To support telling a string is nul-terminated, symbol CURL_ZERO_TERMINATED
has been introduced.

Documentation updated accordingly.

symbols in versions updated. Added form API symbols deprecation info.

Available in HTTP, SMTP and IMAP.
Deprecates the FORM API.
See CURLOPT_MIMEPOST.
Lib code and associated documentation.

Reported-by: Dan Fandrich
Bug: https://curl.haxx.se/mail/lib-2017-08/0121.html
Closes #1843

The CURLSSLBACKEND_WOLFSSL is supposed to be an alias for
CURLSSLBACKEND_CYASSL, but used an erronous value. To reduce the risk
for a similar mistake, define the backend aliases to use the enum values
instead.

Reported-by: Gisle Vanem
Bug: https://curl.haxx.se/mail/lib-2017-08/0120.html

This new feature flag reports When cURL was built with multiple SSL
backends.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Let's add a compile time safe API to select an SSL backend. This
function needs to be called *before* curl_global_init(), and can be
called only once.

Side note: we do not explicitly test that it is called before
curl_global_init(), but we do verify that it is not called multiple times
(even implicitly).

If SSL is used before the function was called, it will use whatever the
CURL_SSL_BACKEND environment variable says (or default to the first
available SSL backend), and if a subsequent call to
curl_global_sslset() disagrees with the previous choice, it will fail
with CURLSSLSET_TOO_LATE.

The function also accepts an "avail" parameter to point to a (read-only)
NULL-terminated list of available backends. This comes in real handy if
an application wants to let the user choose between whatever SSL backends
the currently available libcurl has to offer: simply call

	curl_global_sslset(-1, NULL, &avail);

which will return CURLSSLSET_UNKNOWN_BACKEND and populate the avail
variable to point to the relevant information to present to the user.

Just like with the HTTP/2 push functions, we have to add the function
declaration of curl_global_sslset() function to the header file
*multi.h* because VMS and OS/400 require a stable order of functions
declared in include/curl/*.h (where the header files are sorted
alphabetically). This looks a bit funny, but it cannot be helped.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

There is information about the compiled-in SSL backends that is really
no concern of any code other than the SSL backend itself, such as which
function (if any) implements SHA-256 summing.

And there is information that is really interesting to the user, such as
the name, or the curl_sslbackend value.

Let's factor out the latter into a publicly visible struct. This
information will be used in the upcoming API to set the SSL backend
globally.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

The required low-level logic was already available as part of
`libssh2` (via `LIBSSH2_FLAG_COMPRESS` `libssh2_session_flag()`[1]
option.)

This patch adds the new `libcurl` option `CURLOPT_SSH_COMPRESSION`
(boolean) and the new `curl` command-line option `--compressed-ssh`
to request this `libssh2` feature. To have compression enabled, it
is required that the SSH server supports a (zlib) compatible
compression method and that `libssh2` was built with `zlib` support
enabled.

[1] https://www.libssh2.org/libssh2_session_flag.html

Ref: https://github.com/curl/curl/issues/1732
Closes https://github.com/curl/curl/pull/1735

If libcurl was built with GSS-API support, it unconditionally advertised
GSS-API authentication while connecting to a SOCKS5 proxy.  This caused
problems in environments with improperly configured Kerberos: a stock
libcurl failed to connect, despite libcurl built without GSS-API
connected fine using username and password.

This commit introduces the CURLOPT_SOCKS5_AUTH option to control the
allowed methods for SOCKS5 authentication at run time.

Note that a new option was preferred over reusing CURLOPT_PROXYAUTH
for compatibility reasons because the set of authentication methods
allowed by default was different for HTTP and SOCKS5 proxies.

Bug: https://curl.haxx.se/mail/lib-2017-01/0005.html
Closes https://github.com/curl/curl/pull/1454

... and CURLOPT_REQUEST_TARGET instead of CURLOPT_STRIP_PATH_SLASH.

This option instead provides the full "alternative" target to use in the
request, instead of extracting the path from the URL.

Test 1298 and 1299 updated accordingly.

Idea-by: Evert Pot
Suggestion: https://daniel.haxx.se/blog/2017/06/19/options-with-curl/comment-page-1/#comment-18373

Closes #1593

... to enable sending "OPTIONS *" which wasn't possible previously.

This option currently only works for HTTP.

Added test cases 1298 + 1299 to verify

Fixes #1280
Closes #1462

This change introduces new alternatives for the existing six
curl_easy_getinfo() options that return sizes or speeds as doubles. The
new versions are named like the old ones but with an appended '_T':

CURLINFO_CONTENT_LENGTH_DOWNLOAD_T
CURLINFO_CONTENT_LENGTH_UPLOAD_T
CURLINFO_SIZE_DOWNLOAD_T
CURLINFO_SIZE_UPLOAD_T
CURLINFO_SPEED_DOWNLOAD_T
CURLINFO_SPEED_UPLOAD_T

Closes #1511

Rely entirely on curl/system.h now.

Introduced in Aug 2008 with commit 14240e9e. Now gone.

Fixes #1456

Fixes #1524

system.h is aimed to replace curlbuild.h at a later point in time when
we feel confident system.h works sufficiently well.

curl/system.h is currently used in parallel with curl/curlbuild.h

curl/system.h determines a data sizes, data types and include file
status based on available preprocessor defines instead of getting
generated at build-time. This, in order to avoid relying on a build-time
generated file that makes it complicated to do 32 and 64 bit bields from
the same installed set of headers.

Test 1541 verifies that system.h comes to the same conclusion that
curlbuild.h offers.

Closes #1373

Closes #1356

- Add new option CURLOPT_SUPPRESS_CONNECT_HEADERS to allow suppressing
  proxy CONNECT response headers from the user callback functions
  CURLOPT_HEADERFUNCTION and CURLOPT_WRITEFUNCTION.

- Add new tool option --suppress-connect-headers to expose
  CURLOPT_SUPPRESS_CONNECT_HEADERS and allow suppressing proxy CONNECT
  response headers from --dump-header and --include.

Assisted-by: Jay Satiro
Assisted-by:  <CarloCannas@users.noreply.github.com>
Closes https://github.com/curl/curl/pull/783

This commit introduces the CURL_SSLVERSION_MAX_* constants as well as
the --tls-max option of the curl tool.

Closes https://github.com/curl/curl/pull/1166

Replace use of fixed macro BUFSIZE to define the size of the receive
buffer.  Reappropriate CURLOPT_BUFFERSIZE to include enlarging receive
buffer size.  Upon setting, resize buffer if larger than the current
default size up to a MAX_BUFSIZE (512KB). This can benefit protocols
like SFTP.

Closes #1222

In addition to unix domain sockets, Linux also supports an
abstract namespace which is independent of the filesystem.

In order to support it, add new CURLOPT_ABSTRACT_UNIX_SOCKET
option which uses the same storage as CURLOPT_UNIX_SOCKET_PATH
internally, along with a flag to specify abstract socket.

On non-supporting platforms, the abstract address will be
interpreted as an empty string and fail gracefully.

Also add new --abstract-unix-socket tool parameter.

Signed-off-by: Isaac Boukris <iboukris@gmail.com>
Reported-by: Chungtsun Li (typeless)
Reviewed-by: Daniel Stenberg
Reviewed-by: Peter Wu
Closes #1197
Fixes #1061

This error code was once introduced when some library was dynamically
loaded and a funciton within said library couldn't be found.

CURLOPT_SOCKS_PROXY -> CURLOPT_PRE_PROXY

Added the corresponding --preroxy command line option. Sets a SOCKS
proxy to connect to _before_ connecting to a HTTP(S) proxy.

This was added as part of the SOCKS+HTTPS proxy merge but there's no
need to support this as we prefer to have the protocol specified as a
prefix instead.

In order to make the code style more uniform everywhere

Closes #1142

Adds access to the effectively used protocol/scheme to both libcurl and
curl, both in string and numeric (CURLPROTO_*) form.

Note that the string form will be uppercase, as it is just the internal
string.

As these strings are declared internally as const, and all other strings
returned by curl_easy_getinfo() are de-facto const as well, string
handling in getinfo.c got const-ified.

Closes #1137

* HTTPS proxies:

An HTTPS proxy receives all transactions over an SSL/TLS connection.
Once a secure connection with the proxy is established, the user agent
uses the proxy as usual, including sending CONNECT requests to instruct
the proxy to establish a [usually secure] TCP tunnel with an origin
server. HTTPS proxies protect nearly all aspects of user-proxy
communications as opposed to HTTP proxies that receive all requests
(including CONNECT requests) in vulnerable clear text.

With HTTPS proxies, it is possible to have two concurrent _nested_
SSL/TLS sessions: the "outer" one between the user agent and the proxy
and the "inner" one between the user agent and the origin server
(through the proxy). This change adds supports for such nested sessions
as well.

A secure connection with a proxy requires its own set of the usual SSL
options (their actual descriptions differ and need polishing, see TODO):

  --proxy-cacert FILE        CA certificate to verify peer against
  --proxy-capath DIR         CA directory to verify peer against
  --proxy-cert CERT[:PASSWD] Client certificate file and password
  --proxy-cert-type TYPE     Certificate file type (DER/PEM/ENG)
  --proxy-ciphers LIST       SSL ciphers to use
  --proxy-crlfile FILE       Get a CRL list in PEM format from the file
  --proxy-insecure           Allow connections to proxies with bad certs
  --proxy-key KEY            Private key file name
  --proxy-key-type TYPE      Private key file type (DER/PEM/ENG)
  --proxy-pass PASS          Pass phrase for the private key
  --proxy-ssl-allow-beast    Allow security flaw to improve interop
  --proxy-sslv2              Use SSLv2
  --proxy-sslv3              Use SSLv3
  --proxy-tlsv1              Use TLSv1
  --proxy-tlsuser USER       TLS username
  --proxy-tlspassword STRING TLS password
  --proxy-tlsauthtype STRING TLS authentication type (default SRP)

All --proxy-foo options are independent from their --foo counterparts,
except --proxy-crlfile which defaults to --crlfile and --proxy-capath
which defaults to --capath.

Curl now also supports %{proxy_ssl_verify_result} --write-out variable,
similar to the existing %{ssl_verify_result} variable.

Supported backends: OpenSSL, GnuTLS, and NSS.

* A SOCKS proxy + HTTP/HTTPS proxy combination:

If both --socks* and --proxy options are given, Curl first connects to
the SOCKS proxy and then connects (through SOCKS) to the HTTP or HTTPS
proxy.

TODO: Update documentation for the new APIs and --proxy-* options.
Look for "Added in 7.XXX" marks.

Fully implemented with the NSS backend only for now.

Reviewed-by: Ray Satiro

Add the new option CURLOPT_KEEP_SENDING_ON_ERROR to control whether
sending the request body shall be completed when the server responds
early with an error status code.

This is suitable for manual NTLM authentication.

Reviewed-by: Jay Satiro

Closes https://github.com/curl/curl/pull/904

Since we're using CURLE_FTP_WEIRD_SERVER_REPLY in imap, pop3 and smtp as
more of a generic "failed to parse" introduce an alias without FTP in
the name.

Closes https://github.com/curl/curl/pull/975

Many applications assume the actual contents of the public types and use
that do for example forward declarations (saving them from including our
public header) which then breaks when we switch from void * to a struct
*.

I'm not convinced we were wrong, but since this practise seems
widespread enough I'm willing to (partly) step down.

Now libcurl uses the struct itself when it is built and it allows
applications to use the struct type if CURL_STRICTER is defined at the
time of the #include.

Reported-by: Peter Frühberger
Fixes #926

Instead of typedef'ing to void, typedef to their corresponding actual
struct names to allow compilers to type-check.

Assisted-by: Reinhard Max

Adds access to the effectively used http version to both libcurl and
curl.

Closes #799