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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
slipif_output(struct netif * netif,struct pbuf * p,ip_addr_t * ipaddr)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
slip_sio_read(sio_fd_t fd,u8_t * data,u32_t len,u8_t block)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 *
slipif_input(struct netif * netif,u8_t block)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
slipif_loop_thread(void * nf)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
slipif_init(struct netif * netif)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
slipif_poll(struct netif * netif)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 */
368