buffer for zfs send/recv streams

BSD-Licensed buffering utility that utilizes SCTP as the protocol of choice. Some of the reasons for choosing SCTP are as follows:

• Network-level fault tolerance through support for multihoming
• Minimized delay in data delivery by sending data in multiple streams
• Acknowledged, error-free non-duplicated transfer of data
• Data fragmentation to conform to discovered maximum transmission unit (MTU) size
• Sequenced delivery of user messages with-in multiple streams
• Optional bundling of multiple user messages in to an SCTP packet
• Improved SYN-flood protection by utilizing a 4-way handshake in the intialization of an association
• Preservation of message boundaries

Future work

• Add the ability to choose between TCP/UDP
• Add the ability to use DTLS to encrypt data chunks per RFC 4347
• Add the ability to offload crypto functions via AES-NI instruction sets on CPU