freebsd-dev/sys/netgraph/NOTES

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$FreeBSD$
Development ideas..
Archie's suggestions... :-)
- There should be a new malloc type: M_NETGRAPH
[DONE]
- all mallocs/frees now changed to use this.. JRE
- might further split them out some time.
- Use MALLOC and FREE macros instead of direct function calls
[DONE]
- They allow conditional compilation which keeps
statistics & counters on various memory allocation
(or so it seems)
- Now tend to have NG_FREE_XX() macros. they
allow better debugging
- In struct ng_mesg: at least make "header" into "hdr", if not
getting rid of it altogether. It doesn't seem necessary and
makes all my C code lines too long.
- I understand.. one thought however.. consider..
if char data[0] were not legal, so that data[1] needed to be
used instead, then the only way to get the size of the header
would be sizeof(msg.header) as sizeof(msg) would include the dummy
following bytes. this is a portability issue and I hope
it will be ported eventually :)
- Baloney! you can use sizeof(msg) - 1 then.. or just
make it a macro, then its always portable:
#ifdef __GNU_C__
#define NG_MSG_HDR_SIZE (sizeof(struct ng_message))
#else
#define NG_MSG_HDR_SIZE (sizeof(struct ng_message) - 1)
#endif
- inertia rules :-b
- Have a user level program to print out and manipulate nodes, etc.
- [DONE]
see ngctl, nghook
- "Netgraph global" flags to turn on tracing, etc.
- ngctl needs to be rewritten using libnetgraph. Also it needs a
command to list all existing nodes (in case you don't know the
name of what you're looking for).
[DONE]
- Need a way to get a list of ALL nodes.
[DONE]
- see NGM_LISTNODES
- Enhance "netstat" to display all netgraph nodes -- or at least
all netgraph socket nodes.
[DONE]
- BUG FIX: bind() on a socket should neither require nor allow a
colon character at the end of the name. Note ngctl allows you
to do it either way!
[DONE] (I think)
- bind on a control socket has been disabled
it was a bad idea.
- Need to implement passing meta information through socket nodes
using sendmsg() and recvmsg().
- Stuff needing to be added to manual:
- Awareness of SPL level, use ng_queue*() functions when necessary.
- Malloc all memory with type M_NETGRAPH. -DONE
- Write code so it can be an LKM or built into the kernel.. this means
be careful with things like #ifdef INET.
- All nodes assume that all data mbufs have the M_PKTHDR flag set!
The ng_send_data() and related functions should have an
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#ifdef DIAGNOSTIC check to check this assumption for every mbuf.
-DONE with INVARIANTS. Framework should test this more.
- More generally, netgraph code should make liberal use of the
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#ifdef DIAGNOSTIC definition.
-INVARIANTS.
- Since data and messages are sent functionally, programmers need
to watch out for infinite feedback loops. Should ng_base.c detect
this automatically?
- I've been thinking about this. each node could have a 'colour'
which is set to the colour of the packet as you pass through.
hitting a node already of your colour would abort. Each packet
has another (incremented) colour.
-new 'item' type can hold a hopcount...
NEW in 2001
All piggyback responses have gone away.
use the node ID in the return address field for quick response delivery.
Every node has a queue, plus there is a list of nodes that have queued work.
Extensive use of Mutexes. Getting in shape for SMP.
Messages and data are deliverd in a new form. An Item now has
all information needed to queue such a request and deliver it later, so
it is now the basis of all data transfer since any transfer may need to
be queued.