lib/liblwip/netif/slipif.c

   1 /**
   2  * @file
   3  * SLIP Interface
   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
  12  * modification, are permitted provided that the following conditions
  13  * are met:
  14  * 1. Redistributions of source code must retain the above copyright
  15  *    notice, this list of conditions and the following disclaimer.
  16  * 2. Redistributions in binary form must reproduce the above copyright
  17  *    notice, this list of conditions and the following disclaimer in the
  18  *    documentation and/or other materials provided with the distribution.
  19  * 3. Neither the name of the Institute nor the names of its contributors
  20  *    may be used to endorse or promote products derived from this software
  21  *    without specific prior written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
  24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
  27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  33  * SUCH DAMAGE.
  34  *
  35  * This file is built upon the file: src/arch/rtxc/netif/sioslip.c
  36  *
  37  * Author: Magnus Ivarsson <magnus.ivarsson(at)volvo.com>
  38  */
  39
  40 /*
  41  * This is an arch independent SLIP netif. The specific serial hooks must be
  42  * provided by another file. They are sio_open, sio_read/sio_tryread and sio_send
  43  */
  44
  45 #include "netif/slipif.h"
  46 #include "lwip/opt.h"
  47
  48 #if LWIP_HAVE_SLIPIF
  49
  50 #include "lwip/def.h"
  51 #include "lwip/pbuf.h"
  52 #include "lwip/sys.h"
  53 #include "lwip/stats.h"
  54 #include "lwip/snmp.h"
  55 #include "lwip/sio.h"
  56
  57 #define SLIP_BLOCK     1
  58 #define SLIP_DONTBLOCK 0
  59
  60 #define SLIP_END     0300 /* 0xC0 */
  61 #define SLIP_ESC     0333 /* 0xDB */
  62 #define SLIP_ESC_END 0334 /* 0xDC */
  63 #define SLIP_ESC_ESC 0335 /* 0xDD */
  64
  65 #define SLIP_MAX_SIZE 1500
  66
  67 enum slipif_recv_state {
  68     SLIP_RECV_NORMAL,
  69     SLIP_RECV_ESCAPE,
  70 };
  71
  72 struct slipif_priv {
  73   sio_fd_t sd;
  74   /* q is the whole pbuf chain for a packet, p is the current pbuf in the chain */
  75   struct pbuf *p, *q;
  76   enum slipif_recv_state state;
  77   u16_t i, recved;
  78 };
  79
  80 /**
  81  * Send a pbuf doing the necessary SLIP encapsulation
  82  *
  83  * Uses the serial layer's sio_send()
  84  *
  85  * @param netif the lwip network interface structure for this slipif
  86  * @param p the pbuf chaing packet to send
  87  * @param ipaddr the ip address to send the packet to (not used for slipif)
  88  * @return always returns ERR_OK since the serial layer does not provide return values
  89  */
  90 err_t
  91 slipif_output(struct netif *netif, struct pbuf *p, ip_addr_t *ipaddr)
  92 {
  93   struct slipif_priv *priv;
  94   struct pbuf *q;
  95   u16_t i;
  96   u8_t c;
  97
  98   LWIP_ASSERT("netif != NULL", (netif != NULL));
  99   LWIP_ASSERT("netif->state != NULL", (netif->state != NULL));
 100   LWIP_ASSERT("p != NULL", (p != NULL));
 101
 102   LWIP_UNUSED_ARG(ipaddr);
 103
 104   priv = netif->state;
 105
 106   /* Send pbuf out on the serial I/O device. */
 107   sio_send(SLIP_END, priv->sd);
 108
 109   for (q = p; q != NULL; q = q->next) {
 110     for (i = 0; i < q->len; i++) {
 111       c = ((u8_t *)q->payload)[i];
 112       switch (c) {
 113       case SLIP_END:
 114         sio_send(SLIP_ESC, priv->sd);
 115         sio_send(SLIP_ESC_END, priv->sd);
 116         break;
 117       case SLIP_ESC:
 118         sio_send(SLIP_ESC, priv->sd);
 119         sio_send(SLIP_ESC_ESC, priv->sd);
 120         break;
 121       default:
 122         sio_send(c, priv->sd);
 123         break;
 124       }
 125     }
 126   }
 127   sio_send(SLIP_END, priv->sd);
 128   return ERR_OK;
 129 }
 130
 131 /**
 132  * Static function for easy use of blockig or non-blocking
 133  * sio_read
 134  *
 135  * @param fd serial device handle
 136  * @param data pointer to data buffer for receiving
 137  * @param len maximum length (in bytes) of data to receive
 138  * @param block if 1, call sio_read; if 0, call sio_tryread
 139  * @return return value of sio_read of sio_tryread
 140  */
 141 static u32_t
 142 slip_sio_read(sio_fd_t fd, u8_t* data, u32_t len, u8_t block)
 143 {
 144   if (block) {
 145     return sio_read(fd, data, len);
 146   } else {
 147     return sio_tryread(fd, data, len);
 148   }
 149 }
 150
 151 /**
 152  * Handle the incoming SLIP stream character by character
 153  *
 154  * Poll the serial layer by calling sio_read() or sio_tryread().
 155  *
 156  * @param netif the lwip network interface structure for this slipif
 157  * @param block if 1, block until data is received; if 0, return when all data
 158  *        from the buffer is received (multiple calls to this function will
 159  *        return a complete packet, NULL is returned before - used for polling)
 160  * @return The IP packet when SLIP_END is received
 161  */
 162 static struct pbuf *
 163 slipif_input(struct netif *netif, u8_t block)
 164 {
 165   struct slipif_priv *priv;
 166   u8_t c;
 167   struct pbuf *t;
 168
 169   LWIP_ASSERT("netif != NULL", (netif != NULL));
 170   LWIP_ASSERT("netif->state != NULL", (netif->state != NULL));
 171
 172   priv = netif->state;
 173
 174   while (slip_sio_read(priv->sd, &c, 1, block) > 0) {
 175     switch (priv->state) {
 176     case SLIP_RECV_NORMAL:
 177       switch (c) {
 178       case SLIP_END:
 179         if (priv->recved > 0) {
 180           /* Received whole packet. */
 181           /* Trim the pbuf to the size of the received packet. */
 182           pbuf_realloc(priv->q, priv->recved);
 183
 184           LINK_STATS_INC(link.recv);
 185
 186           LWIP_DEBUGF(SLIP_DEBUG, ("slipif: Got packet\n"));
 187           t = priv->q;
 188           priv->p = priv->q = NULL;
 189           priv->i = priv->recved = 0;
 190           return t;
 191         }
 192         continue;
 193       case SLIP_ESC:
 194         priv->state = SLIP_RECV_ESCAPE;
 195         continue;
 196       }
 197       break;
 198     case SLIP_RECV_ESCAPE:
 199       switch (c) {
 200       case SLIP_ESC_END:
 201         c = SLIP_END;
 202         break;
 203       case SLIP_ESC_ESC:
 204         c = SLIP_ESC;
 205         break;
 206       }
 207       priv->state = SLIP_RECV_NORMAL;
 208       /* FALLTHROUGH */
 209     }
 210
 211     /* byte received, packet not yet completely received */
 212     if (priv->p == NULL) {
 213       /* allocate a new pbuf */
 214       LWIP_DEBUGF(SLIP_DEBUG, ("slipif_input: alloc\n"));
 215       priv->p = pbuf_alloc(PBUF_LINK, (PBUF_POOL_BUFSIZE - PBUF_LINK_HLEN), PBUF_POOL);
 216
 217       if (priv->p == NULL) {
 218         LINK_STATS_INC(link.drop);
 219         LWIP_DEBUGF(SLIP_DEBUG, ("slipif_input: no new pbuf! (DROP)\n"));
 220         /* don't process any further since we got no pbuf to receive to */
 221         break;
 222       }
 223
 224       if (priv->q != NULL) {
 225         /* 'chain' the pbuf to the existing chain */
 226         pbuf_cat(priv->q, priv->p);
 227       } else {
 228         /* p is the first pbuf in the chain */
 229         priv->q = priv->p;
 230       }
 231     }
 232
 233     /* this automatically drops bytes if > SLIP_MAX_SIZE */
 234     if ((priv->p != NULL) && (priv->recved <= SLIP_MAX_SIZE)) {
 235       ((u8_t *)priv->p->payload)[priv->i] = c;
 236       priv->recved++;
 237       priv->i++;
 238       if (priv->i >= priv->p->len) {
 239         /* on to the next pbuf */
 240         priv->i = 0;
 241         if (priv->p->next != NULL && priv->p->next->len > 0) {
 242           /* p is a chain, on to the next in the chain */
 243             priv->p = priv->p->next;
 244         } else {
 245           /* p is a single pbuf, set it to NULL so next time a new
 246            * pbuf is allocated */
 247             priv->p = NULL;
 248         }
 249       }
 250     }
 251   }
 252
 253   return NULL;
 254 }
 255
 256 #if !NO_SYS
 257 /**
 258  * The SLIP input thread.
 259  *
 260  * Feed the IP layer with incoming packets
 261  *
 262  * @param nf the lwip network interface structure for this slipif
 263  */
 264 static void
 265 slipif_loop_thread(void *nf)
 266 {
 267   struct pbuf *p;
 268   struct netif *netif = (struct netif *)nf;
 269
 270   while (1) {
 271     p = slipif_input(netif, SLIP_BLOCK);
 272     if (p != NULL) {
 273       if (netif->input(p, netif) != ERR_OK) {
 274         pbuf_free(p);
 275         p = NULL;
 276       }
 277     }
 278   }
 279 }
 280 #endif /* !NO_SYS */
 281
 282 /**
 283  * SLIP netif initialization
 284  *
 285  * Call the arch specific sio_open and remember
 286  * the opened device in the state field of the netif.
 287  *
 288  * @param netif the lwip network interface structure for this slipif
 289  * @return ERR_OK if serial line could be opened,
 290  *         ERR_MEM if no memory could be allocated,
 291  *         ERR_IF is serial line couldn't be opened
 292  *
 293  * @note netif->num must contain the number of the serial port to open
 294  *       (0 by default)
 295  */
 296 err_t
 297 slipif_init(struct netif *netif)
 298 {
 299   struct slipif_priv *priv;
 300
 301   LWIP_DEBUGF(SLIP_DEBUG, ("slipif_init: netif->num=%"U16_F"\n", (u16_t)netif->num));
 302
 303   /* Allocate private data */
 304   priv = mem_malloc(sizeof(struct slipif_priv));
 305   if (!priv) {
 306     return ERR_MEM;
 307   }
 308
 309   netif->name[0] = 's';
 310   netif->name[1] = 'l';
 311   netif->output = slipif_output;
 312   netif->mtu = SLIP_MAX_SIZE;
 313   netif->flags |= NETIF_FLAG_POINTTOPOINT;
 314
 315   /* Try to open the serial port (netif->num contains the port number). */
 316   priv->sd = sio_open(netif->num);
 317   if (!priv->sd) {
 318     /* Opening the serial port failed. */
 319     mem_free(priv);
 320     return ERR_IF;
 321   }
 322
 323   /* Initialize private data */
 324   priv->p = NULL;
 325   priv->q = NULL;
 326   priv->state = SLIP_RECV_NORMAL;
 327   priv->i = 0;
 328   priv->recved = 0;
 329
 330   netif->state = priv;
 331
 332   /* initialize the snmp variables and counters inside the struct netif
 333    * ifSpeed: no assumption can be made without knowing more about the
 334    * serial line!
 335    */
 336   NETIF_INIT_SNMP(netif, snmp_ifType_slip, 0);
 337
 338   /* Create a thread to poll the serial line. */
 339   sys_thread_new(SLIPIF_THREAD_NAME, slipif_loop_thread, netif,
 340     SLIPIF_THREAD_STACKSIZE, SLIPIF_THREAD_PRIO);
 341   return ERR_OK;
 342 }
 343
 344 /**
 345  * Polls the serial device and feeds the IP layer with incoming packets.
 346  *
 347  * @param netif The lwip network interface structure for this slipif
 348  */
 349 void
 350 slipif_poll(struct netif *netif)
 351 {
 352   struct pbuf *p;
 353   struct slipif_priv *priv;
 354
 355   LWIP_ASSERT("netif != NULL", (netif != NULL));
 356   LWIP_ASSERT("netif->state != NULL", (netif->state != NULL));
 357
 358   priv = netif->state;
 359
 360   while ((p = slipif_input(netif, SLIP_DONTBLOCK)) != NULL) {
 361     if (netif->input(p, netif) != ERR_OK) {
 362       pbuf_free(p);
 363     }
 364   }
 365 }
 366
 367 #endif /* LWIP_HAVE_SLIPIF */