SCTP: handle INIT corner-case handling

As per RFC4960 the INIT chunk could be received in unexpected scenarios
and - depending on the state of the internal state-machine - the INIT
chunk requires different treatment.
This patch addresses section 5.2.1 and 5.2.2 of the RFC4960.

Change-Id: Ib23ef490c6a5ca3da6c46a9584b75e7577cb7042
Signed-off-by: Marco Varlese <marco.varlese@suse.com>

4 files changed, 215 insertions, 5 deletions

diff --git a/src/vnet/sctp/sctp.c b/src/vnet/sctp/sctp.c
index 9a0f47b599f..046eb18dcc2 100644
--- a/src/vnet/sctp/sctp.c
+++ b/src/vnet/sctp/sctp.c
@@ -291,6 +291,8 @@ sctp_sub_connection_add_ip4 (u8 thread_index,
   clib_memcpy (&sctp_conn->
 	       sub_conn[sctp_conn->next_avail_sub_conn].connection.lcl_ip.ip4,
 	       &ipv4_addr->address, sizeof (ipv4_addr->address));
+
+  sctp_conn->forming_association_changed = 1;
 }
 
 void
@@ -302,6 +304,8 @@ sctp_sub_connection_add_ip6 (u8 thread_index,
   clib_memcpy (&sctp_conn->
 	       sub_conn[sctp_conn->next_avail_sub_conn].connection.lcl_ip.ip6,
 	       &ipv6_addr->address, sizeof (ipv6_addr->address));
+
+  sctp_conn->forming_association_changed = 1;
 }
 
 sctp_connection_t *
diff --git a/src/vnet/sctp/sctp.h b/src/vnet/sctp/sctp.h
index 048d153ac55..de5eb8f6685 100644
--- a/src/vnet/sctp/sctp.h
+++ b/src/vnet/sctp/sctp.h
@@ -237,6 +237,9 @@ typedef struct _sctp_connection
 
   u8 next_avail_sub_conn; /**< Represent the index of the next free slot in sub_conn */
 
+  u8 forming_association_changed; /**< This is a flag indicating whether the original association has been modified during
+  	  	  	  	  the life-span of the association itself. For instance, a new sub-connection might have been added. */
+
 } sctp_connection_t;
 
 typedef void (sctp_timer_expiration_handler) (u32 conn_index, u32 timer_id);
@@ -280,6 +283,16 @@ void sctp_init_mss (sctp_connection_t * sctp_conn);
 void sctp_prepare_initack_chunk (sctp_connection_t * sctp_conn, u8 idx,
 				 vlib_buffer_t * b, ip4_address_t * ip4_addr,
 				 ip6_address_t * ip6_addr);
+void
+sctp_prepare_initack_chunk_for_collision (sctp_connection_t * sctp_conn,
+					  u8 idx, vlib_buffer_t * b,
+					  ip4_address_t * ip4_addr,
+					  ip6_address_t * ip6_addr);
+void sctp_prepare_abort_for_collision (sctp_connection_t * sctp_conn, u8 idx,
+				       vlib_buffer_t * b,
+				       ip4_address_t * ip4_addr,
+				       ip6_address_t * ip6_addr);
+
 void sctp_prepare_cookie_echo_chunk (sctp_connection_t * sctp_conn, u8 idx,
 				     vlib_buffer_t * b,
 				     sctp_state_cookie_param_t * sc);
diff --git a/src/vnet/sctp/sctp_input.c b/src/vnet/sctp/sctp_input.c
index 615cdefd134..82adc2aa5b0 100644
--- a/src/vnet/sctp/sctp_input.c
+++ b/src/vnet/sctp/sctp_input.c
@@ -304,12 +304,24 @@ sctp_handle_init (sctp_header_t * sctp_hdr,
     {				/* UNEXPECTED scenario */
       switch (sctp_conn->state)
 	{
-	case SCTP_STATE_COOKIE_WAIT:	/* TODO */
+	case SCTP_STATE_COOKIE_WAIT:
 	  SCTP_ADV_DBG ("Received INIT chunk while in COOKIE_WAIT state");
-	  break;
-	case SCTP_STATE_COOKIE_ECHOED:	/* TODO */
+	  sctp_prepare_initack_chunk_for_collision (sctp_conn,
+						    MAIN_SCTP_SUB_CONN_IDX,
+						    b0, ip4_addr, ip6_addr);
+	  return SCTP_ERROR_NONE;
+	case SCTP_STATE_COOKIE_ECHOED:
+	case SCTP_STATE_SHUTDOWN_ACK_SENT:
 	  SCTP_ADV_DBG ("Received INIT chunk while in COOKIE_ECHOED state");
-	  break;
+	  if (sctp_conn->forming_association_changed == 0)
+	    sctp_prepare_initack_chunk_for_collision (sctp_conn,
+						      MAIN_SCTP_SUB_CONN_IDX,
+						      b0, ip4_addr, ip6_addr);
+	  else
+	    sctp_prepare_abort_for_collision (sctp_conn,
+					      MAIN_SCTP_SUB_CONN_IDX, b0,
+					      ip4_addr, ip6_addr);
+	  return SCTP_ERROR_NONE;
 	}
     }
 
@@ -2353,7 +2365,7 @@ do {                                                       	\
   _(SHUTDOWN_RECEIVED, SHUTDOWN_COMPLETE, SCTP_INPUT_NEXT_DROP, SCTP_ERROR_SHUTDOWN_COMPLETE_VIOLATION);	/* UNEXPECTED SHUTDOWN_COMPLETE chunk */
 
   _(SHUTDOWN_ACK_SENT, DATA, SCTP_INPUT_NEXT_DROP, SCTP_ERROR_DATA_CHUNK_VIOLATION);	/* UNEXPECTED DATA chunk */
-  _(SHUTDOWN_ACK_SENT, INIT, SCTP_INPUT_NEXT_DROP, SCTP_ERROR_INIT_CHUNK_VIOLATION);	/* UNEXPECTED INIT chunk */
+  _(SHUTDOWN_ACK_SENT, INIT, SCTP_INPUT_NEXT_RCV_PHASE, SCTP_ERROR_NONE);	/* UNEXPECTED INIT chunk */
   _(SHUTDOWN_ACK_SENT, INIT_ACK, SCTP_INPUT_NEXT_DROP, SCTP_ERROR_ACK_DUP);	/* UNEXPECTED INIT_ACK chunk */
   _(SHUTDOWN_ACK_SENT, SACK, SCTP_INPUT_NEXT_DROP, SCTP_ERROR_SACK_CHUNK_VIOLATION);	/* UNEXPECTED INIT chunk */
   _(SHUTDOWN_ACK_SENT, HEARTBEAT, SCTP_INPUT_NEXT_DROP, SCTP_ERROR_HEARTBEAT_CHUNK_VIOLATION);	/* UNEXPECTED HEARTBEAT chunk */
diff --git a/src/vnet/sctp/sctp_output.c b/src/vnet/sctp/sctp_output.c
index a9b2417e0c9..e44451c034c 100644
--- a/src/vnet/sctp/sctp_output.c
+++ b/src/vnet/sctp/sctp_output.c
@@ -589,6 +589,187 @@ sctp_prepare_cookie_echo_chunk (sctp_connection_t * sctp_conn, u8 idx,
 }
 
 /**
+ * Convert buffer to ABORT
+ */
+void
+sctp_prepare_abort_for_collision (sctp_connection_t * sctp_conn, u8 idx,
+				  vlib_buffer_t * b, ip4_address_t * ip4_addr,
+				  ip6_address_t * ip6_addr)
+{
+  vlib_main_t *vm = vlib_get_main ();
+
+  sctp_reuse_buffer (vm, b);
+
+  /* The minimum size of the message is given by the sctp_abort_chunk_t */
+  u16 alloc_bytes = sizeof (sctp_abort_chunk_t);
+
+  /* As per RFC 4960 the chunk_length value does NOT contemplate
+   * the size of the first header (see sctp_header_t) and any padding
+   */
+  u16 chunk_len = alloc_bytes - sizeof (sctp_header_t);
+
+  alloc_bytes += vnet_sctp_calculate_padding (alloc_bytes);
+
+  sctp_abort_chunk_t *abort_chunk = vlib_buffer_push_uninit (b, alloc_bytes);
+
+  /* src_port & dst_port are already in network byte-order */
+  abort_chunk->sctp_hdr.checksum = 0;
+  abort_chunk->sctp_hdr.src_port =
+    sctp_conn->sub_conn[idx].connection.lcl_port;
+  abort_chunk->sctp_hdr.dst_port =
+    sctp_conn->sub_conn[idx].connection.rmt_port;
+  /* As per RFC4960 Section 5.2.2: copy the INITIATE_TAG into the VERIFICATION_TAG of the ABORT chunk */
+  abort_chunk->sctp_hdr.verification_tag = sctp_conn->local_tag;
+
+  vnet_sctp_set_chunk_type (&abort_chunk->chunk_hdr, ABORT);
+  vnet_sctp_set_chunk_length (&abort_chunk->chunk_hdr, chunk_len);
+
+  vnet_buffer (b)->sctp.connection_index =
+    sctp_conn->sub_conn[idx].connection.c_index;
+  vnet_buffer (b)->sctp.subconn_idx = idx;
+}
+
+/**
+ * Convert buffer to INIT-ACK
+ */
+void
+sctp_prepare_initack_chunk_for_collision (sctp_connection_t * sctp_conn,
+					  u8 idx, vlib_buffer_t * b,
+					  ip4_address_t * ip4_addr,
+					  ip6_address_t * ip6_addr)
+{
+  vlib_main_t *vm = vlib_get_main ();
+  sctp_ipv4_addr_param_t *ip4_param = 0;
+  sctp_ipv6_addr_param_t *ip6_param = 0;
+
+  sctp_reuse_buffer (vm, b);
+
+  /* The minimum size of the message is given by the sctp_init_ack_chunk_t */
+  u16 alloc_bytes =
+    sizeof (sctp_init_ack_chunk_t) + sizeof (sctp_state_cookie_param_t);
+
+  if (PREDICT_TRUE (ip4_addr != NULL))
+    {
+      /* Create room for variable-length fields in the INIT_ACK chunk */
+      alloc_bytes += SCTP_IPV4_ADDRESS_TYPE_LENGTH;
+    }
+  if (PREDICT_TRUE (ip6_addr != NULL))
+    {
+      /* Create room for variable-length fields in the INIT_ACK chunk */
+      alloc_bytes += SCTP_IPV6_ADDRESS_TYPE_LENGTH;
+    }
+
+  if (sctp_conn->sub_conn[idx].connection.is_ip4)
+    alloc_bytes += sizeof (sctp_ipv4_addr_param_t);
+  else
+    alloc_bytes += sizeof (sctp_ipv6_addr_param_t);
+
+  /* As per RFC 4960 the chunk_length value does NOT contemplate
+   * the size of the first header (see sctp_header_t) and any padding
+   */
+  u16 chunk_len = alloc_bytes - sizeof (sctp_header_t);
+
+  alloc_bytes += vnet_sctp_calculate_padding (alloc_bytes);
+
+  sctp_init_ack_chunk_t *init_ack_chunk =
+    vlib_buffer_push_uninit (b, alloc_bytes);
+
+  u16 pointer_offset = sizeof (sctp_init_ack_chunk_t);
+
+  /* Create State Cookie parameter */
+  sctp_state_cookie_param_t *state_cookie_param =
+    (sctp_state_cookie_param_t *) ((char *) init_ack_chunk + pointer_offset);
+
+  state_cookie_param->param_hdr.type =
+    clib_host_to_net_u16 (SCTP_STATE_COOKIE_TYPE);
+  state_cookie_param->param_hdr.length =
+    clib_host_to_net_u16 (sizeof (sctp_state_cookie_param_t));
+  state_cookie_param->creation_time = clib_host_to_net_u32 (sctp_time_now ());
+  state_cookie_param->cookie_lifespan =
+    clib_host_to_net_u32 (SCTP_VALID_COOKIE_LIFE);
+
+  sctp_compute_mac (sctp_conn, state_cookie_param);
+
+  pointer_offset += sizeof (sctp_state_cookie_param_t);
+
+  if (PREDICT_TRUE (ip4_addr != NULL))
+    {
+      sctp_ipv4_addr_param_t *ipv4_addr =
+	(sctp_ipv4_addr_param_t *) init_ack_chunk + pointer_offset;
+
+      ipv4_addr->param_hdr.type =
+	clib_host_to_net_u16 (SCTP_IPV4_ADDRESS_TYPE);
+      ipv4_addr->param_hdr.length =
+	clib_host_to_net_u16 (SCTP_IPV4_ADDRESS_TYPE_LENGTH);
+      ipv4_addr->address.as_u32 = ip4_addr->as_u32;
+
+      pointer_offset += SCTP_IPV4_ADDRESS_TYPE_LENGTH;
+    }
+  if (PREDICT_TRUE (ip6_addr != NULL))
+    {
+      sctp_ipv6_addr_param_t *ipv6_addr =
+	(sctp_ipv6_addr_param_t *) init_ack_chunk + pointer_offset;
+
+      ipv6_addr->param_hdr.type =
+	clib_host_to_net_u16 (SCTP_IPV6_ADDRESS_TYPE);
+      ipv6_addr->param_hdr.length =
+	clib_host_to_net_u16 (SCTP_IPV6_ADDRESS_TYPE_LENGTH);
+      ipv6_addr->address.as_u64[0] = ip6_addr->as_u64[0];
+      ipv6_addr->address.as_u64[1] = ip6_addr->as_u64[1];
+
+      pointer_offset += SCTP_IPV6_ADDRESS_TYPE_LENGTH;
+    }
+
+  if (sctp_conn->sub_conn[idx].connection.is_ip4)
+    {
+      ip4_param = (sctp_ipv4_addr_param_t *) init_ack_chunk + pointer_offset;
+      ip4_param->address.as_u32 =
+	sctp_conn->sub_conn[idx].connection.lcl_ip.ip4.as_u32;
+
+      pointer_offset += sizeof (sctp_ipv4_addr_param_t);
+    }
+  else
+    {
+      ip6_param = (sctp_ipv6_addr_param_t *) init_ack_chunk + pointer_offset;
+      ip6_param->address.as_u64[0] =
+	sctp_conn->sub_conn[idx].connection.lcl_ip.ip6.as_u64[0];
+      ip6_param->address.as_u64[1] =
+	sctp_conn->sub_conn[idx].connection.lcl_ip.ip6.as_u64[1];
+
+      pointer_offset += sizeof (sctp_ipv6_addr_param_t);
+    }
+
+  /* src_port & dst_port are already in network byte-order */
+  init_ack_chunk->sctp_hdr.checksum = 0;
+  init_ack_chunk->sctp_hdr.src_port =
+    sctp_conn->sub_conn[idx].connection.lcl_port;
+  init_ack_chunk->sctp_hdr.dst_port =
+    sctp_conn->sub_conn[idx].connection.rmt_port;
+  /* the sctp_conn->verification_tag is already in network byte-order (being a copy of the init_tag coming with the INIT chunk) */
+  init_ack_chunk->sctp_hdr.verification_tag = sctp_conn->remote_tag;
+  init_ack_chunk->initial_tsn =
+    clib_host_to_net_u32 (sctp_conn->local_initial_tsn);
+  SCTP_CONN_TRACKING_DBG ("init_ack_chunk->initial_tsn = %u",
+			  init_ack_chunk->initial_tsn);
+
+  vnet_sctp_set_chunk_type (&init_ack_chunk->chunk_hdr, INIT_ACK);
+  vnet_sctp_set_chunk_length (&init_ack_chunk->chunk_hdr, chunk_len);
+
+  init_ack_chunk->initiate_tag = sctp_conn->local_tag;
+
+  init_ack_chunk->a_rwnd =
+    clib_host_to_net_u32 (sctp_conn->sub_conn[idx].cwnd);
+  init_ack_chunk->inboud_streams_count =
+    clib_host_to_net_u16 (INBOUND_STREAMS_COUNT);
+  init_ack_chunk->outbound_streams_count =
+    clib_host_to_net_u16 (OUTBOUND_STREAMS_COUNT);
+
+  vnet_buffer (b)->sctp.connection_index =
+    sctp_conn->sub_conn[idx].connection.c_index;
+  vnet_buffer (b)->sctp.subconn_idx = idx;
+}
+
+/**
  * Convert buffer to INIT-ACK
  */
 void