static BUFFER_HANDLE base32_decode_impl()

in src/azure_base32.c [172:281]

• 96 lines of code
• 14 McCabe index (conditional complexity)

static BUFFER_HANDLE base32_decode_impl(const char* source)
{
    BUFFER_HANDLE result;

    size_t src_length = strlen(source);
    if (src_length % BASE32_INPUT_SIZE != 0)
    {
        /* Codes_SRS_BASE32_07_021: [ If the source length is not evenly divisible by 8, base32_decode_impl shall return NULL. ] */
        LogError("Failure invalid input length %lu", (unsigned long)src_length);
        result = NULL;
    }
    else
    {
        size_t dest_size = 0;
        unsigned char* temp_buffer;
        unsigned char* dest_buff;
        bool continue_processing = true;
        unsigned char input[8];
        const char* iterator = source;

        /* Codes_SRS_BASE32_07_022: [ base32_decode_impl shall allocate a temp buffer to store the in process value. ] */
        size_t allocation_len = base32_decoding_length(src_length);
        if ((temp_buffer = (unsigned char*)malloc(allocation_len)) == NULL)
        {
            /* Codes_SRS_BASE32_07_023: [ If an error is encountered, base32_decode_impl shall return NULL. ] */
            LogError("Failure allocating buffer");
            result = NULL;
        }
        else
        {
            dest_buff = temp_buffer;
            while (*iterator != '\0')
            {
                size_t index = 0;
                /* Codes_SRS_BASE32_07_024: [ base32_decode_impl shall loop through and collect 8 characters from the source variable. ] */
                for (index = 0; index < BASE32_INPUT_SIZE; index++)
                {
                    input[index] = *iterator;
                    iterator++;
                    if (input[index] >= ASCII_VALUE_MAX)
                    {
                        LogError("Failure source encoding");
                        continue_processing = false;
                        break;
                    }

                    input[index] = convert_value_to_base32_char(input[index]);
                }

                if (!continue_processing)
                {
                    result = NULL;
                    break;
                }
                else if ((dest_size + TARGET_BLOCK_SIZE) > allocation_len)
                {
                    LogError("Failure target length exceeded");
                    result = NULL;
                    continue_processing = false;
                    break;
                }
                else
                {
                    // Codes_SRS_BASE32_07_025: [ base32_decode_impl shall group 5 bytes at a time into the temp buffer. ]
                    *dest_buff++ = ((input[0] & 0x1f) << 3) | ((input[1] & 0x1c) >> 2);
                    *dest_buff++ = ((input[1] & 0x03) << 6) | ((input[2] & 0x1f) << 1) | ((input[3] & 0x10) >> 4);
                    *dest_buff++ = ((input[3] & 0x0f) << 4) | ((input[4] & 0x1e) >> 1);
                    *dest_buff++ = ((input[4] & 0x01) << 7) | ((input[5] & 0x1f) << 2) | ((input[6] & 0x18) >> 3);
                    *dest_buff++ = ((input[6] & 0x07) << 5) | (input[7] & 0x1f);
                    dest_size += TARGET_BLOCK_SIZE;
                    // If there is padding remove it
                    // Because we are packing 5 bytes into an 8 byte variable we need to check every other
                    // variable for padding
                    if (input[7] == BASE32_EQUAL_SIGN)
                    {
                        --dest_size;
                        if (input[5] == BASE32_EQUAL_SIGN)
                        {
                            --dest_size;
                            if (input[4] == BASE32_EQUAL_SIGN)
                            {
                                --dest_size;
                                if (input[2] == BASE32_EQUAL_SIGN)
                                {
                                    --dest_size;
                                }
                            }
                        }
                    }
                }
            }

            if (!continue_processing)
            {
                result = NULL;
            }
            else
            {
                /* Codes_SRS_BASE32_07_026: [ Once base32_decode_impl is complete it shall create a BUFFER with the temp buffer. ] */
                result = BUFFER_create(temp_buffer, dest_size);
                if (result == NULL)
                {
                    LogError("Failure: BUFFER_create failed to create decoded buffer");
                }
            }
            free(temp_buffer);
        }
    }
    return result;
}