAW netconn (that is already connected).
 539  *
 540  * @param conn the UDP or RAW netconn over which to send data
 541  * @param buf a netbuf containing the data to send
 542  * @return ERR_OK if data was sent, any other err_t on error
 543  */
 544 err_t
 545 netconn_send(struct netconn *conn, struct netbuf *buf)
 546 {
 547   struct api_msg msg;
 548   err_t err;
 549
 550   LWIP_ERROR("netconn_send: invalid conn",  (conn != NULL), return ERR_ARG;);
 551
 552   LWIP_DEBUGF(API_LIB_DEBUG, ("netconn_send: sending %"U16_F" bytes\n", buf->p->tot_len));
 553   msg.function = do_send;
 554   msg.msg.conn = conn;
 555   msg.msg.msg.b = buf;
 556   err = TCPIP_APIMSG(&msg);
 557
 558   NETCONN_SET_SAFE_ERR(conn, err);
 559   return err;
 560 }
 561
 562 /**
 563  * Send data over a TCP netconn.
 564  *
 565  * @param conn the TCP netconn over which to send data
 566  * @param dataptr pointer to the application buffer that contains the data to send
 567  * @param size size of the application data to send
 568  * @param apiflags combination of following flags :
 569  * - NETCONN_COPY: data will be copied into memory belonging to the stack
 570  * - NETCONN_MORE: for TCP connection, PSH flag will be set on last segment sent
 571  * - NETCONN_DONTBLOCK: only write the data if all dat can be written at once
 572  * @return ERR_OK if data was sent, any other err_t on error
 573  */
 574 err_t
 575 netconn_write(struct netconn *conn, const void *dataptr, size_t size, u8_t apiflags)
 576 {
 577   struct api_msg msg;
 578   err_t err;
 579
 580   LWIP_ERROR("netconn_write: invalid conn",  (conn != NULL), return ERR_ARG;);
 581   LWIP_ERROR("netconn_write: invalid conn->type",  (conn->type == NETCONN_TCP), return ERR_VAL;);
 582   if (size == 0) {
 583     return ERR_OK;
 584   }
 585
 586   /* @todo: for non-blocking write, check if 'size' would ever fit into
 587             snd_queue or snd_buf */
 588   msg.function = do_write;
 589   msg.msg.conn = conn;
 590   msg.msg.msg.w.dataptr = dataptr;
 591   msg.msg.msg.w.apiflags = apiflags;
 592   msg.msg.msg.w.len = size;
 593   /* For locking the core: this _can_ be delayed on low memory/low send buffer,
 594      but if it is, this is done inside api_msg.c:do_write(), so we can use the
 595      non-blocking version here. */
 596   err = TCPIP_APIMSG(&msg);
 597
 598   NETCONN_SET_SAFE_ERR(conn, err);
 599   return err;
 600 }
 601
 602 /**
 603  * Close ot shutdown a TCP netconn (doesn't delete it).
 604  *
 605  * @param conn the TCP netconn to close or shutdown
 606  * @param how fully close or only shutdown one side?
 607  * @return ERR_OK if the netconn was closed, any other err_t on error
 608  */
 609 static err_t
 610 netconn_close_shutdown(struct netconn *conn, u8_t how)
 611 {
 612   struct api_msg msg;
 613   err_t err;
 614
 615   LWIP_ERROR("netconn_close: invalid conn",  (conn != NULL), return ERR_ARG;);
 616
 617   msg.function = do_close;
 618   msg.msg.conn = conn;
 619   /* shutting down both ends is the same as closing */
 620   msg.msg.msg.sd.shut = how;
 621   /* because of the LWIP_TCPIP_CORE_LOCKING implementation of do_close,
 622      don't use TCPIP_APIMSG here */
 623   err = tcpip_apimsg(&msg);
 624
 625   NETCONN_SET_SAFE_ERR(conn, err);
 626   return err;
 627 }
 628
 629 /**
 630  * Close a TCP netconn (doesn't delete it).
 631  *
 632  * @param conn the TCP netconn to close
 633  * @return ERR_OK if the netconn was closed, any other err_t on error
 634  */
 635 err_t
 636 netconn_close(struct netconn *conn)
 637 {
 638   /* shutting down both ends is the same as closing */
 639   return netconn_close_shutdown(conn, NETCONN_SHUT_RDWR);
 640 }
 641
 642 /**
 643  * Shut down one or both sides of a TCP netconn (doesn't delete it).
 644  *
 645  * @param conn the TCP netconn to shut down
 646  * @return ERR_OK if the netconn was closed, any other err_t on error
 647  */
 648 err_t
 649 netconn_shutdown(struct netconn *conn, u8_t shut_rx, u8_t shut_tx)
 650 {
 651   return netconn_close_shutdown(conn, (shut_rx ? NETCONN_SHUT_RD : 0) | (shut_tx ? NETCONN_SHUT_WR : 0));
 652 }
 653
 654 #if LWIP_IGMP
 655 /**
 656  * Join multicast groups for UDP netconns.
 657  *
 658  * @param conn the UDP netconn for which to change multicast addresses
 659  * @param multiaddr IP address of the multicast group to join or leave
 660  * @param netif_addr the IP address of the network interface on which to send
 661  *                  the igmp message
 662  * @param join_or_leave flag whether to send a join- or leave-message
 663  * @return ERR_OK if the action was taken, any err_t on error
 664  */
 665 err_t
 666 netconn_join_leave_group(struct netconn *conn,
 667                          ip_addr_t *multiaddr,
 668                          ip_addr_t *netif_addr,
 669                          enum netconn_igmp join_or_leave)
 670 {
 671   struct api_msg msg;
 672   err_t err;
 673
 674   LWIP_ERROR("netconn_join_leave_group: invalid conn",  (conn != NULL), return ERR_ARG;);
 675
 676   msg.function = do_join_leave_group;
 677   msg.msg.conn = conn;
 678   msg.msg.msg.jl.multiaddr = multiaddr;
 679   msg.msg.msg.jl.netif_addr = netif_addr;
 680   msg.msg.msg.jl.join_or_leave = join_or_leave;
 681   err = TCPIP_APIMSG(&msg);
 682
 683   NETCONN_SET_SAFE_ERR(conn, err);
 684   return err;
 685 }
 686 #endif /* LWIP_IGMP */
 687
 688 #if LWIP_DNS
 689 /**
 690  * Execute a DNS query, only one IP address is returned
 691  *
 692  * @param name a string representation of the DNS host name to query
 693  * @param addr a preallocated ip_addr_t where to store the resolved IP address
 694  * @return ERR_OK: resolving succeeded
 695  *         ERR_MEM: memory error, try again later
 696  *         ERR_ARG: dns client not initialized or invalid hostname
 697  *         ERR_VAL: dns server response was invalid
 698  */
 699 err_t
 700 netconn_gethostbyname(const char *name, ip_addr_t *addr)
 701 {
 702   struct dns_api_msg msg;
 703   err_t err;
 704   sys_sem_t sem;
 705
 706   LWIP_ERROR("netconn_gethostbyname: invalid name", (name != NULL), return ERR_ARG;);
 707   LWIP_ERROR("netconn_gethostbyname: invalid addr", (addr != NULL), return ERR_ARG;);
 708
 709   err = sys_sem_new(&sem, 0);
 710   if (err != ERR_OK) {
 711     return err;
 712   }
 713
 714   msg.name = name;
 715   msg.addr = addr;
 716   msg.err = &err;
 717   msg.sem = &sem;
 718
 719   tcpip_callback(do_gethostbyname, &msg);
 720   sys_sem_wait(&sem);
 721   sys_sem_free(&sem);
 722
 723   return err;
 724 }
 725 #endif /* LWIP_DNS*/
 726
 727 #endif /* LWIP_NETCONN */