text: /*****************************************************************************
  * pppoe.c - PPP Over Ethernet implementation for lwIP.
  *
  * Copyright (c) 2006 by Marc Boucher, Services Informatiques (MBSI) inc.
  *
  * The authors hereby grant permission to use, copy, modify, distribute,
  * and license this software and its documentation for any purpose, provided
  * that existing copyright notices are retained in all copies and that this
  * notice and the following disclaimer are included verbatim in any 
  * distributions. No written agreement, license, or royalty fee is required
  * for any of the authorized uses.
  *
  * THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTORS *AS IS* AND ANY EXPRESS OR
  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 
  * IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  ******************************************************************************
  * REVISION HISTORY
  *
  * 06-01-01 Marc Boucher <marc@mbsi.ca>
  *   Ported to lwIP.
  *****************************************************************************/
  
  
  
  /* based on NetBSD: if_pppoe.c,v 1.64 2006/01/31 23:50:15 martin Exp */
  
  /*-
   * Copyright (c) 2002 The NetBSD Foundation, Inc.
   * All rights reserved.
   *
   * This code is derived from software contributed to The NetBSD Foundation
   * by Martin Husemann <martin@NetBSD.org>.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 3. All advertising materials mentioning features or use of this software
   *    must display the following acknowledgement:
   *        This product includes software developed by the NetBSD
   *        Foundation, Inc. and its contributors.
   * 4. Neither the name of The NetBSD Foundation nor the names of its
   *    contributors may be used to endorse or promote products derived
   *    from this software without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
   * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
   * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
   * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
   * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   * POSSIBILITY OF SUCH DAMAGE.
   */
  
  #include "lwip/opt.h"
  #if PPP_SUPPORT && PPPOE_SUPPORT /* don't build if not configured for use in lwipopts.h */
  
  #if 0 /* UNUSED */
  #include <string.h>
  #include <stdio.h>
  #endif /* UNUSED */
  
  #include "lwip/timers.h"
  #include "lwip/memp.h"
  #include "lwip/stats.h"
  
  #include "netif/ppp/ppp_impl.h"
  #include "netif/ppp/pppoe.h"
  
  /* Add a 16 bit unsigned value to a buffer pointed to by PTR */
  #define PPPOE_ADD_16(PTR, VAL) \
      *(PTR)++ = (u8_t)((VAL) / 256);    \
      *(PTR)++ = (u8_t)((VAL) % 256)
  
  /* Add a complete PPPoE header to the buffer pointed to by PTR */
  #define PPPOE_ADD_HEADER(PTR, CODE, SESS, LEN)  \
      *(PTR)++ = PPPOE_VERTYPE;  \
      *(PTR)++ = (CODE);         \
      PPPOE_ADD_16(PTR, SESS);   \
      PPPOE_ADD_16(PTR, LEN)
  
  #define PPPOE_DISC_TIMEOUT (5*1000)  /* base for quick timeout calculation */
  #define PPPOE_SLOW_RETRY   (60*1000) /* persistent retry interval */
  #define PPPOE_DISC_MAXPADI  4        /* retry PADI four times (quickly) */
  #define PPPOE_DISC_MAXPADR  2        /* retry PADR twice */
  
  #ifdef PPPOE_SERVER
  #error "PPPOE_SERVER is not yet supported under lwIP!"
  /* from if_spppsubr.c */
  #define IFF_PASSIVE IFF_LINK0 /* wait passively for connection */
  #endif
  
  /* FIXME: we should probably remove that, this is only used for debug purposes */
  #ifndef PPPOE_ERRORSTRING_LEN
  #define PPPOE_ERRORSTRING_LEN     64
  #endif
  static char pppoe_error_tmp[PPPOE_ERRORSTRING_LEN];
  
  
  /* management routines */
  static void pppoe_abort_connect(struct pppoe_softc *);
  static void pppoe_clear_softc(struct pppoe_softc *, const char *);
  
  /* internal timeout handling */
  static void pppoe_timeout(void *);
  
  /* sending actual protocol controll packets */
  static err_t pppoe_send_padi(struct pppoe_softc *);
  static err_t pppoe_send_padr(struct pppoe_softc *);
  #ifdef PPPOE_SERVER
  static err_t pppoe_send_pado(struct pppoe_softc *);
  static err_t pppoe_send_pads(struct pppoe_softc *);
  #endif
  static err_t pppoe_send_padt(struct netif *, u_int, const u8_t *);
  
  /* internal helper functions */
  static struct pppoe_softc* pppoe_find_softc_by_session(u_int session, struct netif *rcvif);
  static struct pppoe_softc* pppoe_find_softc_by_hunique(u8_t *token, size_t len, struct netif *rcvif);
  
  /** linked list of created pppoe interfaces */
  static struct pppoe_softc *pppoe_softc_list;
  
  err_t
  pppoe_create(struct netif *ethif, ppp_pcb *pcb, void (*link_status_cb)(ppp_pcb *pcb, int up), struct pppoe_softc **scptr)
  {
    struct pppoe_softc *sc;
  
    sc = (struct pppoe_softc *)memp_malloc(MEMP_PPPOE_IF);
    if (sc == NULL) {
      *scptr = NULL;
      return ERR_MEM;
    }
    memset(sc, 0, sizeof(struct pppoe_softc));
  
    /* changed to real address later */
    MEMCPY(&sc->sc_dest, ethbroadcast.addr, sizeof(sc->sc_dest));
  
    sc->pcb = pcb;
    sc->sc_link_status_cb = link_status_cb;
    sc->sc_ethif = ethif;
  
    /* put the new interface at the head of the list */
    sc->next = pppoe_softc_list;
    pppoe_softc_list = sc;
  
    *scptr = sc;
  
    return ERR_OK;
  }
  
  err_t
  pppoe_destroy(struct pppoe_softc *sc)
  {
    struct pppoe_softc *cur, *prev = NULL;
  
    /* find previous linked list entry */
    for (cur = pppoe_softc_list; cur != NULL; prev = cur, cur = cur->next) {
      if (sc == cur) {
        break;
      }
    }
  
    if (cur != sc) {
      return ERR_IF;
    }
  
    sys_untimeout(pppoe_timeout, sc);
    if (prev == NULL) {
      /* remove sc from the head of the list */
      pppoe_softc_list = sc->next;
    } else {
      /* remove sc from the list */
      prev->next = sc->next;
    }
  
  #ifdef PPPOE_TODO
    if (sc->sc_concentrator_name) {
      mem_free(sc->sc_concentrator_name);
    }
    if (sc->sc_service_name) {
      mem_free(sc->sc_service_name);
    }
  #endif /* PPPOE_TODO */
    memp_free(MEMP_PPPOE_IF, sc);
  
    return ERR_OK;
  }
  
  /*
   * Find the interface handling the specified session.
   * Note: O(number of sessions open), this is a client-side only, mean
   * and lean implementation, so number of open sessions typically should
   * be 1.
   */
  static struct pppoe_softc* pppoe_find_softc_by_session(u_int session, struct netif *rcvif) {
    struct pppoe_softc *sc;
  
    if (session == 0) {
      return NULL;
    }
  
    for (sc = pppoe_softc_list; sc != NULL; sc = sc->next) {
      if (sc->sc_state == PPPOE_STATE_SESSION
          && sc->sc_session == session
           && sc->sc_ethif == rcvif) {
             return sc;
        }
    }
    return NULL;
  }
  
  /* Check host unique token passed and return appropriate softc pointer,
   * or NULL if token is bogus. */
  static struct pppoe_softc* pppoe_find_softc_by_hunique(u8_t *token, size_t len, struct netif *rcvif) {
    struct pppoe_softc *sc, *t;
  
    if (pppoe_softc_list == NULL) {
      return NULL;
    }
  
    if (len != sizeof sc) {
      return NULL;
    }
    MEMCPY(&t, token, len);
  
    for (sc = pppoe_softc_list; sc != NULL; sc = sc->next) {
      if (sc == t) {
        break;
      }
    }
  
    if (sc == NULL) {
      PPPDEBUG(LOG_DEBUG, ("pppoe: alien host unique tag, no session found\n"));
      return NULL;
    }
  
    /* should be safe to access *sc now */
    if (sc->sc_state < PPPOE_STATE_PADI_SENT || sc->sc_state >= PPPOE_STATE_SESSION) {
      PPPDEBUG(LOG_DEBUG, ("%c%c%"U16_F": host unique tag found, but it belongs to a connection in state %d\n",
        sc->sc_ethif->name[0], sc->sc_ethif->name[1], sc->sc_ethif->num, sc->sc_state));
      return NULL;
    }
    if (sc->sc_ethif != rcvif) {
      PPPDEBUG(LOG_DEBUG, ("%c%c%"U16_F": wrong interface, not accepting host unique\n",
        sc->sc_ethif->name[0], sc->sc_ethif->name[1], sc->sc_ethif->num));
      return NULL;
    }
    return sc;
  }
  
  static void
  pppoe_linkstatus_up(struct pppoe_softc *sc)
  {
    sc->sc_link_status_cb(sc->pcb, PPPOE_CB_STATE_UP);
  }
  
  /* analyze and handle a single received packet while not in session state */
  void
  pppoe_disc_input(struct netif *netif, struct pbuf *pb)
  {
    u16_t tag, len;
    u16_t session, plen;
    struct pppoe_softc *sc;
    const char *err_msg;
    char devname[6];
    u8_t *ac_cookie;
    u16_t ac_cookie_len;
  #ifdef PPPOE_SERVER
    u8_t *hunique;
    size_t hunique_len;
  #endif
    struct pppoehdr *ph;
    struct pppoetag pt;
    int off, err;
    struct eth_hdr *ethhdr;
  
    /* don't do anything if there is not a single PPPoE instance */
    if (pppoe_softc_list == NULL) {
      pbuf_free(pb);
      return;
    }
  
    pb = ppp_singlebuf(pb);
  
    strcpy(devname, "pppoe");  /* as long as we don't know which instance */
    err_msg = NULL;
    if (pb->len < sizeof(*ethhdr)) {
      goto done;
    }
    ethhdr = (struct eth_hdr *)pb->payload;
    off = sizeof(*ethhdr);
  
    ac_cookie = NULL;
    ac_cookie_len = 0;
  #ifdef PPPOE_SERVER
    hunique = NULL;
    hunique_len = 0;
  #endif
    session = 0;
    if (pb->len - off < (u16_t)PPPOE_HEADERLEN) {
      PPPDEBUG(LOG_DEBUG, ("pppoe: packet too short: %d\n", pb->len));
      goto done;
    }
  
    ph = (struct pppoehdr *) (ethhdr + 1);
    if (ph->vertype != PPPOE_VERTYPE) {
      PPPDEBUG(LOG_DEBUG, ("pppoe: unknown version/type packet: 0x%x\n", ph->vertype));
      goto done;
    }
    session = ntohs(ph->session);
    plen = ntohs(ph->plen);
    off += sizeof(*ph);
  
    if (plen + off > pb->len) {
      PPPDEBUG(LOG_DEBUG, ("pppoe: packet content does not fit: data available = %d, packet size = %u\n",
          pb->len - off, plen));
      goto done;
    }
    if(pb->tot_len == pb->len) {
      pb->tot_len = pb->len = (u16_t)off + plen; /* ignore trailing garbage */
    }
    tag = 0;
    len = 0;
    sc = NULL;
    while (off + sizeof(pt) <= pb->len) {
      MEMCPY(&pt, (u8_t*)pb->payload + off, sizeof(pt));
      tag = ntohs(pt.tag);
      len = ntohs(pt.len);
      if (off + sizeof(pt) + len > pb->len) {
        PPPDEBUG(LOG_DEBUG, ("pppoe: tag 0x%x len 0x%x is too long\n", tag, len));
        goto done;
      }
      switch (tag) {
        case PPPOE_TAG_EOL:
          goto breakbreak;
        case PPPOE_TAG_SNAME:
          break;  /* ignored */
        case PPPOE_TAG_ACNAME:
          break;  /* ignored */
        case PPPOE_TAG_HUNIQUE:
          if (sc != NULL) {
            break;
          }
  #ifdef PPPOE_SERVER
          hunique = (u8_t*)pb->payload + off + sizeof(pt);
          hunique_len = len;
  #endif
          sc = pppoe_find_softc_by_hunique((u8_t*)pb->payload + off + sizeof(pt), len, netif);
          if (sc != NULL) {
            devname[0] = sc->sc_ethif->name[0];
            devname[1] = sc->sc_ethif->name[1];
            devname[2] = sc->sc_ethif->num;
            devname[3] = '\0';
          }
          break;
        case PPPOE_TAG_ACCOOKIE:
          if (ac_cookie == NULL) {
            ac_cookie = (u8_t*)pb->payload + off + sizeof(pt);
            ac_cookie_len = len;
          }
          break;
        case PPPOE_TAG_SNAME_ERR:
          err_msg = "SERVICE NAME ERROR";
          break;
        case PPPOE_TAG_ACSYS_ERR:
          err_msg = "AC SYSTEM ERROR";
          break;
        case PPPOE_TAG_GENERIC_ERR:
          err_msg = "GENERIC ERROR";
          break;
        default:
          break;
      }
      if (NULL != err_msg) {
        if (len) {
          u16_t error_len = LWIP_MIN(len, sizeof(pppoe_error_tmp)-1);
          strncpy(pppoe_error_tmp, (char*)pb->payload + off + sizeof(pt), error_len);
          pppoe_error_tmp[error_len] = '\0';
          PPPDEBUG(LOG_DEBUG, ("%s: %s: %s\n", devname, err_msg, pppoe_error_tmp));
        } else {
      	PPPDEBUG(LOG_DEBUG, ("%s: %s\n", devname, err_msg));
        }
      }
      off += sizeof(pt) + len;
    }
  
  breakbreak:;
    switch (ph->code) {
      case PPPOE_CODE_PADI:
  #ifdef PPPOE_SERVER
        /*
         * got service name, concentrator name, and/or host unique.
         * ignore if we have no interfaces with IFF_PASSIVE|IFF_UP.
         */
        if (LIST_EMPTY(&pppoe_softc_list)) {
          goto done;
        }
        LIST_FOREACH(sc, &pppoe_softc_list, sc_list) {
          if (!(sc->sc_sppp.pp_if.if_flags & IFF_UP)) {
            continue;
          }
          if (!(sc->sc_sppp.pp_if.if_flags & IFF_PASSIVE)) {
            continue;
          }
          if (sc->sc_state == PPPOE_STATE_INITIAL) {
            break;
          }
        }
        if (sc == NULL) {
          /* PPPDEBUG(LOG_DEBUG, ("pppoe: free passive interface is not found\n")); */
          goto done;
        }
        if (hunique) {
          if (sc->sc_hunique) {
            mem_free(sc->sc_hunique);
          }
          sc->sc_hunique = mem_malloc(hunique_len);
          if (sc->sc_hunique == NULL) {
            goto done;
          }
          sc->sc_hunique_len = hunique_len;
          MEMCPY(sc->sc_hunique, hunique, hunique_len);
        }
        MEMCPY(&sc->sc_dest, eh->ether_shost, sizeof sc->sc_dest);
        sc->sc_state = PPPOE_STATE_PADO_SENT;
        pppoe_send_pado(sc);
        break;
  #endif /* PPPOE_SERVER */
      case PPPOE_CODE_PADR:
  #ifdef PPPOE_SERVER
        /*
         * get sc from ac_cookie if IFF_PASSIVE
         */
        if (ac_cookie == NULL) {
          /* be quiet if there is not a single pppoe instance */
          PPPDEBUG(LOG_DEBUG, ("pppoe: received PADR but not includes ac_cookie\n"));
          goto done;
        }
        sc = pppoe_find_softc_by_hunique(ac_cookie, ac_cookie_len, netif);
        if (sc == NULL) {
          /* be quiet if there is not a single pppoe instance */
          if (!LIST_EMPTY(&pppoe_softc_list)) {
            PPPDEBUG(LOG_DEBUG, ("pppoe: received PADR but could not find request for it\n"));
          }
          goto done;
        }
        if (sc->sc_state != PPPOE_STATE_PADO_SENT) {
          PPPDEBUG(LOG_DEBUG, ("%c%c%"U16_F": received unexpected PADR\n", sc->sc_ethif->name[0], sc->sc_ethif->name[1], sc->sc_ethif->num));
          goto done;
        }
        if (hunique) {
          if (sc->sc_hunique) {
            mem_free(sc->sc_hunique);
          }
          sc->sc_hunique = mem_malloc(hunique_len);
          if (sc->sc_hunique == NULL) {
            goto done;
          }
          sc->sc_hunique_len = hunique_len;
          MEMCPY(sc->sc_hunique, hunique, hunique_len);
        }
        pppoe_send_pads(sc);
        sc->sc_state = PPPOE_STATE_SESSION;
        pppoe_linkstatus_up(sc); /* notify upper layers */
        break;
  #else
        /* ignore, we are no access concentrator */
        goto done;
  #endif /* PPPOE_SERVER */
      case PPPOE_CODE_PADO:
        if (sc == NULL) {
          /* be quiet if there is not a single pppoe instance */
          if (pppoe_softc_list != NULL) {
            PPPDEBUG(LOG_DEBUG, ("pppoe: received PADO but could not find request for it\n"));
          }
          goto done;
        }
        if (sc->sc_state != PPPOE_STATE_PADI_SENT) {
          PPPDEBUG(LOG_DEBUG, ("%c%c%"U16_F": received unexpected PADO\n", sc->sc_ethif->name[0], sc->sc_ethif->name[1], sc->sc_ethif->num));
          goto done;
        }
        if (ac_cookie) {
          sc->sc_ac_cookie_len = ac_cookie_len;
          MEMCPY(sc->sc_ac_cookie, ac_cookie, ac_cookie_len);
        }
        MEMCPY(&sc->sc_dest, ethhdr->src.addr, sizeof(sc->sc_dest.addr));
        sys_untimeout(pppoe_timeout, sc);
        sc->sc_padr_retried = 0;
        sc->sc_state = PPPOE_STATE_PADR_SENT;
        if ((err = pppoe_send_padr(sc)) != 0) {
          PPPDEBUG(LOG_DEBUG, ("pppoe: %c%c%"U16_F": failed to send PADR, error=%d\n", sc->sc_ethif->name[0], sc->sc_ethif->name[1], sc->sc_ethif->num, err));
        }
        sys_timeout(PPPOE_DISC_TIMEOUT * (1 + sc->sc_padr_retried), pppoe_timeout, sc);
        break;
      case PPPOE_CODE_PADS:
        if (sc == NULL) {
          goto done;
        }
        sc->sc_session = session;
        sys_untimeout(pppoe_timeout, sc);
        PPPDEBUG(LOG_DEBUG, ("pppoe: %c%c%"U16_F": session 0x%x connected\n", sc->sc_ethif->name[0], sc->sc_ethif->name[1], sc->sc_ethif->num, session));
        sc->sc_state = PPPOE_STATE_SESSION;
        pppoe_linkstatus_up(sc); /* notify upper layers */
        break;
      case PPPOE_CODE_PADT:
        if (sc == NULL) {
          goto done;
        }
        pppoe_clear_softc(sc, "received PADT");
        break;
      default:
        if(sc) {
          PPPDEBUG(LOG_DEBUG, ("%c%c%"U16_F": unknown code (0x%"X16_F") session = 0x%"X16_F"\n",
              sc->sc_ethif->name[0], sc->sc_ethif->name[1], sc->sc_ethif->num,
              (u16_t)ph->code, session));
        } else {
          PPPDEBUG(LOG_DEBUG, ("pppoe: unknown code (0x%"X16_F") session = 0x%"X16_F"\n", (u16_t)ph->code, session));
        }
        break;
    }
  
  done:
    pbuf_free(pb);
    return;
  }
  
  void
  pppoe_data_input(struct netif *netif, struct pbuf *pb)
  {
    u16_t session, plen;
    struct pppoe_softc *sc;
    struct pppoehdr *ph;
  #ifdef PPPOE_TERM_UNKNOWN_SESSIONS
    u8_t shost[ETHER_ADDR_LEN];
  #endif
  
  #ifdef PPPOE_TERM_UNKNOWN_SESSIONS
    MEMCPY(shost, ((struct eth_hdr *)pb->payload)->src.addr, sizeof(shost));
  #endif
    if (pbuf_header(pb, -(int)sizeof(struct eth_hdr)) != 0) {
      /* bail out */
      PPPDEBUG(LOG_ERR, ("pppoe_data_input: pbuf_header failed\n"));
      LINK_STATS_INC(link.lenerr);
      goto drop;
    } 
  
    pb = ppp_singlebuf (pb);
  
    if (pb->len <= PPPOE_HEADERLEN) {
      PPPDEBUG(LOG_DEBUG, ("pppoe (data): dropping too short packet: %d bytes\n", pb->len));
      goto drop;
    }
  
    if (pb->len < sizeof(*ph)) {
      PPPDEBUG(LOG_DEBUG, ("pppoe_data_input: could not get PPPoE header\n"));
      goto drop;
    }
    ph = (struct pppoehdr *)pb->payload;
  
    if (ph->vertype != PPPOE_VERTYPE) {
      PPPDEBUG(LOG_DEBUG, ("pppoe (data): unknown version/type packet: 0x%x\n", ph->vertype));
      goto drop;
    }
    if (ph->code != 0) {
      goto drop;
    }
  
    session = ntohs(ph->session);
    sc = pppoe_find_softc_by_session(session, netif);
    if (sc == NULL) {
  #ifdef PPPOE_TERM_UNKNOWN_SESSIONS
      PPPDEBUG(LOG_DEBUG, ("pppoe: input for unknown session 0x%x, sending PADT\n", session));
      pppoe_send_padt(netif, session, shost);
  #endif
      goto drop;
    }
  
    plen = ntohs(ph->plen);
  
    if (pbuf_header(pb, -(int)(PPPOE_HEADERLEN)) != 0) {
      /* bail out */
      PPPDEBUG(LOG_ERR, ("pppoe_data_input: pbuf_header PPPOE_HEADERLEN failed\n"));
      LINK_STATS_INC(link.lenerr);
      goto drop;
    } 
  
    PPPDEBUG(LOG_DEBUG, ("pppoe_data_input: %c%c%"U16_F": pkthdr.len=%d, pppoe.len=%d\n",
          sc->sc_ethif->name[0], sc->sc_ethif->name[1], sc->sc_ethif->num,
          pb->len, plen));
  
    if (pb->len < plen) {
      goto drop;
    }
  
    /* Dispatch the packet thereby consuming it. */
    ppp_input(sc->pcb, pb);
    return;
  
  drop:
    pbuf_free(pb);
  }
  
  static err_t
  pppoe_output(struct pppoe_softc *sc, struct pbuf *pb)
  {
    struct eth_hdr *ethhdr;
    u16_t etype;
    err_t res;
  
    if (!sc->sc_ethif) {
      pbuf_free(pb);
      return ERR_IF;
    }
  
    /* make room for Ethernet header - should not fail */
    if (pbuf_header(pb, (u16_t)(sizeof(struct eth_hdr))) != 0) {
      /* bail out */
      PPPDEBUG(LOG_ERR, ("pppoe: %c%c%"U16_F": pppoe_output: could not allocate room for Ethernet header\n", sc->sc_ethif->name[0], sc->sc_ethif->name[1], sc->sc_ethif->num));
      LINK_STATS_INC(link.lenerr);
      pbuf_free(pb);
      return ERR_BUF;
    }
    ethhdr = (struct eth_hdr *)pb->payload;
    etype = sc->sc_state == PPPOE_STATE_SESSION ? ETHTYPE_PPPOE : ETHTYPE_PPPOEDISC;
    ethhdr->type = htons(etype);
    MEMCPY(&ethhdr->dest.addr, &sc->sc_dest.addr, sizeof(ethhdr->dest.addr));
    MEMCPY(&ethhdr->src.addr, &sc->sc_ethif->hwaddr, sizeof(ethhdr->src.addr));
  
    PPPDEBUG(LOG_DEBUG, ("pppoe: %c%c%"U16_F" (%x) state=%d, session=0x%x output -> %02"X16_F":%02"X16_F":%02"X16_F":%02"X16_F":%02"X16_F":%02"X16_F", len=%d\n",
        sc->sc_ethif->name[0], sc->sc_ethif->name[1], sc->sc_ethif->num, etype,
        sc->sc_state, sc->sc_session,
        sc->sc_dest.addr[0], sc->sc_dest.addr[1], sc->sc_dest.addr[2], sc->sc_dest.addr[3], sc->sc_dest.addr[4], sc->sc_dest.addr[5],
        pb->tot_len));
  
    res = sc->sc_ethif->linkoutput(sc->sc_ethif, pb);
  
    pbuf_free(pb);
  
    return res;
  }
  
  static err_t
  pppoe_send_padi(struct pppoe_softc *sc)
  {
    struct pbuf *pb;
    u8_t *p;
    int len;
  #ifdef PPPOE_TODO
    int l1 = 0, l2 = 0; /* XXX: gcc */
  #endif /* PPPOE_TODO */
  
    if (sc->sc_state >PPPOE_STATE_PADI_SENT) {
      PPPDEBUG(LOG_ERR, ("ERROR: pppoe_send_padi in state %d", sc->sc_state));
    }
  
    /* calculate length of frame (excluding ethernet header + pppoe header) */
    len = 2 + 2 + 2 + 2 + sizeof sc;  /* service name tag is required, host unique is send too */
  #ifdef PPPOE_TODO
    if (sc->sc_service_name != NULL) {
      l1 = (int)strlen(sc->sc_service_name);
      len += l1;
    }
    if (sc->sc_concentrator_name != NULL) {
      l2 = (int)strlen(sc->sc_concentrator_name);
      len += 2 + 2 + l2;
    }
  #endif /* PPPOE_TODO */
    LWIP_ASSERT("sizeof(struct eth_hdr) + PPPOE_HEADERLEN + len <= 0xffff",
      sizeof(struct eth_hdr) + PPPOE_HEADERLEN + len <= 0xffff);
  
    /* allocate a buffer */
    pb = pbuf_alloc(PBUF_LINK, (u16_t)(PPPOE_HEADERLEN + len), PBUF_RAM);
    if (!pb) {
      return ERR_MEM;
    }
    LWIP_ASSERT("pb->tot_len == pb->len", pb->tot_len == pb->len);
  
    p = (u8_t*)pb->payload;
    /* fill in pkt */
    PPPOE_ADD_HEADER(p, PPPOE_CODE_PADI, 0, (u16_t)len);
    PPPOE_ADD_16(p, PPPOE_TAG_SNAME);
  #ifdef PPPOE_TODO
    if (sc->sc_service_name != NULL) {
      PPPOE_ADD_16(p, l1);
      MEMCPY(p, sc->sc_service_name, l1);
      p += l1;
    } else
  #endif /* PPPOE_TODO */
    {
      PPPOE_ADD_16(p, 0);
    }
  #ifdef PPPOE_TODO
    if (sc->sc_concentrator_name != NULL) {
      PPPOE_ADD_16(p, PPPOE_TAG_ACNAME);
      PPPOE_ADD_16(p, l2);
      MEMCPY(p, sc->sc_concentrator_name, l2);
      p += l2;
    }
  #endif /* PPPOE_TODO */
    PPPOE_ADD_16(p, PPPOE_TAG_HUNIQUE);
    PPPOE_ADD_16(p, sizeof(sc));
    MEMCPY(p, &sc, sizeof sc);
  
    /* send pkt */
    return pppoe_output(sc, pb);
  }
  
  static void
  pppoe_timeout(void *arg)
  {
    u32_t retry_wait;
    int err;
    struct pppoe_softc *sc = (struct pppoe_softc*)arg;
  
    PPPDEBUG(LOG_DEBUG, ("pppoe: %c%c%"U16_F": timeout\n", sc->sc_ethif->name[0], sc->sc_ethif->name[1], sc->sc_ethif->num));
  
    switch (sc->sc_state) {
      case PPPOE_STATE_PADI_SENT:
        /*
         * We have two basic ways of retrying:
         *  - Quick retry mode: try a few times in short sequence
         *  - Slow retry mode: we already had a connection successfully
         *    established and will try infinitely (without user
         *    intervention)
         * We only enter slow retry mode if IFF_LINK1 (aka autodial)
         * is not set.
         */
        if (sc->sc_padi_retried < 0xff) {
          sc->sc_padi_retried++;
        }
        if (!sc->pcb->settings.persist && sc->sc_padi_retried >= PPPOE_DISC_MAXPADI) {
  #if 0
          if ((sc->sc_sppp.pp_if.if_flags & IFF_LINK1) == 0) {
            /* slow retry mode */
            retry_wait = PPPOE_SLOW_RETRY;
          } else
  #endif
          {
            pppoe_abort_connect(sc);
            return;
          }
        }
        /* initialize for quick retry mode */
        retry_wait = LWIP_MIN(PPPOE_DISC_TIMEOUT * sc->sc_padi_retried, PPPOE_SLOW_RETRY);
        if ((err = pppoe_send_padi(sc)) != 0) {
          sc->sc_padi_retried--;
          PPPDEBUG(LOG_DEBUG, ("pppoe: %c%c%"U16_F": failed to transmit PADI, error=%d\n", sc->sc_ethif->name[0], sc->sc_ethif->name[1], sc->sc_ethif->num, err));
        }
        sys_timeout(retry_wait, pppoe_timeout, sc);
        break;
  
      case PPPOE_STATE_PADR_SENT:
        sc->sc_padr_retried++;
        if (sc->sc_padr_retried >= PPPOE_DISC_MAXPADR) {
          MEMCPY(&sc->sc_dest, ethbroadcast.addr, sizeof(sc->sc_dest));
          sc->sc_state = PPPOE_STATE_PADI_SENT;
          sc->sc_padr_retried = 0;
          if ((err = pppoe_send_padi(sc)) != 0) {
            PPPDEBUG(LOG_DEBUG, ("pppoe: %c%c%"U16_F": failed to send PADI, error=%d\n", sc->sc_ethif->name[0], sc->sc_ethif->name[1], sc->sc_ethif->num, err));
          }
          sys_timeout(PPPOE_DISC_TIMEOUT * (1 + sc->sc_padi_retried), pppoe_timeout, sc);
          return;
        }
        if ((err = pppoe_send_padr(sc)) != 0) {
          sc->sc_padr_retried--;
          PPPDEBUG(LOG_DEBUG, ("pppoe: %c%c%"U16_F": failed to send PADR, error=%d\n", sc->sc_ethif->name[0], sc->sc_ethif->name[1], sc->sc_ethif->num, err));
        }
        sys_timeout(PPPOE_DISC_TIMEOUT * (1 + sc->sc_padr_retried), pppoe_timeout, sc);
        break;
      default:
        return;  /* all done, work in peace */
    }
  }
  
  /* Start a connection (i.e. initiate discovery phase) */
  int
  pppoe_connect(struct pppoe_softc *sc)
  {
    int err;
  
    if (sc->sc_state != PPPOE_STATE_INITIAL) {
      return EBUSY;
    }
  
    /* stop any timer */
    sys_untimeout(pppoe_timeout, sc);
    sc->sc_session = 0;
    sc->sc_padi_retried = 0;
    sc->sc_padr_retried = 0;
  #ifdef PPPOE_SERVER
    /* wait PADI if IFF_PASSIVE */
    if ((sc->sc_sppp.pp_if.if_flags & IFF_PASSIVE)) {
      return 0;
    }
  #endif
    /* save state, in case we fail to send PADI */
    sc->sc_state = PPPOE_STATE_PADI_SENT;
    if ((err = pppoe_send_padi(sc)) != 0) {
      PPPDEBUG(LOG_DEBUG, ("pppoe: %c%c%"U16_F": failed to send PADI, error=%d\n", sc->sc_ethif->name[0], sc->sc_ethif->name[1], sc->sc_ethif->num, err));
    }
    sys_timeout(PPPOE_DISC_TIMEOUT, pppoe_timeout, sc);
    return err;
  }
  
  /* disconnect */
  void
  pppoe_disconnect(struct pppoe_softc *sc)
  {
    if (sc->sc_state < PPPOE_STATE_SESSION) {
      return;
    }
  
    PPPDEBUG(LOG_DEBUG, ("pppoe: %c%c%"U16_F": disconnecting\n", sc->sc_ethif->name[0], sc->sc_ethif->name[1], sc->sc_ethif->num));
    pppoe_send_padt(sc->sc_ethif, sc->sc_session, (const u8_t *)&sc->sc_dest);
  
    /* cleanup softc */
    sc->sc_state = PPPOE_STATE_INITIAL;
    MEMCPY(&sc->sc_dest, ethbroadcast.addr, sizeof(sc->sc_dest));
    sc->sc_ac_cookie_len = 0;
  #ifdef PPPOE_SERVER
    if (sc->sc_hunique) {
      mem_free(sc->sc_hunique);
      sc->sc_hunique = NULL;
    }
    sc->sc_hunique_len = 0;
  #endif
    sc->sc_session = 0;
    sc->sc_padi_retried = 0;
    sc->sc_padr_retried = 0;
  
    sc->sc_link_status_cb(sc->pcb, PPPOE_CB_STATE_DOWN); /* notify upper layers */
    return;
  }
  
  /* Connection attempt aborted */
  static void
  pppoe_abort_connect(struct pppoe_softc *sc)
  {
    PPPDEBUG(LOG_DEBUG, ("%c%c%"U16_F": could not establish connection\n", sc->sc_ethif->name[0], sc->sc_ethif->name[1], sc->sc_ethif->num));
  
    /* clear connection state */
    sc->sc_state = PPPOE_STATE_INITIAL;
    MEMCPY(&sc->sc_dest, ethbroadcast.addr, sizeof(sc->sc_dest));
    sc->sc_ac_cookie_len = 0;
    sc->sc_session = 0;
    sc->sc_padi_retried = 0;
    sc->sc_padr_retried = 0;
  
    sc->sc_link_status_cb(sc->pcb, PPPOE_CB_STATE_FAILED); /* notify upper layers */
  }
  
  /* Send a PADR packet */
  static err_t
  pppoe_send_padr(struct pppoe_softc *sc)
  {
    struct pbuf *pb;
    u8_t *p;
    size_t len;
  #ifdef PPPOE_TODO
    size_t l1 = 0; /* XXX: gcc */
  #endif /* PPPOE_TODO */
  
    if (sc->sc_state != PPPOE_STATE_PADR_SENT) {
      return ERR_CONN;
    }
  
    len = 2 + 2 + 2 + 2 + sizeof(sc);    /* service name, host unique */
  #ifdef PPPOE_TODO
    if (sc->sc_service_name != NULL) {    /* service name tag maybe empty */
      l1 = strlen(sc->sc_service_name);
      len += l1;
    }
  #endif /* PPPOE_TODO */
    if (sc->sc_ac_cookie_len > 0) {
      len += 2 + 2 + sc->sc_ac_cookie_len;  /* AC cookie */
    }
    LWIP_ASSERT("sizeof(struct eth_hdr) + PPPOE_HEADERLEN + len <= 0xffff",
      sizeof(struct eth_hdr) + PPPOE_HEADERLEN + len <= 0xffff);
    pb = pbuf_alloc(PBUF_LINK, (u16_t)(PPPOE_HEADERLEN + len), PBUF_RAM);
    if (!pb) {
      return ERR_MEM;
    }
    LWIP_ASSERT("pb->tot_len == pb->len", pb->tot_len == pb->len);
    p = (u8_t*)pb->payload;
    PPPOE_ADD_HEADER(p, PPPOE_CODE_PADR, 0, len);
    PPPOE_ADD_16(p, PPPOE_TAG_SNAME);
  #ifdef PPPOE_TODO
    if (sc->sc_service_name != NULL) {
      PPPOE_ADD_16(p, l1);
      MEMCPY(p, sc->sc_service_name, l1);
      p += l1;
    } else
  #endif /* PPPOE_TODO */
    {
      PPPOE_ADD_16(p, 0);
    }
    if (sc->sc_ac_cookie_len > 0) {
      PPPOE_ADD_16(p, PPPOE_TAG_ACCOOKIE);
      PPPOE_ADD_16(p, sc->sc_ac_cookie_len);
      MEMCPY(p, sc->sc_ac_cookie, sc->sc_ac_cookie_len);
      p += sc->sc_ac_cookie_len;
    }
    PPPOE_ADD_16(p, PPPOE_TAG_HUNIQUE);
    PPPOE_ADD_16(p, sizeof(sc));
    MEMCPY(p, &sc, sizeof sc);
  
    return pppoe_output(sc, pb);
  }
  
  /* send a PADT packet */
  static err_t
  pppoe_send_padt(struct netif *outgoing_if, u_int session, const u8_t *dest)
  {
    struct pbuf *pb;
    struct eth_hdr *ethhdr;
    err_t res;
    u8_t *p;
  
    pb = pbuf_alloc(PBUF_LINK, (u16_t)(PPPOE_HEADERLEN), PBUF_RAM);
    if (!pb) {
      return ERR_MEM;
    }
    LWIP_ASSERT("pb->tot_len == pb->len", pb->tot_len == pb->len);
  
    pbuf_header(pb, sizeof(struct eth_hdr));
    ethhdr = (struct eth_hdr *)pb->payload;
    ethhdr->type = PP_HTONS(ETHTYPE_PPPOEDISC);
    MEMCPY(&ethhdr->dest.addr, dest, sizeof(ethhdr->dest.addr));
    MEMCPY(&ethhdr->src.addr, &outgoing_if->hwaddr, sizeof(ethhdr->src.addr));
  
    p = (u8_t*)(ethhdr + 1);
    PPPOE_ADD_HEADER(p, PPPOE_CODE_PADT, session, 0);
  
    res = outgoing_if->linkoutput(outgoing_if, pb);
  
    pbuf_free(pb);
  
    return res;
  }
  
  #ifdef PPPOE_SERVER
  static err_t
  pppoe_send_pado(struct pppoe_softc *sc)
  {
    struct pbuf *pb;
    u8_t *p;
    size_t len;
  
    if (sc->sc_state != PPPOE_STATE_PADO_SENT) {
      return ERR_CONN;
    }
  
    /* calc length */
    len = 0;
    /* include ac_cookie */
    len += 2 + 2 + sizeof(sc);
    /* include hunique */
    len += 2 + 2 + sc->sc_hunique_len;
    pb = pbuf_alloc(PBUF_LINK, (u16_t)(PPPOE_HEADERLEN + len), PBUF_RAM);
    if (!pb) {
      return ERR_MEM;
    }
    LWIP_ASSERT("pb->tot_len == pb->len", pb->tot_len == pb->len);
    p = (u8_t*)pb->payload;
    PPPOE_ADD_HEADER(p, PPPOE_CODE_PADO, 0, len);
    PPPOE_ADD_16(p, PPPOE_TAG_ACCOOKIE);
    PPPOE_ADD_16(p, sizeof(sc));
    MEMCPY(p, &sc, sizeof(sc));
    p += sizeof(sc);
    PPPOE_ADD_16(p, PPPOE_TAG_HUNIQUE);
    PPPOE_ADD_16(p, sc->sc_hunique_len);
    MEMCPY(p, sc->sc_hunique, sc->sc_hunique_len);
    return pppoe_output(sc, pb);
  }
  
  static err_t
  pppoe_send_pads(struct pppoe_softc *sc)
  {
    struct pbuf *pb;
    u8_t *p;
    size_t len, l1 = 0;  /* XXX: gcc */
  
    if (sc->sc_state != PPPOE_STATE_PADO_SENT) {
      return ERR_CONN;
    }
  
    sc->sc_session = mono_time.tv_sec % 0xff + 1;
    /* calc length */
    len = 0;
    /* include hunique */
    len += 2 + 2 + 2 + 2 + sc->sc_hunique_len;  /* service name, host unique*/
    if (sc->sc_service_name != NULL) {    /* service name tag maybe empty */
      l1 = strlen(sc->sc_service_name);
      len += l1;
    }
    pb = pbuf_alloc(PBUF_LINK, (u16_t)(PPPOE_HEADERLEN + len), PBUF_RAM);
    if (!pb) {
      return ERR_MEM;
    }
    LWIP_ASSERT("pb->tot_len == pb->len", pb->tot_len == pb->len);
    p = (u8_t*)pb->payload;
    PPPOE_ADD_HEADER(p, PPPOE_CODE_PADS, sc->sc_session, len);
    PPPOE_ADD_16(p, PPPOE_TAG_SNAME);
    if (sc->sc_service_name != NULL) {
      PPPOE_ADD_16(p, l1);
      MEMCPY(p, sc->sc_service_name, l1);
      p += l1;
    } else {
      PPPOE_ADD_16(p, 0);
    }
    PPPOE_ADD_16(p, PPPOE_TAG_HUNIQUE);
    PPPOE_ADD_16(p, sc->sc_hunique_len);
    MEMCPY(p, sc->sc_hunique, sc->sc_hunique_len);
    return pppoe_output(sc, pb);
  }
  #endif
  
  err_t
  pppoe_xmit(struct pppoe_softc *sc, struct pbuf *pb)
  {
    u8_t *p;
    size_t len;
  
    /* are we ready to process data yet? */
    if (sc->sc_state < PPPOE_STATE_SESSION) {
      /*sppp_flush(&sc->sc_sppp.pp_if);*/
      pbuf_free(pb);
      return ERR_CONN;
    }
  
    len = pb->tot_len;
  
    /* make room for PPPoE header - should not fail */
    if (pbuf_header(pb, (u16_t)(PPPOE_HEADERLEN)) != 0) {
      /* bail out */
      PPPDEBUG(LOG_ERR, ("pppoe: %c%c%"U16_F": pppoe_xmit: could not allocate room for PPPoE header\n", sc->sc_ethif->name[0], sc->sc_ethif->name[1], sc->sc_ethif->num));
      LINK_STATS_INC(link.lenerr);
      pbuf_free(pb);
      return ERR_BUF;
    }
  
    p = (u8_t*)pb->payload;
    PPPOE_ADD_HEADER(p, 0, sc->sc_session, len);
  
    return pppoe_output(sc, pb);
  }
  
  #if 0 /*def PFIL_HOOKS*/
  static int
  pppoe_ifattach_hook(void *arg, struct pbuf **mp, struct netif *ifp, int dir)
  {
    struct pppoe_softc *sc;
    int s;
  
    if (mp != (struct pbuf **)PFIL_IFNET_DETACH) {
      return 0;
    }
  
    LIST_FOREACH(sc, &pppoe_softc_list, sc_list) {
      if (sc->sc_ethif != ifp) {
        continue;
      }
      if (sc->sc_sppp.pp_if.if_flags & IFF_UP) {
        sc->sc_sppp.pp_if.if_flags &= ~(IFF_UP|IFF_RUNNING);
        PPPDEBUG(LOG_DEBUG, ("%c%c%"U16_F": ethernet interface detached, going down\n",
            sc->sc_ethif->name[0], sc->sc_ethif->name[1], sc->sc_ethif->num));
      }
      sc->sc_ethif = NULL;
      pppoe_clear_softc(sc, "ethernet interface detached");
    }
  
    return 0;
  }
  #endif
  
  static void
  pppoe_clear_softc(struct pppoe_softc *sc, const char *message)
  {
    LWIP_UNUSED_ARG(message);
  
    /* stop timer */
    sys_untimeout(pppoe_timeout, sc);
    PPPDEBUG(LOG_DEBUG, ("pppoe: %c%c%"U16_F": session 0x%x terminated, %s\n", sc->sc_ethif->name[0], sc->sc_ethif->name[1], sc->sc_ethif->num, sc->sc_session, message));
    /* fix our state */
    sc->sc_state = PPPOE_STATE_INITIAL;
  
    /* notify upper layers */
    sc->sc_link_status_cb(sc->pcb, PPPOE_CB_STATE_DOWN);
  
    /* clean up softc */
    MEMCPY(&sc->sc_dest, ethbroadcast.addr, sizeof(sc->sc_dest));
    sc->sc_ac_cookie_len = 0;
    sc->sc_session = 0;
    sc->sc_padi_retried = 0;
    sc->sc_padr_retried = 0;
  }
  #endif /* PPP_SUPPORT && PPPOE_SUPPORT */
  