This seems to be the idiomatic way to fix libressl compatibility issues,
judging by what most other open source projects seem to be doing.
I've confirmed that transmission builds with libressl for me after this
patch is applied.
This way all the qualifiers (`const`, `volatile`, `mutable`) are grouped
together, e.g. `T const* const x` vs. `const T* const x`. Also helps reading
types right-to-left, e.g. "constant pointer to constant T" vs. "constant
pointer to T which is constant".
There're places where manual intervention is still required as uncrustify
is not ideal (unfortunately), but at least one may rely on it to do the
right thing most of the time (e.g. when sending in a patch).
The style itself is quite different from what we had before but making it
uniform across all the codebase is the key. I also hope that it'll make the
code more readable (YMMV) and less sensitive to further changes.
Some crypto libraries (like CyaSSL, MatrixSSL and CommonCrypto) either
don't have or expose this functionality at all, expose only part of it,
or (like OpenSSL) have heavyweight API for it. Also, for the task as
easy as BASE64 encoding and decoding it's much better to use small and
simple specialized library.
On a way to factoring out OpenSSL support to a standalone file to ease
addition of other crypto libraries support in the future, move helpers
providing BASE64 encoding and decoding to crypto-utils.{c,h}. OpenSSL-
related functionality is moved to crypto-utils-openssl.c.
Add new functions to be implemented by crypto backends:
* tr_base64_encode_impl - encode from binary to BASE64,
* tr_base64_decode_impl - decode from BASE64 to binary.
Change `tr_base64_encode` and `tr_base64_decode` functions to expect
non-negative input data length which is considered real and never adjusted.
To process null-terminated strings (which was achieved before by passing 0
or -1 as input data length), add new `tr_base64_encode_str` and
`tr_base64_decode_str` functions which do not accept input data length as
an argument but calculate it on their own.
On a way to factoring out OpenSSL support to a standalone file to ease
addition of other crypto libraries support in the future, move helpers
providing DH key exchange to crypto-utils.{c,h}. OpenSSL-related
functionality (DH context management) is moved to crypto-utils-openssl.c.
Since we know in advance that DH secret key management code will be the
same for most of backends, implement common functionality in separate
crypto-utils-fallback.c.
Add new tr_dh_ctx_t and tr_dh_secret_t types and functions to be
implemented by crypto backends:
* tr_dh_new - allocate DH context,
* tr_dh_free - free the context,
* tr_dh_make_key - generate private/public keypair,
* tr_dh_agree - perform DH key exchange and generate secret key,
* tr_dh_secret_derive - calculate secret key hash,
* tr_dh_secret_free - free the secret key,
* tr_dh_align_key - align some DH key in the buffer allocated for it.
Make DH secret key not accessible in plain form outside the crypto
backend. This allows for implementations where the key is managed by
the underlying library and is not even exposed to our backend.
On a way to factoring out OpenSSL support to a standalone file to ease
addition of other crypto libraries support in the future, move helpers
providing RC4 ciphering to crypto-utils.{c,h}. OpenSSL-related
functionality (RC4 context management) is moved to crypto-utils-openssl.c.
Add new tr_rc4_ctx_t type and functions to be implemented by crypto
backends:
* tr_rc4_new - allocate RC4 context,
* tr_rc4_free - free the context,
* tr_rc4_set_key - set cipher key,
* tr_rc4_process - cipher memory block.
On a way to factoring out OpenSSL support to a standalone file to ease
addition of other crypto libraries support in the future, move helpers
providing SHA1 calculation to crypto-utils.{c,h}. OpenSSL-related
functionality (SHA1 context management) is moved to crypto-utils-openssl.c.
Add new tr_sha1_ctx_t type and functions to be implemented by crypto
backends:
* tr_sha1_init - allocate SHA1 context and and initialize it,
* tr_sha1_update - hash some [more] data,
* tr_sha1_final - finish hash calculation and free the context.
Add new files to CMakeLists.txt (leftover from previous commit) to fix
CMake-based configuration.
On a way to factoring out OpenSSL support to a standalone file to ease
addition of other crypto libraries support in the future, move helpers
providing random numbers/data generation to crypto-utils.{c,h}. OpenSSL-
related functionality (generation of cryptographically strong random
data) is moved to crypto-utils-openssl.c.
Rename functions to follow currently accepted style:
* tr_cryptoRandBuf -> tr_rand_buffer
* tr_cryptoRandInt -> tr_rand_int
* tr_cryptoWeakRandInt -> tr_rand_int_weak
Fix rare case of invalid value being returned from tr_rand_int. Return
value for abs(INT_MIN) may be undefined and thus negative, and so
tr_rand_int will return negative value which is incorrect (out of
requested and expected range).
Charles Kerr