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_impl.h"
00045 #include "lwip/snmp.h"
00046 #include "lwip/igmp.h"
00047 #include "netif/etharp.h"
00048 #include "lwip/stats.h"
00049 #if ENABLE_LOOPBACK
00050 #include "lwip/sys.h"
00051 #if LWIP_NETIF_LOOPBACK_MULTITHREADING
00052 #include "lwip/tcpip.h"
00053 #endif /* LWIP_NETIF_LOOPBACK_MULTITHREADING */
00054 #endif /* ENABLE_LOOPBACK */
00055 
00056 #if LWIP_AUTOIP
00057 #include "lwip/autoip.h"
00058 #endif /* LWIP_AUTOIP */
00059 #if LWIP_DHCP
00060 #include "lwip/dhcp.h "
00061 #endif /* LWIP_DHCP */
00062 
00063 #if LWIP_NETIF_STATUS_CALLBACK
00064 #define NETIF_STATUS_CALLBACK(n) do{ if (n->status_callback) { (n->status_callback)(n); }}while(0)
00065 #else
00066 #define NETIF_STATUS_CALLBACK(n)
00067 #endif /* LWIP_NETIF_STATUS_CALLBACK */ 
00068 
00069 #if LWIP_NETIF_LINK_CALLBACK
00070 #define NETIF_LINK_CALLBACK(n) do{ if (n->link_callback) { (n->link_callback)(n); }}while(0)
00071 #else
00072 #define NETIF_LINK_CALLBACK(n)
00073 #endif /* LWIP_NETIF_LINK_CALLBACK */ 
00074 
00075 struct netif *netif_list;
00076 struct netif *netif_default;
00077 
00078 #if LWIP_HAVE_LOOPIF
00079 static struct netif loop_netif;
00080 
00081 /**
00082  * Initialize a lwip network interface structure for a loopback interface
00083  *
00084  * @param netif the lwip network interface structure for this loopif
00085  * @return ERR_OK if the loopif is initialized
00086  *         ERR_MEM if private data couldn't be allocated
00087  */
00088 static err_t
00089 netif_loopif_init(struct netif *netif)
00090 {
00091   /* initialize the snmp variables and counters inside the struct netif
00092    * ifSpeed: no assumption can be made!
00093    */
00094   NETIF_INIT_SNMP(netif, snmp_ifType_softwareLoopback, 0);
00095 
00096   netif->name[0] = 'l';
00097   netif->name[1] = 'o';
00098   netif->output = netif_loop_output;
00099   return ERR_OK;
00100 }
00101 #endif /* LWIP_HAVE_LOOPIF */
00102 
00103 void
00104 netif_init(void)
00105 {
00106 #if LWIP_HAVE_LOOPIF
00107   ip_addr_t loop_ipaddr, loop_netmask, loop_gw;
00108   IP4_ADDR(&loop_gw, 127,0,0,1);
00109   IP4_ADDR(&loop_ipaddr, 127,0,0,1);
00110   IP4_ADDR(&loop_netmask, 255,0,0,0);
00111 
00112 #if NO_SYS
00113   netif_add(&loop_netif, &loop_ipaddr, &loop_netmask, &loop_gw, NULL, netif_loopif_init, ip_input);
00114 #else  /* NO_SYS */
00115   netif_add(&loop_netif, &loop_ipaddr, &loop_netmask, &loop_gw, NULL, netif_loopif_init, tcpip_input);
00116 #endif /* NO_SYS */
00117   netif_set_up(&loop_netif);
00118 
00119 #endif /* LWIP_HAVE_LOOPIF */
00120 }
00121 
00122 /**
00123  * Add a network interface to the list of lwIP netifs.
00124  *
00125  * @param netif a pre-allocated netif structure
00126  * @param ipaddr IP address for the new netif
00127  * @param netmask network mask for the new netif
00128  * @param gw default gateway IP address for the new netif
00129  * @param state opaque data passed to the new netif
00130  * @param init callback function that initializes the interface
00131  * @param input callback function that is called to pass
00132  * ingress packets up in the protocol layer stack.
00133  *
00134  * @return netif, or NULL if failed.
00135  */
00136 struct netif *
00137 netif_add(struct netif *netif, ip_addr_t *ipaddr, ip_addr_t *netmask,
00138   ip_addr_t *gw, void *state, netif_init_fn init, netif_input_fn input)
00139 {
00140   static u8_t netifnum = 0;
00141 
00142   LWIP_ASSERT("No init function given", init != NULL);
00143 
00144   /* reset new interface configuration state */
00145   ip_addr_set_zero(&netif->ip_addr);
00146   ip_addr_set_zero(&netif->netmask);
00147   ip_addr_set_zero(&netif->gw);
00148   netif->flags = 0;
00149 #if LWIP_DHCP
00150   /* netif not under DHCP control by default */
00151   netif->dhcp = NULL;
00152 #endif /* LWIP_DHCP */
00153 #if LWIP_AUTOIP
00154   /* netif not under AutoIP control by default */
00155   netif->autoip = NULL;
00156 #endif /* LWIP_AUTOIP */
00157 #if LWIP_NETIF_STATUS_CALLBACK
00158   netif->status_callback = NULL;
00159 #endif /* LWIP_NETIF_STATUS_CALLBACK */
00160 #if LWIP_NETIF_LINK_CALLBACK
00161   netif->link_callback = NULL;
00162 #endif /* LWIP_NETIF_LINK_CALLBACK */
00163 #if LWIP_IGMP
00164   netif->igmp_mac_filter = NULL;
00165 #endif /* LWIP_IGMP */
00166 #if ENABLE_LOOPBACK
00167   netif->loop_first = NULL;
00168   netif->loop_last = NULL;
00169 #endif /* ENABLE_LOOPBACK */
00170 
00171   /* remember netif specific state information data */
00172   netif->state = state;
00173   netif->num = netifnum++;
00174   netif->input = input;
00175 #if LWIP_NETIF_HWADDRHINT
00176   netif->addr_hint = NULL;
00177 #endif /* LWIP_NETIF_HWADDRHINT*/
00178 #if ENABLE_LOOPBACK && LWIP_LOOPBACK_MAX_PBUFS
00179   netif->loop_cnt_current = 0;
00180 #endif /* ENABLE_LOOPBACK && LWIP_LOOPBACK_MAX_PBUFS */
00181 
00182   netif_set_addr(netif, ipaddr, netmask, gw);
00183 
00184   /* call user specified initialization function for netif */
00185   if (init(netif) != ERR_OK) {
00186     return NULL;
00187   }
00188 
00189   /* add this netif to the list */
00190   netif->next = netif_list;
00191   netif_list = netif;
00192   snmp_inc_iflist();
00193 
00194 #if LWIP_IGMP
00195   /* start IGMP processing */
00196   if (netif->flags & NETIF_FLAG_IGMP) {
00197     igmp_start(netif);
00198   }
00199 #endif /* LWIP_IGMP */
00200 
00201   LWIP_DEBUGF(NETIF_DEBUG, ("netif: added interface %c%c IP addr ",
00202     netif->name[0], netif->name[1]));
00203   ip_addr_debug_print(NETIF_DEBUG, ipaddr);
00204   LWIP_DEBUGF(NETIF_DEBUG, (" netmask "));
00205   ip_addr_debug_print(NETIF_DEBUG, netmask);
00206   LWIP_DEBUGF(NETIF_DEBUG, (" gw "));
00207   ip_addr_debug_print(NETIF_DEBUG, gw);
00208   LWIP_DEBUGF(NETIF_DEBUG, ("\n"));
00209   return netif;
00210 }
00211 
00212 /**
00213  * Change IP address configuration for a network interface (including netmask
00214  * and default gateway).
00215  *
00216  * @param netif the network interface to change
00217  * @param ipaddr the new IP address
00218  * @param netmask the new netmask
00219  * @param gw the new default gateway
00220  */
00221 void
00222 netif_set_addr(struct netif *netif, ip_addr_t *ipaddr, ip_addr_t *netmask,
00223     ip_addr_t *gw)
00224 {
00225   netif_set_ipaddr(netif, ipaddr);
00226   netif_set_netmask(netif, netmask);
00227   netif_set_gw(netif, gw);
00228 }
00229 
00230 /**
00231  * Remove a network interface from the list of lwIP netifs.
00232  *
00233  * @param netif the network interface to remove
00234  */
00235 void
00236 netif_remove(struct netif *netif)
00237 {
00238   if (netif == NULL) {
00239     return;
00240   }
00241 
00242 #if LWIP_IGMP
00243   /* stop IGMP processing */
00244   if (netif->flags & NETIF_FLAG_IGMP) {
00245     igmp_stop(netif);
00246   }
00247 #endif /* LWIP_IGMP */
00248   if (netif_is_up(netif)) {
00249     /* set netif down before removing (call callback function) */
00250     netif_set_down(netif);
00251   }
00252 
00253   snmp_delete_ipaddridx_tree(netif);
00254 
00255   /*  is it the first netif? */
00256   if (netif_list == netif) {
00257     netif_list = netif->next;
00258   } else {
00259     /*  look for netif further down the list */
00260     struct netif * tmpNetif;
00261     for (tmpNetif = netif_list; tmpNetif != NULL; tmpNetif = tmpNetif->next) {
00262       if (tmpNetif->next == netif) {
00263         tmpNetif->next = netif->next;
00264         break;
00265       }
00266     }
00267     if (tmpNetif == NULL)
00268       return; /*  we didn't find any netif today */
00269   }
00270   snmp_dec_iflist();
00271   /* this netif is default? */
00272   if (netif_default == netif) {
00273     /* reset default netif */
00274     netif_set_default(NULL);
00275   }
00276   LWIP_DEBUGF( NETIF_DEBUG, ("netif_remove: removed netif\n") );
00277 }
00278 
00279 /**
00280  * Find a network interface by searching for its name
00281  *
00282  * @param name the name of the netif (like netif->name) plus concatenated number
00283  * in ascii representation (e.g. 'en0')
00284  */
00285 struct netif *
00286 netif_find(char *name)
00287 {
00288   struct netif *netif;
00289   u8_t num;
00290 
00291   if (name == NULL) {
00292     return NULL;
00293   }
00294 
00295   num = name[2] - '0';
00296 
00297   for(netif = netif_list; netif != NULL; netif = netif->next) {
00298     if (num == netif->num &&
00299        name[0] == netif->name[0] &&
00300        name[1] == netif->name[1]) {
00301       LWIP_DEBUGF(NETIF_DEBUG, ("netif_find: found %c%c\n", name[0], name[1]));
00302       return netif;
00303     }
00304   }
00305   LWIP_DEBUGF(NETIF_DEBUG, ("netif_find: didn't find %c%c\n", name[0], name[1]));
00306   return NULL;
00307 }
00308 
00309 /**
00310  * Change the IP address of a network interface
00311  *
00312  * @param netif the network interface to change
00313  * @param ipaddr the new IP address
00314  *
00315  * @note call netif_set_addr() if you also want to change netmask and
00316  * default gateway
00317  */
00318 void
00319 netif_set_ipaddr(struct netif *netif, ip_addr_t *ipaddr)
00320 {
00321   /* TODO: Handling of obsolete pcbs */
00322   /* See:  http://mail.gnu.org/archive/html/lwip-users/2003-03/msg00118.html */
00323 #if LWIP_TCP
00324   struct tcp_pcb *pcb;
00325   struct tcp_pcb_listen *lpcb;
00326 
00327   /* address is actually being changed? */
00328   if ((ip_addr_cmp(ipaddr, &(netif->ip_addr))) == 0) {
00329     /* extern struct tcp_pcb *tcp_active_pcbs; defined by tcp.h */
00330     LWIP_DEBUGF(NETIF_DEBUG | LWIP_DBG_STATE, ("netif_set_ipaddr: netif address being changed\n"));
00331     pcb = tcp_active_pcbs;
00332     while (pcb != NULL) {
00333       /* PCB bound to current local interface address? */
00334       if (ip_addr_cmp(&(pcb->local_ip), &(netif->ip_addr))
00335 #if LWIP_AUTOIP
00336         /* connections to link-local addresses must persist (RFC3927 ch. 1.9) */
00337         && !ip_addr_islinklocal(&(pcb->local_ip))
00338 #endif /* LWIP_AUTOIP */
00339         ) {
00340         /* this connection must be aborted */
00341         struct tcp_pcb *next = pcb->next;
00342         LWIP_DEBUGF(NETIF_DEBUG | LWIP_DBG_STATE, ("netif_set_ipaddr: aborting TCP pcb %p\n", (void *)pcb));
00343         tcp_abort(pcb);
00344         pcb = next;
00345       } else {
00346         pcb = pcb->next;
00347       }
00348     }
00349     for (lpcb = tcp_listen_pcbs.listen_pcbs; lpcb != NULL; lpcb = lpcb->next) {
00350       /* PCB bound to current local interface address? */
00351       if ((!(ip_addr_isany(&(lpcb->local_ip)))) &&
00352           (ip_addr_cmp(&(lpcb->local_ip), &(netif->ip_addr)))) {
00353         /* The PCB is listening to the old ipaddr and
00354          * is set to listen to the new one instead */
00355         ip_addr_set(&(lpcb->local_ip), ipaddr);
00356       }
00357     }
00358   }
00359 #endif
00360   snmp_delete_ipaddridx_tree(netif);
00361   snmp_delete_iprteidx_tree(0,netif);
00362   /* set new IP address to netif */
00363   ip_addr_set(&(netif->ip_addr), ipaddr);
00364   snmp_insert_ipaddridx_tree(netif);
00365   snmp_insert_iprteidx_tree(0,netif);
00366 
00367   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",
00368     netif->name[0], netif->name[1],
00369     ip4_addr1_16(&netif->ip_addr),
00370     ip4_addr2_16(&netif->ip_addr),
00371     ip4_addr3_16(&netif->ip_addr),
00372     ip4_addr4_16(&netif->ip_addr)));
00373 }
00374 
00375 /**
00376  * Change the default gateway for a network interface
00377  *
00378  * @param netif the network interface to change
00379  * @param gw the new default gateway
00380  *
00381  * @note call netif_set_addr() if you also want to change ip address and netmask
00382  */
00383 void
00384 netif_set_gw(struct netif *netif, ip_addr_t *gw)
00385 {
00386   ip_addr_set(&(netif->gw), gw);
00387   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",
00388     netif->name[0], netif->name[1],
00389     ip4_addr1_16(&netif->gw),
00390     ip4_addr2_16(&netif->gw),
00391     ip4_addr3_16(&netif->gw),
00392     ip4_addr4_16(&netif->gw)));
00393 }
00394 
00395 /**
00396  * Change the netmask of a network interface
00397  *
00398  * @param netif the network interface to change
00399  * @param netmask the new netmask
00400  *
00401  * @note call netif_set_addr() if you also want to change ip address and
00402  * default gateway
00403  */
00404 void
00405 netif_set_netmask(struct netif *netif, ip_addr_t *netmask)
00406 {
00407   snmp_delete_iprteidx_tree(0, netif);
00408   /* set new netmask to netif */
00409   ip_addr_set(&(netif->netmask), netmask);
00410   snmp_insert_iprteidx_tree(0, netif);
00411   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",
00412     netif->name[0], netif->name[1],
00413     ip4_addr1_16(&netif->netmask),
00414     ip4_addr2_16(&netif->netmask),
00415     ip4_addr3_16(&netif->netmask),
00416     ip4_addr4_16(&netif->netmask)));
00417 }
00418 
00419 /**
00420  * Set a network interface as the default network interface
00421  * (used to output all packets for which no specific route is found)
00422  *
00423  * @param netif the default network interface
00424  */
00425 void
00426 netif_set_default(struct netif *netif)
00427 {
00428   if (netif == NULL) {
00429     /* remove default route */
00430     snmp_delete_iprteidx_tree(1, netif);
00431   } else {
00432     /* install default route */
00433     snmp_insert_iprteidx_tree(1, netif);
00434   }
00435   netif_default = netif;
00436   LWIP_DEBUGF(NETIF_DEBUG, ("netif: setting default interface %c%c\n",
00437            netif ? netif->name[0] : '\'', netif ? netif->name[1] : '\''));
00438 }
00439 
00440 /**
00441  * Bring an interface up, available for processing
00442  * traffic.
00443  * 
00444  * @note: Enabling DHCP on a down interface will make it come
00445  * up once configured.
00446  * 
00447  * @see dhcp_start()
00448  */ 
00449 void netif_set_up(struct netif *netif)
00450 {
00451   if (!(netif->flags & NETIF_FLAG_UP)) {
00452     netif->flags |= NETIF_FLAG_UP;
00453     
00454 #if LWIP_SNMP
00455     snmp_get_sysuptime(&netif->ts);
00456 #endif /* LWIP_SNMP */
00457 
00458     NETIF_STATUS_CALLBACK(netif);
00459 
00460     if (netif->flags & NETIF_FLAG_LINK_UP) {
00461 #if LWIP_ARP
00462       /* For Ethernet network interfaces, we would like to send a "gratuitous ARP" */ 
00463       if (netif->flags & (NETIF_FLAG_ETHARP)) {
00464         etharp_gratuitous(netif);
00465       }
00466 #endif /* LWIP_ARP */
00467 
00468 #if LWIP_IGMP
00469       /* resend IGMP memberships */
00470       if (netif->flags & NETIF_FLAG_IGMP) {
00471         igmp_report_groups( netif);
00472       }
00473 #endif /* LWIP_IGMP */
00474     }
00475   }
00476 }
00477 
00478 /**
00479  * Bring an interface down, disabling any traffic processing.
00480  *
00481  * @note: Enabling DHCP on a down interface will make it come
00482  * up once configured.
00483  * 
00484  * @see dhcp_start()
00485  */ 
00486 void netif_set_down(struct netif *netif)
00487 {
00488   if (netif->flags & NETIF_FLAG_UP) {
00489     netif->flags &= ~NETIF_FLAG_UP;
00490 #if LWIP_SNMP
00491     snmp_get_sysuptime(&netif->ts);
00492 #endif
00493 
00494     NETIF_STATUS_CALLBACK(netif);
00495   }
00496 }
00497 
00498 #if LWIP_NETIF_STATUS_CALLBACK
00499 /**
00500  * Set callback to be called when interface is brought up/down
00501  */
00502 void netif_set_status_callback(struct netif *netif, netif_status_callback_fn status_callback)
00503 {
00504   if (netif) {
00505     netif->status_callback = status_callback;
00506   }
00507 }
00508 #endif /* LWIP_NETIF_STATUS_CALLBACK */
00509 
00510 /**
00511  * Called by a driver when its link goes up
00512  */
00513 void netif_set_link_up(struct netif *netif )
00514 {
00515   if (!(netif->flags & NETIF_FLAG_LINK_UP)) {
00516     netif->flags |= NETIF_FLAG_LINK_UP;
00517 
00518 #if LWIP_DHCP
00519     if (netif->dhcp) {
00520       dhcp_network_changed(netif);
00521     }
00522 #endif /* LWIP_DHCP */
00523 
00524 #if LWIP_AUTOIP
00525     if (netif->autoip) {
00526       autoip_network_changed(netif);
00527     }
00528 #endif /* LWIP_AUTOIP */
00529 
00530     if (netif->flags & NETIF_FLAG_UP) {
00531 #if LWIP_ARP
00532       /* For Ethernet network interfaces, we would like to send a "gratuitous ARP" */ 
00533       if (netif->flags & NETIF_FLAG_ETHARP) {
00534         etharp_gratuitous(netif);
00535       }
00536 #endif /* LWIP_ARP */
00537 
00538 #if LWIP_IGMP
00539       /* resend IGMP memberships */
00540       if (netif->flags & NETIF_FLAG_IGMP) {
00541         igmp_report_groups( netif);
00542       }
00543 #endif /* LWIP_IGMP */
00544     }
00545     NETIF_LINK_CALLBACK(netif);
00546   }
00547 }
00548 
00549 /**
00550  * Called by a driver when its link goes down
00551  */
00552 void netif_set_link_down(struct netif *netif )
00553 {
00554   if (netif->flags & NETIF_FLAG_LINK_UP) {
00555     netif->flags &= ~NETIF_FLAG_LINK_UP;
00556     NETIF_LINK_CALLBACK(netif);
00557   }
00558 }
00559 
00560 #if LWIP_NETIF_LINK_CALLBACK
00561 /**
00562  * Set callback to be called when link is brought up/down
00563  */
00564 void netif_set_link_callback(struct netif *netif, netif_status_callback_fn link_callback)
00565 {
00566   if (netif) {
00567     netif->link_callback = link_callback;
00568   }
00569 }
00570 #endif /* LWIP_NETIF_LINK_CALLBACK */
00571 
00572 #if ENABLE_LOOPBACK
00573 /**
00574  * Send an IP packet to be received on the same netif (loopif-like).
00575  * The pbuf is simply copied and handed back to netif->input.
00576  * In multithreaded mode, this is done directly since netif->input must put
00577  * the packet on a queue.
00578  * In callback mode, the packet is put on an internal queue and is fed to
00579  * netif->input by netif_poll().
00580  *
00581  * @param netif the lwip network interface structure
00582  * @param p the (IP) packet to 'send'
00583  * @param ipaddr the ip address to send the packet to (not used)
00584  * @return ERR_OK if the packet has been sent
00585  *         ERR_MEM if the pbuf used to copy the packet couldn't be allocated
00586  */
00587 err_t
00588 netif_loop_output(struct netif *netif, struct pbuf *p,
00589        ip_addr_t *ipaddr)
00590 {
00591   struct pbuf *r;
00592   err_t err;
00593   struct pbuf *last;
00594 #if LWIP_LOOPBACK_MAX_PBUFS
00595   u8_t clen = 0;
00596 #endif /* LWIP_LOOPBACK_MAX_PBUFS */
00597   /* If we have a loopif, SNMP counters are adjusted for it,
00598    * if not they are adjusted for 'netif'. */
00599 #if LWIP_SNMP
00600 #if LWIP_HAVE_LOOPIF
00601   struct netif *stats_if = &loop_netif;
00602 #else /* LWIP_HAVE_LOOPIF */
00603   struct netif *stats_if = netif;
00604 #endif /* LWIP_HAVE_LOOPIF */
00605 #endif /* LWIP_SNMP */
00606   SYS_ARCH_DECL_PROTECT(lev);
00607   LWIP_UNUSED_ARG(ipaddr);
00608 
00609   /* Allocate a new pbuf */
00610   r = pbuf_alloc(PBUF_LINK, p->tot_len, PBUF_RAM);
00611   if (r == NULL) {
00612     LINK_STATS_INC(link.memerr);
00613     LINK_STATS_INC(link.drop);
00614     snmp_inc_ifoutdiscards(stats_if);
00615     return ERR_MEM;
00616   }
00617 #if LWIP_LOOPBACK_MAX_PBUFS
00618   clen = pbuf_clen(r);
00619   /* check for overflow or too many pbuf on queue */
00620   if(((netif->loop_cnt_current + clen) < netif->loop_cnt_current) ||
00621      ((netif->loop_cnt_current + clen) > LWIP_LOOPBACK_MAX_PBUFS)) {
00622     pbuf_free(r);
00623     LINK_STATS_INC(link.memerr);
00624     LINK_STATS_INC(link.drop);
00625     snmp_inc_ifoutdiscards(stats_if);
00626     return ERR_MEM;
00627   }
00628   netif->loop_cnt_current += clen;
00629 #endif /* LWIP_LOOPBACK_MAX_PBUFS */
00630 
00631   /* Copy the whole pbuf queue p into the single pbuf r */
00632   if ((err = pbuf_copy(r, p)) != ERR_OK) {
00633     pbuf_free(r);
00634     LINK_STATS_INC(link.memerr);
00635     LINK_STATS_INC(link.drop);
00636     snmp_inc_ifoutdiscards(stats_if);
00637     return err;
00638   }
00639 
00640   /* Put the packet on a linked list which gets emptied through calling
00641      netif_poll(). */
00642 
00643   /* let last point to the last pbuf in chain r */
00644   for (last = r; last->next != NULL; last = last->next);
00645 
00646   SYS_ARCH_PROTECT(lev);
00647   if(netif->loop_first != NULL) {
00648     LWIP_ASSERT("if first != NULL, last must also be != NULL", netif->loop_last != NULL);
00649     netif->loop_last->next = r;
00650     netif->loop_last = last;
00651   } else {
00652     netif->loop_first = r;
00653     netif->loop_last = last;
00654   }
00655   SYS_ARCH_UNPROTECT(lev);
00656 
00657   LINK_STATS_INC(link.xmit);
00658   snmp_add_ifoutoctets(stats_if, p->tot_len);
00659   snmp_inc_ifoutucastpkts(stats_if);
00660 
00661 #if LWIP_NETIF_LOOPBACK_MULTITHREADING
00662   /* For multithreading environment, schedule a call to netif_poll */
00663   tcpip_callback((tcpip_callback_fn)netif_poll, netif);
00664 #endif /* LWIP_NETIF_LOOPBACK_MULTITHREADING */
00665 
00666   return ERR_OK;
00667 }
00668 
00669 /**
00670  * Call netif_poll() in the main loop of your application. This is to prevent
00671  * reentering non-reentrant functions like tcp_input(). Packets passed to
00672  * netif_loop_output() are put on a list that is passed to netif->input() by
00673  * netif_poll().
00674  */
00675 void
00676 netif_poll(struct netif *netif)
00677 {
00678   struct pbuf *in;
00679   /* If we have a loopif, SNMP counters are adjusted for it,
00680    * if not they are adjusted for 'netif'. */
00681 #if LWIP_SNMP
00682 #if LWIP_HAVE_LOOPIF
00683   struct netif *stats_if = &loop_netif;
00684 #else /* LWIP_HAVE_LOOPIF */
00685   struct netif *stats_if = netif;
00686 #endif /* LWIP_HAVE_LOOPIF */
00687 #endif /* LWIP_SNMP */
00688   SYS_ARCH_DECL_PROTECT(lev);
00689 
00690   do {
00691     /* Get a packet from the list. With SYS_LIGHTWEIGHT_PROT=1, this is protected */
00692     SYS_ARCH_PROTECT(lev);
00693     in = netif->loop_first;
00694     if (in != NULL) {
00695       struct pbuf *in_end = in;
00696 #if LWIP_LOOPBACK_MAX_PBUFS
00697       u8_t clen = pbuf_clen(in);
00698       /* adjust the number of pbufs on queue */
00699       LWIP_ASSERT("netif->loop_cnt_current underflow",
00700         ((netif->loop_cnt_current - clen) < netif->loop_cnt_current));
00701       netif->loop_cnt_current -= clen;
00702 #endif /* LWIP_LOOPBACK_MAX_PBUFS */
00703       while (in_end->len != in_end->tot_len) {
00704         LWIP_ASSERT("bogus pbuf: len != tot_len but next == NULL!", in_end->next != NULL);
00705         in_end = in_end->next;
00706       }
00707       /* 'in_end' now points to the last pbuf from 'in' */
00708       if (in_end == netif->loop_last) {
00709         /* this was the last pbuf in the list */
00710         netif->loop_first = netif->loop_last = NULL;
00711       } else {
00712         /* pop the pbuf off the list */
00713         netif->loop_first = in_end->next;
00714         LWIP_ASSERT("should not be null since first != last!", netif->loop_first != NULL);
00715       }
00716       /* De-queue the pbuf from its successors on the 'loop_' list. */
00717       in_end->next = NULL;
00718     }
00719     SYS_ARCH_UNPROTECT(lev);
00720 
00721     if (in != NULL) {
00722       LINK_STATS_INC(link.recv);
00723       snmp_add_ifinoctets(stats_if, in->tot_len);
00724       snmp_inc_ifinucastpkts(stats_if);
00725       /* loopback packets are always IP packets! */
00726       if (ip_input(in, netif) != ERR_OK) {
00727         pbuf_free(in);
00728       }
00729       /* Don't reference the packet any more! */
00730       in = NULL;
00731     }
00732   /* go on while there is a packet on the list */
00733   } while (netif->loop_first != NULL);
00734 }
00735 
00736 #if !LWIP_NETIF_LOOPBACK_MULTITHREADING
00737 /**
00738  * Calls netif_poll() for every netif on the netif_list.
00739  */
00740 void
00741 netif_poll_all(void)
00742 {
00743   struct netif *netif = netif_list;
00744   /* loop through netifs */
00745   while (netif != NULL) {
00746     netif_poll(netif);
00747     /* proceed to next network interface */
00748     netif = netif->next;
00749   }
00750 }
00751 #endif /* !LWIP_NETIF_LOOPBACK_MULTITHREADING */
00752 #endif /* ENABLE_LOOPBACK */