pim-msdp: part-1 - initial protocol infra.

This commit includes the following changes -
1. Support for MSDP peer DB (hash and sorted list).
2. Support for the following timers - keepalive, connect-retry, hold.
3. TCP session management (lower-ip is active, higher-ip is passive).
4. MSDP KA packet rx/tx.
5. Limited temporary config (will be replaced with the more automation
friendly RP-set).

Testing done -
Peer bringup/deletion (including interop with another vendor)

Sample out -
root@dell-s6000-04:~# sudo vtysh -c "show ip msdp peer"
Peer                       Local        Mesh-group        State Uptime
100.1.1.1              100.1.2.1           default  established 00:07:27
100.1.3.1              100.1.2.1           default  established 00:31:50
root@dell-s6000-04:~#

Coming soon -
1. part-2: SA cache management.
2. part-3: SPT setup using source in SA cache.
3. part-4: CLI cleanup.

Ticket: CM-13306

Signed-off-by: Anuradha Karuppiah <anuradhak@cumulusnetworks.com>
Acked-by: Donald Sharp <sharpd@cumulusnetworks.com>

1 files changed, 380 insertions, 0 deletions

diff --git a/pimd/pim_msdp_packet.c b/pimd/pim_msdp_packet.c
new file mode 100644
index 0000000000..458d5e4621
--- /dev/null
+++ b/pimd/pim_msdp_packet.c
@@ -0,0 +1,380 @@
+/*
+ * 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 "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_dump(struct pim_msdp_peer *mp, int type, int len, bool rx)
+{
+  char key_str[PIM_MSDP_PEER_KEY_STRLEN];
+  char type_str[PIM_MSDP_PKT_TYPE_STRLEN];
+
+  pim_msdp_peer_key_dump(mp, key_str, sizeof(key_str), false);
+  pim_msdp_pkt_type_dump(type, type_str, sizeof(type_str));
+
+  zlog_debug("%s pkt %s type %s len %d",
+      key_str, rx?"rx":"tx", type_str, len);
+  /* XXX: dump actual data */
+}
+
+/* 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 */
+    /* XXX:revisit; reset TCP connection */
+    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");
+    /* XXX:revisit; reset TCP connection */
+    pim_msdp_peer_reset_tcp_conn(mp, "connect-failed");
+    return;
+  }
+
+  /* When status is 0 then TCP connection is established. */
+  if (PIM_DEBUG_MSDP_INTERNAL) {
+    char key_str[PIM_MSDP_PEER_KEY_STRLEN];
+
+    pim_msdp_peer_key_dump(mp, key_str, sizeof(key_str), false);
+    zlog_debug("%s pim_connect_check %s", key_str, status?"fail":"success");
+  }
+  if (status == 0) {
+    pim_msdp_peer_established(mp);
+  } else {
+    /* XXX:revisit; reset TCP connection */
+    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_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;
+
+  mp = THREAD_ARG(thread);
+  mp->t_write = NULL;
+
+  if (PIM_DEBUG_MSDP_INTERNAL) {
+    char key_str[PIM_MSDP_PEER_KEY_STRLEN];
+
+    pim_msdp_peer_key_dump(mp, key_str, sizeof(key_str), false);
+    zlog_debug("%s pim_msdp_write", 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))
+        break;
+
+      /* XXX:revisit; reset TCP connection */
+      pim_msdp_peer_reset_tcp_conn(mp, "pkt-tx-failed");
+      return 0;
+    }
+
+    if (num != writenum) {
+      /* Partial write */
+      stream_forward_getp(s, num);
+      break;
+    }
+
+    /* Retrieve msdp packet type. */
+    type = stream_getc(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, writenum, false /*rx*/);
+    }
+
+    /* packet sent delete it. */
+    pim_msdp_pkt_delete(mp);
+
+    /* XXX - may need to pause if we have done too much work in this
+     * loop */
+  } while ((s = stream_fifo_head(mp->obuf)) != NULL);
+  pim_msdp_write_proceed_actions(mp);
+
+  sockopt_cork (mp->fd, 0);
+
+  return 0;
+}
+
+static void
+pim_msdp_pkt_send(struct pim_msdp_peer *mp, struct stream *s)
+{
+  /* Add packet to the end of list. */
+  stream_fifo_push(mp->obuf, s);
+
+  PIM_MSDP_PEER_WRITE_ON(mp);
+}
+
+/* Make keepalive packet and send it to the peer
+ 0                   1                   2                   3
+ 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+|       4      |              3                 |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+*/
+void
+pim_msdp_pkt_ka_tx(struct pim_msdp_peer *mp)
+{
+  struct stream *s;
+
+  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_rxed_with_fatal_error(struct pim_msdp_peer *mp)
+{
+  /* XXX:revisit; reset TCP connection */
+  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(struct pim_msdp_peer *mp, int len)
+{
+  mp->sa_rx_cnt++;
+  /* XXX: proc SA ... */
+  pim_msdp_peer_pkt_rxed(mp);
+}
+
+/* Theoretically you could have different tlv types in the same message.
+ * For the time being I am assuming one; will revisit before 3.2 - XXX */
+static void
+pim_msdp_pkt_rx(struct pim_msdp_peer *mp, int nbytes)
+{
+  enum pim_msdp_tlv type;
+  int len;
+
+  type = stream_getc(mp->ibuf);
+  len = stream_getw(mp->ibuf);
+  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 (len > nbytes) {
+    /* we got a partial read or the packet is malformed */
+    pim_msdp_pkt_rxed_with_fatal_error(mp);
+    return;
+  }
+
+  if (PIM_DEBUG_MSDP_PACKETS) {
+    pim_msdp_pkt_dump(mp, type, len, true /*rx*/);
+  }
+
+  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++;
+  }
+  /* XXX: process next tlv*/
+}
+
+/* pim msdp read utility function. */
+static int
+pim_msdp_read_packet(struct pim_msdp_peer *mp)
+{
+  int nbytes;
+  /* Read packet from fd. */
+  nbytes = stream_read_try(mp->ibuf, mp->fd, PIM_MSDP_MAX_PACKET_SIZE);
+  if (nbytes < PIM_MSDP_HEADER_SIZE) {
+    if (nbytes == -2) {
+      /* transient error retry */
+      return -1;
+    }
+    pim_msdp_pkt_rxed_with_fatal_error(mp);
+    return -1;
+  }
+  return nbytes;
+}
+
+int
+pim_msdp_read(struct thread *thread)
+{
+  struct pim_msdp_peer *mp;
+  int rc;
+
+  mp = THREAD_ARG(thread);
+  mp->t_read = NULL;
+
+  if (PIM_DEBUG_MSDP_INTERNAL) {
+    char key_str[PIM_MSDP_PEER_KEY_STRLEN];
+
+    pim_msdp_peer_key_dump(mp, key_str, sizeof(key_str), false);
+    zlog_debug("%s pim_msdp_read", 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;
+  }
+
+  THREAD_READ_ON(msdp->master, mp->t_read, pim_msdp_read, mp, mp->fd);
+
+  rc = pim_msdp_read_packet(mp);
+  if (rc > 0) {
+    pim_msdp_pkt_rx(mp, rc);
+  }
+
+  stream_reset(mp->ibuf);
+  return 0;
+}