text: /*
   * QEMU BOOTP/DHCP server
   *
   * Copyright (c) 2004 Fabrice Bellard
   *
   * Permission is hereby granted, free of charge, to any person obtaining a copy
   * of this software and associated documentation files (the "Software"), to deal
   * in the Software without restriction, including without limitation the rights
   * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   * copies of the Software, and to permit persons to whom the Software is
   * furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice shall be included in
   * all copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
   * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
   * THE SOFTWARE.
   */
  #include <slirp.h>
  
  /* XXX: only DHCP is supported */
  
  #define LEASE_TIME (24 * 3600)
  
  static const uint8_t rfc1533_cookie[] = { RFC1533_COOKIE };
  
  #ifdef DEBUG
  #define DPRINTF(fmt, ...) \
  do if (slirp_debug & DBG_CALL) { fprintf(dfd, fmt, ##  __VA_ARGS__); fflush(dfd); } while (0)
  #else
  #define DPRINTF(fmt, ...) do{}while(0)
  #endif
  
  static BOOTPClient *get_new_addr(Slirp *slirp, struct in_addr *paddr,
                                   const uint8_t *macaddr)
  {
      BOOTPClient *bc;
      int i;
  
      for(i = 0; i < NB_BOOTP_CLIENTS; i++) {
          bc = &slirp->bootp_clients[i];
          if (!bc->allocated || !memcmp(macaddr, bc->macaddr, 6))
              goto found;
      }
      return NULL;
   found:
      bc = &slirp->bootp_clients[i];
      bc->allocated = 1;
      paddr->s_addr = slirp->vdhcp_startaddr.s_addr + htonl(i);
      return bc;
  }
  
  static BOOTPClient *request_addr(Slirp *slirp, const struct in_addr *paddr,
                                   const uint8_t *macaddr)
  {
      uint32_t req_addr = ntohl(paddr->s_addr);
      uint32_t dhcp_addr = ntohl(slirp->vdhcp_startaddr.s_addr);
      BOOTPClient *bc;
  
      if (req_addr >= dhcp_addr &&
          req_addr < (dhcp_addr + NB_BOOTP_CLIENTS)) {
          bc = &slirp->bootp_clients[req_addr - dhcp_addr];
          if (!bc->allocated || !memcmp(macaddr, bc->macaddr, 6)) {
              bc->allocated = 1;
              return bc;
          }
      }
      return NULL;
  }
  
  static BOOTPClient *find_addr(Slirp *slirp, struct in_addr *paddr,
                                const uint8_t *macaddr)
  {
      BOOTPClient *bc;
      int i;
  
      for(i = 0; i < NB_BOOTP_CLIENTS; i++) {
          if (!memcmp(macaddr, slirp->bootp_clients[i].macaddr, 6))
              goto found;
      }
      return NULL;
   found:
      bc = &slirp->bootp_clients[i];
      bc->allocated = 1;
      paddr->s_addr = slirp->vdhcp_startaddr.s_addr + htonl(i);
      return bc;
  }
  
  static void dhcp_decode(const struct bootp_t *bp, int *pmsg_type,
                          struct in_addr *preq_addr)
  {
      const uint8_t *p, *p_end;
      int len, tag;
  
      *pmsg_type = 0;
      preq_addr->s_addr = htonl(0L);
  
      p = bp->bp_vend;
      p_end = p + DHCP_OPT_LEN;
      if (memcmp(p, rfc1533_cookie, 4) != 0)
          return;
      p += 4;
      while (p < p_end) {
          tag = p[0];
          if (tag == RFC1533_PAD) {
              p++;
          } else if (tag == RFC1533_END) {
              break;
          } else {
              p++;
              if (p >= p_end)
                  break;
              len = *p++;
              DPRINTF("dhcp: tag=%d len=%d\n", tag, len);
  
              switch(tag) {
              case RFC2132_MSG_TYPE:
                  if (len >= 1)
                      *pmsg_type = p[0];
                  break;
              case RFC2132_REQ_ADDR:
                  if (len >= 4) {
                      memcpy(&(preq_addr->s_addr), p, 4);
                  }
                  break;
              default:
                  break;
              }
              p += len;
          }
      }
      if (*pmsg_type == DHCPREQUEST && preq_addr->s_addr == htonl(0L) &&
          bp->bp_ciaddr.s_addr) {
          memcpy(&(preq_addr->s_addr), &bp->bp_ciaddr, 4);
      }
  }
  
  static void bootp_reply(Slirp *slirp, const struct bootp_t *bp)
  {
      BOOTPClient *bc = NULL;
      struct mbuf *m;
      struct bootp_t *rbp;
      struct sockaddr_in saddr, daddr;
      struct in_addr preq_addr;
      int dhcp_msg_type, val;
      uint8_t *q;
      uint8_t client_ethaddr[ETH_ALEN];
  
      /* extract exact DHCP msg type */
      dhcp_decode(bp, &dhcp_msg_type, &preq_addr);
      DPRINTF("bootp packet op=%d msgtype=%d", bp->bp_op, dhcp_msg_type);
      if (preq_addr.s_addr != htonl(0L))
          DPRINTF(" req_addr=%08x\n", ntohl(preq_addr.s_addr));
      else
          DPRINTF("\n");
  
      if (dhcp_msg_type == 0)
          dhcp_msg_type = DHCPREQUEST; /* Force reply for old BOOTP clients */
  
      if (dhcp_msg_type != DHCPDISCOVER &&
          dhcp_msg_type != DHCPREQUEST)
          return;
  
      /* Get client's hardware address from bootp request */
      memcpy(client_ethaddr, bp->bp_hwaddr, ETH_ALEN);
  
      m = m_get(slirp);
      if (!m) {
          return;
      }
      m->m_data += IF_MAXLINKHDR;
      rbp = (struct bootp_t *)m->m_data;
      m->m_data += sizeof(struct udpiphdr);
      memset(rbp, 0, sizeof(struct bootp_t));
  
      if (dhcp_msg_type == DHCPDISCOVER) {
          if (preq_addr.s_addr != htonl(0L)) {
              bc = request_addr(slirp, &preq_addr, client_ethaddr);
              if (bc) {
                  daddr.sin_addr = preq_addr;
              }
          }
          if (!bc) {
           new_addr:
              bc = get_new_addr(slirp, &daddr.sin_addr, client_ethaddr);
              if (!bc) {
                  DPRINTF("no address left\n");
                  return;
              }
          }
          memcpy(bc->macaddr, client_ethaddr, ETH_ALEN);
      } else if (preq_addr.s_addr != htonl(0L)) {
          bc = request_addr(slirp, &preq_addr, client_ethaddr);
          if (bc) {
              daddr.sin_addr = preq_addr;
              memcpy(bc->macaddr, client_ethaddr, ETH_ALEN);
          } else {
              /* DHCPNAKs should be sent to broadcast */
              daddr.sin_addr.s_addr = 0xffffffff;
          }
      } else {
          bc = find_addr(slirp, &daddr.sin_addr, bp->bp_hwaddr);
          if (!bc) {
              /* if never assigned, behaves as if it was already
                 assigned (windows fix because it remembers its address) */
              goto new_addr;
          }
      }
  
      /* Update ARP table for this IP address */
      arp_table_add(slirp, daddr.sin_addr.s_addr, client_ethaddr);
  
      saddr.sin_addr = slirp->vhost_addr;
      saddr.sin_port = htons(BOOTP_SERVER);
  
      daddr.sin_port = htons(BOOTP_CLIENT);
  
      rbp->bp_op = BOOTP_REPLY;
      rbp->bp_xid = bp->bp_xid;
      rbp->bp_htype = 1;
      rbp->bp_hlen = 6;
      memcpy(rbp->bp_hwaddr, bp->bp_hwaddr, ETH_ALEN);
  
      rbp->bp_yiaddr = daddr.sin_addr; /* Client IP address */
      rbp->bp_siaddr = saddr.sin_addr; /* Server IP address */
  
      q = rbp->bp_vend;
      memcpy(q, rfc1533_cookie, 4);
      q += 4;
  
      if (bc) {
          DPRINTF("%s addr=%08x\n",
                  (dhcp_msg_type == DHCPDISCOVER) ? "offered" : "ack'ed",
                  ntohl(daddr.sin_addr.s_addr));
  
          if (dhcp_msg_type == DHCPDISCOVER) {
              *q++ = RFC2132_MSG_TYPE;
              *q++ = 1;
              *q++ = DHCPOFFER;
          } else /* DHCPREQUEST */ {
              *q++ = RFC2132_MSG_TYPE;
              *q++ = 1;
              *q++ = DHCPACK;
          }
  
          if (slirp->bootp_filename)
              snprintf((char *)rbp->bp_file, sizeof(rbp->bp_file), "%s",
                       slirp->bootp_filename);
  
          *q++ = RFC2132_SRV_ID;
          *q++ = 4;
          memcpy(q, &saddr.sin_addr, 4);
          q += 4;
  
          *q++ = RFC1533_NETMASK;
          *q++ = 4;
          memcpy(q, &slirp->vnetwork_mask, 4);
          q += 4;
  
          if (!slirp->restricted) {
              *q++ = RFC1533_GATEWAY;
              *q++ = 4;
              memcpy(q, &saddr.sin_addr, 4);
              q += 4;
  
              *q++ = RFC1533_DNS;
              *q++ = 4;
              memcpy(q, &slirp->vnameserver_addr, 4);
              q += 4;
          }
  
          *q++ = RFC2132_LEASE_TIME;
          *q++ = 4;
          val = htonl(LEASE_TIME);
          memcpy(q, &val, 4);
          q += 4;
  
          if (*slirp->client_hostname) {
              val = strlen(slirp->client_hostname);
              *q++ = RFC1533_HOSTNAME;
              *q++ = val;
              memcpy(q, slirp->client_hostname, val);
              q += val;
          }
  
          if (slirp->vdnssearch) {
              size_t spaceleft = sizeof(rbp->bp_vend) - (q - rbp->bp_vend);
              val = slirp->vdnssearch_len;
              if (val + 1 > spaceleft) {
                  g_warning("DHCP packet size exceeded, "
                      "omitting domain-search option.");
              } else {
                  memcpy(q, slirp->vdnssearch, val);
                  q += val;
              }
          }
      } else {
          static const char nak_msg[] = "requested address not available";
  
          DPRINTF("nak'ed addr=%08x\n", ntohl(preq_addr.s_addr));
  
          *q++ = RFC2132_MSG_TYPE;
          *q++ = 1;
          *q++ = DHCPNAK;
  
          *q++ = RFC2132_MESSAGE;
          *q++ = sizeof(nak_msg) - 1;
          memcpy(q, nak_msg, sizeof(nak_msg) - 1);
          q += sizeof(nak_msg) - 1;
      }
      *q = RFC1533_END;
  
      daddr.sin_addr.s_addr = 0xffffffffu;
  
      m->m_len = sizeof(struct bootp_t) -
          sizeof(struct ip) - sizeof(struct udphdr);
      udp_output2(NULL, m, &saddr, &daddr, IPTOS_LOWDELAY);
  }
  
  void bootp_input(struct mbuf *m)
  {
      struct bootp_t *bp = mtod(m, struct bootp_t *);
  
      if (bp->bp_op == BOOTP_REQUEST) {
          bootp_reply(m->slirp, bp);
      }
  }
  