[Swan] converting Pluto externs to file-statics, and more

[D. Hugh Redelmeier]

I don't know as much as I should of the structure of the Libreswan
source code.  I think that there is a lot of junk DNA there.

One goal I have is to reduce the scope of variables and functions.
Today, I'm trying to convert externals to file-statics if they are not
used outside the file in which they are defined.

That's kind of laborious to do by hand: an awful lot of grepping.  So
I'm using the compiler to help.

I've not built a script to do this, but here are the commands that I
used.

	make clean programs

Build the userland .o files

	find . -name '*.o' -print | while read x ; do nm "$x" | sed -n 's/^                 [A-Z] //p' ; done | sort -u >imports

For each object file, list the imports, and sort them into an
alphabetic list with duplicates removed, putting the result in the
file "imports".

	find . -name '*.o' -print | while read x ; do nm "$x" | sed -n 's/^[0-9a-f]............... [A-Z] //p' ; done | sort -u >exports

Similarly, create an alphabetic list of exports,
with duplicates removed, putting the result in the file "exports"

	comm -23 exports imports

List all the exports that are not imported.

This gives me a large list of candidates to examine.

- I mostly ignored code used by KLIPS since I didn't have .o files for
  KLIPS.  And I don't understand how it all fits together

- I ignored code that had been copied into libreswan (e.g. zlib and
  DES)

- I ignored generic library routines like atodata etc.

- I was fairly circumspect of things in parsers since I didn't know if
  yacc or lex generated code would use them.

The compiler warns about unused file-statics but doesn't know to warn
about unused externs.  So by making unimported things file-static, I
enabled the compiler to warned about unused things.

I deleted most things that were not used at all.

I left a few that I imagine maybe should have been used.

Questions:
==========

It looks as if programs/pluto/stubs.c is pointless.  Can we delete it?

It looks as if a number of files are not compiled.  Should these be
deleted?

 programs/spi/spi.c
 programs/addconn/addconn.c
 programs/readwriteconf/readwriteconf.c
 programs/showhostkey/showhostkey.c

These important-looking functions are not used.  Should they be?

 linux/net/ipsec/pfkey_v2_parser.c:3561:int pfkey_build_reply(struct sadb_msg *pfkey_msg,
 programs/pf_key/pf_key.c:296:		pfkey_print(msg, stdout);
 programs/pluto/state.c:363:void rehash_state(struct state *st)
 programs/pluto/state.c:883:void rekey_p2states_by_connection(struct connection *c)
 programs/pluto/state.c:1879:void replace_states_by_peer(const ip_address *peer)
 lib/libswan/certload.c:202:bool same_cert(const cert_t *a, const cert_t *b)
 lib/libswan/udpfromto.c:186:int sendfromto(int s, void *buf, size_t len, int flags,
 programs/pluto/kernel.c:3049:bool update_ipsec_sa(struct state *st USED_BY_KLIPS)

 delete_p2states_by_connection
 get_x509cert
 get_x509_private_key
 ikev2_acceptable_group
 kernel_alg_esp_sadb_alg

Some things are only used by files that are not compiled.  Should they
too be deleted?  For example, these are used by spi.c
  kernel_alg_proc_read
  kernel_alg_sadb_alg_get

These kernel externs appear pointless (a very small sample of the odd
code):
  linux/net/ipsec/radij.c:464:unsigned char *dumper;
  modobj/radij.c:464:unsigned char *dumper;
  linux/net/ipsec/radij.c:465:int dumper_len;
  modobj/radij.c:465:int dumper_len;