to make it obvious to users trying to use the feature with TLS backends
not supporting it.

Discussed in #781
Reported-by: Travis Burtrum

Carrying on from commit 037cd0d9, removed the following unimplemented
instances of curlssl_close_all():

Curl_axtls_close_all()
Curl_darwinssl_close_all()
Curl_cyassl_close_all()
Curl_gskit_close_all()
Curl_gtls_close_all()
Curl_nss_close_all()
Curl_polarssl_close_all()

Slight code cleanup as the SSL backend #define is mixed up with the API
function setup.

Also known as "status_request" or OCSP stapling, defined in RFC6066 section 8.

This requires NSS 3.15 or higher.

Prefer void for unused parameters, rather than assigning an argument to
itself as a) unintelligent compilers won't optimize it out, b) it can't
be used for const parameters, c) it will cause compilation warnings for
clang with -Wself-assign and d) is inconsistent with other areas of the
curl source code.

curl_schannel.h:123: warning: right-hand operand of comma expression
                     has no effect

Some instances of the curlssl_close_all() function were declared with a
void return type whilst others as int. The schannel version returned
CURLE_NOT_BUILT_IN and others simply returned zero, but in all cases the
return code was ignored by the calling function Curl_ssl_close_all().

For the time being and to keep the internal API consistent, changed all
declarations to use a void return type.

To reduce code we might want to consider removing the unimplemented
versions and use a void #define like schannel does.

Bug: http://curl.haxx.se/bug/view.cgi?id=1457
Patch-by: Tomasz Kojm

Each backend now defines CURL_SSL_BACKEND accordingly. Added the *AXTLS
one which was missing previously.

To force each backend implementation to really attempt to provide proper
random. If a proper random function is missing, then we can explicitly
make use of the default one we use when TLS support is missing.

This commit makes sure it works for darwinssl, gnutls, nss and openssl.

When doing multi-part formposts, libcurl used a pseudo-random value that
was seeded with time(). This turns out to be bad for users who formpost
data that is provided with users who then can guess how the boundary
string will look like and then they can forge a different formpost part
and trick the receiver.

My advice to such implementors is (still even after this change) to not
rely on the boundary strings being cryptographically strong. Fix your
code and logic to not depend on them that much!

I moved the Curl_rand() function into the sslgen.c source file now to be
able to take advantage of the SSL library's random function if it
provides one. If not, try to use the RANDOM_FILE for seeding and as a
last resort keep the old logic, just modified to also add microseconds
which makes it harder to properly guess the exact seed.

The formboundary() function in formdata.c is now using 64 bit entropy
for the boundary and therefore the string of dashes was reduced by 4
letters and there are 16 hex digits following it. The total length is
thus still the same.

Bug: http://curl.haxx.se/bug/view.cgi?id=1251
Reported-by: "Floris"

This commit renames lib/setup.h to lib/curl_setup.h and
renames lib/setup_once.h to lib/curl_setup_once.h.

Removes the need and usage of a header inclusion guard foreign
to libcurl. [1]

Removes the need and presence of an alarming notice we carried
in old setup_once.h [2]

----------------------------------------

1 - lib/setup_once.h used __SETUP_ONCE_H macro as header inclusion guard
    up to commit ec691ca3 which changed this to HEADER_CURL_SETUP_ONCE_H,
    this single inclusion guard is enough to ensure that inclusion of
    lib/setup_once.h done from lib/setup.h is only done once.

    Additionally lib/setup.h has always used __SETUP_ONCE_H macro to
    protect inclusion of setup_once.h even after commit ec691ca3, this
    was to avoid a circular header inclusion triggered when building a
    c-ares enabled version with c-ares sources available which also has
    a setup_once.h header. Commit ec691ca3 exposes the real nature of
    __SETUP_ONCE_H usage in lib/setup.h, it is a header inclusion guard
    foreign to libcurl belonging to c-ares's setup_once.h

    The renaming this commit does, fixes the circular header inclusion,
    and as such removes the need and usage of a header inclusion guard
    foreign to libcurl. Macro __SETUP_ONCE_H no longer used in libcurl.

2 - Due to the circular interdependency of old lib/setup_once.h and the
    c-ares setup_once.h header, old file lib/setup_once.h has carried
    back from 2006 up to now days an alarming and prominent notice about
    the need of keeping libcurl's and c-ares's setup_once.h in sync.

    Given that this commit fixes the circular interdependency, the need
    and presence of mentioned notice is removed.

    All mentioned interdependencies come back from now old days when
    the c-ares project lived inside a curl subdirectory. This commit
    removes last traces of such fact.

This reverts renaming and usage of lib/*.h header files done
28-12-2012, reverting 2 commits:

  f871de00... build: make use of 76 lib/*.h renamed files
  ffd8e127... build: rename 76 lib/*.h files

This also reverts removal of redundant include guard (redundant thanks
to changes in above commits) done 2-12-2013, reverting 1 commit:

  c087374c... curl_setup.h: remove redundant include guard

This also reverts renaming and usage of lib/*.c source files done
3-12-2013, reverting 3 commits:

  13606bbf... build: make use of 93 lib/*.c renamed files
  5b6e7927... build: rename 93 lib/*.c files
  7d83dfff... build: commit 13606bbf follow-up 1

Start of related discussion thread:

  http://curl.haxx.se/mail/lib-2013-01/0012.html

Asking for confirmation on pushing this revertion commit:

  http://curl.haxx.se/mail/lib-2013-01/0048.html

Confirmation summary:

  http://curl.haxx.se/mail/lib-2013-01/0079.html

NOTICE: The list of 2 files that have been modified by other
intermixed commits, while renamed, and also by at least one
of the 6 commits this one reverts follows below. These 2 files
will exhibit a hole in history unless git's '--follow' option
is used when viewing logs.

  lib/curl_imap.h
  lib/curl_smtp.h

93 *.c source files renamed to use our standard naming scheme.

This change affects 77 files in libcurl's source tree.

76 private header files renamed to use our standard naming scheme.

This commit only does the file renaming.

----------------------------------------

  renamed:    amigaos.h -> curl_amigaos.h
  renamed:    arpa_telnet.h -> curl_arpa_telnet.h
  renamed:    asyn.h -> curl_asyn.h
  renamed:    axtls.h -> curl_axtls.h
  renamed:    bundles.h -> curl_bundles.h
  renamed:    conncache.h -> curl_conncache.h
  renamed:    connect.h -> curl_connect.h
  renamed:    content_encoding.h -> curl_content_encoding.h
  renamed:    cookie.h -> curl_cookie.h
  renamed:    cyassl.h -> curl_cyassl.h
  renamed:    dict.h -> curl_dict.h
  renamed:    easyif.h -> curl_easyif.h
  renamed:    escape.h -> curl_escape.h
  renamed:    file.h -> curl_file.h
  renamed:    fileinfo.h -> curl_fileinfo.h
  renamed:    formdata.h -> curl_formdata.h
  renamed:    ftp.h -> curl_ftp.h
  renamed:    ftplistparser.h -> curl_ftplistparser.h
  renamed:    getinfo.h -> curl_getinfo.h
  renamed:    gopher.h -> curl_gopher.h
  renamed:    gtls.h -> curl_gtls.h
  renamed:    hash.h -> curl_hash.h
  renamed:    hostcheck.h -> curl_hostcheck.h
  renamed:    hostip.h -> curl_hostip.h
  renamed:    http.h -> curl_http.h
  renamed:    http_chunks.h -> curl_http_chunks.h
  renamed:    http_digest.h -> curl_http_digest.h
  renamed:    http_negotiate.h -> curl_http_negotiate.h
  renamed:    http_proxy.h -> curl_http_proxy.h
  renamed:    if2ip.h -> curl_if2ip.h
  renamed:    imap.h -> curl_imap.h
  renamed:    inet_ntop.h -> curl_inet_ntop.h
  renamed:    inet_pton.h -> curl_inet_pton.h
  renamed:    krb4.h -> curl_krb4.h
  renamed:    llist.h -> curl_llist.h
  renamed:    memdebug.h -> curl_memdebug.h
  renamed:    multiif.h -> curl_multiif.h
  renamed:    netrc.h -> curl_netrc.h
  renamed:    non-ascii.h -> curl_non-ascii.h
  renamed:    nonblock.h -> curl_nonblock.h
  renamed:    nssg.h -> curl_nssg.h
  renamed:    parsedate.h -> curl_parsedate.h
  renamed:    pingpong.h -> curl_pingpong.h
  renamed:    polarssl.h -> curl_polarssl.h
  renamed:    pop3.h -> curl_pop3.h
  renamed:    progress.h -> curl_progress.h
  renamed:    qssl.h -> curl_qssl.h
  renamed:    rawstr.h -> curl_rawstr.h
  renamed:    rtsp.h -> curl_rtsp.h
  renamed:    select.h -> curl_select.h
  renamed:    sendf.h -> curl_sendf.h
  renamed:    setup.h -> curl_setup.h
  renamed:    setup_once.h -> curl_setup_once.h
  renamed:    share.h -> curl_share.h
  renamed:    slist.h -> curl_slist.h
  renamed:    smtp.h -> curl_smtp.h
  renamed:    sockaddr.h -> curl_sockaddr.h
  renamed:    socks.h -> curl_socks.h
  renamed:    speedcheck.h -> curl_speedcheck.h
  renamed:    splay.h -> curl_splay.h
  renamed:    ssh.h -> curl_ssh.h
  renamed:    sslgen.h -> curl_sslgen.h
  renamed:    ssluse.h -> curl_ssluse.h
  renamed:    strdup.h -> curl_strdup.h
  renamed:    strequal.h -> curl_strequal.h
  renamed:    strerror.h -> curl_strerror.h
  renamed:    strtok.h -> curl_strtok.h
  renamed:    strtoofft.h -> curl_strtoofft.h
  renamed:    telnet.h -> curl_telnet.h
  renamed:    tftp.h -> curl_tftp.h
  renamed:    timeval.h -> curl_timeval.h
  renamed:    transfer.h -> curl_transfer.h
  renamed:    url.h -> curl_url.h
  renamed:    urldata.h -> curl_urldata.h
  renamed:    warnless.h -> curl_warnless.h
  renamed:    wildcard.h -> curl_wildcard.h

----------------------------------------

76 private header files renamed to use our standard naming scheme.

This change affects 322 files in libcurl's source tree.

curl_ntlm_msgs.c would previously use an #ifdef maze and direct
SSL-library calls instead of using the SSL layer we have for this
purpose.

Stop the abuse of CURLE_FAILED_INIT as return code for things not being
init related by introducing two new return codes:

CURLE_NOT_BUILT_IN and CURLE_UNKNOWN_OPTION

CURLE_NOT_BUILT_IN replaces return code 4 that has been obsoleted for
several years. It is used for returning error when something is
attempted to be used but the feature/option was not enabled or
explictitly disabled at build-time. Getting this error mostly means that
libcurl needs to be rebuilt.

CURLE_FAILED_INIT is now saved and used strictly for init
failures. Getting this problem means something went seriously wrong,
like a resource shortage or similar.

CURLE_UNKNOWN_OPTION is the option formerly known as
CURLE_UNKNOWN_TELNET_OPTION (and the old name is still present,
separately defined to be removed in a very distant future). This error
code is meant to be used to return when an option is given to libcurl
that isn't known. This problem would mostly indicate a problem in the
program that uses libcurl.

When configured with '--without-ssl --with-nss', NTLM authentication
now uses NSS crypto library for MD5 and DES.  For MD4 we have a local
implementation in that case.  More details are available at
https://bugzilla.redhat.com/603783

In order to get it working, curl_global_init() must be called with
CURL_GLOBAL_SSL or CURL_GLOBAL_ALL.  That's necessary because NSS needs
to be initialized globally and we do so only when the NSS library is
actually required by protocol.  The mentioned call of curl_global_init()
is responsible for creating of the initialization mutex.

There was also slightly changed the NSS initialization scenario, in
particular, loading of the NSS PEM module.  It used to be loaded always
right after the NSS library was initialized.  Now the library is
initialized as soon as any SSL or NTLM is required, while the PEM module
is prevented from being loaded until the SSL is actually required.

Howard Chu brought the bulk work of this patch that properly
moves out the sending and recving of data to the parts of the
code that are properly responsible for the various ways of doing
so.

Daniel Stenberg assisted with polishing a few bits and fixed some
minor flaws in the original patch.

Another upside of this patch is that we now abuse CURLcodes less
with the "magic" -1 return codes and instead use CURLE_AGAIN more
consistently.

GTLS.

  libraries are supported. Starting now, each underlying SSL library support
  code does a set of defines for the 16 functions the generic layer (sslgen.c)
  uses (all these new function defines use the prefix "curlssl_"). This
  greatly simplified the generic layer in readability by involving much less
  #ifdefs and other preprocessor stuff and should make it easier for people to
  make libcurl work with new SSL libraries.

  Hopefully I can later on document these 16 functions somewhat as well.

  I also made most of the internal SSL-dependent functions (using Curl_ssl_
  prefix) #defined to nothing when no SSL support is requested - previously
  they would unnecessarily call mostly empty functions.

passed to it with curl_easy_setopt()! Previously it has always just refered
to the data, forcing the user to keep the data around until libcurl is done
with it. That is now history and libcurl will instead clone the given
strings and keep private copies.

SSL/TLS layer. http://www.mozilla.org/projects/security/pki/nss/