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 static u8_t netif_num;
00079 
00080 #if LWIP_HAVE_LOOPIF
00081 static struct netif loop_netif;
00082 
00083 /**
00084  * Initialize a lwip network interface structure for a loopback interface
00085  *
00086  * @param netif the lwip network interface structure for this loopif
00087  * @return ERR_OK if the loopif is initialized
00088  *         ERR_MEM if private data couldn't be allocated
00089  */
00090 static err_t
00091 netif_loopif_init(struct netif *netif)
00092 {
00093   /* initialize the snmp variables and counters inside the struct netif
00094    * ifSpeed: no assumption can be made!
00095    */
00096   NETIF_INIT_SNMP(netif, snmp_ifType_softwareLoopback, 0);
00097 
00098   netif->name[0] = 'l';
00099   netif->name[1] = 'o';
00100   netif->output = netif_loop_output;
00101   return ERR_OK;
00102 }
00103 #endif /* LWIP_HAVE_LOOPIF */
00104 
00105 void
00106 netif_init(void)
00107 {
00108 #if LWIP_HAVE_LOOPIF
00109   ip_addr_t loop_ipaddr, loop_netmask, loop_gw;
00110   IP4_ADDR(&loop_gw, 127,0,0,1);
00111   IP4_ADDR(&loop_ipaddr, 127,0,0,1);
00112   IP4_ADDR(&loop_netmask, 255,0,0,0);
00113 
00114 #if NO_SYS
00115   netif_add(&loop_netif, &loop_ipaddr, &loop_netmask, &loop_gw, NULL, netif_loopif_init, ip_input);
00116 #else  /* NO_SYS */
00117   netif_add(&loop_netif, &loop_ipaddr, &loop_netmask, &loop_gw, NULL, netif_loopif_init, tcpip_input);
00118 #endif /* NO_SYS */
00119   netif_set_up(&loop_netif);
00120 
00121 #endif /* LWIP_HAVE_LOOPIF */
00122 }
00123 
00124 /**
00125  * Add a network interface to the list of lwIP netifs.
00126  *
00127  * @param netif a pre-allocated netif structure
00128  * @param ipaddr IP address for the new netif
00129  * @param netmask network mask for the new netif
00130  * @param gw default gateway IP address for the new netif
00131  * @param state opaque data passed to the new netif
00132  * @param init callback function that initializes the interface
00133  * @param input callback function that is called to pass
00134  * ingress packets up in the protocol layer stack.
00135  *
00136  * @return netif, or NULL if failed.
00137  */
00138 struct netif *
00139 netif_add(struct netif *netif, ip_addr_t *ipaddr, ip_addr_t *netmask,
00140   ip_addr_t *gw, void *state, netif_init_fn init, netif_input_fn input)
00141 {
00142 
00143   LWIP_ASSERT("No init function given", init != NULL);
00144 
00145   /* reset new interface configuration state */
00146   ip_addr_set_zero(&netif->ip_addr);
00147   ip_addr_set_zero(&netif->netmask);
00148   ip_addr_set_zero(&netif->gw);
00149   netif->flags = 0;
00150 #if LWIP_DHCP
00151   /* netif not under DHCP control by default */
00152   netif->dhcp = NULL;
00153 #endif /* LWIP_DHCP */
00154 #if LWIP_AUTOIP
00155   /* netif not under AutoIP control by default */
00156   netif->autoip = NULL;
00157 #endif /* LWIP_AUTOIP */
00158 #if LWIP_NETIF_STATUS_CALLBACK
00159   netif->status_callback = NULL;
00160 #endif /* LWIP_NETIF_STATUS_CALLBACK */
00161 #if LWIP_NETIF_LINK_CALLBACK
00162   netif->link_callback = NULL;
00163 #endif /* LWIP_NETIF_LINK_CALLBACK */
00164 #if LWIP_IGMP
00165   netif->igmp_mac_filter = NULL;
00166 #endif /* LWIP_IGMP */
00167 #if ENABLE_LOOPBACK
00168   netif->loop_first = NULL;
00169   netif->loop_last = NULL;
00170 #endif /* ENABLE_LOOPBACK */
00171 
00172   /* remember netif specific state information data */
00173   netif->state = state;
00174   netif->num = netif_num++;
00175   netif->input = input;
00176   NETIF_SET_HWADDRHINT(netif, NULL);
00177 #if ENABLE_LOOPBACK && LWIP_LOOPBACK_MAX_PBUFS
00178   netif->loop_cnt_current = 0;
00179 #endif /* ENABLE_LOOPBACK && LWIP_LOOPBACK_MAX_PBUFS */
00180 
00181   netif_set_addr(netif, ipaddr, netmask, gw);
00182 
00183   /* call user specified initialization function for netif */
00184   if (init(netif) != ERR_OK) {
00185     return NULL;
00186   }
00187 
00188   /* add this netif to the list */
00189   netif->next = netif_list;
00190   netif_list = netif;
00191   snmp_inc_iflist();
00192 
00193 #if LWIP_IGMP
00194   /* start IGMP processing */
00195   if (netif->flags & NETIF_FLAG_IGMP) {
00196     igmp_start(netif);
00197   }
00198 #endif /* LWIP_IGMP */
00199 
00200   LWIP_DEBUGF(NETIF_DEBUG, ("netif: added interface %c%c IP addr ",
00201     netif->name[0], netif->name[1]));
00202   ip_addr_debug_print(NETIF_DEBUG, ipaddr);
00203   LWIP_DEBUGF(NETIF_DEBUG, (" netmask "));
00204   ip_addr_debug_print(NETIF_DEBUG, netmask);
00205   LWIP_DEBUGF(NETIF_DEBUG, (" gw "));
00206   ip_addr_debug_print(NETIF_DEBUG, gw);
00207   LWIP_DEBUGF(NETIF_DEBUG, ("\n"));
00208   return netif;
00209 }
00210 
00211 /**
00212  * Change IP address configuration for a network interface (including netmask
00213  * and default gateway).
00214  *
00215  * @param netif the network interface to change
00216  * @param ipaddr the new IP address
00217  * @param netmask the new netmask
00218  * @param gw the new default gateway
00219  */
00220 void
00221 netif_set_addr(struct netif *netif, ip_addr_t *ipaddr, ip_addr_t *netmask,
00222     ip_addr_t *gw)
00223 {
00224   netif_set_ipaddr(netif, ipaddr);
00225   netif_set_netmask(netif, netmask);
00226   netif_set_gw(netif, gw);
00227 }
00228 
00229 /**
00230  * Remove a network interface from the list of lwIP netifs.
00231  *
00232  * @param netif the network interface to remove
00233  */
00234 void
00235 netif_remove(struct netif *netif)
00236 {
00237   if (netif == NULL) {
00238     return;
00239   }
00240 
00241 #if LWIP_IGMP
00242   /* stop IGMP processing */
00243   if (netif->flags & NETIF_FLAG_IGMP) {
00244     igmp_stop(netif);
00245   }
00246 #endif /* LWIP_IGMP */
00247   if (netif_is_up(netif)) {
00248     /* set netif down before removing (call callback function) */
00249     netif_set_down(netif);
00250   }
00251 
00252   snmp_delete_ipaddridx_tree(netif);
00253 
00254   /*  is it the first netif? */
00255   if (netif_list == netif) {
00256     netif_list = netif->next;
00257   } else {
00258     /*  look for netif further down the list */
00259     struct netif * tmpNetif;
00260     for (tmpNetif = netif_list; tmpNetif != NULL; tmpNetif = tmpNetif->next) {
00261       if (tmpNetif->next == netif) {
00262         tmpNetif->next = netif->next;
00263         break;
00264       }
00265     }
00266     if (tmpNetif == NULL)
00267       return; /*  we didn't find any netif today */
00268   }
00269   snmp_dec_iflist();
00270   /* this netif is default? */
00271   if (netif_default == netif) {
00272     /* reset default netif */
00273     netif_set_default(NULL);
00274   }
00275 #if LWIP_NETIF_REMOVE_CALLBACK
00276   if (netif->remove_callback) {
00277     netif->remove_callback(netif);
00278   }
00279 #endif /* LWIP_NETIF_REMOVE_CALLBACK */
00280   LWIP_DEBUGF( NETIF_DEBUG, ("netif_remove: removed netif\n") );
00281 }
00282 
00283 /**
00284  * Find a network interface by searching for its name
00285  *
00286  * @param name the name of the netif (like netif->name) plus concatenated number
00287  * in ascii representation (e.g. 'en0')
00288  */
00289 struct netif *
00290 netif_find(char *name)
00291 {
00292   struct netif *netif;
00293   u8_t num;
00294 
00295   if (name == NULL) {
00296     return NULL;
00297   }
00298 
00299   num = name[2] - '0';
00300 
00301   for(netif = netif_list; netif != NULL; netif = netif->next) {
00302     if (num == netif->num &&
00303        name[0] == netif->name[0] &&
00304        name[1] == netif->name[1]) {
00305       LWIP_DEBUGF(NETIF_DEBUG, ("netif_find: found %c%c\n", name[0], name[1]));
00306       return netif;
00307     }
00308   }
00309   LWIP_DEBUGF(NETIF_DEBUG, ("netif_find: didn't find %c%c\n", name[0], name[1]));
00310   return NULL;
00311 }
00312 
00313 /**
00314  * Change the IP address of a network interface
00315  *
00316  * @param netif the network interface to change
00317  * @param ipaddr the new IP address
00318  *
00319  * @note call netif_set_addr() if you also want to change netmask and
00320  * default gateway
00321  */
00322 void
00323 netif_set_ipaddr(struct netif *netif, ip_addr_t *ipaddr)
00324 {
00325   /* TODO: Handling of obsolete pcbs */
00326   /* See:  http://mail.gnu.org/archive/html/lwip-users/2003-03/msg00118.html */
00327 #if LWIP_TCP
00328   struct tcp_pcb *pcb;
00329   struct tcp_pcb_listen *lpcb;
00330 
00331   /* address is actually being changed? */
00332   if (ipaddr && (ip_addr_cmp(ipaddr, &(netif->ip_addr))) == 0) {
00333     /* extern struct tcp_pcb *tcp_active_pcbs; defined by tcp.h */
00334     LWIP_DEBUGF(NETIF_DEBUG | LWIP_DBG_STATE, ("netif_set_ipaddr: netif address being changed\n"));
00335     pcb = tcp_active_pcbs;
00336     while (pcb != NULL) {
00337       /* PCB bound to current local interface address? */
00338       if (ip_addr_cmp(&(pcb->local_ip), &(netif->ip_addr))
00339 #if LWIP_AUTOIP
00340         /* connections to link-local addresses must persist (RFC3927 ch. 1.9) */
00341         && !ip_addr_islinklocal(&(pcb->local_ip))
00342 #endif /* LWIP_AUTOIP */
00343         ) {
00344         /* this connection must be aborted */
00345         struct tcp_pcb *next = pcb->next;
00346         LWIP_DEBUGF(NETIF_DEBUG | LWIP_DBG_STATE, ("netif_set_ipaddr: aborting TCP pcb %p\n", (void *)pcb));
00347         tcp_abort(pcb);
00348         pcb = next;
00349       } else {
00350         pcb = pcb->next;
00351       }
00352     }
00353     for (lpcb = tcp_listen_pcbs.listen_pcbs; lpcb != NULL; lpcb = lpcb->next) {
00354       /* PCB bound to current local interface address? */
00355       if ((!(ip_addr_isany(&(lpcb->local_ip)))) &&
00356           (ip_addr_cmp(&(lpcb->local_ip), &(netif->ip_addr)))) {
00357         /* The PCB is listening to the old ipaddr and
00358          * is set to listen to the new one instead */
00359         ip_addr_set(&(lpcb->local_ip), ipaddr);
00360       }
00361     }
00362   }
00363 #endif
00364   snmp_delete_ipaddridx_tree(netif);
00365   snmp_delete_iprteidx_tree(0,netif);
00366   /* set new IP address to netif */
00367   ip_addr_set(&(netif->ip_addr), ipaddr);
00368   snmp_insert_ipaddridx_tree(netif);
00369   snmp_insert_iprteidx_tree(0,netif);
00370 
00371   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",
00372     netif->name[0], netif->name[1],
00373     ip4_addr1_16(&netif->ip_addr),
00374     ip4_addr2_16(&netif->ip_addr),
00375     ip4_addr3_16(&netif->ip_addr),
00376     ip4_addr4_16(&netif->ip_addr)));
00377 }
00378 
00379 /**
00380  * Change the default gateway for a network interface
00381  *
00382  * @param netif the network interface to change
00383  * @param gw the new default gateway
00384  *
00385  * @note call netif_set_addr() if you also want to change ip address and netmask
00386  */
00387 void
00388 netif_set_gw(struct netif *netif, ip_addr_t *gw)
00389 {
00390   ip_addr_set(&(netif->gw), gw);
00391   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",
00392     netif->name[0], netif->name[1],
00393     ip4_addr1_16(&netif->gw),
00394     ip4_addr2_16(&netif->gw),
00395     ip4_addr3_16(&netif->gw),
00396     ip4_addr4_16(&netif->gw)));
00397 }
00398 
00399 /**
00400  * Change the netmask of a network interface
00401  *
00402  * @param netif the network interface to change
00403  * @param netmask the new netmask
00404  *
00405  * @note call netif_set_addr() if you also want to change ip address and
00406  * default gateway
00407  */
00408 void
00409 netif_set_netmask(struct netif *netif, ip_addr_t *netmask)
00410 {
00411   snmp_delete_iprteidx_tree(0, netif);
00412   /* set new netmask to netif */
00413   ip_addr_set(&(netif->netmask), netmask);
00414   snmp_insert_iprteidx_tree(0, netif);
00415   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",
00416     netif->name[0], netif->name[1],
00417     ip4_addr1_16(&netif->netmask),
00418     ip4_addr2_16(&netif->netmask),
00419     ip4_addr3_16(&netif->netmask),
00420     ip4_addr4_16(&netif->netmask)));
00421 }
00422 
00423 /**
00424  * Set a network interface as the default network interface
00425  * (used to output all packets for which no specific route is found)
00426  *
00427  * @param netif the default network interface
00428  */
00429 void
00430 netif_set_default(struct netif *netif)
00431 {
00432   if (netif == NULL) {
00433     /* remove default route */
00434     snmp_delete_iprteidx_tree(1, netif);
00435   } else {
00436     /* install default route */
00437     snmp_insert_iprteidx_tree(1, netif);
00438   }
00439   netif_default = netif;
00440   LWIP_DEBUGF(NETIF_DEBUG, ("netif: setting default interface %c%c\n",
00441            netif ? netif->name[0] : '\'', netif ? netif->name[1] : '\''));
00442 }
00443 
00444 /**
00445  * Bring an interface up, available for processing
00446  * traffic.
00447  * 
00448  * @note: Enabling DHCP on a down interface will make it come
00449  * up once configured.
00450  * 
00451  * @see dhcp_start()
00452  */ 
00453 void netif_set_up(struct netif *netif)
00454 {
00455   if (!(netif->flags & NETIF_FLAG_UP)) {
00456     netif->flags |= NETIF_FLAG_UP;
00457     
00458 #if LWIP_SNMP
00459     snmp_get_sysuptime(&netif->ts);
00460 #endif /* LWIP_SNMP */
00461 
00462     NETIF_STATUS_CALLBACK(netif);
00463 
00464     if (netif->flags & NETIF_FLAG_LINK_UP) {
00465 #if LWIP_ARP
00466       /* For Ethernet network interfaces, we would like to send a "gratuitous ARP" */ 
00467       if (netif->flags & (NETIF_FLAG_ETHARP)) {
00468         etharp_gratuitous(netif);
00469       }
00470 #endif /* LWIP_ARP */
00471 
00472 #if LWIP_IGMP
00473       /* resend IGMP memberships */
00474       if (netif->flags & NETIF_FLAG_IGMP) {
00475         igmp_report_groups( netif);
00476       }
00477 #endif /* LWIP_IGMP */
00478     }
00479   }
00480 }
00481 
00482 /**
00483  * Bring an interface down, disabling any traffic processing.
00484  *
00485  * @note: Enabling DHCP on a down interface will make it come
00486  * up once configured.
00487  * 
00488  * @see dhcp_start()
00489  */ 
00490 void netif_set_down(struct netif *netif)
00491 {
00492   if (netif->flags & NETIF_FLAG_UP) {
00493     netif->flags &= ~NETIF_FLAG_UP;
00494 #if LWIP_SNMP
00495     snmp_get_sysuptime(&netif->ts);
00496 #endif
00497 
00498 #if LWIP_ARP
00499     if (netif->flags & NETIF_FLAG_ETHARP) {
00500       etharp_cleanup_netif(netif);
00501     }
00502 #endif /* LWIP_ARP */
00503     NETIF_STATUS_CALLBACK(netif);
00504   }
00505 }
00506 
00507 #if LWIP_NETIF_STATUS_CALLBACK
00508 /**
00509  * Set callback to be called when interface is brought up/down
00510  */
00511 void netif_set_status_callback(struct netif *netif, netif_status_callback_fn status_callback)
00512 {
00513   if (netif) {
00514     netif->status_callback = status_callback;
00515   }
00516 }
00517 #endif /* LWIP_NETIF_STATUS_CALLBACK */
00518 
00519 #if LWIP_NETIF_REMOVE_CALLBACK
00520 /**
00521  * Set callback to be called when the interface has been removed
00522  */
00523 void
00524 netif_set_remove_callback(struct netif *netif, netif_status_callback_fn remove_callback)
00525 {
00526   if (netif) {
00527     netif->remove_callback = remove_callback;
00528   }
00529 }
00530 #endif /* LWIP_NETIF_REMOVE_CALLBACK */
00531 
00532 /**
00533  * Called by a driver when its link goes up
00534  */
00535 void netif_set_link_up(struct netif *netif )
00536 {
00537   if (!(netif->flags & NETIF_FLAG_LINK_UP)) {
00538     netif->flags |= NETIF_FLAG_LINK_UP;
00539 
00540 #if LWIP_DHCP
00541     if (netif->dhcp) {
00542       dhcp_network_changed(netif);
00543     }
00544 #endif /* LWIP_DHCP */
00545 
00546 #if LWIP_AUTOIP
00547     if (netif->autoip) {
00548       autoip_network_changed(netif);
00549     }
00550 #endif /* LWIP_AUTOIP */
00551 
00552     if (netif->flags & NETIF_FLAG_UP) {
00553 #if LWIP_ARP
00554       /* For Ethernet network interfaces, we would like to send a "gratuitous ARP" */ 
00555       if (netif->flags & NETIF_FLAG_ETHARP) {
00556         etharp_gratuitous(netif);
00557       }
00558 #endif /* LWIP_ARP */
00559 
00560 #if LWIP_IGMP
00561       /* resend IGMP memberships */
00562       if (netif->flags & NETIF_FLAG_IGMP) {
00563         igmp_report_groups( netif);
00564       }
00565 #endif /* LWIP_IGMP */
00566     }
00567     NETIF_LINK_CALLBACK(netif);
00568   }
00569 }
00570 
00571 /**
00572  * Called by a driver when its link goes down
00573  */
00574 void netif_set_link_down(struct netif *netif )
00575 {
00576   if (netif->flags & NETIF_FLAG_LINK_UP) {
00577     netif->flags &= ~NETIF_FLAG_LINK_UP;
00578     NETIF_LINK_CALLBACK(netif);
00579   }
00580 }
00581 
00582 #if LWIP_NETIF_LINK_CALLBACK
00583 /**
00584  * Set callback to be called when link is brought up/down
00585  */
00586 void netif_set_link_callback(struct netif *netif, netif_status_callback_fn link_callback)
00587 {
00588   if (netif) {
00589     netif->link_callback = link_callback;
00590   }
00591 }
00592 #endif /* LWIP_NETIF_LINK_CALLBACK */
00593 
00594 #if ENABLE_LOOPBACK
00595 /**
00596  * Send an IP packet to be received on the same netif (loopif-like).
00597  * The pbuf is simply copied and handed back to netif->input.
00598  * In multithreaded mode, this is done directly since netif->input must put
00599  * the packet on a queue.
00600  * In callback mode, the packet is put on an internal queue and is fed to
00601  * netif->input by netif_poll().
00602  *
00603  * @param netif the lwip network interface structure
00604  * @param p the (IP) packet to 'send'
00605  * @param ipaddr the ip address to send the packet to (not used)
00606  * @return ERR_OK if the packet has been sent
00607  *         ERR_MEM if the pbuf used to copy the packet couldn't be allocated
00608  */
00609 err_t
00610 netif_loop_output(struct netif *netif, struct pbuf *p,
00611        ip_addr_t *ipaddr)
00612 {
00613   struct pbuf *r;
00614   err_t err;
00615   struct pbuf *last;
00616 #if LWIP_LOOPBACK_MAX_PBUFS
00617   u8_t clen = 0;
00618 #endif /* LWIP_LOOPBACK_MAX_PBUFS */
00619   /* If we have a loopif, SNMP counters are adjusted for it,
00620    * if not they are adjusted for 'netif'. */
00621 #if LWIP_SNMP
00622 #if LWIP_HAVE_LOOPIF
00623   struct netif *stats_if = &loop_netif;
00624 #else /* LWIP_HAVE_LOOPIF */
00625   struct netif *stats_if = netif;
00626 #endif /* LWIP_HAVE_LOOPIF */
00627 #endif /* LWIP_SNMP */
00628   SYS_ARCH_DECL_PROTECT(lev);
00629   LWIP_UNUSED_ARG(ipaddr);
00630 
00631   /* Allocate a new pbuf */
00632   r = pbuf_alloc(PBUF_LINK, p->tot_len, PBUF_RAM);
00633   if (r == NULL) {
00634     LINK_STATS_INC(link.memerr);
00635     LINK_STATS_INC(link.drop);
00636     snmp_inc_ifoutdiscards(stats_if);
00637     return ERR_MEM;
00638   }
00639 #if LWIP_LOOPBACK_MAX_PBUFS
00640   clen = pbuf_clen(r);
00641   /* check for overflow or too many pbuf on queue */
00642   if(((netif->loop_cnt_current + clen) < netif->loop_cnt_current) ||
00643      ((netif->loop_cnt_current + clen) > LWIP_LOOPBACK_MAX_PBUFS)) {
00644     pbuf_free(r);
00645     LINK_STATS_INC(link.memerr);
00646     LINK_STATS_INC(link.drop);
00647     snmp_inc_ifoutdiscards(stats_if);
00648     return ERR_MEM;
00649   }
00650   netif->loop_cnt_current += clen;
00651 #endif /* LWIP_LOOPBACK_MAX_PBUFS */
00652 
00653   /* Copy the whole pbuf queue p into the single pbuf r */
00654   if ((err = pbuf_copy(r, p)) != ERR_OK) {
00655     pbuf_free(r);
00656     LINK_STATS_INC(link.memerr);
00657     LINK_STATS_INC(link.drop);
00658     snmp_inc_ifoutdiscards(stats_if);
00659     return err;
00660   }
00661 
00662   /* Put the packet on a linked list which gets emptied through calling
00663      netif_poll(). */
00664 
00665   /* let last point to the last pbuf in chain r */
00666   for (last = r; last->next != NULL; last = last->next);
00667 
00668   SYS_ARCH_PROTECT(lev);
00669   if(netif->loop_first != NULL) {
00670     LWIP_ASSERT("if first != NULL, last must also be != NULL", netif->loop_last != NULL);
00671     netif->loop_last->next = r;
00672     netif->loop_last = last;
00673   } else {
00674     netif->loop_first = r;
00675     netif->loop_last = last;
00676   }
00677   SYS_ARCH_UNPROTECT(lev);
00678 
00679   LINK_STATS_INC(link.xmit);
00680   snmp_add_ifoutoctets(stats_if, p->tot_len);
00681   snmp_inc_ifoutucastpkts(stats_if);
00682 
00683 #if LWIP_NETIF_LOOPBACK_MULTITHREADING
00684   /* For multithreading environment, schedule a call to netif_poll */
00685   tcpip_callback((tcpip_callback_fn)netif_poll, netif);
00686 #endif /* LWIP_NETIF_LOOPBACK_MULTITHREADING */
00687 
00688   return ERR_OK;
00689 }
00690 
00691 /**
00692  * Call netif_poll() in the main loop of your application. This is to prevent
00693  * reentering non-reentrant functions like tcp_input(). Packets passed to
00694  * netif_loop_output() are put on a list that is passed to netif->input() by
00695  * netif_poll().
00696  */
00697 void
00698 netif_poll(struct netif *netif)
00699 {
00700   struct pbuf *in;
00701   /* If we have a loopif, SNMP counters are adjusted for it,
00702    * if not they are adjusted for 'netif'. */
00703 #if LWIP_SNMP
00704 #if LWIP_HAVE_LOOPIF
00705   struct netif *stats_if = &loop_netif;
00706 #else /* LWIP_HAVE_LOOPIF */
00707   struct netif *stats_if = netif;
00708 #endif /* LWIP_HAVE_LOOPIF */
00709 #endif /* LWIP_SNMP */
00710   SYS_ARCH_DECL_PROTECT(lev);
00711 
00712   do {
00713     /* Get a packet from the list. With SYS_LIGHTWEIGHT_PROT=1, this is protected */
00714     SYS_ARCH_PROTECT(lev);
00715     in = netif->loop_first;
00716     if (in != NULL) {
00717       struct pbuf *in_end = in;
00718 #if LWIP_LOOPBACK_MAX_PBUFS
00719       u8_t clen = pbuf_clen(in);
00720       /* adjust the number of pbufs on queue */
00721       LWIP_ASSERT("netif->loop_cnt_current underflow",
00722         ((netif->loop_cnt_current - clen) < netif->loop_cnt_current));
00723       netif->loop_cnt_current -= clen;
00724 #endif /* LWIP_LOOPBACK_MAX_PBUFS */
00725       while (in_end->len != in_end->tot_len) {
00726         LWIP_ASSERT("bogus pbuf: len != tot_len but next == NULL!", in_end->next != NULL);
00727         in_end = in_end->next;
00728       }
00729       /* 'in_end' now points to the last pbuf from 'in' */
00730       if (in_end == netif->loop_last) {
00731         /* this was the last pbuf in the list */
00732         netif->loop_first = netif->loop_last = NULL;
00733       } else {
00734         /* pop the pbuf off the list */
00735         netif->loop_first = in_end->next;
00736         LWIP_ASSERT("should not be null since first != last!", netif->loop_first != NULL);
00737       }
00738       /* De-queue the pbuf from its successors on the 'loop_' list. */
00739       in_end->next = NULL;
00740     }
00741     SYS_ARCH_UNPROTECT(lev);
00742 
00743     if (in != NULL) {
00744       LINK_STATS_INC(link.recv);
00745       snmp_add_ifinoctets(stats_if, in->tot_len);
00746       snmp_inc_ifinucastpkts(stats_if);
00747       /* loopback packets are always IP packets! */
00748       if (ip_input(in, netif) != ERR_OK) {
00749         pbuf_free(in);
00750       }
00751       /* Don't reference the packet any more! */
00752       in = NULL;
00753     }
00754   /* go on while there is a packet on the list */
00755   } while (netif->loop_first != NULL);
00756 }
00757 
00758 #if !LWIP_NETIF_LOOPBACK_MULTITHREADING
00759 /**
00760  * Calls netif_poll() for every netif on the netif_list.
00761  */
00762 void
00763 netif_poll_all(void)
00764 {
00765   struct netif *netif = netif_list;
00766   /* loop through netifs */
00767   while (netif != NULL) {
00768     netif_poll(netif);
00769     /* proceed to next network interface */
00770     netif = netif->next;
00771   }
00772 }
00773 #endif /* !LWIP_NETIF_LOOPBACK_MULTITHREADING */
00774 #endif /* ENABLE_LOOPBACK */