elks-enhanced - XT-Emporium

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/*
 * Upstream uIP DHCP client.
 *
 * Vendored from adamdunkels/uip with ELKS integration changes limited to
 * coexistence with the existing unified UDP app dispatcher.
 */

#include <string.h>
#include <stddef.h>

#include "uip.h"
#include "dhcpc.h"

extern void uip_tracef(const char *fmt, ...);

#define STATE_INITIAL         0
#define STATE_SENDING         1
#define STATE_OFFER_RECEIVED  2
#define STATE_CONFIG_RECEIVED 3

extern char dhcpc_appstate_tag;

static struct dhcpc_state s;

struct dhcp_msg {
  u8_t op, htype, hlen, hops;
  u8_t xid[4];
  u16_t secs, flags;
  u8_t ciaddr[4];
  u8_t yiaddr[4];
  u8_t siaddr[4];
  u8_t giaddr[4];
  u8_t chaddr[16];
#ifndef UIP_CONF_DHCP_LIGHT
  u8_t sname[64];
  u8_t file[128];
#endif
  u8_t options[312];
};

#define BOOTP_BROADCAST 0x8000

#define DHCP_REQUEST        1
#define DHCP_REPLY          2
#define DHCP_HTYPE_ETHERNET 1
#define DHCP_HLEN_ETHERNET  6
#define DHCP_CHADDR_LEN    16

#define DHCP_MSG_HEADER_LEN (offsetof(struct dhcp_msg, chaddr) + DHCP_CHADDR_LEN)
#define DHCP_MSG_LEN       236
#define DHCPC_SERVER_PORT  67
#define DHCPC_CLIENT_PORT  68

#define DHCPDISCOVER  1
#define DHCPOFFER     2
#define DHCPREQUEST   3
#define DHCPACK       5

#define DHCP_OPTION_SUBNET_MASK   1
#define DHCP_OPTION_ROUTER        3
#define DHCP_OPTION_DNS_SERVER    6
#define DHCP_OPTION_REQ_IPADDR   50
#define DHCP_OPTION_LEASE_TIME   51
#define DHCP_OPTION_MSG_TYPE     53
#define DHCP_OPTION_SERVER_ID    54
#define DHCP_OPTION_REQ_LIST     55
#define DHCP_OPTION_END         255

static const u8_t xid[4] = {0xad, 0xde, 0x12, 0x23};
static const u8_t magic_cookie[4] = {99, 130, 83, 99};

static u8_t *msg_options(struct dhcp_msg *m)
{
  return ((u8_t *)m) + DHCP_MSG_LEN;
}

static u8_t *add_msg_type(u8_t *optptr, u8_t type)
{
  *optptr++ = DHCP_OPTION_MSG_TYPE;
  *optptr++ = 1;
  *optptr++ = type;
  return optptr;
}

static u8_t *add_server_id(u8_t *optptr)
{
  *optptr++ = DHCP_OPTION_SERVER_ID;
  *optptr++ = 4;
  memcpy(optptr, s.serverid, 4);
  return optptr + 4;
}

static u8_t *add_req_ipaddr(u8_t *optptr)
{
  *optptr++ = DHCP_OPTION_REQ_IPADDR;
  *optptr++ = 4;
  memcpy(optptr, s.ipaddr, 4);
  return optptr + 4;
}

static u8_t *add_req_options(u8_t *optptr)
{
  *optptr++ = DHCP_OPTION_REQ_LIST;
  *optptr++ = 3;
  *optptr++ = DHCP_OPTION_SUBNET_MASK;
  *optptr++ = DHCP_OPTION_ROUTER;
  *optptr++ = DHCP_OPTION_DNS_SERVER;
  return optptr;
}

static u8_t *add_end(u8_t *optptr)
{
  *optptr++ = DHCP_OPTION_END;
  return optptr;
}

static void create_msg(struct dhcp_msg *m)
{
  u8_t *options;

  m->op = DHCP_REQUEST;
  m->htype = DHCP_HTYPE_ETHERNET;
  m->hlen = s.mac_len;
  m->hops = 0;
  memcpy(m->xid, xid, sizeof(m->xid));
  m->secs = 0;
  m->flags = HTONS(BOOTP_BROADCAST);
  memcpy(m->ciaddr, uip_hostaddr, sizeof(m->ciaddr));
  memset(m->yiaddr, 0, sizeof(m->yiaddr));
  memset(m->siaddr, 0, sizeof(m->siaddr));
  memset(m->giaddr, 0, sizeof(m->giaddr));
  memcpy(m->chaddr, s.mac_addr, s.mac_len);
  memset(&m->chaddr[s.mac_len], 0, DHCP_CHADDR_LEN - s.mac_len);
  memset(((u8_t *)m) + DHCP_MSG_HEADER_LEN, 0,
         DHCP_MSG_LEN - DHCP_MSG_HEADER_LEN);
  options = msg_options(m);
  memcpy(options, magic_cookie, sizeof(magic_cookie));
}

static void send_discover(void)
{
  u8_t *end;
  struct dhcp_msg *m = (struct dhcp_msg *)uip_appdata;
  u8_t *options;

  create_msg(m);
  options = msg_options(m);
  end = add_msg_type(options + 4, DHCPDISCOVER);
  end = add_req_options(end);
  end = add_end(end);
  uip_send(uip_appdata, end - (u8_t *)uip_appdata);
}

static void send_request(void)
{
  u8_t *end;
  struct dhcp_msg *m = (struct dhcp_msg *)uip_appdata;
  u8_t *options;

  create_msg(m);
  options = msg_options(m);
  end = add_msg_type(options + 4, DHCPREQUEST);
  end = add_server_id(end);
  end = add_req_ipaddr(end);
  end = add_end(end);
  uip_send(uip_appdata, end - (u8_t *)uip_appdata);
}

static u8_t parse_options(u8_t *optptr, int len)
{
  u8_t *end = optptr + len;
  u8_t type = 0;

  while(optptr < end) {
    if(*optptr == 0) {
      ++optptr;
      continue;
    }

    switch(*optptr) {
    case DHCP_OPTION_SUBNET_MASK:
      memcpy(s.netmask, optptr + 2, 4);
      break;
    case DHCP_OPTION_ROUTER:
      memcpy(s.default_router, optptr + 2, 4);
      break;
    case DHCP_OPTION_DNS_SERVER:
      memcpy(s.dnsaddr, optptr + 2, 4);
      break;
    case DHCP_OPTION_MSG_TYPE:
      type = *(optptr + 2);
      break;
    case DHCP_OPTION_SERVER_ID:
      memcpy(s.serverid, optptr + 2, 4);
      break;
    case DHCP_OPTION_LEASE_TIME:
      memcpy(s.lease_time, optptr + 2, 4);
      break;
    case DHCP_OPTION_END:
      return type;
    }

    optptr += optptr[1] + 2;
  }
  return type;
}

static u8_t parse_msg(void)
{
  struct dhcp_msg *m = (struct dhcp_msg *)uip_appdata;
  int len = uip_datalen();
  u8_t *options;
  u8_t type;

  if(len < DHCP_MSG_LEN + (int)sizeof(magic_cookie)) {
    uip_tracef("dhcp short len=%d\n", len);
    return 0;
  }

  options = msg_options(m);

  if(m->op == DHCP_REPLY &&
     memcmp(m->xid, xid, sizeof(xid)) == 0 &&
     memcmp(m->chaddr, s.mac_addr, s.mac_len) == 0) {
    memcpy(s.ipaddr, m->yiaddr, 4);
    type = parse_options(options + 4,
                         len - DHCP_MSG_LEN - sizeof(magic_cookie));
    uip_tracef("dhcp msg type=%u len=%d\n", type, len);
    return type;
  }
  return 0;
}

static PT_THREAD(handle_dhcp(void))
{
  PT_BEGIN(&s.pt);

  s.state = STATE_SENDING;
  s.ticks = CLOCK_SECOND;

  do {
    send_discover();
    timer_set(&s.timer, s.ticks);
    PT_WAIT_UNTIL(&s.pt, uip_newdata() || timer_expired(&s.timer));

    if(uip_newdata() && parse_msg() == DHCPOFFER) {
      s.state = STATE_OFFER_RECEIVED;
      break;
    }

    if(s.ticks < CLOCK_SECOND * 60) {
      s.ticks *= 2;
    }
  } while(s.state != STATE_OFFER_RECEIVED);

  PT_YIELD(&s.pt);
  s.ticks = CLOCK_SECOND;

  do {
    send_request();
    timer_set(&s.timer, s.ticks);
    PT_WAIT_UNTIL(&s.pt, uip_newdata() || timer_expired(&s.timer));

    if(uip_newdata() && parse_msg() == DHCPACK) {
      s.state = STATE_CONFIG_RECEIVED;
      break;
    }

    if(s.ticks <= CLOCK_SECOND * 10) {
      s.ticks += CLOCK_SECOND;
    } else {
      PT_RESTART(&s.pt);
    }
  } while(s.state != STATE_CONFIG_RECEIVED);

  dhcpc_configured(&s);

  while(1) {
    PT_YIELD(&s.pt);
  }

  PT_END(&s.pt);
}

void dhcpc_init(const void *mac_addr, int mac_len)
{
  uip_ipaddr_t addr;

  memset(&s, 0, sizeof(s));
  s.mac_addr = mac_addr;
  s.mac_len  = mac_len;
  s.state = STATE_INITIAL;
  uip_ipaddr(addr, 255,255,255,255);
  s.conn = uip_udp_new(&addr, HTONS(DHCPC_SERVER_PORT));
  if(s.conn != NULL) {
    uip_udp_bind(s.conn, HTONS(DHCPC_CLIENT_PORT));
    s.conn->appstate = &dhcpc_appstate_tag;
  }
  PT_INIT(&s.pt);
}

void dhcpc_appcall(void)
{
  handle_dhcp();
}

void dhcpc_request(void)
{
  u16_t ipaddr[2];

  if(s.state == STATE_INITIAL) {
    uip_ipaddr(ipaddr, 0,0,0,0);
    uip_sethostaddr(ipaddr);
  }
}
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