(http://curl.haxx.se/docs/adv_20090303.html also known as CVE-2009-0037) in
which previous libcurl versions (by design) can be tricked to access an
arbitrary local/different file instead of a remote one when
CURLOPT_FOLLOWLOCATION is enabled. This flaw is now fixed in this release
together this the addition of two new setopt options for controlling this
new behavior:
o CURLOPT_REDIR_PROTOCOLS controls what protocols libcurl is allowed to
follow to when CURLOPT_FOLLOWLOCATION is enabled. By default, this option
excludes the FILE and SCP protocols and thus you nee to explicitly allow
them in your app if you really want that behavior.
o CURLOPT_PROTOCOLS controls what protocol(s) libcurl is allowed to fetch
using the primary URL option. This is useful if you want to allow a user or
other outsiders control what URL to pass to libcurl and yet not allow all
protocols libcurl may have been built to support.
plain FTP connections, and it will then allow MKD to fail once and retry the
CWD afterwards. This is especially useful if you're doing many simultanoes
connections against the same server and they all have this option enabled,
as then CWD may first fail but then another connection does MKD before this
connection and thus MKD fails but trying CWD works! The numbers can
(should?) now be set with the convenience enums now called
CURLFTP_CREATE_DIR and CURLFTP_CREATE_DIR_RETRY.
Tests has proven that if you're making an application that uploads a set of
files to an ftp server, you will get a noticable gain in speed if you're
using multiple connections and this option will be then be very useful.
interface and setting CURLMOPT_MAXCONNECTS to something less than the number
of handles you add to the multi handle. All the connections that didn't fit
in the cache would not be properly disconnected nor freed!
version 1.1 instead of 1.0 like before. This change also introduces the new
proxy type for libcurl called 'CURLPROXY_HTTP_1_0' that then allows apps to
switch (back) to CONNECT 1.0 requests. The curl tool also got a --proxy1.0
option that works exactly like --proxy but sets CURLPROXY_HTTP_1_0.
I updated all test cases cases that use CONNECT and I tried to do some using
--proxy1.0 and some updated to do CONNECT 1.1 to get both versions run.
CURLOPT_SOCKS5_GSSAPI_SERVICE and CURLOPT_SOCKS5_GSSAPI_NEC to allow libcurl
to do GSS-style authentication with SOCKS5 proxies. The curl tool got the
options called --socks5-gssapi-service and --socks5-gssapi-nec to enable
these.
They basically offer the same thing the NO_PROXY environment variable only
offered previously: list a set of host names that shall not use the proxy
even if one is specified.
clarity. This does fix one problem that causes ;type=i FTP URLs
to fail in the Turkish locale when CURLOPT_PROXY_TRANSFER_MODE is
used (test case 561)
Added tests 561 and 1092 through 1094 to test various combinations
of ;type= and ;mode= URLs that could potentially fail in the Turkish
locale.
curl_easy_reset() by creating Curl_init_userdefined(). This had the side effect
of fixing curl_easy_reset() so it now also resets CURLOPT_FTP_FILEMETHOD and
CURLOPT_SSL_SESSIONID_CACHE
(http://curl.haxx.se/bug/view.cgi?id=2413067) that identified a problem that
would cause libcurl to mark a DNS cache entry "in use" eternally if the
subsequence TCP connect failed. It would thus never get pruned and refreshed
as it should've been.
now has an improved ability to do right when the multi interface (both
"regular" and multi_socket) is used for SCP and SFTP transfers. This should
result in (much) less busy-loop situations and thus less CPU usage with no
speed loss.
there are servers "out there" that relies on the client doing this broken
Digest authentication. Apache even comes with an option to work with such
broken clients.
The difference is only for URLs that contain a query-part (a '?'-letter and
text to the right of it).
libcurl now supports this quirk, and you enable it by setting the
CURLAUTH_DIGEST_IE bit in the bitmask you pass to the CURLOPT_HTTPAUTH or
CURLOPT_PROXYAUTH options. They are thus individually controlled to server
and proxy.
(http://curl.haxx.se/bug/view.cgi?id=2351645) that identified a problem with
the multi interface that occured if you removed an easy handle while in
progress and the handle was used in a HTTP pipeline.
when uploading files to a single FTP server using multiple easy handle
handles with the multi interface. Occasionally a handle would stall in
mysterious ways.
The problem turned out to be a side-effect of the ConnectionExists()
function's eagerness to re-use a handle for HTTP pipelining so it would
select it even if already being in use, due to an inadequate check for its
chances of being used for pipelnining.
problem with my CURLINFO_PRIMARY_IP fix from October 7th that caused a NULL
pointer read. I also took the opportunity to clean up this logic (storing of
the connection's IP address) somewhat as we had it stored in two different
places and ways previously and they are now unified.
Changed checkprefix() to use it and those instances of strnequal() that
compare host names or other protocol strings that are defined to be
independent of case in the C locale. This should fix a few more
Turkish locale problems.
make CURLOPT_PROXYUSERPWD sort of deprecated. The primary motive for adding
these new options is that they have no problems with the colon separator
that the CURLOPT_PROXYUSERPWD option does.
(http://curl.haxx.se/bug/view.cgi?id=2154627) which pointed out that libcurl
uses strcasecmp() in multiple places where it causes failures when the
Turkish locale is used. This is because 'i' and 'I' isn't the same letter so
strcasecmp() on those letters are different in Turkish than in English (or
just about all other languages). I thus introduced a totally new internal
function in libcurl (called Curl_ascii_equal) for doing case insentive
comparisons for english-(ascii?) style strings that thus will make "file"
and "FILE" match even if the Turkish locale is selected.
curl_easy_setopt: CURLOPT_USERNAME and CURLOPT_PASSWORD that sort of
deprecates the good old CURLOPT_USERPWD since they allow applications to set
the user name and password independently and perhaps more importantly allow
both to contain colon(s) which CURLOPT_USERPWD doesn't fully support.
the app re-used the handle to do a connection to host B and then again
re-used the handle to host A, it would not update the info with host A's IP
address (due to the connection being re-used) but it would instead report
the info from host B.
switching from one protocol to another in a single request (e.g.
redirecting from HTTP to FTP as in test 1055) by resetting
state.expect100header before every request.
CURLOPT_POST301 (but adds a define for backwards compatibility for you who
don't define CURL_NO_OLDIES). This option allows you to now also change the
libcurl behavior for a HTTP response 302 after a POST to not use GET in the
subsequent request (when CURLOPT_FOLLOWLOCATION is enabled). I edited the
patch somewhat before commit. The curl tool got a matching --post302
option. Test case 1076 was added to verify this.
enabling this feature with CURLOPT_CERTINFO for a request using SSL (HTTPS
or FTPS), libcurl will gather lots of server certificate info and that info
can then get extracted by a client after the request has completed with
curl_easy_getinfo()'s CURLINFO_CERTINFO option. Linus Nielsen Feltzing
helped me test and smoothen out this feature.
Unfortunately, this feature currently only works with libcurl built to use
OpenSSL.
This feature was sponsored by networking4all.com - thanks!
an unlock in between) for a certain case and that in fact works when using
regular windows mutexes but not with pthreads'! Locks should of course not
get locked again so this is now fixed.
http://curl.haxx.se/mail/lib-2008-08/0422.html
remain in use as internal curl_off_t print formatting strings for the internal
*printf functions which still cannot handle print formatting string directives
such as "I64d", "I64u", and others available on MSVC, MinGW, Intel's ICC, and
other DOS/Windows compilers.
This reverts previous commit part which did:
FORMAT_OFF_T -> CURL_FORMAT_CURL_OFF_T
FORMAT_OFF_TU -> CURL_FORMAT_CURL_OFF_TU
the names of the curl_off_t formatting string directives now become
CURL_FORMAT_CURL_OFF_T and CURL_FORMAT_CURL_OFF_TU.
CURL_FMT_OFF_T -> CURL_FORMAT_CURL_OFF_T
CURL_FMT_OFF_TU -> CURL_FORMAT_CURL_OFF_TU
Remove the use of an internal name for the curl_off_t formatting string directives
and use the common one available from the inside and outside of the library.
FORMAT_OFF_T -> CURL_FORMAT_CURL_OFF_T
FORMAT_OFF_TU -> CURL_FORMAT_CURL_OFF_TU
(http://curl.haxx.se/bug/view.cgi?id=2042440) with a patch. He identified a
problem when using NTLM over a proxy but the end-point does Basic, and then
libcurl would do wrong when the host sent "Connection: close" as the proxy's
NTLM state was erroneously cleared.
incorrectly--the host name is treated as part of the user name and the
port number becomes the password. This can be observed in test 279
(was KNOWN_ISSUE #54).
an URL in a Location: header didn't have the scope ID removed, so an
invalid host name was used. Second, when the scope ID was removed, it
also removed any port number that may have existed in the URL.
parser to allow numerical IPv6-addresses to be specified with the scope
given, as per RFC4007 - with a percent letter that itself needs to be URL
escaped. For example, for an address of fe80::1234%1 the HTTP URL is:
"http://[fe80::1234%251]/"
CURLINFO_APPCONNECT_TIME. This is set with the "application layer"
handshake/connection is completed (typically SSL, TLS or SSH). By using this
you can figure out the application layer's own connect time. You can extract
the time stamp using curl's -w option and the new variable named
'time_appconnect'. This feature was sponsored by Lenny Rachitsky at NeuStar.
multi interface with pipelining enabled as it would wrongly check for,
detect and close "dead connections" even though that connection was already
in use!
redirections and thus cannot use CURLOPT_FOLLOWLOCATION easily, we now
introduce the new CURLINFO_REDIRECT_URL option that lets applications
extract the URL libcurl would've redirected to if it had been told to. This
then enables the application to continue to that URL as it thinks is
suitable, without having to re-implement the magic of creating the new URL
from the Location: header etc. Test 1029 verifies it.
GET simply because previously when you set CURLOPT_NOBODY to TRUE first and
then FALSE you'd end up in a broken state where a HTTP request would do a
HEAD by still act a lot like for a GET and hang waiting for the content etc.
default instead of a ca bundle. The configure script will also look for a
ca path if no ca bundle is found and no option given.
- Fixed detection of previously installed curl-ca-bundle.crt
better control at the exact state of the connection's SSL status so that we
know exactly when it has completed the SSL negotiation or not so that there
won't be accidental re-uses of connections that are wrongly believed to be
in SSL-completed-negotiate state.
such as the CURLOPT_SSL_CTX_FUNCTION one treat that as if it was a Location:
following. The patch that introduced this feature was done for 7.11.0, but
this code and functionality has been broken since about 7.15.4 (March 2006)
with the introduction of non-blocking OpenSSL "connects".
It was a hack to begin with and since it doesn't work and hasn't worked
correctly for a long time and nobody has even noticed, I consider it a very
suitable subject for plain removal. And so it was done.
DONE before the entire request operation is complete and thus we can't know in
what state it is for re-using, so we're forced to close it. In a perfect world
we can add code that keep track of if we really must close it here or not, but
currently we have no such detail knowledge.
Jerome Muffat-Meridol helped us work this out.
the SingleRequest one to make pipelining better. It is a bit tricky to keep
them in the right place, to keep things related to the actual request or to
the actual connection in the right place.
previously had a number of flaws, perhaps most notably when an application
fired up N transfers at once as then they wouldn't pipeline at all that
nicely as anyone would think... Test case 530 was also updated to take the
improved functionality into account.
The signalling of that a global DNS cache is wanted is done by setting the
option but the setting of the internal variable that it is in use must not be
done until it finally actually gets used!
NOTE and WARNING: I noticed that you can't actually switch off the global dns
cache with CURLOPT_DNS_USE_GLOBAL_CACHE but you couldn't do that previously
either and the option is very clearly and loudly documented as DO NOTE USE so
I won't bother to fix this bug now.
silly code left from when we switched to let the multi handle "hold" the dns
cache when using the multi interface... Of course this only triggered when a
certain function call returned error at the correct moment.
libcurl to seek in a given input stream. This is particularly important when
doing upload resumes when there's already a huge part of the file present
remotely. Before, and still if this callback isn't used, libcurl will read
and through away the entire file up to the point to where the resuming
begins (which of course can be a slow opereration depending on file size,
I/O bandwidth and more). This new function will also be preferred to get
used instead of the CURLOPT_IOCTLFUNCTION for seeking back in a stream when
doing multi-stage HTTP auth with POST/PUT.
code to instead introduce support for a new proxy type called
CURLPROXY_SOCKS5_HOSTNAME that is used to send the host name to the proxy
instead of IP address and there's thus no longer any need for a new
curl_easy_setopt() option.
The default SOCKS5 proxy is again back to sending the IP address to the
proxy. The new curl command line option for enabling sending host name to a
SOCKS5 proxy is now --socks5-hostname.
proxy do the host name resolving and only if --socks5ip (or
CURLOPT_SOCKS5_RESOLVE_LOCAL) is used we resolve the host name locally and
pass on the IP address only to the proxy.
is an inofficial PROXY4 variant that sends the hostname to the proxy instead
of the resolved address (which is already supported by SOCKS5). --socks4a is
the curl command line option for it and CURLOPT_PROXYTYPE can now be set to
CURLPROXY_SOCKS4A as well.
the appending of the "type=" thing on FTP URLs when they are passed to a
HTTP proxy. Some proxies just don't like that appending (which is done
unconditionally in 7.17.1), and some proxies treat binary/ascii transfers
better with the appending done!
is inited at the start of the DO action. I removed the Curl_transfer_keeper
struct completely, and I had to move out a few struct members (that had to
be set before DO or used after DONE) to the UrlState struct. The SingleRequest
struct is accessed with SessionHandle->req.
One of the biggest reasons for doing this was the bunch of duplicate struct
members in HandleData and Curl_transfer_keeper since it was really messy to
keep track of two variables with the same name and basically the same purpose!
do_init() and do_complete() which now are called first and last in the DO
function. It simplified the flow in multi.c and the functions got more
sensible names!
forwarded from the Gentoo bug tracker by Daniel Black and was originally
submitted by Robin Johnson, pointed out that libcurl would do bad memory
references when it failed and bailed out before the handler thing was
setup. My fix is not done like the provided patch does it, but instead I
make sure that there's never any chance for a NULL pointer in that struct
member.
https://bugzilla.novell.com/show_bug.cgi?id=332917 about a HTTP redirect to
FTP that caused memory havoc. His work together with my efforts created two
fixes:
#1 - FTP::file was moved to struct ftp_conn, because is has to be dealt with
at connection cleanup, at which time the struct HandleData could be
used by another connection.
Also, the unused char *urlpath member is removed from struct FTP.
#2 - provide a Curl_reset_reqproto() function that frees
data->reqdata.proto.* on connection setup if needed (that is if the
SessionHandle was used by a different connection).
CURLOPT_OPENSOCKETDATA to set a callback that allows an application to replace
the socket() call used by libcurl. It basically allows the app to change
address, protocol or whatever of the socket. (I also did some whitespace
indent/cleanups in lib/url.c which kind of hides some of these changes, sorry
for mixing those in.)
CURLOPT_SSH_HOST_PUBLIC_KEY_MD5 and the curl tool --hostpubmd5. They both make
the SCP or SFTP connection verify the remote host's md5 checksum of the public
key before doing a connect, to reduce the risk of a man-in-the-middle attack.
curl_easy_setopt() that alters how libcurl functions when following
redirects. It makes libcurl obey the RFC2616 when a 301 response is received
after a non-GET request is made. Default libcurl behaviour is to change
method to GET in the subsequent request (like it does for response code 302
- because that's what many/most browsers do), but with this CURLOPT_POST301
option enabled it will do what the spec says and do the next request using
the same method again. I.e keep POST after 301.
The curl tool got this option as --post301
Test case 1011 and 1012 were added to verify.
and allow reuse by multiple protocols. Several unused error codes were
removed. In all cases, macros were added to preserve source (and binary)
compatibility with the old names. These macros are subject to removal at
a future date, but probably not before 2009. An application can be
tested to see if it is using any obsolete code by compiling it with the
CURL_NO_OLDIES macro defined.
Documented some newer error codes in libcurl-error(3)
the configure script checks for openldap and friends and we link with those
libs just like we link all other third party libraries, and we no longer
dlopen() those libraries. Our private header file lib/ldap.h was renamed to
lib/curl_ldap.h due to this. I set a tag in CVS (curl-7_17_0-preldapfix)
just before this commit, just in case.
(http://curl.haxx.se/bug/view.cgi?id=1766320) pointing out that the libcurl
code accessed two curl_easy_setopt() options (CURLOPT_DNS_CACHE_TIMEOUT and
CURLOPT_DNS_USE_GLOBAL_CACHE) as ints even though they're documented to be
passed in as longs, and that makes a difference on 64 bit architectures.
after 7.16.2. This is much due to the different treatment file:// gets
internally, but now I added test 231 to make it less likely to happen again
without us noticing!
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.
and CURLOPT_NEW_DIRECTORY_PERMS. These control the premissions for files
and directories created on the remote server. CURLOPT_NEW_FILE_PERMS
defaults to 0644 and CURLOPT_NEW_DIRECTORY_PERMS defaults to 0755
the CURLOPT_RESUME_FROM or CURLOPT_RANGE options and an existing connection
in the connection cache is closed to make room for the new one when you call
curl_easy_perform(). It would then wrongly free range-related data in the
connection close funtion.
server through a proxy and have the remote https server port set using the
CURLOPT_PORT option, protocol gets reset to http from https after the first
request.
User defined URL was modified internally by libcurl and subsequent reuse of
the easy handle may lead to connection using a different protocol (if not
originally http).
I found that libcurl hardcoded the protocol to "http" when it tries to
regenerate the URL if CURLOPT_PORT is set. I tried to fix the problem as
follows and it's working fine so far
fixing some bugs:
o Don't mix GET and POST requests in a pipeline
o Fix the order in which requests are dispatched from the pipeline
o Fixed several curl bugs with pipelining when the server is returning
chunked encoding:
* Added states to chunked parsing for final CRLF
* Rewind buffer after parsing chunk with data remaining
* Moved chunked header initializing to a spot just before receiving
headers
the multi interface and connection re-use that could make a
curl_multi_remove_handle() ruin a pointer in another handle.
The second problem was less of an actual problem but more of minor quirk:
the re-using of connections wasn't properly checking if the connection was
marked for closure.
to the debug callback.
- Shmulik Regev added CURLOPT_HTTP_CONTENT_DECODING and
CURLOPT_HTTP_TRANSFER_DECODING that if set to zero will disable libcurl's
internal decoding of content or transfer encoded content. This may be
preferable in cases where you use libcurl for proxy purposes or similar. The
command line tool got a --raw option to disable both at once.
and CURLOPT_CONNECTTIMEOUT_MS that, as their names should hint, do the
timeouts with millisecond resolution instead. The only restriction to that
is the alarm() (sometimes) used to abort name resolves as that uses full
seconds. I fixed the FTP response timeout part of the patch.
Internally we now count and keep the timeouts in milliseconds but it also
means we multiply set timeouts with 1000. The effect of this is that no
timeout can be set to more than 2^31 milliseconds (on 32 bit systems), which
equals 24.86 days. We probably couldn't before either since the code did
*1000 on the timeout values on several places already.
doing an FTP transfer is removed from a multi handle before completion. The
fix also fixed the "alive counter" to be correct on "premature removal" for
all protocols.
non-ASCII platforms. It does add some complexity, most notably with more
#ifdefs, but I want to see this supported added and I can't see how we can
add it without the extra stuff added.
curl that uses the new CURLOPT_FTP_SSL_CCC option in libcurl. If enabled, it
will make libcurl shutdown SSL/TLS after the authentication is done on a
FTP-SSL operation.
get confused and not acknowledge the 'no_proxy' variable properly once it
had used the proxy and you re-used the same easy handle. I made sure the
proxy name is properly stored in the connect struct rather than the
sessionhandle/easy struct.
(http://curl.haxx.se/bug/view.cgi?id=1618359) and subsequently provided a
patch for it: when downloading 2 zero byte files in a row, curl 7.16.0
enters an infinite loop, while curl 7.16.1-20061218 does one additional
unnecessary request.
Fix: During the "Major overhaul introducing http pipelining support and
shared connection cache within the multi handle." change, headerbytecount
was moved to live in the Curl_transfer_keeper structure. But that structure
is reset in the Transfer method, losing the information that we had about
the header size. This patch moves it back to the connectdata struct.
something went wrong like it got a bad response code back from the server,
libcurl would leak memory. Added test case 538 to verify the fix.
I also noted that the connection would get cached in that case, which
doesn't make sense since it cannot be re-use when the authentication has
failed. I fixed that issue too at the same time, and also that the path
would be "remembered" in vain for cases where the connection was about to
get closed.
(http://curl.haxx.se/bug/view.cgi?id=1604956) which identified setting
CURLOPT_MAXCONNECTS to zero caused libcurl to SIGSEGV. Starting now, libcurl
will always internally use no less than 1 entry in the connection cache.
KNOWN_BUGS #25, which happens when a proxy closes the connection when
libcurl has sent CONNECT, as part of an authentication negotiation. Starting
now, libcurl will re-connect accordingly and continue the authentication as
it should.
Assigning the const value zero to a pointer to function
results in a null pointer value assignment to the function
pointer.
Assignment of any nonzero value is what should result in a
implementation compiler dependent result.
Since what we want to do here is the first case, this should
not trigger compiler warnings related with conversions from
'pointer to data' to 'pointer to function'.
Our autobuild test suite will judge.
could very well cause a negate number get passed in and thus cause reading
outside of the array usually used for this purpose.
We avoid this by using the uppercase macro versions introduced just now that
does some extra crazy typecasts to avoid byte codes > 127 to cause negative
int values.
would crash if a bad function sequence was used when shutting down after
using the multi interface (i.e using easy_cleanup after multi_cleanup) so
precautions have been added to make sure it doesn't any more - test case 529
was added to verify.
it basically was that we didn't remove the current connection from the pipe
list when following a redirect. Also in this commit: several cases of
additional debug code for debug builds helping to check and track down some
signs of run-time trouble.
handle that is part of a multi handle first removes the handle from the
stack.
- Added CURLOPT_SSL_SESSIONID_CACHE and --no-sessionid to disable SSL
session-ID re-use on demand since there obviously are broken servers out
there that misbehave with session-IDs used.
problem with it (SIGSEGV-style). It clearly showed that the existing
socket-state and state-difference function wasn't good enough so I rewrote
it and could then re-run Jeff's program without any crash. The previous
version clearly could miss to tell the application when a handle changed
from using one socket to using another.
While I was at it (as I could use this as a means to track this problem
down), I've now added a 'magic' number to the easy handle struct that is
inited at curl_easy_init() time and cleared at curl_easy_cleanup() time that
we can use internally to detect that an easy handle seems to be fine, or at
least not closed or freed (freeing in debug builds fill the area with 0x13
bytes but in normal builds we can of course not assume any particular data
in the freed areas).
while not fixing things very nicely, it does make the SOCKS5 proxy
connection slightly better as it now acknowledges the timeout for connection
and it no longer segfaults in the case when SOCKS requires authentication
and you did not specify username:password.
the crash was that libcurl internally was a bit confused about who owned the
DNS cache at all times so if you created an easy handle that uses a shared
DNS cache and added that to a multi handle it would crash. Now we keep more
careful internal track of exactly what kind of DNS cache each easy handle
uses: None, Private (allocated for and used only by this single handle),
Shared (points to a cache held by a shared object), Global (points to the
global cache) or Multi (points to the cache within the multi handle that is
automatically shared between all easy handles that are added with private
caches).
CURLOPT_MAX_RECV_SPEED_LARGE that limit tha maximum rate libcurl is allowed
to send or receive data. This kind of adds the the command line tool's
option --limit-rate to the library.
The rate limiting logic in the curl app is now removed and is instead
provided by libcurl itself. Transfer rate limiting will now also work for -d
and -F, which it didn't before.
with the multi interface and multi-part formposts. The fix from February
22nd could make the Curl_done() function get called twice on the same
connection and it was not designed for that and thus tried to call free() on
an already freed memory area!
(http://curl.haxx.se/bug/view.cgi?id=1431750) helped me identify and fix two
different but related bugs:
1) Removing an easy handle from a multi handle before the transfer is done
could leave a connection in the connection cache for that handle that is
in a state that isn't suitable for re-use. A subsequent re-use could then
read from a NULL pointer and segfault.
2) When an easy handle was removed from the multi handle, there could be an
outstanding c-ares DNS name resolve request. When the response arrived,
it caused havoc since the connection struct it "belonged" to could've
been freed already.
Now Curl_done() is called when an easy handle is removed from a multi handle
pre-maturely (that is, before the transfer was complteted). Curl_done() also
makes sure to cancel all (if any) outstanding c-ares requests.
type to the already provided type CURLPROXY_SOCKS4.
I added a --socks4 option that works like the current --socks5 option but
instead use the socks4 protocol.
