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1 /**
2  * @file
3  * lwIP network interface abstraction
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 #include "lwip/opt.h"
40 
41 #include "lwip/def.h"
42 #include "lwip/ip_addr.h"
43 #include "lwip/netif.h"
44 #include "lwip/tcp_impl.h"
45 #include "lwip/snmp.h"
46 #include "lwip/igmp.h"
47 #include "netif/etharp.h"
48 #include "lwip/stats.h"
49 #if ENABLE_LOOPBACK
50 #include "lwip/sys.h"
51 #if LWIP_NETIF_LOOPBACK_MULTITHREADING
52 #include "lwip/tcpip.h"
53 #endif /* LWIP_NETIF_LOOPBACK_MULTITHREADING */
54 #endif /* ENABLE_LOOPBACK */
55 
56 #if LWIP_AUTOIP
57 #include "lwip/autoip.h"
58 #endif /* LWIP_AUTOIP */
59 #if LWIP_DHCP
60 #include "lwip/dhcp.h"
61 #endif /* LWIP_DHCP */
62 
63 #if LWIP_NETIF_STATUS_CALLBACK
64 #define NETIF_STATUS_CALLBACK(n) do{ if (n->status_callback) { (n->status_callback)(n); }}while(0)
65 #else
66 #define NETIF_STATUS_CALLBACK(n)
67 #endif /* LWIP_NETIF_STATUS_CALLBACK */
68 
69 #if LWIP_NETIF_LINK_CALLBACK
70 #define NETIF_LINK_CALLBACK(n) do{ if (n->link_callback) { (n->link_callback)(n); }}while(0)
71 #else
72 #define NETIF_LINK_CALLBACK(n)
73 #endif /* LWIP_NETIF_LINK_CALLBACK */
74 
75 struct netif *netif_list;
76 struct netif *netif_default;
77 
78 #if LWIP_HAVE_LOOPIF
79 static struct netif loop_netif;
80 
81 /**
82  * Initialize a lwip network interface structure for a loopback interface
83  *
84  * @param netif the lwip network interface structure for this loopif
85  * @return ERR_OK if the loopif is initialized
86  *         ERR_MEM if private data couldn't be allocated
87  */
88 static err_t
netif_loopif_init(struct netif * netif)89 netif_loopif_init(struct netif *netif)
90 {
91   /* initialize the snmp variables and counters inside the struct netif
92    * ifSpeed: no assumption can be made!
93    */
94   NETIF_INIT_SNMP(netif, snmp_ifType_softwareLoopback, 0);
95 
96   netif->name[0] = 'l';
97   netif->name[1] = 'o';
98   netif->output = netif_loop_output;
99   return ERR_OK;
100 }
101 #endif /* LWIP_HAVE_LOOPIF */
102 
103 void
netif_init(void)104 netif_init(void)
105 {
106 #if LWIP_HAVE_LOOPIF
107   ip_addr_t loop_ipaddr, loop_netmask, loop_gw;
108   IP4_ADDR(&loop_gw, 127,0,0,1);
109   IP4_ADDR(&loop_ipaddr, 127,0,0,1);
110   IP4_ADDR(&loop_netmask, 255,0,0,0);
111 
112 #if NO_SYS
113   netif_add(&loop_netif, &loop_ipaddr, &loop_netmask, &loop_gw, NULL, netif_loopif_init, ip_input);
114 #else  /* NO_SYS */
115   netif_add(&loop_netif, &loop_ipaddr, &loop_netmask, &loop_gw, NULL, netif_loopif_init, tcpip_input);
116 #endif /* NO_SYS */
117   netif_set_up(&loop_netif);
118 
119 #endif /* LWIP_HAVE_LOOPIF */
120 }
121 
122 /**
123  * Add a network interface to the list of lwIP netifs.
124  *
125  * @param netif a pre-allocated netif structure
126  * @param ipaddr IP address for the new netif
127  * @param netmask network mask for the new netif
128  * @param gw default gateway IP address for the new netif
129  * @param state opaque data passed to the new netif
130  * @param init callback function that initializes the interface
131  * @param input callback function that is called to pass
132  * ingress packets up in the protocol layer stack.
133  *
134  * @return netif, or NULL if failed.
135  */
136 struct netif *
netif_add(struct netif * netif,ip_addr_t * ipaddr,ip_addr_t * netmask,ip_addr_t * gw,void * state,netif_init_fn init,netif_input_fn input)137 netif_add(struct netif *netif, ip_addr_t *ipaddr, ip_addr_t *netmask,
138   ip_addr_t *gw, void *state, netif_init_fn init, netif_input_fn input)
139 {
140   static u8_t netifnum = 0;
141 
142   LWIP_ASSERT("No init function given", init != NULL);
143 
144   /* reset new interface configuration state */
145   ip_addr_set_zero(&netif->ip_addr);
146   ip_addr_set_zero(&netif->netmask);
147   ip_addr_set_zero(&netif->gw);
148   netif->flags = 0;
149 #if LWIP_DHCP
150   /* netif not under DHCP control by default */
151   netif->dhcp = NULL;
152 #endif /* LWIP_DHCP */
153 #if LWIP_AUTOIP
154   /* netif not under AutoIP control by default */
155   netif->autoip = NULL;
156 #endif /* LWIP_AUTOIP */
157 #if LWIP_NETIF_STATUS_CALLBACK
158   netif->status_callback = NULL;
159 #endif /* LWIP_NETIF_STATUS_CALLBACK */
160 #if LWIP_NETIF_LINK_CALLBACK
161   netif->link_callback = NULL;
162 #endif /* LWIP_NETIF_LINK_CALLBACK */
163 #if LWIP_IGMP
164   netif->igmp_mac_filter = NULL;
165 #endif /* LWIP_IGMP */
166 #if ENABLE_LOOPBACK
167   netif->loop_first = NULL;
168   netif->loop_last = NULL;
169 #endif /* ENABLE_LOOPBACK */
170 
171   /* remember netif specific state information data */
172   netif->state = state;
173   netif->num = netifnum++;
174   netif->input = input;
175 #if LWIP_NETIF_HWADDRHINT
176   netif->addr_hint = NULL;
177 #endif /* LWIP_NETIF_HWADDRHINT*/
178 #if ENABLE_LOOPBACK && LWIP_LOOPBACK_MAX_PBUFS
179   netif->loop_cnt_current = 0;
180 #endif /* ENABLE_LOOPBACK && LWIP_LOOPBACK_MAX_PBUFS */
181 
182   netif_set_addr(netif, ipaddr, netmask, gw);
183 
184   /* call user specified initialization function for netif */
185   if (init(netif) != ERR_OK) {
186     return NULL;
187   }
188 
189   /* add this netif to the list */
190   netif->next = netif_list;
191   netif_list = netif;
192   snmp_inc_iflist();
193 
194 #if LWIP_IGMP
195   /* start IGMP processing */
196   if (netif->flags & NETIF_FLAG_IGMP) {
197     igmp_start(netif);
198   }
199 #endif /* LWIP_IGMP */
200 
201   LWIP_DEBUGF(NETIF_DEBUG, ("netif: added interface %c%c IP addr ",
202     netif->name[0], netif->name[1]));
203   ip_addr_debug_print(NETIF_DEBUG, ipaddr);
204   LWIP_DEBUGF(NETIF_DEBUG, (" netmask "));
205   ip_addr_debug_print(NETIF_DEBUG, netmask);
206   LWIP_DEBUGF(NETIF_DEBUG, (" gw "));
207   ip_addr_debug_print(NETIF_DEBUG, gw);
208   LWIP_DEBUGF(NETIF_DEBUG, ("\n"));
209   return netif;
210 }
211 
212 /**
213  * Change IP address configuration for a network interface (including netmask
214  * and default gateway).
215  *
216  * @param netif the network interface to change
217  * @param ipaddr the new IP address
218  * @param netmask the new netmask
219  * @param gw the new default gateway
220  */
221 void
netif_set_addr(struct netif * netif,ip_addr_t * ipaddr,ip_addr_t * netmask,ip_addr_t * gw)222 netif_set_addr(struct netif *netif, ip_addr_t *ipaddr, ip_addr_t *netmask,
223     ip_addr_t *gw)
224 {
225   netif_set_ipaddr(netif, ipaddr);
226   netif_set_netmask(netif, netmask);
227   netif_set_gw(netif, gw);
228 }
229 
230 /**
231  * Remove a network interface from the list of lwIP netifs.
232  *
233  * @param netif the network interface to remove
234  */
235 void
netif_remove(struct netif * netif)236 netif_remove(struct netif *netif)
237 {
238   if (netif == NULL) {
239     return;
240   }
241 
242 #if LWIP_IGMP
243   /* stop IGMP processing */
244   if (netif->flags & NETIF_FLAG_IGMP) {
245     igmp_stop(netif);
246   }
247 #endif /* LWIP_IGMP */
248   if (netif_is_up(netif)) {
249     /* set netif down before removing (call callback function) */
250     netif_set_down(netif);
251   }
252 
253   snmp_delete_ipaddridx_tree(netif);
254 
255   /*  is it the first netif? */
256   if (netif_list == netif) {
257     netif_list = netif->next;
258   } else {
259     /*  look for netif further down the list */
260     struct netif * tmpNetif;
261     for (tmpNetif = netif_list; tmpNetif != NULL; tmpNetif = tmpNetif->next) {
262       if (tmpNetif->next == netif) {
263         tmpNetif->next = netif->next;
264         break;
265       }
266     }
267     if (tmpNetif == NULL)
268       return; /*  we didn't find any netif today */
269   }
270   snmp_dec_iflist();
271   /* this netif is default? */
272   if (netif_default == netif) {
273     /* reset default netif */
274     netif_set_default(NULL);
275   }
276   LWIP_DEBUGF( NETIF_DEBUG, ("netif_remove: removed netif\n") );
277 }
278 
279 /**
280  * Find a network interface by searching for its name
281  *
282  * @param name the name of the netif (like netif->name) plus concatenated number
283  * in ascii representation (e.g. 'en0')
284  */
285 struct netif *
netif_find(char * name)286 netif_find(char *name)
287 {
288   struct netif *netif;
289   u8_t num;
290 
291   if (name == NULL) {
292     return NULL;
293   }
294 
295   num = name[2] - '0';
296 
297   for(netif = netif_list; netif != NULL; netif = netif->next) {
298     if (num == netif->num &&
299        name[0] == netif->name[0] &&
300        name[1] == netif->name[1]) {
301       LWIP_DEBUGF(NETIF_DEBUG, ("netif_find: found %c%c\n", name[0], name[1]));
302       return netif;
303     }
304   }
305   LWIP_DEBUGF(NETIF_DEBUG, ("netif_find: didn't find %c%c\n", name[0], name[1]));
306   return NULL;
307 }
308 
309 /**
310  * Change the IP address of a network interface
311  *
312  * @param netif the network interface to change
313  * @param ipaddr the new IP address
314  *
315  * @note call netif_set_addr() if you also want to change netmask and
316  * default gateway
317  */
318 void
netif_set_ipaddr(struct netif * netif,ip_addr_t * ipaddr)319 netif_set_ipaddr(struct netif *netif, ip_addr_t *ipaddr)
320 {
321   /* TODO: Handling of obsolete pcbs */
322   /* See:  http://mail.gnu.org/archive/html/lwip-users/2003-03/msg00118.html */
323 #if LWIP_TCP
324   struct tcp_pcb *pcb;
325   struct tcp_pcb_listen *lpcb;
326 
327   /* address is actually being changed? */
328   if ((ip_addr_cmp(ipaddr, &(netif->ip_addr))) == 0) {
329     /* extern struct tcp_pcb *tcp_active_pcbs; defined by tcp.h */
330     LWIP_DEBUGF(NETIF_DEBUG | LWIP_DBG_STATE, ("netif_set_ipaddr: netif address being changed\n"));
331     pcb = tcp_active_pcbs;
332     while (pcb != NULL) {
333       /* PCB bound to current local interface address? */
334       if (ip_addr_cmp(&(pcb->local_ip), &(netif->ip_addr))
335 #if LWIP_AUTOIP
336         /* connections to link-local addresses must persist (RFC3927 ch. 1.9) */
337         && !ip_addr_islinklocal(&(pcb->local_ip))
338 #endif /* LWIP_AUTOIP */
339         ) {
340         /* this connection must be aborted */
341         struct tcp_pcb *next = pcb->next;
342         LWIP_DEBUGF(NETIF_DEBUG | LWIP_DBG_STATE, ("netif_set_ipaddr: aborting TCP pcb %p\n", (void *)pcb));
343         tcp_abort(pcb);
344         pcb = next;
345       } else {
346         pcb = pcb->next;
347       }
348     }
349     for (lpcb = tcp_listen_pcbs.listen_pcbs; lpcb != NULL; lpcb = lpcb->next) {
350       /* PCB bound to current local interface address? */
351       if ((!(ip_addr_isany(&(lpcb->local_ip)))) &&
352           (ip_addr_cmp(&(lpcb->local_ip), &(netif->ip_addr)))) {
353         /* The PCB is listening to the old ipaddr and
354          * is set to listen to the new one instead */
355         ip_addr_set(&(lpcb->local_ip), ipaddr);
356       }
357     }
358   }
359 #endif
360   snmp_delete_ipaddridx_tree(netif);
361   snmp_delete_iprteidx_tree(0,netif);
362   /* set new IP address to netif */
363   ip_addr_set(&(netif->ip_addr), ipaddr);
364   snmp_insert_ipaddridx_tree(netif);
365   snmp_insert_iprteidx_tree(0,netif);
366 
367   LWIP_DEBUGF(NETIF_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("netif: IP address of interface %c%c set to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
368     netif->name[0], netif->name[1],
369     ip4_addr1_16(&netif->ip_addr),
370     ip4_addr2_16(&netif->ip_addr),
371     ip4_addr3_16(&netif->ip_addr),
372     ip4_addr4_16(&netif->ip_addr)));
373 }
374 
375 /**
376  * Change the default gateway for a network interface
377  *
378  * @param netif the network interface to change
379  * @param gw the new default gateway
380  *
381  * @note call netif_set_addr() if you also want to change ip address and netmask
382  */
383 void
netif_set_gw(struct netif * netif,ip_addr_t * gw)384 netif_set_gw(struct netif *netif, ip_addr_t *gw)
385 {
386   ip_addr_set(&(netif->gw), gw);
387   LWIP_DEBUGF(NETIF_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("netif: GW address of interface %c%c set to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
388     netif->name[0], netif->name[1],
389     ip4_addr1_16(&netif->gw),
390     ip4_addr2_16(&netif->gw),
391     ip4_addr3_16(&netif->gw),
392     ip4_addr4_16(&netif->gw)));
393 }
394 
395 /**
396  * Change the netmask of a network interface
397  *
398  * @param netif the network interface to change
399  * @param netmask the new netmask
400  *
401  * @note call netif_set_addr() if you also want to change ip address and
402  * default gateway
403  */
404 void
netif_set_netmask(struct netif * netif,ip_addr_t * netmask)405 netif_set_netmask(struct netif *netif, ip_addr_t *netmask)
406 {
407   snmp_delete_iprteidx_tree(0, netif);
408   /* set new netmask to netif */
409   ip_addr_set(&(netif->netmask), netmask);
410   snmp_insert_iprteidx_tree(0, netif);
411   LWIP_DEBUGF(NETIF_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("netif: netmask of interface %c%c set to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
412     netif->name[0], netif->name[1],
413     ip4_addr1_16(&netif->netmask),
414     ip4_addr2_16(&netif->netmask),
415     ip4_addr3_16(&netif->netmask),
416     ip4_addr4_16(&netif->netmask)));
417 }
418 
419 /**
420  * Set a network interface as the default network interface
421  * (used to output all packets for which no specific route is found)
422  *
423  * @param netif the default network interface
424  */
425 void
netif_set_default(struct netif * netif)426 netif_set_default(struct netif *netif)
427 {
428   if (netif == NULL) {
429     /* remove default route */
430     snmp_delete_iprteidx_tree(1, netif);
431   } else {
432     /* install default route */
433     snmp_insert_iprteidx_tree(1, netif);
434   }
435   netif_default = netif;
436   LWIP_DEBUGF(NETIF_DEBUG, ("netif: setting default interface %c%c\n",
437            netif ? netif->name[0] : '\'', netif ? netif->name[1] : '\''));
438 }
439 
440 /**
441  * Bring an interface up, available for processing
442  * traffic.
443  *
444  * @note: Enabling DHCP on a down interface will make it come
445  * up once configured.
446  *
447  * @see dhcp_start()
448  */
netif_set_up(struct netif * netif)449 void netif_set_up(struct netif *netif)
450 {
451   if (!(netif->flags & NETIF_FLAG_UP)) {
452     netif->flags |= NETIF_FLAG_UP;
453 
454 #if LWIP_SNMP
455     snmp_get_sysuptime(&netif->ts);
456 #endif /* LWIP_SNMP */
457 
458     NETIF_STATUS_CALLBACK(netif);
459 
460     if (netif->flags & NETIF_FLAG_LINK_UP) {
461 #if LWIP_ARP
462       /* For Ethernet network interfaces, we would like to send a "gratuitous ARP" */
463       if (netif->flags & (NETIF_FLAG_ETHARP)) {
464         etharp_gratuitous(netif);
465       }
466 #endif /* LWIP_ARP */
467 
468 #if LWIP_IGMP
469       /* resend IGMP memberships */
470       if (netif->flags & NETIF_FLAG_IGMP) {
471         igmp_report_groups( netif);
472       }
473 #endif /* LWIP_IGMP */
474     }
475   }
476 }
477 
478 /**
479  * Bring an interface down, disabling any traffic processing.
480  *
481  * @note: Enabling DHCP on a down interface will make it come
482  * up once configured.
483  *
484  * @see dhcp_start()
485  */
netif_set_down(struct netif * netif)486 void netif_set_down(struct netif *netif)
487 {
488   if (netif->flags & NETIF_FLAG_UP) {
489     netif->flags &= ~NETIF_FLAG_UP;
490 #if LWIP_SNMP
491     snmp_get_sysuptime(&netif->ts);
492 #endif
493 
494     NETIF_STATUS_CALLBACK(netif);
495   }
496 }
497 
498 #if LWIP_NETIF_STATUS_CALLBACK
499 /**
500  * Set callback to be called when interface is brought up/down
501  */
netif_set_status_callback(struct netif * netif,netif_status_callback_fn status_callback)502 void netif_set_status_callback(struct netif *netif, netif_status_callback_fn status_callback)
503 {
504   if (netif) {
505     netif->status_callback = status_callback;
506   }
507 }
508 #endif /* LWIP_NETIF_STATUS_CALLBACK */
509 
510 /**
511  * Called by a driver when its link goes up
512  */
netif_set_link_up(struct netif * netif)513 void netif_set_link_up(struct netif *netif )
514 {
515   if (!(netif->flags & NETIF_FLAG_LINK_UP)) {
516     netif->flags |= NETIF_FLAG_LINK_UP;
517 
518 #if LWIP_DHCP
519     if (netif->dhcp) {
520       dhcp_network_changed(netif);
521     }
522 #endif /* LWIP_DHCP */
523 
524 #if LWIP_AUTOIP
525     if (netif->autoip) {
526       autoip_network_changed(netif);
527     }
528 #endif /* LWIP_AUTOIP */
529 
530     if (netif->flags & NETIF_FLAG_UP) {
531 #if LWIP_ARP
532       /* For Ethernet network interfaces, we would like to send a "gratuitous ARP" */
533       if (netif->flags & NETIF_FLAG_ETHARP) {
534         etharp_gratuitous(netif);
535       }
536 #endif /* LWIP_ARP */
537 
538 #if LWIP_IGMP
539       /* resend IGMP memberships */
540       if (netif->flags & NETIF_FLAG_IGMP) {
541         igmp_report_groups( netif);
542       }
543 #endif /* LWIP_IGMP */
544     }
545     NETIF_LINK_CALLBACK(netif);
546   }
547 }
548 
549 /**
550  * Called by a driver when its link goes down
551  */
netif_set_link_down(struct netif * netif)552 void netif_set_link_down(struct netif *netif )
553 {
554   if (netif->flags & NETIF_FLAG_LINK_UP) {
555     netif->flags &= ~NETIF_FLAG_LINK_UP;
556     NETIF_LINK_CALLBACK(netif);
557   }
558 }
559 
560 #if LWIP_NETIF_LINK_CALLBACK
561 /**
562  * Set callback to be called when link is brought up/down
563  */
netif_set_link_callback(struct netif * netif,netif_status_callback_fn link_callback)564 void netif_set_link_callback(struct netif *netif, netif_status_callback_fn link_callback)
565 {
566   if (netif) {
567     netif->link_callback = link_callback;
568   }
569 }
570 #endif /* LWIP_NETIF_LINK_CALLBACK */
571 
572 #if ENABLE_LOOPBACK
573 /**
574  * Send an IP packet to be received on the same netif (loopif-like).
575  * The pbuf is simply copied and handed back to netif->input.
576  * In multithreaded mode, this is done directly since netif->input must put
577  * the packet on a queue.
578  * In callback mode, the packet is put on an internal queue and is fed to
579  * netif->input by netif_poll().
580  *
581  * @param netif the lwip network interface structure
582  * @param p the (IP) packet to 'send'
583  * @param ipaddr the ip address to send the packet to (not used)
584  * @return ERR_OK if the packet has been sent
585  *         ERR_MEM if the pbuf used to copy the packet couldn't be allocated
586  */
587 err_t
netif_loop_output(struct netif * netif,struct pbuf * p,ip_addr_t * ipaddr)588 netif_loop_output(struct netif *netif, struct pbuf *p,
589        ip_addr_t *ipaddr)
590 {
591   struct pbuf *r;
592   err_t err;
593   struct pbuf *last;
594 #if LWIP_LOOPBACK_MAX_PBUFS
595   u8_t clen = 0;
596 #endif /* LWIP_LOOPBACK_MAX_PBUFS */
597   /* If we have a loopif, SNMP counters are adjusted for it,
598    * if not they are adjusted for 'netif'. */
599 #if LWIP_SNMP
600 #if LWIP_HAVE_LOOPIF
601   struct netif *stats_if = &loop_netif;
602 #else /* LWIP_HAVE_LOOPIF */
603   struct netif *stats_if = netif;
604 #endif /* LWIP_HAVE_LOOPIF */
605 #endif /* LWIP_SNMP */
606   SYS_ARCH_DECL_PROTECT(lev);
607   LWIP_UNUSED_ARG(ipaddr);
608 
609   /* Allocate a new pbuf */
610   r = pbuf_alloc(PBUF_LINK, p->tot_len, PBUF_RAM);
611   if (r == NULL) {
612     LINK_STATS_INC(link.memerr);
613     LINK_STATS_INC(link.drop);
614     snmp_inc_ifoutdiscards(stats_if);
615     return ERR_MEM;
616   }
617 #if LWIP_LOOPBACK_MAX_PBUFS
618   clen = pbuf_clen(r);
619   /* check for overflow or too many pbuf on queue */
620   if(((netif->loop_cnt_current + clen) < netif->loop_cnt_current) ||
621      ((netif->loop_cnt_current + clen) > LWIP_LOOPBACK_MAX_PBUFS)) {
622     pbuf_free(r);
623     LINK_STATS_INC(link.memerr);
624     LINK_STATS_INC(link.drop);
625     snmp_inc_ifoutdiscards(stats_if);
626     return ERR_MEM;
627   }
628   netif->loop_cnt_current += clen;
629 #endif /* LWIP_LOOPBACK_MAX_PBUFS */
630 
631   /* Copy the whole pbuf queue p into the single pbuf r */
632   if ((err = pbuf_copy(r, p)) != ERR_OK) {
633     pbuf_free(r);
634     LINK_STATS_INC(link.memerr);
635     LINK_STATS_INC(link.drop);
636     snmp_inc_ifoutdiscards(stats_if);
637     return err;
638   }
639 
640   /* Put the packet on a linked list which gets emptied through calling
641      netif_poll(). */
642 
643   /* let last point to the last pbuf in chain r */
644   for (last = r; last->next != NULL; last = last->next);
645 
646   SYS_ARCH_PROTECT(lev);
647   if(netif->loop_first != NULL) {
648     LWIP_ASSERT("if first != NULL, last must also be != NULL", netif->loop_last != NULL);
649     netif->loop_last->next = r;
650     netif->loop_last = last;
651   } else {
652     netif->loop_first = r;
653     netif->loop_last = last;
654   }
655   SYS_ARCH_UNPROTECT(lev);
656 
657   LINK_STATS_INC(link.xmit);
658   snmp_add_ifoutoctets(stats_if, p->tot_len);
659   snmp_inc_ifoutucastpkts(stats_if);
660 
661 #if LWIP_NETIF_LOOPBACK_MULTITHREADING
662   /* For multithreading environment, schedule a call to netif_poll */
663   tcpip_callback((tcpip_callback_fn)netif_poll, netif);
664 #endif /* LWIP_NETIF_LOOPBACK_MULTITHREADING */
665 
666   return ERR_OK;
667 }
668 
669 /**
670  * Call netif_poll() in the main loop of your application. This is to prevent
671  * reentering non-reentrant functions like tcp_input(). Packets passed to
672  * netif_loop_output() are put on a list that is passed to netif->input() by
673  * netif_poll().
674  */
675 void
netif_poll(struct netif * netif)676 netif_poll(struct netif *netif)
677 {
678   struct pbuf *in;
679   /* If we have a loopif, SNMP counters are adjusted for it,
680    * if not they are adjusted for 'netif'. */
681 #if LWIP_SNMP
682 #if LWIP_HAVE_LOOPIF
683   struct netif *stats_if = &loop_netif;
684 #else /* LWIP_HAVE_LOOPIF */
685   struct netif *stats_if = netif;
686 #endif /* LWIP_HAVE_LOOPIF */
687 #endif /* LWIP_SNMP */
688   SYS_ARCH_DECL_PROTECT(lev);
689 
690   do {
691     /* Get a packet from the list. With SYS_LIGHTWEIGHT_PROT=1, this is protected */
692     SYS_ARCH_PROTECT(lev);
693     in = netif->loop_first;
694     if (in != NULL) {
695       struct pbuf *in_end = in;
696 #if LWIP_LOOPBACK_MAX_PBUFS
697       u8_t clen = pbuf_clen(in);
698       /* adjust the number of pbufs on queue */
699       LWIP_ASSERT("netif->loop_cnt_current underflow",
700         ((netif->loop_cnt_current - clen) < netif->loop_cnt_current));
701       netif->loop_cnt_current -= clen;
702 #endif /* LWIP_LOOPBACK_MAX_PBUFS */
703       while (in_end->len != in_end->tot_len) {
704         LWIP_ASSERT("bogus pbuf: len != tot_len but next == NULL!", in_end->next != NULL);
705         in_end = in_end->next;
706       }
707       /* 'in_end' now points to the last pbuf from 'in' */
708       if (in_end == netif->loop_last) {
709         /* this was the last pbuf in the list */
710         netif->loop_first = netif->loop_last = NULL;
711       } else {
712         /* pop the pbuf off the list */
713         netif->loop_first = in_end->next;
714         LWIP_ASSERT("should not be null since first != last!", netif->loop_first != NULL);
715       }
716       /* De-queue the pbuf from its successors on the 'loop_' list. */
717       in_end->next = NULL;
718     }
719     SYS_ARCH_UNPROTECT(lev);
720 
721     if (in != NULL) {
722       LINK_STATS_INC(link.recv);
723       snmp_add_ifinoctets(stats_if, in->tot_len);
724       snmp_inc_ifinucastpkts(stats_if);
725       /* loopback packets are always IP packets! */
726       if (ip_input(in, netif) != ERR_OK) {
727         pbuf_free(in);
728       }
729       /* Don't reference the packet any more! */
730       in = NULL;
731     }
732   /* go on while there is a packet on the list */
733   } while (netif->loop_first != NULL);
734 }
735 
736 #if !LWIP_NETIF_LOOPBACK_MULTITHREADING
737 /**
738  * Calls netif_poll() for every netif on the netif_list.
739  */
740 void
netif_poll_all(void)741 netif_poll_all(void)
742 {
743   struct netif *netif = netif_list;
744   /* loop through netifs */
745   while (netif != NULL) {
746     netif_poll(netif);
747     /* proceed to next network interface */
748     netif = netif->next;
749   }
750 }
751 #endif /* !LWIP_NETIF_LOOPBACK_MULTITHREADING */
752 #endif /* ENABLE_LOOPBACK */
753