frr/pimd/pim_msdp_packet.c

/*
 * IP MSDP packet helper
 * Copyright (C) 2016 Cumulus Networks, Inc.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; see the file COPYING; if not, write to the
 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
 * MA 02110-1301 USA
 */
#include <zebra.h>

#include <lib/log.h>
#include <lib/network.h>
#include <lib/stream.h>
#include <lib/thread.h>
#include <lib/vty.h>

#include "pimd.h"
#include "pim_str.h"

#include "pim_msdp.h"
#include "pim_msdp_packet.h"
#include "pim_msdp_socket.h"

static char *
pim_msdp_pkt_type_dump(enum pim_msdp_tlv type, char *buf, int buf_size)
{
  switch (type) {
    case PIM_MSDP_V4_SOURCE_ACTIVE:
      snprintf(buf, buf_size, "%s", "SA");
      break;
    case PIM_MSDP_V4_SOURCE_ACTIVE_REQUEST:
      snprintf(buf, buf_size, "%s", "SA_REQ");
      break;
    case PIM_MSDP_V4_SOURCE_ACTIVE_RESPONSE:
      snprintf(buf, buf_size, "%s", "SA_RESP");
      break;
    case PIM_MSDP_KEEPALIVE:
      snprintf(buf, buf_size, "%s", "KA");
      break;
    case PIM_MSDP_RESERVED:
      snprintf(buf, buf_size, "%s", "RSVD");
      break;
    case PIM_MSDP_TRACEROUTE_PROGRESS:
      snprintf(buf, buf_size, "%s", "TRACE_PROG");
      break;
    case PIM_MSDP_TRACEROUTE_REPLY:
      snprintf(buf, buf_size, "%s", "TRACE_REPLY");
      break;
    default:
      snprintf(buf, buf_size, "UNK-%d", type);
  }
  return buf;
}

static void
pim_msdp_pkt_sa_dump_one(struct stream *s)
{
  struct prefix_sg sg;

  /* just throw away the three reserved bytes */
  stream_get3(s);
  /* throw away the prefix length also */
  stream_getc(s);

  memset(&sg, 0, sizeof (struct prefix_sg));
  sg.grp.s_addr = stream_get_ipv4(s);
  sg.src.s_addr = stream_get_ipv4(s);

  zlog_debug("  sg %s", pim_str_sg_dump(&sg));
}

static void
pim_msdp_pkt_sa_dump(struct stream *s)
{
  int entry_cnt;
  int i;
  struct in_addr rp; /* Last RP address associated with this SA */

  entry_cnt = stream_getc(s);
  rp.s_addr = stream_get_ipv4(s);

  if (PIM_DEBUG_MSDP_PACKETS) {
    char rp_str[INET_ADDRSTRLEN];
    pim_inet4_dump("<rp?>", rp, rp_str, sizeof(rp_str));
    zlog_debug("  entry_cnt %d rp %s", entry_cnt, rp_str);
  }

  /* dump SAs */
  for (i = 0; i < entry_cnt; ++i) {
    pim_msdp_pkt_sa_dump_one(s);
  }
}

static void
pim_msdp_pkt_dump(struct pim_msdp_peer *mp, int type, int len, bool rx,
                  struct stream *s)
{
  char type_str[PIM_MSDP_PKT_TYPE_STRLEN];

  pim_msdp_pkt_type_dump(type, type_str, sizeof(type_str));

  zlog_debug("MSDP peer %s pkt %s type %s len %d",
      mp->key_str, rx?"rx":"tx", type_str, len);

  if (!s) {
    return;
  }

  switch(type) {
      case PIM_MSDP_V4_SOURCE_ACTIVE:
        pim_msdp_pkt_sa_dump(s);
        break;
      default:;
  }
}

/* Check file descriptor whether connect is established. */
static void
pim_msdp_connect_check(struct pim_msdp_peer *mp)
{
  int status;
  socklen_t slen;
  int ret;

  if (mp->state != PIM_MSDP_CONNECTING) {
    /* if we are here it means we are not in a connecting or established state
     * for now treat this as a fatal error */
    pim_msdp_peer_reset_tcp_conn(mp, "invalid-state");
    return;
  }

  PIM_MSDP_PEER_READ_OFF(mp);
  PIM_MSDP_PEER_WRITE_OFF(mp);

  /* Check file descriptor. */
  slen = sizeof(status);
  ret = getsockopt(mp->fd, SOL_SOCKET, SO_ERROR, (void *)&status, &slen);

  /* If getsockopt is fail, this is fatal error. */
  if (ret < 0) {
    zlog_err("can't get sockopt for nonblocking connect");
    pim_msdp_peer_reset_tcp_conn(mp, "connect-failed");
    return;
  }

  /* When status is 0 then TCP connection is established. */
  if (PIM_DEBUG_MSDP_INTERNAL) {
    zlog_debug("MSDP peer %s pim_connect_check %s", mp->key_str, status?"fail":"success");
  }
  if (status == 0) {
    pim_msdp_peer_established(mp);
  } else {
    pim_msdp_peer_reset_tcp_conn(mp, "connect-failed");
  }
}

static void
pim_msdp_pkt_delete(struct pim_msdp_peer *mp)
{
  stream_free(stream_fifo_pop(mp->obuf));
}

static void
pim_msdp_pkt_add(struct pim_msdp_peer *mp, struct stream *s)
{
  stream_fifo_push(mp->obuf, s);
}

static void
pim_msdp_write_proceed_actions(struct pim_msdp_peer *mp)
{
  if (stream_fifo_head(mp->obuf)) {
    PIM_MSDP_PEER_WRITE_ON(mp);
  }
}

int
pim_msdp_write(struct thread *thread)
{
  struct pim_msdp_peer *mp;
  struct stream *s;
  int num;
  enum pim_msdp_tlv type;
  int len;
  int work_cnt = 0;
  int work_max_cnt = 12;

  mp = THREAD_ARG(thread);
  mp->t_write = NULL;

  if (PIM_DEBUG_MSDP_INTERNAL) {
    zlog_debug("MSDP peer %s pim_msdp_write", mp->key_str);
  }
  if (mp->fd < 0) {
    return -1;
  }

  /* check if TCP connection is established */
  if (mp->state != PIM_MSDP_ESTABLISHED) {
    pim_msdp_connect_check(mp);
    return 0;
  }

  s = stream_fifo_head(mp->obuf);
  if (!s) {
    pim_msdp_write_proceed_actions(mp);
    return 0;
  }

  sockopt_cork(mp->fd, 1);

  /* Nonblocking write until TCP output buffer is full  */
  do
  {
    int writenum;

    /* Number of bytes to be sent */
    writenum = stream_get_endp(s) - stream_get_getp(s);

    /* Call write() system call */
    num = write(mp->fd, STREAM_PNT(s), writenum);
    if (num < 0) {
      /* write failed either retry needed or error */
      if (ERRNO_IO_RETRY(errno)) {
        if (PIM_DEBUG_MSDP_INTERNAL) {
          zlog_debug("MSDP peer %s pim_msdp_write io retry", mp->key_str);
        }
        break;
      }

      pim_msdp_peer_reset_tcp_conn(mp, "pkt-tx-failed");
      return 0;
    }

    if (num != writenum) {
      /* Partial write */
      stream_forward_getp(s, num);
      if (PIM_DEBUG_MSDP_INTERNAL) {
        zlog_debug("MSDP peer %s pim_msdp_partial_write", mp->key_str);
      }
      break;
    }

    /* Retrieve msdp packet type. */
    stream_set_getp(s,0);
    type = stream_getc(s);
    len = stream_getw(s);
    switch (type)
    {
      case PIM_MSDP_KEEPALIVE:
        mp->ka_tx_cnt++;
        break;
      case PIM_MSDP_V4_SOURCE_ACTIVE:
        mp->sa_tx_cnt++;
        break;
      default:;
    }
    if (PIM_DEBUG_MSDP_PACKETS) {
      pim_msdp_pkt_dump(mp, type, len, false /*rx*/, s);
    }

    /* packet sent delete it. */
    pim_msdp_pkt_delete(mp);

    ++work_cnt;
    /* may need to pause if we have done too much work in this
     * loop */
    if (work_cnt >= work_max_cnt) {
      break;
    }
  } while ((s = stream_fifo_head(mp->obuf)) != NULL);
  pim_msdp_write_proceed_actions(mp);

  sockopt_cork(mp->fd, 0);

  if (PIM_DEBUG_MSDP_INTERNAL) {
    zlog_debug("MSDP peer %s pim_msdp_write wrote %d packets", mp->key_str, work_cnt);
  }

  return 0;
}

static void
pim_msdp_pkt_send(struct pim_msdp_peer *mp, struct stream *s)
{
  /* Add packet to the end of list. */
  pim_msdp_pkt_add(mp, s);

  PIM_MSDP_PEER_WRITE_ON(mp);
}

void
pim_msdp_pkt_ka_tx(struct pim_msdp_peer *mp)
{
  struct stream *s;

  if (mp->state != PIM_MSDP_ESTABLISHED) {
    /* don't tx anything unless a session is established */
    return;
  }
  s = stream_new(PIM_MSDP_KA_TLV_MAX_SIZE);
  stream_putc(s, PIM_MSDP_KEEPALIVE);
  stream_putw(s, PIM_MSDP_KA_TLV_MAX_SIZE);

  pim_msdp_pkt_send(mp, s);
}

static void
pim_msdp_pkt_sa_push_to_one_peer(struct pim_msdp_peer *mp)
{
  struct stream *s;

  if (mp->state != PIM_MSDP_ESTABLISHED) {
    /* don't tx anything unless a session is established */
    return;
  }
  s = stream_dup(msdp->work_obuf);
  if (s) {
    pim_msdp_pkt_send(mp, s);
    mp->flags |= PIM_MSDP_PEERF_SA_JUST_SENT;
  }
}

/* push the stream into the obuf fifo of all the peers */
static void
pim_msdp_pkt_sa_push(struct pim_msdp_peer *mp)
{
  struct listnode *mpnode;

  if (mp) {
    pim_msdp_pkt_sa_push_to_one_peer(mp);
  } else {
    for (ALL_LIST_ELEMENTS_RO(msdp->peer_list, mpnode, mp)) {
      if (PIM_DEBUG_MSDP_INTERNAL) {
        zlog_debug("MSDP peer %s pim_msdp_pkt_sa_push", mp->key_str);
      }
      pim_msdp_pkt_sa_push_to_one_peer(mp);
    }
  }
}

static int
pim_msdp_pkt_sa_fill_hdr(int local_cnt)
{
  int curr_tlv_ecnt;

  stream_reset(msdp->work_obuf);
  curr_tlv_ecnt = local_cnt>PIM_MSDP_SA_MAX_ENTRY_CNT?PIM_MSDP_SA_MAX_ENTRY_CNT:local_cnt;
  local_cnt -= curr_tlv_ecnt;
  stream_putc(msdp->work_obuf, PIM_MSDP_V4_SOURCE_ACTIVE);
  stream_putw(msdp->work_obuf, PIM_MSDP_SA_ENTRY_CNT2SIZE(curr_tlv_ecnt));
  stream_putc(msdp->work_obuf, curr_tlv_ecnt);
  stream_put_ipv4(msdp->work_obuf, msdp->originator_id.s_addr);

  return local_cnt;
}

static void
pim_msdp_pkt_sa_fill_one(struct pim_msdp_sa *sa)
{
  stream_put3(msdp->work_obuf, 0 /* reserved */);
  stream_putc(msdp->work_obuf, 32 /* sprefix len */);
  stream_put_ipv4(msdp->work_obuf, sa->sg.grp.s_addr);
  stream_put_ipv4(msdp->work_obuf, sa->sg.src.s_addr);
}

static void
pim_msdp_pkt_sa_gen(struct pim_msdp_peer *mp)
{
  struct listnode *sanode;
  struct pim_msdp_sa *sa;
  int sa_count;
  int local_cnt = msdp->local_cnt;

  sa_count = 0;
  if (PIM_DEBUG_MSDP_INTERNAL) {
    zlog_debug("  sa gen  %d", local_cnt);
  }

  local_cnt = pim_msdp_pkt_sa_fill_hdr(local_cnt);

  for (ALL_LIST_ELEMENTS_RO(msdp->sa_list, sanode, sa)) {
    if (!(sa->flags & PIM_MSDP_SAF_LOCAL)) {
      /* current implementation of MSDP is for anycast i.e. full mesh. so
       * no re-forwarding of SAs that we learnt from other peers */
      continue;
    }
    /* add sa into scratch pad */
    pim_msdp_pkt_sa_fill_one(sa);
    ++sa_count;
    if (sa_count >= PIM_MSDP_SA_MAX_ENTRY_CNT) {
      pim_msdp_pkt_sa_push(mp);
      /* reset headers */
      sa_count = 0;
      if (PIM_DEBUG_MSDP_INTERNAL) {
          zlog_debug("  sa gen for remainder %d", local_cnt);
      }
      local_cnt = pim_msdp_pkt_sa_fill_hdr(local_cnt);
    }
  }

  if (sa_count) {
    pim_msdp_pkt_sa_push(mp);
  }
  return;
}

static void
pim_msdp_pkt_sa_tx_done(void)
{
  struct listnode *mpnode;
  struct pim_msdp_peer *mp;

  /* if SA were sent to the peers we restart ka timer and avoid
   * unnecessary ka noise */
  for (ALL_LIST_ELEMENTS_RO(msdp->peer_list, mpnode, mp)) {
    if (mp->flags & PIM_MSDP_PEERF_SA_JUST_SENT) {
      mp->flags &= ~PIM_MSDP_PEERF_SA_JUST_SENT;
      pim_msdp_peer_pkt_txed(mp);
    }
  }
}

void
pim_msdp_pkt_sa_tx(void)
{
  pim_msdp_pkt_sa_gen(NULL /* mp */);
  pim_msdp_pkt_sa_tx_done();
}

void
pim_msdp_pkt_sa_tx_one(struct pim_msdp_sa *sa)
{
  pim_msdp_pkt_sa_fill_hdr(1 /* cnt */);
  pim_msdp_pkt_sa_fill_one(sa);
  pim_msdp_pkt_sa_push(NULL);
  pim_msdp_pkt_sa_tx_done();
}

/* when a connection is first established we push all SAs immediately */
void
pim_msdp_pkt_sa_tx_to_one_peer(struct pim_msdp_peer *mp)
{
  pim_msdp_pkt_sa_gen(mp);
  pim_msdp_pkt_sa_tx_done();
}

static void
pim_msdp_pkt_rxed_with_fatal_error(struct pim_msdp_peer *mp)
{
  pim_msdp_peer_reset_tcp_conn(mp, "invalid-pkt-rx");
}

static void
pim_msdp_pkt_ka_rx(struct pim_msdp_peer *mp, int len)
{
  mp->ka_rx_cnt++;
  if (len !=  PIM_MSDP_KA_TLV_MAX_SIZE) {
    pim_msdp_pkt_rxed_with_fatal_error(mp);
    return;
  }
  pim_msdp_peer_pkt_rxed(mp);
}

static void
pim_msdp_pkt_sa_rx_one(struct pim_msdp_peer *mp, struct in_addr rp)
{
  int prefix_len;
  struct prefix_sg sg;

  /* just throw away the three reserved bytes */
  stream_get3(mp->ibuf);
  prefix_len = stream_getc(mp->ibuf);

  memset(&sg, 0, sizeof (struct prefix_sg));
  sg.grp.s_addr = stream_get_ipv4(mp->ibuf);
  sg.src.s_addr = stream_get_ipv4(mp->ibuf);

  if (prefix_len != 32) {
    /* ignore SA update if the prefix length is not 32 */
    zlog_err("rxed sa update with invalid prefix length %d", prefix_len);
    return;
  }
  if (PIM_DEBUG_MSDP_PACKETS) {
    zlog_debug("  sg %s", pim_str_sg_dump(&sg));
  }
  pim_msdp_sa_ref(mp, &sg, rp);
}

static void
pim_msdp_pkt_sa_rx(struct pim_msdp_peer *mp, int len)
{
  int entry_cnt;
  int i;
  struct in_addr rp; /* Last RP address associated with this SA */

  mp->sa_rx_cnt++;

  if (len <  PIM_MSDP_SA_TLV_MIN_SIZE) {
    pim_msdp_pkt_rxed_with_fatal_error(mp);
    return;
  }

  entry_cnt = stream_getc(mp->ibuf);
  /* some vendors include the actual multicast data in the tlv (at the end).
   * we will ignore such data. in the future we may consider pushing it down
   * the RPT */
  if (len < PIM_MSDP_SA_ENTRY_CNT2SIZE(entry_cnt)) {
    pim_msdp_pkt_rxed_with_fatal_error(mp);
    return;
  }
  rp.s_addr = stream_get_ipv4(mp->ibuf);

  if (PIM_DEBUG_MSDP_PACKETS) {
    char rp_str[INET_ADDRSTRLEN];
    pim_inet4_dump("<rp?>", rp, rp_str, sizeof(rp_str));
    zlog_debug("  entry_cnt %d rp %s", entry_cnt, rp_str);
  }

  if (!pim_msdp_peer_rpf_check(mp, rp)) {
    /* if peer-RPF check fails don't process the packet any further */
    if (PIM_DEBUG_MSDP_PACKETS) {
      zlog_debug("  peer RPF check failed");
    }
    return;
  }

  pim_msdp_peer_pkt_rxed(mp);

  /* update SA cache */
  for (i = 0; i < entry_cnt; ++i) {
    pim_msdp_pkt_sa_rx_one(mp, rp);
  }
}

static void
pim_msdp_pkt_rx(struct pim_msdp_peer *mp)
{
  enum pim_msdp_tlv type;
  int len;

  /* re-read type and len */
  type = stream_getc_from(mp->ibuf, 0);
  len = stream_getw_from(mp->ibuf, 1);
  if (len <  PIM_MSDP_HEADER_SIZE) {
    pim_msdp_pkt_rxed_with_fatal_error(mp);
    return;
  }

  if (len > PIM_MSDP_SA_TLV_MAX_SIZE) {
    /* if tlv size if greater than max just ignore the tlv */
    return;
  }

  if (PIM_DEBUG_MSDP_PACKETS) {
    pim_msdp_pkt_dump(mp, type, len, true /*rx*/, NULL /*s*/);
  }

  switch(type) {
      case PIM_MSDP_KEEPALIVE:
        pim_msdp_pkt_ka_rx(mp, len);
        break;
      case PIM_MSDP_V4_SOURCE_ACTIVE:
        mp->sa_rx_cnt++;
        pim_msdp_pkt_sa_rx(mp, len);
        break;
      default:
        mp->unk_rx_cnt++;
  }
}

/* pim msdp read utility function. */
static int
pim_msdp_read_packet(struct pim_msdp_peer *mp)
{
  int nbytes;
  int readsize;

  readsize = mp->packet_size - stream_get_endp(mp->ibuf);
  if (!readsize) {
    return 0;
  }

  /* Read packet from fd */
  nbytes = stream_read_try(mp->ibuf, mp->fd, readsize);
  if (nbytes < 0) {
    if (nbytes == -2) {
      /* transient error retry */
      return -1;
    }
    pim_msdp_pkt_rxed_with_fatal_error(mp);
    return -1;
  }

  if (!nbytes) {
    pim_msdp_peer_reset_tcp_conn(mp, "peer-down");
    return -1;
  }

  /* We read partial packet. */
  if (stream_get_endp(mp->ibuf) != mp->packet_size)
    return -1;

  return 0;
}

int
pim_msdp_read(struct thread *thread)
{
  struct pim_msdp_peer *mp;
  int rc;
  uint32_t len;

  mp = THREAD_ARG(thread);
  mp->t_read = NULL;

  if (PIM_DEBUG_MSDP_INTERNAL) {
    zlog_debug("MSDP peer %s pim_msdp_read", mp->key_str);
  }

  if (mp->fd < 0) {
    return -1;
  }

  /* check if TCP connection is established */
  if (mp->state != PIM_MSDP_ESTABLISHED) {
    pim_msdp_connect_check(mp);
    return 0;
  }

  PIM_MSDP_PEER_READ_ON(mp);

  if (!mp->packet_size) {
    mp->packet_size = PIM_MSDP_HEADER_SIZE;
  }

  if (stream_get_endp(mp->ibuf) < PIM_MSDP_HEADER_SIZE) {
    /* start by reading the TLV header */
    rc = pim_msdp_read_packet(mp);
    if (rc < 0) {
      goto pim_msdp_read_end;
    }

    /* Find TLV type and len  */
    stream_getc(mp->ibuf);
    len = stream_getw(mp->ibuf);
    if (len < PIM_MSDP_HEADER_SIZE) {
      pim_msdp_pkt_rxed_with_fatal_error(mp);
      goto pim_msdp_read_end;
    }
    /* read complete TLV */
    mp->packet_size = len;
  }

  rc = pim_msdp_read_packet(mp);
  if (rc < 0) {
    goto pim_msdp_read_end;
  }

  pim_msdp_pkt_rx(mp);

  /* reset input buffers and get ready for the next packet */
  mp->packet_size = 0;
  stream_reset(mp->ibuf);

pim_msdp_read_end:
  return 0;
}