[Xorp-cvs] XORP cvs commit: xorp/libcomm

[Bruce Simpson]

CVSROOT:	/usr/local/www/data/cvs
Module name:	xorp
Changes by:	bms at chum.icir.org	2008-04-22 13:53:02 UTC

XORP CVS repository


Modified files:
	libcomm       comm_api.h comm_sock.c comm_user.c 

Log message:
	Import libcomm enhancements which are needed by OLSRv1 for
	generating IPv4 limited broadcast traffic (255.255.255.255).
	
	 * Most IP stacks have certain quirks regarding how IPv4 broadcasts
	   are sent and received, because the BSD socket API did not historically
	   handle them with completeness.
	
	  * For example, like a multicast channel (S,G), the limited broadcast
	    address on its own does not supply enough information to the BSD kernel
	    ip_output() function.
	
	  * These inconsistencies have been addressed since, by deprecating the use
	    of limited broadcast in favour of link-scope multicast. In the case of
	    IPv6, limited broadcast has been completely eliminated from the
	    network layer protocol.
	
	  * Unfortunately, protocols such as OLSRv1 and RIPv1 have seen operational
	    deployment WITHOUT being updated to use link-scope multicast, therefore
	    we need to make the appropriate changes to support this behaviour.
	
	 * Add functions:
	
	   * comm_set_send_broadcast()
	     Most implementations require that SO_BROADCAST is set to permit the
	     transmission of broadcast messages on a socket.
	
	   * comm_set_unicast_ttl()
	     Set the TTL field or hop-count field in outgoing IPv4/IPv6 messages.
	
	   * comm_set_tos()
	     Set the TOS field in outgoing IPv4 messages.
	
	   * The following functions MUST NOT be used by user routing processes.
	     They exist only to address the specific issue described above regarding
	     the addressing of limited broadcasts.
	
	    * comm_set_onesbcast()
	      BSD specific. Enables a kernel feature whereby sends to the network
	      broadcast address configured on a vif, are automatically rewritten
	      to contain the limited broadcast address.
	
	    * comm_set_bindtodevice()
	      Linux specific. Bind a socket to a link-layer device for all receives
	      and transmits. Operates independently of the socket API function bind().
	
	    * comm_set_receive_broadcast()
	      Windows Vista and Windows Server 2003 specific. The new TCP/IP
	      implementation requires that processes explicitly request to
	      receive broadcast messages.
	      Windows creates a separate connected FIB entry for each NDIS interface
	      with the TCPIP.SYS transport bound to it which points to the limited
	      broadcast address.
	
	   * Additionally add *_present() functions to allow libcomm clients to
	     test for the presence of these features.
	
	 * These functions may potentially be used by RIPv1 at a later date.
	
	 * The FEA support will come in a later patch.
	
	Note: In the XORP/OLSR branch, the new function for setting the TTL
	on an IPV4 socket is named "comm_set_ttl()". This clashes with the
	existing function in CVS, which sets the multicast ttl.
	
	Therefore the following functions are renamed in this CVS commit:
	the import of this change set is atomic in CVS:
	 comm_ttl_present       -> comm_unicast_ttl_present
	 comm_set_ttl           -> comm_set_unicast_ttl
	
	Obtained from:  XORP/OLSR
	Sponsored by:   CenGen, Inc.

Revision  Changes                                Path
1.31      +94 -1;  commitid: e6dd480ded6641a7;   xorp/libcomm/comm_api.h
1.45      +218 -8;  commitid: e6dd480ded6641a7;  xorp/libcomm/comm_sock.c
1.32      +41 -1;  commitid: e6dd480ded6641a7;   xorp/libcomm/comm_user.c