When building software for the masses, it is sometimes not possible to
decide for all users which SSL backend is appropriate.
Git for Windows, for example, uses cURL to perform clones, fetches and
pushes via HTTPS, and some users strongly prefer OpenSSL, while other
users really need to use Secure Channel because it offers
enterprise-ready tools to manage credentials via Windows' Credential
Store.
The current Git for Windows versions use the ugly work-around of
building libcurl once with OpenSSL support and once with Secure Channel
support, and switching out the binaries in the installer depending on
the user's choice.
Needless to say, this is a super ugly workaround that actually only
works in some cases: Git for Windows also comes in a portable form, and
in a form intended for third-party applications requiring Git
functionality, in which cases this "swap out libcurl-4.dll" simply is
not an option.
Therefore, the Git for Windows project has a vested interest in teaching
cURL to make the SSL backend a *runtime* option.
This patch makes that possible.
By running ./configure with multiple --with-<backend> options, cURL will
be built with multiple backends.
For the moment, the backend can be configured using the environment
variable CURL_SSL_BACKEND (valid values are e.g. "openssl" and
"schannel").
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
So far, all of the SSL backends' private data has been declared as
part of the ssl_connect_data struct, in one big #if .. #elif .. #endif
block.
This can only work as long as the SSL backend is a compile-time option,
something we want to change in the next commits.
Therefore, let's encapsulate the exact data needed by each SSL backend
into a private struct, and let's avoid bleeding any SSL backend-specific
information into urldata.h. This is also necessary to allow multiple SSL
backends to be compiled in at the same time, as e.g. OpenSSL's and
CyaSSL's headers cannot be included in the same .c file.
To avoid too many malloc() calls, we simply append the private structs
to the connectdata struct in allocate_conn().
This requires us to take extra care of alignment issues: struct fields
often need to be aligned on certain boundaries e.g. 32-bit values need to
be stored at addresses that divide evenly by 4 (= 32 bit / 8
bit-per-byte).
We do that by assuming that no SSL backend's private data contains any
fields that need to be aligned on boundaries larger than `long long`
(typically 64-bit) would need. Under this assumption, we simply add a
dummy field of type `long long` to the `struct connectdata` struct. This
field will never be accessed but acts as a placeholder for the four
instances of ssl_backend_data instead. the size of each ssl_backend_data
struct is stored in the SSL backend-specific metadata, to allow
allocate_conn() to know how much extra space to allocate, and how to
initialize the ssl[sockindex]->backend and proxy_ssl[sockindex]->backend
pointers.
This would appear to be a little complicated at first, but is really
necessary to encapsulate the private data of each SSL backend correctly.
And we need to encapsulate thusly if we ever want to allow selecting
CyaSSL and OpenSSL at runtime, as their headers cannot be included within
the same .c file (there are just too many conflicting definitions and
declarations for that).
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
At the moment, cURL's SSL backend needs to be configured at build time.
As such, it is totally okay for them to hard-code their backend-specific
data in the ssl_connect_data struct.
In preparation for making the SSL backend a runtime option, let's make
the access of said private data a bit more abstract so that it can be
adjusted later in an easy manner.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
In the ongoing endeavor to abstract out all SSL backend-specific
functionality, this is the next step: Instead of hard-coding how the
different SSL backends access their internal data in getinfo.c, let's
implement backend-specific functions to do that task.
This will also allow for switching SSL backends as a runtime option.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
These functions are all available via the Curl_ssl struct now, no need
to declare them separately anymore.
As the global declarations are removed, the corresponding function
definitions are marked as file-local. The only two exceptions here are
Curl_mbedtls_shutdown() and Curl_polarssl_shutdown(): only the
declarations were removed, there are no function definitions to mark
file-local.
Please note that Curl_nss_force_init() is *still* declared globally, as
the only SSL backend-specific function, because it was introduced
specifically for the use case where cURL was compiled with
`--without-ssl --with-nss`. For details, see f3b77e561 (http_ntlm: add
support for NSS, 2010-06-27).
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
The entire idea of introducing the Curl_ssl struct to describe SSL
backends is to prepare for choosing the SSL backend at runtime.
To that end, convert all the #ifdef have_curlssl_* style conditionals
to use bit flags instead.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
The SHA-256 checksumming is also an SSL backend-specific function.
Let's include it in the struct declaring the functionality of SSL
backends.
In contrast to MD5, there is no fall-back code. To indicate this, the
respective entries are NULL for those backends that offer no support for
SHA-256 checksumming.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
The MD5 summing is also an SSL backend-specific function. So let's
include it, offering the previous fall-back code as a separate function
now: Curl_none_md5sum(). To allow for that, the signature had to be
changed so that an error could be returned from the implementation
(Curl_none_md5sum() can run out of memory).
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
This is the first step to unify the SSL backend handling. Now all the
SSL backend-specific functionality is accessed via a global instance of
the Curl_ssl struct.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
The idea of introducing the Curl_ssl struct was to unify how the SSL
backends are declared and called. To this end, we now provide an
instance of the Curl_ssl struct for each and every SSL backend.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
... to make all libcurl internals able to use the same data types for
the struct members. The timeval struct differs subtly on several
platforms so it makes it cumbersome to use everywhere.
Ref: #1652Closes#1693
ERR_error_string with NULL parameter is not thread-safe. The library
writes the string into some static buffer. Two threads doing this at
once may clobber each other and run into problems. Switch to
ERR_error_string_n which avoids this problem and is explicitly
bounds-checked.
Also clean up some remnants of OpenSSL 0.9.5 around here. A number of
comments (fixed buffer size, explaining that ERR_error_string_n was
added in a particular version) date to when ossl_strerror tried to
support pre-ERR_error_string_n OpenSSLs.
Closes#1424
- If SSL_get_error is called but no extended error detail is available
then show that SSL_ERROR_* as a string.
Prior to this change there was some inconsistency in that case: the
SSL_ERROR_* code may or may not have been shown, or may have been shown
as unknown even if it was known.
Ref: https://github.com/curl/curl/issues/1300
Closes https://github.com/curl/curl/pull/1348
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
Mark intended fallthroughs with /* FALLTHROUGH */ so that gcc will know
it's expected and won't warn on [-Wimplicit-fallthrough=].
Closes https://github.com/curl/curl/pull/1297
SSL_CTX_add_extra_chain_cert takes ownership of the given certificate
while, despite the similar name, SSL_CTX_add_client_CA does not. Thus
it's best to call SSL_CTX_add_client_CA before
SSL_CTX_add_extra_chain_cert, while the code still has ownership of the
argument.
Closes https://github.com/curl/curl/pull/1236
ERR_PACK is an internal detail of OpenSSL. Also, when using it, a
function name must be specified which is overly specific: the test will
break whenever OpenSSL internally change things so that a different
function creates the error.
Closes#1157
