Support for Riak security

[tomhel]

This patch adds support for Riak security/authentication using passwords or certificates. To support TLS connections WolfSSL is used. Building with TLS/security support is optional.

Besides Riak security this patch also does the following:

• fix ints.h include problem on Linux.
• set NOSIGPIPE on socket write.

Build example:

cmake -DBUILD_SHARED_LIBS=1 -DWITH_WOLFSSL=1 src/

To connect to Riak securely, do this:

1. create riack security options
2. initialize riack security options
3. connect to Riak
4. start TLS
5. perform authentication

Code example, connect to Riak securely using username and password:

riack_init();
riack_security_options security;
riack_init_security_options(&security);
riack_client *client = riack_new_client(0);
riack_connect(client, "127.0.0.1", 8087, 0);

riack_start_tls(client, &security);
riack_string user;
riack_string pw;
user.value = "riakuser";
user.len = strlen(user.value);
pw.value = "pass";
pw.len = strlen(pw.value);
riack_auth(client, &user, &pw);

if (riack_ping(client) == RIACK_SUCCESS)
    printf("pong");
}

riack_free(client);
riack_cleanup();

More examples are available in README.md.

Security options are set on the riack_security_options struct (in riack_defines.h):

/* Riack security options */
typedef struct _riack_security_options {
    /* Limit available ciphers, colon delimited list */
    char* ciphers;
    /* Load from file, PEM format */
    char* ca_file;
    char* cert_file;
    char* key_file;
    /* Load from memory, PEM format */
    unsigned char* ca_buffer;
    unsigned char* cert_buffer;
    unsigned char* key_buffer;
    /* Size of memory buffers */
    size_t ca_size;
    size_t cert_size;
    size_t key_size;
    /* SSL/TLS session timeout in seconds */
    unsigned int session_timeout;
} riack_security_options;