implement sendto()/recvfrom() equivalents.

request(), seek() or deliver_xxx() in order to start the data flow.
Autonomous generators must be genuinely autonomous (having their own
process), or otherwise arrange to be called.  TCP does this by
starting the retry timer immediately.

Add some debugging statements.

Achieved via Perl using:

perl -pi -e 's/pk_buff/io_buffer/g; s/Packet buffer/I\/O buffer/ig; ' \
	-e 's/pkbuff\.h/iobuf.h/g; s/pkb_/iob_/g; s/_pkb/_iob/g; ' \
	-e 's/pkb/iobuf/g; s/PKB/IOB/g;'

to avoid drops even on slow NICs.

almost everywhere else.

tcpip_tx().  This avoids the irritating wait when you accidentally type
"kernel pxelinux.0" before bringing up the network interface.

Add ENETUNREACH to strerror()'s list.

transmissions.

skb_tailroom().  Add pkb_headroom().

  "when SYN is ACKed and we have already received SYN", or
  "when SYN is received and we have already had SYN ACKed"

rather than just

  "when SYN is ACKed"

This avoids spuriously calling the connected() method when we receive
a RST,ACK in response to a SYN.

out-of-range ACK.

Simplify checksum generation on the TX datapath.

Truncate TX length to TCP window at time of transmission rather than at
time of adding to TX packet; this is conceptually cleaner and also allows
the application to call tcp_send() multiple times to build up a single
packet.

"flags that are currently being sent".  This allows at least one special
case (checking that we haven't already sent a FIN in tcp_rx_fin()) to be
collapsed.

TCP_CLOSED state (i.e. after the final FIN/ACK exchange), and has been
removed from the list of TCP connections.

already stopped.

Don't call start_timer() when sending a dataless ACK.  This may or may
not be the right thing to do; I can't tell.

Back out broken "send ACK only if required to" logic temporarily.

subsequent runs.

Use just random() to allocate initial sequence numbers; the previous
algorithm ended up with a high probability of zeroing the high word.

a TCP packet before passing to newdata().

Introduced struct sockaddr_tcpip, to simplify code that deals with
both IPv4 and IPv6 addresses.

Reorganised parts of tcpip.c and udp.c.

transition away from uIP.

Prepared ipv4.c for transition away from uIP.

Kill off the static single net device and move to proper dynamic
registration (which we need with the new device model).

Break the (flawed) assumption that all network-layer protocols can use
ARP; such network-layer protocols (i.e. IPv4) must now register as an ARP
protocol using ARP_NET_PROTOCOL() and provide a single method for checking
the existence of a local network-layer address.