netif.c

00001 /**
00002  * @file
00003  * lwIP network interface abstraction
00004  *
00005  */
00006 
00007 /*
00008  * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
00009  * All rights reserved.
00010  *
00011  * Redistribution and use in source and binary forms, with or without modification,
00012  * are permitted provided that the following conditions are met:
00013  *
00014  * 1. Redistributions of source code must retain the above copyright notice,
00015  *    this list of conditions and the following disclaimer.
00016  * 2. Redistributions in binary form must reproduce the above copyright notice,
00017  *    this list of conditions and the following disclaimer in the documentation
00018  *    and/or other materials provided with the distribution.
00019  * 3. The name of the author may not be used to endorse or promote products
00020  *    derived from this software without specific prior written permission.
00021  *
00022  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
00023  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
00024  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
00025  * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
00026  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
00027  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
00028  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
00029  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
00030  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
00031  * OF SUCH DAMAGE.
00032  *
00033  * This file is part of the lwIP TCP/IP stack.
00034  *
00035  * Author: Adam Dunkels <adam@sics.se>
00036  *
00037  */
00038 
00039 #include "lwip/opt.h"
00040 
00041 #include "lwip/def.h"
00042 #include "lwip/ip_addr.h"
00043 #include "lwip/netif.h"
00044 #include "lwip/tcp.h"
00045 #include "lwip/snmp.h"
00046 #include "lwip/igmp.h"
00047 #include "netif/etharp.h"
00048 #if ENABLE_LOOPBACK
00049 #include "lwip/sys.h"
00050 #if LWIP_NETIF_LOOPBACK_MULTITHREADING
00051 #include "lwip/tcpip.h"
00052 #endif /* LWIP_NETIF_LOOPBACK_MULTITHREADING */
00053 #endif /* ENABLE_LOOPBACK */
00054 
00055 #if LWIP_NETIF_STATUS_CALLBACK
00056 #define NETIF_STATUS_CALLBACK(n) { if (n->status_callback) (n->status_callback)(n); }
00057 #else
00058 #define NETIF_STATUS_CALLBACK(n) { /* NOP */ }
00059 #endif /* LWIP_NETIF_STATUS_CALLBACK */ 
00060 
00061 #if LWIP_NETIF_LINK_CALLBACK
00062 #define NETIF_LINK_CALLBACK(n) { if (n->link_callback) (n->link_callback)(n); }
00063 #else
00064 #define NETIF_LINK_CALLBACK(n) { /* NOP */ }
00065 #endif /* LWIP_NETIF_LINK_CALLBACK */ 
00066 
00067 struct netif *netif_list;
00068 struct netif *netif_default;
00069 
00070 /**
00071  * Add a network interface to the list of lwIP netifs.
00072  *
00073  * @param netif a pre-allocated netif structure
00074  * @param ipaddr IP address for the new netif
00075  * @param netmask network mask for the new netif
00076  * @param gw default gateway IP address for the new netif
00077  * @param state opaque data passed to the new netif
00078  * @param init callback function that initializes the interface
00079  * @param input callback function that is called to pass
00080  * ingress packets up in the protocol layer stack.
00081  *
00082  * @return netif, or NULL if failed.
00083  */
00084 struct netif *
00085 netif_add(struct netif *netif, struct ip_addr *ipaddr, struct ip_addr *netmask,
00086   struct ip_addr *gw,
00087   void *state,
00088   err_t (* init)(struct netif *netif),
00089   err_t (* input)(struct pbuf *p, struct netif *netif))
00090 {
00091   static u8_t netifnum = 0;
00092 
00093   /* reset new interface configuration state */
00094   netif->ip_addr.addr = 0;
00095   netif->netmask.addr = 0;
00096   netif->gw.addr = 0;
00097   netif->flags = 0;
00098 #if LWIP_DHCP
00099   /* netif not under DHCP control by default */
00100   netif->dhcp = NULL;
00101 #endif /* LWIP_DHCP */
00102 #if LWIP_AUTOIP
00103   /* netif not under AutoIP control by default */
00104   netif->autoip = NULL;
00105 #endif /* LWIP_AUTOIP */
00106 #if LWIP_NETIF_STATUS_CALLBACK
00107   netif->status_callback = NULL;
00108 #endif /* LWIP_NETIF_STATUS_CALLBACK */
00109 #if LWIP_NETIF_LINK_CALLBACK
00110   netif->link_callback = NULL;
00111 #endif /* LWIP_NETIF_LINK_CALLBACK */
00112 #if LWIP_IGMP
00113   netif->igmp_mac_filter = NULL;
00114 #endif /* LWIP_IGMP */
00115 #if ENABLE_LOOPBACK
00116   netif->loop_first = NULL;
00117   netif->loop_last = NULL;
00118 #endif /* ENABLE_LOOPBACK */
00119 
00120   /* remember netif specific state information data */
00121   netif->state = state;
00122   netif->num = netifnum++;
00123   netif->input = input;
00124 #if LWIP_NETIF_HWADDRHINT
00125   netif->addr_hint = NULL;
00126 #endif /* LWIP_NETIF_HWADDRHINT*/
00127 #if ENABLE_LOOPBACK && LWIP_LOOPBACK_MAX_PBUFS
00128   netif->loop_cnt_current = 0;
00129 #endif /* ENABLE_LOOPBACK && LWIP_LOOPBACK_MAX_PBUFS */
00130 
00131   netif_set_addr(netif, ipaddr, netmask, gw);
00132 
00133   /* call user specified initialization function for netif */
00134   if (init(netif) != ERR_OK) {
00135     return (struct netif *)(NULL);
00136   }
00137 
00138   /* add this netif to the list */
00139   netif->next = netif_list;
00140   netif_list = netif;
00141   snmp_inc_iflist();
00142 
00143 #if LWIP_IGMP
00144   /* start IGMP processing */
00145   if (netif->flags & NETIF_FLAG_IGMP) {
00146     igmp_start( netif);
00147   }
00148 #endif /* LWIP_IGMP */
00149 
00150   LWIP_DEBUGF(NETIF_DEBUG, ("netif: added interface %c%c IP addr ",
00151     netif->name[0], netif->name[1]));
00152   ip_addr_debug_print(NETIF_DEBUG, ipaddr);
00153   LWIP_DEBUGF(NETIF_DEBUG, (" netmask "));
00154   ip_addr_debug_print(NETIF_DEBUG, netmask);
00155   LWIP_DEBUGF(NETIF_DEBUG, (" gw "));
00156   ip_addr_debug_print(NETIF_DEBUG, gw);
00157   LWIP_DEBUGF(NETIF_DEBUG, ("\n"));
00158   return netif;
00159 }
00160 
00161 /**
00162  * Change IP address configuration for a network interface (including netmask
00163  * and default gateway).
00164  *
00165  * @param netif the network interface to change
00166  * @param ipaddr the new IP address
00167  * @param netmask the new netmask
00168  * @param gw the new default gateway
00169  */
00170 void
00171 netif_set_addr(struct netif *netif, struct ip_addr *ipaddr, struct ip_addr *netmask,
00172     struct ip_addr *gw)
00173 {
00174   netif_set_ipaddr(netif, ipaddr);
00175   netif_set_netmask(netif, netmask);
00176   netif_set_gw(netif, gw);
00177 }
00178 
00179 /**
00180  * Remove a network interface from the list of lwIP netifs.
00181  *
00182  * @param netif the network interface to remove
00183  */
00184 void netif_remove(struct netif * netif)
00185 {
00186   if ( netif == NULL ) return;
00187 
00188 #if LWIP_IGMP
00189   /* stop IGMP processing */
00190   if (netif->flags & NETIF_FLAG_IGMP) {
00191     igmp_stop( netif);
00192   }
00193 #endif /* LWIP_IGMP */
00194 
00195   snmp_delete_ipaddridx_tree(netif);
00196 
00197   /*  is it the first netif? */
00198   if (netif_list == netif) {
00199     netif_list = netif->next;
00200     snmp_dec_iflist();
00201   }
00202   else {
00203     /*  look for netif further down the list */
00204     struct netif * tmpNetif;
00205     for (tmpNetif = netif_list; tmpNetif != NULL; tmpNetif = tmpNetif->next) {
00206       if (tmpNetif->next == netif) {
00207         tmpNetif->next = netif->next;
00208         snmp_dec_iflist();
00209         break;
00210       }
00211     }
00212     if (tmpNetif == NULL)
00213       return; /*  we didn't find any netif today */
00214   }
00215   /* this netif is default? */
00216   if (netif_default == netif)
00217     /* reset default netif */
00218     netif_set_default((struct netif *)(NULL));
00219   LWIP_DEBUGF( NETIF_DEBUG, ("netif_remove: removed netif\n") );
00220 }
00221 
00222 /**
00223  * Find a network interface by searching for its name
00224  *
00225  * @param name the name of the netif (like netif->name) plus concatenated number
00226  * in ascii representation (e.g. 'en0')
00227  */
00228 struct netif *
00229 netif_find(char *name)
00230 {
00231   struct netif *netif;
00232   u8_t num;
00233 
00234   if (name == NULL) {
00235     return (struct netif *)(NULL);
00236   }
00237 
00238   num = name[2] - '0';
00239 
00240   for(netif = netif_list; netif != NULL; netif = netif->next) {
00241     if (num == netif->num &&
00242        name[0] == netif->name[0] &&
00243        name[1] == netif->name[1]) {
00244       LWIP_DEBUGF(NETIF_DEBUG, ("netif_find: found %c%c\n", name[0], name[1]));
00245       return netif;
00246     }
00247   }
00248   LWIP_DEBUGF(NETIF_DEBUG, ("netif_find: didn't find %c%c\n", name[0], name[1]));
00249   return (struct netif *)(NULL);
00250 }
00251 
00252 /**
00253  * Change the IP address of a network interface
00254  *
00255  * @param netif the network interface to change
00256  * @param ipaddr the new IP address
00257  *
00258  * @note call netif_set_addr() if you also want to change netmask and
00259  * default gateway
00260  */
00261 void
00262 netif_set_ipaddr(struct netif *netif, struct ip_addr *ipaddr)
00263 {
00264   /* TODO: Handling of obsolete pcbs */
00265   /* See:  http://mail.gnu.org/archive/html/lwip-users/2003-03/msg00118.html */
00266 #if LWIP_TCP
00267   struct tcp_pcb *pcb;
00268   struct tcp_pcb_listen *lpcb;
00269 
00270   /* address is actually being changed? */
00271   if ((ip_addr_cmp(ipaddr, &(netif->ip_addr))) == 0)
00272   {
00273     /* extern struct tcp_pcb *tcp_active_pcbs; defined by tcp.h */
00274     LWIP_DEBUGF(NETIF_DEBUG | 1, ("netif_set_ipaddr: netif address being changed\n"));
00275     pcb = tcp_active_pcbs;
00276     while (pcb != NULL) {
00277       /* PCB bound to current local interface address? */
00278       if (ip_addr_cmp(&(pcb->local_ip), &(netif->ip_addr))) {
00279         /* this connection must be aborted */
00280         struct tcp_pcb *next = pcb->next;
00281         LWIP_DEBUGF(NETIF_DEBUG | 1, ("netif_set_ipaddr: aborting TCP pcb %p\n", (void *)pcb));
00282         tcp_abort(pcb);
00283         pcb = next;
00284       } else {
00285         pcb = pcb->next;
00286       }
00287     }
00288     for (lpcb = tcp_listen_pcbs.listen_pcbs; lpcb != NULL; lpcb = lpcb->next) {
00289       /* PCB bound to current local interface address? */
00290       if ((!(ip_addr_isany(&(lpcb->local_ip)))) &&
00291           (ip_addr_cmp(&(lpcb->local_ip), &(netif->ip_addr)))) {
00292         /* The PCB is listening to the old ipaddr and
00293          * is set to listen to the new one instead */
00294         ip_addr_set(&(lpcb->local_ip), ipaddr);
00295       }
00296     }
00297   }
00298 #endif
00299   snmp_delete_ipaddridx_tree(netif);
00300   snmp_delete_iprteidx_tree(0,netif);
00301   /* set new IP address to netif */
00302   ip_addr_set(&(netif->ip_addr), ipaddr);
00303   snmp_insert_ipaddridx_tree(netif);
00304   snmp_insert_iprteidx_tree(0,netif);
00305 
00306   LWIP_DEBUGF(NETIF_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE | 3, ("netif: IP address of interface %c%c set to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
00307     netif->name[0], netif->name[1],
00308     ip4_addr1(&netif->ip_addr),
00309     ip4_addr2(&netif->ip_addr),
00310     ip4_addr3(&netif->ip_addr),
00311     ip4_addr4(&netif->ip_addr)));
00312 }
00313 
00314 /**
00315  * Change the default gateway for a network interface
00316  *
00317  * @param netif the network interface to change
00318  * @param gw the new default gateway
00319  *
00320  * @note call netif_set_addr() if you also want to change ip address and netmask
00321  */
00322 void
00323 netif_set_gw(struct netif *netif, struct ip_addr *gw)
00324 {
00325   ip_addr_set(&(netif->gw), gw);
00326   LWIP_DEBUGF(NETIF_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE | 3, ("netif: GW address of interface %c%c set to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
00327     netif->name[0], netif->name[1],
00328     ip4_addr1(&netif->gw),
00329     ip4_addr2(&netif->gw),
00330     ip4_addr3(&netif->gw),
00331     ip4_addr4(&netif->gw)));
00332 }
00333 
00334 /**
00335  * Change the netmask of a network interface
00336  *
00337  * @param netif the network interface to change
00338  * @param netmask the new netmask
00339  *
00340  * @note call netif_set_addr() if you also want to change ip address and
00341  * default gateway
00342  */
00343 void
00344 netif_set_netmask(struct netif *netif, struct ip_addr *netmask)
00345 {
00346   snmp_delete_iprteidx_tree(0, netif);
00347   /* set new netmask to netif */
00348   ip_addr_set(&(netif->netmask), netmask);
00349   snmp_insert_iprteidx_tree(0, netif);
00350   LWIP_DEBUGF(NETIF_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE | 3, ("netif: netmask of interface %c%c set to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
00351     netif->name[0], netif->name[1],
00352     ip4_addr1(&netif->netmask),
00353     ip4_addr2(&netif->netmask),
00354     ip4_addr3(&netif->netmask),
00355     ip4_addr4(&netif->netmask)));
00356 }
00357 
00358 /**
00359  * Set a network interface as the default network interface
00360  * (used to output all packets for which no specific route is found)
00361  *
00362  * @param netif the default network interface
00363  */
00364 void
00365 netif_set_default(struct netif *netif)
00366 {
00367   if (netif == NULL)
00368   {
00369     /* remove default route */
00370     snmp_delete_iprteidx_tree(1, netif);
00371   }
00372   else
00373   {
00374     /* install default route */
00375     snmp_insert_iprteidx_tree(1, netif);
00376   }
00377   netif_default = netif;
00378   LWIP_DEBUGF(NETIF_DEBUG, ("netif: setting default interface %c%c\n",
00379            netif ? netif->name[0] : '\'', netif ? netif->name[1] : '\''));
00380 }
00381 
00382 /**
00383  * Bring an interface up, available for processing
00384  * traffic.
00385  * 
00386  * @note: Enabling DHCP on a down interface will make it come
00387  * up once configured.
00388  * 
00389  * @see dhcp_start()
00390  */ 
00391 void netif_set_up(struct netif *netif)
00392 {
00393   if ( !(netif->flags & NETIF_FLAG_UP )) {
00394     netif->flags |= NETIF_FLAG_UP;
00395     
00396 #if LWIP_SNMP
00397     snmp_get_sysuptime(&netif->ts);
00398 #endif /* LWIP_SNMP */
00399 
00400     NETIF_LINK_CALLBACK(netif);
00401     NETIF_STATUS_CALLBACK(netif);
00402 
00403 #if LWIP_ARP
00404     /** For Ethernet network interfaces, we would like to send a
00405      *  "gratuitous ARP"; this is an ARP packet sent by a node in order
00406      *  to spontaneously cause other nodes to update an entry in their
00407      *  ARP cache. From RFC 3220 "IP Mobility Support for IPv4" section 4.6.
00408      */ 
00409     if (netif->flags & NETIF_FLAG_ETHARP) {
00410       etharp_query(netif, &(netif->ip_addr), (struct pbuf *)(NULL));
00411     }
00412 #endif /* LWIP_ARP */
00413     
00414   }
00415 }
00416 
00417 /**
00418  * Bring an interface down, disabling any traffic processing.
00419  *
00420  * @note: Enabling DHCP on a down interface will make it come
00421  * up once configured.
00422  * 
00423  * @see dhcp_start()
00424  */ 
00425 void netif_set_down(struct netif *netif)
00426 {
00427   if ( netif->flags & NETIF_FLAG_UP )
00428     {
00429       netif->flags &= ~NETIF_FLAG_UP;
00430 #if LWIP_SNMP
00431       snmp_get_sysuptime(&netif->ts);
00432 #endif
00433       
00434       NETIF_LINK_CALLBACK(netif);
00435       NETIF_STATUS_CALLBACK(netif);
00436     }
00437 }
00438 
00439 /**
00440  * Ask if an interface is up
00441  */ 
00442 u8_t netif_is_up(struct netif *netif)
00443 {
00444   return (netif->flags & NETIF_FLAG_UP)?1:0;
00445 }
00446 
00447 #if LWIP_NETIF_STATUS_CALLBACK
00448 /**
00449  * Set callback to be called when interface is brought up/down
00450  */
00451 void netif_set_status_callback(struct netif *netif, void (* status_callback)(struct netif *netif ))
00452 {
00453     if ( netif )
00454         netif->status_callback = status_callback;
00455 }
00456 #endif /* LWIP_NETIF_STATUS_CALLBACK */
00457 
00458 #if LWIP_NETIF_LINK_CALLBACK
00459 /**
00460  * Called by a driver when its link goes up
00461  */
00462 void netif_set_link_up(struct netif *netif )
00463 {
00464   netif->flags |= NETIF_FLAG_LINK_UP;
00465 
00466 #if LWIP_ARP
00467   /** For Ethernet network interfaces, we would like to send a
00468    *  "gratuitous ARP"; this is an ARP packet sent by a node in order
00469    *  to spontaneously cause other nodes to update an entry in their
00470    *  ARP cache. From RFC 3220 "IP Mobility Support for IPv4" section 4.6.
00471    */ 
00472   if (netif->flags & NETIF_FLAG_ETHARP) {
00473     etharp_query(netif, &(netif->ip_addr), NULL);
00474   }
00475 #endif /* LWIP_ARP */
00476 
00477 #if LWIP_IGMP
00478   /* resend IGMP memberships */
00479   if (netif->flags & NETIF_FLAG_IGMP) {
00480     igmp_report_groups( netif);
00481   }
00482 #endif /* LWIP_IGMP */
00483 
00484   NETIF_LINK_CALLBACK(netif);
00485 }
00486 
00487 /**
00488  * Called by a driver when its link goes down
00489  */
00490 void netif_set_link_down(struct netif *netif )
00491 {
00492   netif->flags &= ~NETIF_FLAG_LINK_UP;
00493   NETIF_LINK_CALLBACK(netif);
00494 }
00495 
00496 /**
00497  * Ask if a link is up
00498  */ 
00499 u8_t netif_is_link_up(struct netif *netif)
00500 {
00501   return (netif->flags & NETIF_FLAG_LINK_UP) ? 1 : 0;
00502 }
00503 
00504 /**
00505  * Set callback to be called when link is brought up/down
00506  */
00507 void netif_set_link_callback(struct netif *netif, void (* link_callback)(struct netif *netif ))
00508 {
00509   if (netif) {
00510     netif->link_callback = link_callback;
00511   }
00512 }
00513 #endif /* LWIP_NETIF_LINK_CALLBACK */
00514 
00515 #if ENABLE_LOOPBACK
00516 /**
00517  * Send an IP packet to be received on the same netif (loopif-like).
00518  * The pbuf is simply copied and handed back to netif->input.
00519  * In multithreaded mode, this is done directly since netif->input must put
00520  * the packet on a queue.
00521  * In callback mode, the packet is put on an internal queue and is fed to
00522  * netif->input by netif_poll().
00523  *
00524  * @param netif the lwip network interface structure
00525  * @param p the (IP) packet to 'send'
00526  * @param ipaddr the ip address to send the packet to (not used)
00527  * @return ERR_OK if the packet has been sent
00528  *         ERR_MEM if the pbuf used to copy the packet couldn't be allocated
00529  */
00530 err_t
00531 netif_loop_output(struct netif *netif, struct pbuf *p,
00532        struct ip_addr *ipaddr)
00533 {
00534   struct pbuf *r;
00535   err_t err;
00536   struct pbuf *last;
00537 #if LWIP_LOOPBACK_MAX_PBUFS
00538   u8_t clen = 0;
00539 #endif /* LWIP_LOOPBACK_MAX_PBUFS */
00540   SYS_ARCH_DECL_PROTECT(lev);
00541   LWIP_UNUSED_ARG(ipaddr);
00542 
00543   /* Allocate a new pbuf */
00544   r = pbuf_alloc(PBUF_LINK, p->tot_len, PBUF_RAM);
00545   if (r == NULL) {
00546     return ERR_MEM;
00547   }
00548 #if LWIP_LOOPBACK_MAX_PBUFS
00549   clen = pbuf_clen(r);
00550   /* check for overflow or too many pbuf on queue */
00551   if(((netif->loop_cnt_current + clen) < netif->loop_cnt_current) ||
00552     ((netif->loop_cnt_current + clen) > LWIP_LOOPBACK_MAX_PBUFS)) {
00553       pbuf_free(r);
00554       r = NULL;
00555       return ERR_MEM;
00556   }
00557   netif->loop_cnt_current += clen;
00558 #endif /* LWIP_LOOPBACK_MAX_PBUFS */
00559 
00560   /* Copy the whole pbuf queue p into the single pbuf r */
00561   if ((err = pbuf_copy(r, p)) != ERR_OK) {
00562     pbuf_free(r);
00563     r = NULL;
00564     return err;
00565   }
00566 
00567   /* Put the packet on a linked list which gets emptied through calling
00568      netif_poll(). */
00569 
00570   /* let last point to the last pbuf in chain r */
00571   for (last = r; last->next != NULL; last = last->next);
00572 
00573   SYS_ARCH_PROTECT(lev);
00574   if(netif->loop_first != NULL) {
00575     LWIP_ASSERT("if first != NULL, last must also be != NULL", netif->loop_last != NULL);
00576     netif->loop_last->next = r;
00577     netif->loop_last = last;
00578   } else {
00579     netif->loop_first = r;
00580     netif->loop_last = last;
00581   }
00582   SYS_ARCH_UNPROTECT(lev);
00583 
00584 #if LWIP_NETIF_LOOPBACK_MULTITHREADING
00585   /* For multithreading environment, schedule a call to netif_poll */
00586   tcpip_callback(netif_poll, netif);
00587 #endif /* LWIP_NETIF_LOOPBACK_MULTITHREADING */
00588 
00589   return ERR_OK;
00590 }
00591 
00592 /**
00593  * Call netif_poll() in the main loop of your application. This is to prevent
00594  * reentering non-reentrant functions like tcp_input(). Packets passed to
00595  * netif_loop_output() are put on a list that is passed to netif->input() by
00596  * netif_poll().
00597  */
00598 void
00599 netif_poll(struct netif *netif)
00600 {
00601   struct pbuf *in;
00602   SYS_ARCH_DECL_PROTECT(lev);
00603 
00604   do {
00605     /* Get a packet from the list. With SYS_LIGHTWEIGHT_PROT=1, this is protected */
00606     SYS_ARCH_PROTECT(lev);
00607     in = netif->loop_first;
00608     if(in != NULL) {
00609       struct pbuf *in_end = in;
00610 #if LWIP_LOOPBACK_MAX_PBUFS
00611       u8_t clen = pbuf_clen(in);
00612       /* adjust the number of pbufs on queue */
00613       LWIP_ASSERT("netif->loop_cnt_current underflow",
00614         ((netif->loop_cnt_current - clen) < netif->loop_cnt_current));
00615       netif->loop_cnt_current -= clen;
00616 #endif /* LWIP_LOOPBACK_MAX_PBUFS */
00617       while(in_end->len != in_end->tot_len) {
00618         LWIP_ASSERT("bogus pbuf: len != tot_len but next == NULL!", in_end->next != NULL);
00619         in_end = in_end->next;
00620       }
00621       /* 'in_end' now points to the last pbuf from 'in' */
00622       if(in_end == netif->loop_last) {
00623         /* this was the last pbuf in the list */
00624         netif->loop_first = netif->loop_last = NULL;
00625       } else {
00626         /* pop the pbuf off the list */
00627         netif->loop_first = in_end->next;
00628         LWIP_ASSERT("should not be null since first != last!", netif->loop_first != NULL);
00629       }
00630       /* De-queue the pbuf from its successors on the 'loop_' list. */
00631       in_end->next = NULL;
00632     }
00633     SYS_ARCH_UNPROTECT(lev);
00634 
00635     if(in != NULL) {
00636       /* loopback packets are always IP packets! */
00637       if(ip_input(in, netif) != ERR_OK) {
00638         pbuf_free(in);
00639       }
00640       /* Don't reference the packet any more! */
00641       in = NULL;
00642     }
00643   /* go on while there is a packet on the list */
00644   } while(netif->loop_first != NULL);
00645 }
00646 
00647 #if !LWIP_NETIF_LOOPBACK_MULTITHREADING
00648 /**
00649  * Calls netif_poll() for every netif on the netif_list.
00650  */
00651 void
00652 netif_poll_all(void)
00653 {
00654   struct netif *netif = netif_list;
00655   /* loop through netifs */
00656   while (netif != NULL) {
00657     netif_poll(netif);
00658     /* proceed to next network interface */
00659     netif = netif->next;
00660   }
00661 }
00662 #endif /* !LWIP_NETIF_LOOPBACK_MULTITHREADING */
00663 #endif /* ENABLE_LOOPBACK */