Start Timer T3 when starting Timer T1 after expiry, to avoid a situation
wherein two RR command polling frames may be sent within close proximity
of one another
When handling I frames, stop Timer T2 if the number of unacknowledged
frames has reached k/2
Other changes:
* Provide annotations from the AX.25 v2.2 standards document
* Improve implementation of I frame reception P/F procedure
Always send RR when Timer T3 runs out, as we are not likely (with modern
hardware with MMUs) to be unable to receive; furthermore, RNR would have
only been sent erroneously if the outward flow of traffic had been
stopped
Changes:
* Use patty_ax25_sock_reset() when receiving a FRMR, SABM, or SABME
frame
* Reply to an SABM or SABME frame with a UA when received by an
ESTABLISHED socket
Implement AX.25 v2.2, Section 6.4.6 "Receiving Acknowledgement"
semantics more consistently
Changes:
* Add frame_ack() method in src/server.c to unify logic for
acknowledging frames and handling I frame transmission flow
control
* Ensure that the Timer T1 retry counter is reset as appropriate
when Timer T1 is restarted
* Add excerpts from the AX.25 v2.2 documentation to accompanying
code to better document the purpose of important aspects of the
state machine and protocol
* When receiving an S frame with N(R) acknowledgement of a frame
sent earlier than indicated by V(S), set V(S) to that N(R) value
* Implement patty_ax25_sock_resend_pending() as a means to resend
one frame previously sent which remains unacknowledged; this
uses V(S) to determine the frame to resend, and increments V(S) if
there was indeed an unacknowledged frame
* Call patty_ax25_sock_resend_pending() in src/server.c, method
handle_sock() to send a single frame previously sent but pending
acknowledgement
Changes:
* Make patty_ax25_sock_ack() take a N(R) argument directly, rather
than having the caller specify N(R)-1
* Only perform acknowledgement of frames within the range between
V(A) and N(R)-1
Implement patty_timer_init() to allow the caller to specify a timer
value to use each time patty_timer_start() is called, obviating the need
to pass the same argument redundantly; if the timer value must be
changed, then another call to patty_timer_init() may be used
Implement frame segmentation/reassembly state machine as per AX.25 v2.2
specifications, as per Section 6.6 "Disassembler/Reassembler" and
associated appendices
When a remote station wishes to connect by sending an XID frame, use
Timer T1 to send an XID response up to the retry count before closing
the socket pending negotiation
Changes:
* Add validation to accept() to ensure file descriptors provided
refer to SOCK_STREAM sockets in the SOCK_LISTENING state
* Rather than writing a reply to the patty client socket when
accepting a SABM or SABME request, write a message to the
remote end of the listening socket; this avoids issues wherein
a client receives an unexpected accept() response that may be
unrelated to another pending request; this also allows client
code to use select(2) on listening sockets
* In patty_client_accept(), send the initial request to validate
that the local socket can accept connections, and then wait for
a connection to be made, reading a message written to the
listening socket from the patty server
* Allow select(2) to notify on accepted connections
Changes:
* Replace usage of gettimeofday() with clock_gettime() in the main
event loop, patty_ax25_server_run(), as gettimeofday() apparently
goes backwards in time occasionally, as per:
https://bugzilla.redhat.com/show_bug.cgi?id=174390
Thanks Iain MM0ROR!
* Fix patty_timer_expired() to properly return true if the
remaining number of seconds is zero, but the remaining higher
precision time is less than zero
* Implement patty_timer_sub() to subtract two struct timespec
values, as glibc lacks timespecsub()
Changes:
* Implement handle_sock_dgram() to specifically handle datagram
(UI frame-only) sockets; this fixes issues wherein logic
specific to SOCK_STREAM timers would be erroneously applied
to datagram sockets
* Always tick Timers T1, T2 and T3
* Some slight code reorganization for improved readability of
control flow
Fix select() portability issues in src/server.c by using gettimeofday()
immediately prior to and after calling select() to calculate elapsed
time since blocking on select()
Implement PATTY_AX25_SOCK_DGRAM type sockets as a means of exchanging UI
frames between stations without requiring calling code to encode and
decode UI frames explicitly
Add SOCK_PARAMS to patty_client_setsockopt() to allow for setting
(presently) the MTU and TX window of a given socket to accommodate the
needs of specific remote stations
Implement the SOCK_WAIT and SOCK_READY socket flow control states to
indicate a Receive Ready or Receive Not Ready state on the remote end
Other changes:
* Fix issue wherein flow control was never halted when the remote
end has received k (window) number of frames without the sending
station asking for acknowledgment
Changes:
* Reimplement patty_ax25_sock_send() to be geared specifically for
sending raw frames; the function which formerly held this name is
now a private method
* Implement patty_ax25_sock_recv() to receive a frame from a raw
socket
* Implement patty_ax25_sock_recv_pending() to determine how many raw
frames are pending receipt in the buffer
* When handling raw sockets, use patty_ax25_sock_recv_pending() to
ensure any raw pending frames read from a client intended for
transmission on an interface are read completely
Changes:
* When associating a promiscuous socket with an interface, rather
than creating a patty_kiss_tnc object, simply store the socket
file descriptor and use patty_kiss_frame_send() to send incoming
or outgoing frames for that interface to the promiscuous socket
* Add special initialization code in src/sock.c for SOCK_RAW; don't
allocate any buffers, but instead set a few flags and otherwise
use 0-initialized defaults
* Implement handle_sock_raw() in src/server.c to check to see if any
raw frames are pending, and if so, send them to the associated
interface if provided by setsockopt()
* Make patty_ax25_sock_bind_if() only call the function
patty_ax25_if_add_promisc() only if the socket status is PROMISC;
this allows support for non-promiscuous sockets used for outbound
purposes
Changes:
* When handling RR commands with the P/F flag set, check to see if
the socket file descriptor is currently being monitored; if so,
reply RR, otherwise reply RNR
* When handling RNR commands with the P/F flag set, apply the same
aforementioned logic as used for handling RR commands
* When handling RNR responses, clear the socket file descriptor so
as to avoid infinite loop polling and to indicate that the remote
station cannot receive packets currently
