nuttx/net/tcp/Kconfig
2023-02-20 09:06:46 +08:00

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#
# For a description of the syntax of this configuration file,
# see the file kconfig-language.txt in the NuttX tools repository.
#
menu "TCP/IP Networking"
config NET_TCP
bool "TCP/IP Networking"
default n
select NET_READAHEAD if !NET_TCP_NO_STACK
---help---
Enable or disable TCP networking support.
config NET_TCP_NO_STACK
bool "Disable TCP/IP Stack"
default n
select NET_TCP
---help---
Build without TCP/IP stack even if TCP networking support enabled.
if NET_TCP && !NET_TCP_NO_STACK
config NET_TCP_DELAYED_ACK
bool "TCP/IP Delayed ACK"
default n
---help---
RFC 1122: A host that is receiving a stream of TCP data segments
can increase efficiency in both the Internet and the hosts
by sending fewer than one ACK (acknowledgment) segment per data
segment received; this is known as a "delayed ACK".
TCP should implement a delayed ACK, but an ACK should not be
excessively delayed; in particular, the delay MUST be less than
0.5 seconds, and in a stream of full-sized segments there should
be an ACK for at least every second segments.
config NET_TCP_KEEPALIVE
bool "TCP/IP Keep-alive support"
default n
select NET_TCPPROTO_OPTIONS
---help---
Enable support for the SO_KEEPALIVE socket option
config NET_TCPURGDATA
bool "Urgent data"
default n
---help---
Determines if support for TCP urgent data notification should be
compiled in. Urgent data (out-of-band data) is a rarely used TCP feature
that is very seldom would be required.
config NET_TCP_PREALLOC_CONNS
int "Preallocated TCP/IP connections"
default 8
---help---
Number of TCP/IP connections (all tasks).
This number of connections will be pre-allocated during system boot.
If dynamic connections allocation is enabled, more connections may
be allocated at a later time, as the system needs them. Else this
will be the maximum number of connections available to the system
at all times.
Set to 0 to disable (and rely only on dynamic allocations).
config NET_TCP_ALLOC_CONNS
int "Dynamic TCP/IP connections allocation"
default 0
---help---
Dynamic memory allocations for TCP/IP.
When set to 0 all dynamic allocations are disabled.
When set to 1 a new connection will be allocated every time,
and it will be free'd when no longer needed.
Setting this to 2 or more will allocate the connections in
batches (with batch size equal to this config). When a
connection is no longer needed, it will be returned to the
free connections pool, and it will never be deallocated!
config NET_TCP_MAX_CONNS
int "Maximum number of TCP/IP connections"
default 0
depends on NET_TCP_ALLOC_CONNS > 0
---help---
If dynamic connections allocation is selected (NET_TCP_ALLOC_CONNS > 0)
this will limit the number of connections that can be allocated.
This is useful in case the system is under very heavy load (or
under attack), ensuring that the heap will not be exhausted.
config NET_TCP_NPOLLWAITERS
int "Number of TCP poll waiters"
default 1
config NET_TCP_RTO
int "RTO of TCP/IP connections"
default 3
---help---
RTO of TCP/IP connections (all tasks)
config NET_TCP_MAXRTX
int "Maximum retransmitted number of TCP/IP data packet"
default 8
config NET_TCP_MAXSYNRTX
int "Maximum retransmitted number of TCP/IP SYN packet"
default 5
config NET_TCP_WAIT_TIMEOUT
int "TIME_WAIT Length of TCP/IP connections"
default 120
---help---
TIME_WAIT Length of TCP/IP connections (all tasks). In units
of seconds.
config NET_MAX_LISTENPORTS
int "Number of listening ports"
default 20
---help---
Maximum number of listening TCP/IP ports (all tasks). Default: 20
config NET_TCP_FAST_RETRANSMIT
bool "Enable the Fast Retransmit algorithm"
default y
---help---
RFC2001:
3. Fast Retransmit
Modifications to the congestion avoidance algorithm were proposed in
1990 [3]. Before describing the change, realize that TCP may
generate an immediate acknowledgment (a duplicate ACK) when an out-
of-order segment is received (Section 4.2.2.21 of [1], with a note
that one reason for doing so was for the experimental fast-
retransmit algorithm). This duplicate ACK should not be delayed.
The purpose of this duplicate ACK is to let the other end know that a
segment was received out of order, and to tell it what sequence
number is expected.
Since TCP does not know whether a duplicate ACK is caused by a lost
segment or just a reordering of segments, it waits for a small number
of duplicate ACKs to be received. It is assumed that if there is
just a reordering of the segments, there will be only one or two
duplicate ACKs before the reordered segment is processed, which will
then generate a new ACK. If three or more duplicate ACKs are
received in a row, it is a strong indication that a segment has been
lost. TCP then performs a retransmission of what appears to be the
missing segment, without waiting for a retransmission timer to
expire.
config NET_TCP_WINDOW_SCALE
bool "Enable TCP/IP Window Scale Option"
default n
---help---
RFC1323:
2. TCP WINDOW SCALE OPTION
The window scale extension expands the definition of the TCP
window to 32 bits and then uses a scale factor to carry this 32-
bit value in the 16-bit Window field of the TCP header (SEG.WND in
RFC-793).
if NET_TCP_WINDOW_SCALE
config NET_TCP_WINDOW_SCALE_FACTOR
int "TCP/IP Window Scale Factor"
default 0
---help---
This is the default value for window scale factor.
endif # NET_TCP_WINDOW_SCALE
config NET_TCP_OUT_OF_ORDER
bool "Enable TCP/IP Out Of Order segments"
default n
---help---
TCP will queue segments that arrive out of order.
if NET_TCP_OUT_OF_ORDER
config NET_TCP_OUT_OF_ORDER_BUFSIZE
int "TCP/IP Out Of Order buffer size"
default 16384
---help---
This is the default value for out-of-order buffer size.
endif # NET_TCP_OUT_OF_ORDER
config NET_TCP_SELECTIVE_ACK
bool "Enable TCP/IP Selective Acknowledgment Options"
default n
select NET_TCP_OUT_OF_ORDER
---help---
Enable RFC2018(TCP Selective Acknowledgment Options):
Selective Acknowledgment (SACK) is a strategy which corrects this
behavior in the face of multiple dropped segments. With selective
acknowledgments, the data receiver can inform the sender about all
segments that have arrived successfully, so the sender need
retransmit only the segments that have actually been lost.
config NET_TCP_NOTIFIER
bool "Support TCP notifications"
default n
depends on SCHED_WORKQUEUE
select WQUEUE_NOTIFIER
---help---
Enable building of TCP notifier logic that will execute a worker
function on the low priority work queue when read-ahead data
is available or when a TCP connection is lost. This is is a general
purpose notifier, but was developed specifically to support poll()
logic where the poll must wait for these events.
config NET_TCP_WRITE_BUFFERS
bool "Enable TCP/IP write buffering"
default n
select NET_WRITE_BUFFERS
---help---
Write buffers allows buffering of ongoing TCP/IP packets, providing
for higher performance, streamed output.
You might want to disable TCP/IP write buffering on a highly memory
memory constrained system where there are no performance issues.
if NET_TCP_WRITE_BUFFERS
config NET_TCP_NWRBCHAINS
int "Number of pre-allocated I/O buffer chain heads"
default 8
---help---
These tiny nodes are used as "containers" to support queuing of
TCP write buffers. This setting will limit the number of TCP write
operations that can be "in-flight" at any give time. So a good
choice for this value would be the same as the maximum number of
TCP connections.
config NET_TCP_WRBUFFER_DEBUG
bool "Force write buffer debug"
default n
depends on DEBUG_FEATURES
select IOB_DEBUG
---help---
This option will force debug output from TCP write buffer logic,
even without network debug output. This is not normally something
that would want to do but is convenient if you are debugging the
write buffer logic and do not want to get overloaded with other
network-related debug output.
config NET_TCP_WRBUFFER_DUMP
bool "Force write buffer dump"
default n
depends on DEBUG_NET || NET_TCP_WRBUFFER_DEBUG
select IOB_DEBUG
---help---
Dump the contents of the write buffers. You do not want to do this
unless you really want to analyze the write buffer transfers in
detail.
endif # NET_TCP_WRITE_BUFFERS
config NET_TCP_RECV_PACK
bool "Enable TCP/IP receive data in a continuous poll"
default y
---help---
This option will enable TCP/IP receive data into a continuous iob chain.
Fragmentation of network data will intensify iob consumption, if
the device receives a message storm of fragmented packets, the iob
cache will not be effectively used, this is not allowed on iot devices
since the resources of such devices are limited. Of course, this
also takes some disadvantages: data needs to be copied.
This option will brings some balance on resource-constrained devices,
enable this config to reduce the consumption of iob, the received iob
buffers will be merged into the contiguous iob chain.
config NET_TCPBACKLOG
bool "TCP/IP backlog support"
default n
---help---
Incoming connections pend in a backlog until accept() is called.
The size of the backlog is selected when listen() is called.
if NET_TCPBACKLOG
config NET_TCPBACKLOG_CONNS
int "TCP backlog conns threshold"
default 8
---help---
Maximum number of TCP backlog connections (all tasks).
endif # NET_TCPBACKLOG
config NET_SENDFILE
bool "Optimized network sendfile()"
default n
---help---
Support larger, higher performance sendfile() for transferring
files out a TCP connection.
endif # NET_TCP && !NET_TCP_NO_STACK
if NET_STATISTICS
config NET_TCP_DEBUG_DROP_RECV
bool "TCP/IP debug feature to drop receive packet"
default n
---help---
This is the debug feature to drop TCP/IP received packet
if NET_TCP_DEBUG_DROP_RECV
config NET_TCP_DEBUG_DROP_RECV_PROBABILITY
int "TCP/IP drop probability of received packet"
range 50 10000
default 50
---help---
This is the drop probability of received packet, Default: 1/50
endif # NET_TCP_DEBUG_DROP_RECV
config NET_TCP_DEBUG_DROP_SEND
bool "TCP/IP debug feature to drop send packet"
default n
---help---
This is the debug feature to drop TCP/IP send packet
if NET_TCP_DEBUG_DROP_SEND
config NET_TCP_DEBUG_DROP_SEND_PROBABILITY
int "TCP/IP drop probability of send packet"
range 50 10000
default 50
---help---
This is the drop probability of send packet, Default: 1/50
endif # NET_TCP_DEBUG_DROP_SEND
endif # NET_STATISTICS
endmenu # TCP/IP Networking