mirror of
https://github.com/Valeh2012/PersonalVotingMachine
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142 lines
4.4 KiB
C++
142 lines
4.4 KiB
C++
#ifndef MAIN_INCLUDE_CONVERTER_H_
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#define MAIN_INCLUDE_CONVERTER_H_
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/**
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* @file converter.h
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* @brief converter namespace - collection of frequently used conversion/encoding/decoding functions
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*
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* */
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#include <stdint.h>
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#include <string.h>
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#include "expat.h"
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/** Buffer size for xml parsing */
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#define output_size 10240
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/**
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* \namespace converter
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* */
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namespace converter{
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/** @brief a helper function to convert pem files to der.
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*
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* source: https://github.com/ARMmbed/mbedtls/blob/master/programs/util/pem2der.c
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*
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* @param input pem file buffer
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* @param ilen input buffer length
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* @param output buffer to store converted der content
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* @param olen length of data written in output buffer
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*
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* @returns 0 if OK, else -1
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* */
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int convert_pem_to_der( const unsigned char *input, size_t ilen,
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unsigned char *output, size_t *olen );
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/**
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* @brief a helper function to convert long hex numbers to base b = 2^32
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*
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* In base 2^32, every digit is 32 bit length unsigned integers (uint32_t).
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* Therefore, each consequent 4 bytes in hex converted into one digit in base b.
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* Note: numbers may contain '0x00' in hex representation which is treated as end of string
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* in string functions. Another parameter is required to indicate length of hex representation
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*
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* @param hex input number buffer
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* @param len input buffer length
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*
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* @returns long base-b number
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*/
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uint32_t* hex2u32(unsigned char* hex, size_t len);
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/**
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* @brief a helper function to convert long base-b number to hex values for DER encoding
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*
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* Inverse of hex2u32 function
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*
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* @param x long base-b number
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* @param length length of input number
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* @param len output buffer length
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*
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* @returns buffer containing number in hex representation
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* */
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unsigned char * nb(uint32_t *x, int length, size_t *olen);
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/**
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* @brief a helper function convert to first hash, then base64 encode
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*
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* This function wraps to mbed_tls functions. Given input string buffer,
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* it first finds SHA256 hash, then converts the resulting hash into base64.
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*
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* @param input string buffer
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* @param len input buffer length
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*
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* @returns output buffer
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* */
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unsigned char * base64hash(unsigned char* input, size_t len);
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/** @brief struct used in xml parsing functions
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* */
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typedef struct {
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int depth; /**< depth of recursion*/
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char* output; /**< output buffer (for parsed xml) */
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int output_off; /**< output buffer offset (last written index, i.e length of written data)*/
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const char *last_name; /**< last opened xml tag */
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} xml_data_t;
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/**
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* @brief a helper function to insert space for indentation
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*
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* This function prints extra whitespaces to output buffer for indentation purposes.
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*
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* @param user_data parsed xml data
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* */
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static void insert_space(xml_data_t *user_data);
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/**
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* @brief a callback function called at start of new xml node
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*
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* XMLParser traverses through xml nodes and each time it reaches a new node, this callback function is called.
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* Copy tag name and attributes to output buffer
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*
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* @param user_data parsed xml data
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* @param name just opened current xml node tag name
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* @param atts other attributes of current xml node
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* */
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static void XMLCALL start_element(void *userData, const XML_Char *name, const XML_Char **atts);
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/**
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* @brief a callback function called at the end of new xml node
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*
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* XMLParser traverses through xml nodes and each time it reaches a closing tags of current node, this callback function is called.
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* If current node is leaf node, add closing tags immediately. Otherwise, add whitespace before closing tags.
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*
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* @param user_data parsed xml data
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* @param name to be closed current xml node tag name
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* */
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static void XMLCALL end_element(void *userData, const XML_Char *name);
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/**
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* @brief a function to define how to parse xml elements
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*
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* In between starting and closing tags, this functions is called by XMLParser.
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* Here, it just copies data buffer to output buffer without adding extra whitespace.
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*
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* @param user_data parsed xml data
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* @param s data in current xml node
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* @param len length of data
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* */
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static void data_handler(void *userData, const XML_Char *s, int len);
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/**
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* @brief a helper funciton to canonicalize xml data (XMLC14N11).
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*
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* Specifications can be found here: \see https://www.w3.org/TR/xml-c14n11/#Example-SETags
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*
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* @param str xml input buffer
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* @param len input buffer length
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* */
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void xmlc14n11(char* str, size_t len);
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}
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#endif
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