Get rid of the compiler warning about strict aliasing rule.

[bpdyndnsd] / src / util.cpp

/** @file
 * @brief Util namespace implementation.
 *
 *
 *
 * @copyright Intra2net AG
 * @license GPLv2
*/

#include "util.h"

#include <sstream>
#include <openssl/evp.h>

using namespace std;

/**
 * Computes a MD5 Digest from the given string and returns the HEX representation
 * @param data The string to compute the md5 for
 * @return The computed md5 in hex
 */
string Util::compute_md5_digest(string data) throw (invalid_argument)
{
    // compute an MD5 digest.

    EVP_MD_CTX mdctx;
    const EVP_MD *md;
    unsigned char md_value[EVP_MAX_MD_SIZE];
    unsigned int md_len = 0;

    // Add all digest algorithms to the internal table.
    OpenSSL_add_all_digests();

    // Get the md5 digest algorithm from the internal table.
    md = EVP_get_digestbyname("md5");

    // Test if md is initialized.
    if ( (md == NULL) || (EVP_MD_size(md) == 0) )
        throw invalid_argument("NULL pointer: md");

    // Initalize digest content mdctx.
    EVP_MD_CTX_init(&mdctx);

    // Now we can call init_ex.
    EVP_DigestInit_ex(&mdctx, md, NULL);

    // Test if data is empty.
    if ( data.empty() )
        throw invalid_argument("Passed data is empty");

    // Hash the data. At this point data is not empty and &mdctx is initialized.
    EVP_DigestUpdate(&mdctx, data.c_str(), data.size());

    // Retrieve the digest value from &mdctx and place it in md_value.
    EVP_DigestFinal_ex(&mdctx, md_value, &md_len);

    // Test if md_value is filled correctly and md_len is not zero.
    if ( (md_len == 0) || (md_value == NULL) || (EVP_MD_CTX_size(&mdctx) == 0) )
        throw invalid_argument("Retrieved invalid digest value");

    // Internal cleanup of the digest content.
    EVP_MD_CTX_cleanup(&mdctx);
    EVP_cleanup();

    // Convert md5 digest C string to hex.
    ostringstream oss_digest_md5_hex;
    for(unsigned int i = 0; i < md_len; ++i)
    {
        // We have to do a static cast to an decimal representation, cause otherwise ostringstream would interpret
        // the stream as a character and output the character representation of the hex value.
        oss_digest_md5_hex << hex << static_cast<unsigned short>(md_value[i]);
    }

    return oss_digest_md5_hex.str();
}


/**
 * Get the status code from the given data.
 * @param data The data containing the status code at front, limited by " ".
 * @return The parsed status code.
 */
string Util::parse_status_code(string data)
{
    list<string> tokens;
    ba::split(tokens,data,boost::is_any_of(" "));
    return tokens.front();
}