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/*
* Copyright (c) 2014, Peter Thorson. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of the WebSocket++ Project nor the
* names of its contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL PETER THORSON BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
#ifndef WEBSOCKETPP_FRAME_HPP
#define WEBSOCKETPP_FRAME_HPP
#include <algorithm>
#include <string>
#include <websocketpp/common/system_error.hpp>
#include <websocketpp/common/network.hpp>
#include <websocketpp/utilities.hpp>
namespace websocketpp {
/// Data structures and utility functions for manipulating WebSocket frames
/**
* namespace frame provides a number of data structures and utility functions
* for reading, writing, and manipulating binary encoded WebSocket frames.
*/
namespace frame {
/// Minimum length of a WebSocket frame header.
static unsigned int const BASIC_HEADER_LENGTH = 2;
/// Maximum length of a WebSocket header
static unsigned int const MAX_HEADER_LENGTH = 14;
/// Maximum length of the variable portion of the WebSocket header
static unsigned int const MAX_EXTENDED_HEADER_LENGTH = 12;
/// Two byte conversion union
union uint16_converter {
uint16_t i;
uint8_t c[2];
};
/// Four byte conversion union
union uint32_converter {
uint32_t i;
uint8_t c[4];
};
/// Eight byte conversion union
union uint64_converter {
uint64_t i;
uint8_t c[8];
};
/// Constants and utility functions related to WebSocket opcodes
/**
* WebSocket Opcodes are 4 bits. See RFC6455 section 5.2.
*/
namespace opcode {
enum value {
continuation = 0x0,
text = 0x1,
binary = 0x2,
rsv3 = 0x3,
rsv4 = 0x4,
rsv5 = 0x5,
rsv6 = 0x6,
rsv7 = 0x7,
close = 0x8,
ping = 0x9,
pong = 0xA,
control_rsvb = 0xB,
control_rsvc = 0xC,
control_rsvd = 0xD,
control_rsve = 0xE,
control_rsvf = 0xF,
CONTINUATION = 0x0,
TEXT = 0x1,
BINARY = 0x2,
RSV3 = 0x3,
RSV4 = 0x4,
RSV5 = 0x5,
RSV6 = 0x6,
RSV7 = 0x7,
CLOSE = 0x8,
PING = 0x9,
PONG = 0xA,
CONTROL_RSVB = 0xB,
CONTROL_RSVC = 0xC,
CONTROL_RSVD = 0xD,
CONTROL_RSVE = 0xE,
CONTROL_RSVF = 0xF
};
/// Check if an opcode is reserved
/**
* @param v The opcode to test.
* @return Whether or not the opcode is reserved.
*/
inline bool reserved(value v) {
return (v >= rsv3 && v <= rsv7) ||
(v >= control_rsvb && v <= control_rsvf);
}
/// Check if an opcode is invalid
/**
* Invalid opcodes are negative or require greater than 4 bits to store.
*
* @param v The opcode to test.
* @return Whether or not the opcode is invalid.
*/
inline bool invalid(value v) {
return (v > 0xF || v < 0);
}
/// Check if an opcode is for a control frame
/**
* @param v The opcode to test.
* @return Whether or not the opcode is a control opcode.
*/
inline bool is_control(value v) {
return v >= 0x8;
}
}
/// Constants related to frame and payload limits
namespace limits {
/// Minimum length of a WebSocket frame header.
static unsigned int const basic_header_length = 2;
/// Maximum length of a WebSocket header
static unsigned int const max_header_length = 14;
/// Maximum length of the variable portion of the WebSocket header
static unsigned int const max_extended_header_length = 12;
/// Maximum size of a basic WebSocket payload
static uint8_t const payload_size_basic = 125;
/// Maximum size of an extended WebSocket payload (basic payload = 126)
static uint16_t const payload_size_extended = 0xFFFF; // 2^16, 65535
/// Maximum size of a jumbo WebSocket payload (basic payload = 127)
static uint64_t const payload_size_jumbo = 0x7FFFFFFFFFFFFFFFLL;//2^63
/// Maximum size of close frame reason
/**
* This is payload_size_basic - 2 bytes (as first two bytes are used for
* the close code
*/
static uint8_t const close_reason_size = 123;
}
// masks for fields in the basic header
static uint8_t const BHB0_OPCODE = 0x0F;
static uint8_t const BHB0_RSV3 = 0x10;
static uint8_t const BHB0_RSV2 = 0x20;
static uint8_t const BHB0_RSV1 = 0x40;
static uint8_t const BHB0_FIN = 0x80;
static uint8_t const BHB1_PAYLOAD = 0x7F;
static uint8_t const BHB1_MASK = 0x80;
static uint8_t const payload_size_code_16bit = 0x7E; // 126
static uint8_t const payload_size_code_64bit = 0x7F; // 127
typedef uint32_converter masking_key_type;
/// The constant size component of a WebSocket frame header
struct basic_header {
basic_header() : b0(0x00),b1(0x00) {}
basic_header(uint8_t p0, uint8_t p1) : b0(p0), b1(p1) {}
basic_header(opcode::value op, uint64_t size, bool fin, bool mask,
bool rsv1 = false, bool rsv2 = false, bool rsv3 = false) : b0(0x00),
b1(0x00)
{
if (fin) {
b0 |= BHB0_FIN;
}
if (rsv1) {
b0 |= BHB0_RSV1;
}
if (rsv2) {
b0 |= BHB0_RSV2;
}
if (rsv3) {
b0 |= BHB0_RSV3;
}
b0 |= (op & BHB0_OPCODE);
if (mask) {
b1 |= BHB1_MASK;
}
uint8_t basic_value;
if (size <= limits::payload_size_basic) {
basic_value = static_cast<uint8_t>(size);
} else if (size <= limits::payload_size_extended) {
basic_value = payload_size_code_16bit;
} else {
basic_value = payload_size_code_64bit;
}
b1 |= basic_value;
}
uint8_t b0;
uint8_t b1;
};
/// The variable size component of a WebSocket frame header
struct extended_header {
extended_header() {
std::fill_n(this->bytes,MAX_EXTENDED_HEADER_LENGTH,0x00);
}
extended_header(uint64_t payload_size) {
std::fill_n(this->bytes,MAX_EXTENDED_HEADER_LENGTH,0x00);
copy_payload(payload_size);
}
extended_header(uint64_t payload_size, uint32_t masking_key) {
std::fill_n(this->bytes,MAX_EXTENDED_HEADER_LENGTH,0x00);
// Copy payload size
int offset = copy_payload(payload_size);
// Copy Masking Key
uint32_converter temp32;
temp32.i = masking_key;
std::copy(temp32.c,temp32.c+4,bytes+offset);
}
uint8_t bytes[MAX_EXTENDED_HEADER_LENGTH];
private:
int copy_payload(uint64_t payload_size) {
int payload_offset = 0;
if (payload_size <= limits::payload_size_basic) {
payload_offset = 8;
} else if (payload_size <= limits::payload_size_extended) {
payload_offset = 6;
}
uint64_converter temp64;
temp64.i = lib::net::_htonll(payload_size);
std::copy(temp64.c+payload_offset,temp64.c+8,bytes);
return 8-payload_offset;
}
};
bool get_fin(basic_header const &h);
void set_fin(basic_header &h, bool value);
bool get_rsv1(basic_header const &h);
void set_rsv1(basic_header &h, bool value);
bool get_rsv2(basic_header const &h);
void set_rsv2(basic_header &h, bool value);
bool get_rsv3(basic_header const &h);
void set_rsv3(basic_header &h, bool value);
opcode::value get_opcode(basic_header const &h);
bool get_masked(basic_header const &h);
void set_masked(basic_header &h, bool value);
uint8_t get_basic_size(basic_header const &);
size_t get_header_len(basic_header const &);
unsigned int get_masking_key_offset(basic_header const &);
std::string write_header(basic_header const &, extended_header const &);
masking_key_type get_masking_key(basic_header const &, extended_header const &);
uint16_t get_extended_size(extended_header const &);
uint64_t get_jumbo_size(extended_header const &);
uint64_t get_payload_size(basic_header const &, extended_header const &);
size_t prepare_masking_key(masking_key_type const & key);
size_t circshift_prepared_key(size_t prepared_key, size_t offset);
// Functions for performing xor based masking and unmasking
template <typename input_iter, typename output_iter>
void byte_mask(input_iter b, input_iter e, output_iter o, masking_key_type
const & key, size_t key_offset = 0);
template <typename iter_type>
void byte_mask(iter_type b, iter_type e, masking_key_type const & key,
size_t key_offset = 0);
void word_mask_exact(uint8_t * input, uint8_t * output, size_t length,
masking_key_type const & key);
void word_mask_exact(uint8_t * data, size_t length, masking_key_type const &
key);
size_t word_mask_circ(uint8_t * input, uint8_t * output, size_t length,
size_t prepared_key);
size_t word_mask_circ(uint8_t * data, size_t length, size_t prepared_key);
/// Check whether the frame's FIN bit is set.
/**
* @param [in] h The basic header to extract from.
* @return True if the header's fin bit is set.
*/
inline bool get_fin(basic_header const & h) {
return ((h.b0 & BHB0_FIN) == BHB0_FIN);
}
/// Set the frame's FIN bit
/**
* @param [out] h Header to set.
* @param [in] value Value to set it to.
*/
inline void set_fin(basic_header & h, bool value) {
h.b0 = (value ? h.b0 | BHB0_FIN : h.b0 & ~BHB0_FIN);
}
/// check whether the frame's RSV1 bit is set
/**
* @param [in] h The basic header to extract from.
* @return True if the header's RSV1 bit is set.
*/
inline bool get_rsv1(const basic_header &h) {
return ((h.b0 & BHB0_RSV1) == BHB0_RSV1);
}
/// Set the frame's RSV1 bit
/**
* @param [out] h Header to set.
* @param [in] value Value to set it to.
*/
inline void set_rsv1(basic_header &h, bool value) {
h.b0 = (value ? h.b0 | BHB0_RSV1 : h.b0 & ~BHB0_RSV1);
}
/// check whether the frame's RSV2 bit is set
/**
* @param [in] h The basic header to extract from.
* @return True if the header's RSV2 bit is set.
*/
inline bool get_rsv2(const basic_header &h) {
return ((h.b0 & BHB0_RSV2) == BHB0_RSV2);
}
/// Set the frame's RSV2 bit
/**
* @param [out] h Header to set.
* @param [in] value Value to set it to.
*/
inline void set_rsv2(basic_header &h, bool value) {
h.b0 = (value ? h.b0 | BHB0_RSV2 : h.b0 & ~BHB0_RSV2);
}
/// check whether the frame's RSV3 bit is set
/**
* @param [in] h The basic header to extract from.
* @return True if the header's RSV3 bit is set.
*/
inline bool get_rsv3(const basic_header &h) {
return ((h.b0 & BHB0_RSV3) == BHB0_RSV3);
}
/// Set the frame's RSV3 bit
/**
* @param [out] h Header to set.
* @param [in] value Value to set it to.
*/
inline void set_rsv3(basic_header &h, bool value) {
h.b0 = (value ? h.b0 | BHB0_RSV3 : h.b0 & ~BHB0_RSV3);
}
/// Extract opcode from basic header
/**
* @param [in] h The basic header to extract from.
* @return The opcode value of the header.
*/
inline opcode::value get_opcode(const basic_header &h) {
return opcode::value(h.b0 & BHB0_OPCODE);
}
/// check whether the frame is masked
/**
* @param [in] h The basic header to extract from.
* @return True if the header mask bit is set.
*/
inline bool get_masked(basic_header const & h) {
return ((h.b1 & BHB1_MASK) == BHB1_MASK);
}
/// Set the frame's MASK bit
/**
* @param [out] h Header to set.
* @param value Value to set it to.
*/
inline void set_masked(basic_header & h, bool value) {
h.b1 = (value ? h.b1 | BHB1_MASK : h.b1 & ~BHB1_MASK);
}
/// Extracts the raw payload length specified in the basic header
/**
* A basic WebSocket frame header contains a 7 bit value that represents the
* payload size. There are two reserved values that are used to indicate that
* the actual payload size will not fit in 7 bits and that the full payload
* size is included in a separate field. The values are as follows:
*
* PAYLOAD_SIZE_CODE_16BIT (0x7E) indicates that the actual payload is less
* than 16 bit
*
* PAYLOAD_SIZE_CODE_64BIT (0x7F) indicates that the actual payload is less
* than 63 bit
*
* @param [in] h Basic header to read value from.
* @return The exact size encoded in h.
*/
inline uint8_t get_basic_size(const basic_header &h) {
return h.b1 & BHB1_PAYLOAD;
}
/// Calculates the full length of the header based on the first bytes.
/**
* A WebSocket frame header always has at least two bytes. Encoded within the
* first two bytes is all the information necessary to calculate the full
* (variable) header length. get_header_len() calculates the full header
* length for the given two byte basic header.
*
* @param h Basic frame header to extract size from.
* @return Full length of the extended header.
*/
inline size_t get_header_len(basic_header const & h) {
// TODO: check extensions?
// masking key offset represents the space used for the extended length
// fields
size_t size = BASIC_HEADER_LENGTH + get_masking_key_offset(h);
// If the header is masked there is a 4 byte masking key
if (get_masked(h)) {
size += 4;
}
return size;
}
/// Calculate the offset location of the masking key within the extended header
/**
* Calculate the offset location of the masking key within the extended header
* using information from its corresponding basic header
*
* @param h Corresponding basic header to calculate from.
*
* @return byte offset of the first byte of the masking key
*/
inline unsigned int get_masking_key_offset(const basic_header &h) {
if (get_basic_size(h) == payload_size_code_16bit) {
return 2;
} else if (get_basic_size(h) == payload_size_code_64bit) {
return 8;
} else {
return 0;
}
}
/// Generate a properly sized contiguous string that encodes a full frame header
/**
* Copy the basic header h and extended header e into a properly sized
* contiguous frame header string for the purposes of writing out to the wire.
*
* @param h The basic header to include
* @param e The extended header to include
*
* @return A contiguous string containing h and e
*/
inline std::string prepare_header(const basic_header &h, const
extended_header &e)
{
std::string ret;
ret.push_back(char(h.b0));
ret.push_back(char(h.b1));
ret.append(
reinterpret_cast<const char*>(e.bytes),
get_header_len(h)-BASIC_HEADER_LENGTH
);
return ret;
}
/// Extract the masking key from a frame header
/**
* Note that while read and written as an integer at times, this value is not
* an integer and should never be interpreted as one. Big and little endian
* machines will generate and store masking keys differently without issue as
* long as the integer values remain irrelivant.
*
* @param h The basic header to extract from
* @param e The extended header to extract from
*
* @return The masking key as an integer.
*/
inline masking_key_type get_masking_key(const basic_header &h, const
extended_header &e)
{
masking_key_type temp32;
if (!get_masked(h)) {
temp32.i = 0;
} else {
unsigned int offset = get_masking_key_offset(h);
std::copy(e.bytes+offset,e.bytes+offset+4,temp32.c);
}
return temp32;
}
/// Extract the extended size field from an extended header
/**
* It is the responsibility of the caller to verify that e is a valid extended
* header. This function assumes that e contains an extended payload size.
*
* @param e The extended header to extract from
*
* @return The size encoded in the extended header in host byte order
*/
inline uint16_t get_extended_size(const extended_header &e) {
uint16_converter temp16;
std::copy(e.bytes,e.bytes+2,temp16.c);
return ntohs(temp16.i);
}
/// Extract the jumbo size field from an extended header
/**
* It is the responsibility of the caller to verify that e is a valid extended
* header. This function assumes that e contains a jumbo payload size.
*
* @param e The extended header to extract from
*
* @return The size encoded in the extended header in host byte order
*/
inline uint64_t get_jumbo_size(const extended_header &e) {
uint64_converter temp64;
std::copy(e.bytes,e.bytes+8,temp64.c);
return lib::net::_ntohll(temp64.i);
}
/// Extract the full payload size field from a WebSocket header
/**
* It is the responsibility of the caller to verify that h and e together
* represent a valid WebSocket frame header. This function assumes only that h
* and e are valid. It uses information in the basic header to determine where
* to look for the payload_size
*
* @param h The basic header to extract from
* @param e The extended header to extract from
*
* @return The size encoded in the combined header in host byte order.
*/
inline uint64_t get_payload_size(const basic_header &h, const
extended_header &e)
{
uint8_t val = get_basic_size(h);
if (val <= limits::payload_size_basic) {
return val;
} else if (val == payload_size_code_16bit) {
return get_extended_size(e);
} else {
return get_jumbo_size(e);
}
}
/// Extract a masking key into a value the size of a machine word.
/**
* Machine word size must be 4 or 8.
*
* @param key Masking key to extract from
*
* @return prepared key as a machine word
*/
inline size_t prepare_masking_key(const masking_key_type& key) {
size_t low_bits = static_cast<size_t>(key.i);
if (sizeof(size_t) == 8) {
uint64_t high_bits = static_cast<size_t>(key.i);
return static_cast<size_t>((high_bits << 32) | low_bits);
} else {
return low_bits;
}
}
/// circularly shifts the supplied prepared masking key by offset bytes
/**
* Prepared_key must be the output of prepare_masking_key with the associated
* restrictions on the machine word size. offset must be greater than or equal
* to zero and less than sizeof(size_t).
*/
inline size_t circshift_prepared_key(size_t prepared_key, size_t offset) {
if (offset == 0) {
return prepared_key;
}
if (lib::net::is_little_endian()) {
size_t temp = prepared_key << (sizeof(size_t)-offset)*8;
return (prepared_key >> offset*8) | temp;
} else {
size_t temp = prepared_key >> (sizeof(size_t)-offset)*8;
return (prepared_key << offset*8) | temp;
}
}
/// Byte by byte mask/unmask
/**
* Iterator based byte by byte masking and unmasking for WebSocket payloads.
* Performs masking in place using the supplied key offset by the supplied
* offset number of bytes.
*
* This function is simple and can be done in place on input with arbitrary
* lengths and does not vary based on machine word size. It is slow.
*
* @param b Beginning iterator to start masking
*
* @param e Ending iterator to end masking
*
* @param o Beginning iterator to store masked results
*
* @param key 32 bit key to mask with.
*
* @param key_offset offset value to start masking at.
*/
template <typename input_iter, typename output_iter>
void byte_mask(input_iter first, input_iter last, output_iter result,
masking_key_type const & key, size_t key_offset)
{
size_t key_index = key_offset%4;
while (first != last) {
*result = *first ^ key.c[key_index++];
key_index %= 4;
++result;
++first;
}
}
/// Byte by byte mask/unmask (in place)
/**
* Iterator based byte by byte masking and unmasking for WebSocket payloads.
* Performs masking in place using the supplied key offset by the supplied
* offset number of bytes.
*
* This function is simple and can be done in place on input with arbitrary
* lengths and does not vary based on machine word size. It is slow.
*
* @param b Beginning iterator to start masking
*
* @param e Ending iterator to end masking
*
* @param key 32 bit key to mask with.
*
* @param key_offset offset value to start masking at.
*/
template <typename iter_type>
void byte_mask(iter_type b, iter_type e, masking_key_type const & key,
size_t key_offset)
{
byte_mask(b,e,b,key,key_offset);
}
/// Exact word aligned mask/unmask
/**
* Balanced combination of byte by byte and circular word by word masking.
* Best used to mask complete messages at once. Has much higher setup costs than
* word_mask_circ but works with exact sized buffers.
*
* Buffer based word by word masking and unmasking for WebSocket payloads.
* Masking is done in word by word chunks with the remainder not divisible by
* the word size done byte by byte.
*
* input and output must both be at least length bytes. Exactly length bytes
* will be written.
*
* @param input buffer to mask or unmask
*
* @param output buffer to store the output. May be the same as input.
*
* @param length length of data buffer
*
* @param key Masking key to use
*/
inline void word_mask_exact(uint8_t* input, uint8_t* output, size_t length,
const masking_key_type& key)
{
size_t prepared_key = prepare_masking_key(key);
size_t n = length/sizeof(size_t);
size_t* input_word = reinterpret_cast<size_t*>(input);
size_t* output_word = reinterpret_cast<size_t*>(output);
for (size_t i = 0; i < n; i++) {
output_word[i] = input_word[i] ^ prepared_key;
}
for (size_t i = n*sizeof(size_t); i < length; i++) {
output[i] = input[i] ^ key.c[i%4];
}
}
/// Exact word aligned mask/unmask (in place)
/**
* In place version of word_mask_exact
*
* @see word_mask_exact
*
* @param data buffer to read and write from
*
* @param length length of data buffer
*
* @param key Masking key to use
*/
inline void word_mask_exact(uint8_t* data, size_t length, const
masking_key_type& key)
{
word_mask_exact(data,data,length,key);
}
/// Circular word aligned mask/unmask
/**
* Performs a circular mask/unmask in word sized chunks using pre-prepared keys
* that store state between calls. Best for providing streaming masking or
* unmasking of small chunks at a time of a larger message. Requires that the
* underlying allocated size of the data buffer be a multiple of the word size.
* Data in the buffer after `length` will be overwritten only with the same
* values that were originally present.
*
* Buffer based word by word masking and unmasking for WebSocket payloads.
* Performs masking in place using the supplied key. Casts the data buffer to
* an array of size_t's and performs masking word by word. The underlying
* buffer size must be a muliple of the word size.
*
* word_mask returns a copy of prepared_key circularly shifted based on the
* length value. The returned value may be fed back into word_mask when more
* data is available.
*
* input and output must both have length at least:
* ceil(length/sizeof(size_t))*sizeof(size_t)
* Exactly that many bytes will be written, although only exactly length bytes
* will be changed (trailing bytes will be replaced without masking)
*
* @param data Character buffer to mask
*
* @param length Length of data
*
* @param prepared_key Prepared key to use.
*
* @return the prepared_key shifted to account for the input length
*/
inline size_t word_mask_circ(uint8_t * input, uint8_t * output, size_t length,
size_t prepared_key)
{
size_t n = length / sizeof(size_t); // whole words
size_t l = length - (n * sizeof(size_t)); // remaining bytes
size_t * input_word = reinterpret_cast<size_t *>(input);
size_t * output_word = reinterpret_cast<size_t *>(output);
// mask word by word
for (size_t i = 0; i < n; i++) {
output_word[i] = input_word[i] ^ prepared_key;
}
// mask partial word at the end
size_t start = length - l;
uint8_t * byte_key = reinterpret_cast<uint8_t *>(&prepared_key);
for (size_t i = 0; i < l; ++i) {
output[start+i] = input[start+i] ^ byte_key[i];
}
return circshift_prepared_key(prepared_key,l);
}
/// Circular word aligned mask/unmask (in place)
/**
* In place version of word_mask_circ
*
* @see word_mask_circ
*
* @param data Character buffer to read from and write to
*
* @param length Length of data
*
* @param prepared_key Prepared key to use.
*
* @return the prepared_key shifted to account for the input length
*/
inline size_t word_mask_circ(uint8_t* data, size_t length, size_t prepared_key){
return word_mask_circ(data,data,length,prepared_key);
}
/// Circular byte aligned mask/unmask
/**
* Performs a circular mask/unmask in byte sized chunks using pre-prepared keys
* that store state between calls. Best for providing streaming masking or
* unmasking of small chunks at a time of a larger message. Requires that the
* underlying allocated size of the data buffer be a multiple of the word size.
* Data in the buffer after `length` will be overwritten only with the same
* values that were originally present.
*
* word_mask returns a copy of prepared_key circularly shifted based on the
* length value. The returned value may be fed back into byte_mask when more
* data is available.
*
* @param data Character buffer to mask
*
* @param length Length of data
*
* @param prepared_key Prepared key to use.
*
* @return the prepared_key shifted to account for the input length
*/
inline size_t byte_mask_circ(uint8_t * input, uint8_t * output, size_t length,
size_t prepared_key)
{
uint32_converter key;
key.i = prepared_key;
for (size_t i = 0; i < length; ++i) {
output[i] = input[i] ^ key.c[i % 4];
}
return circshift_prepared_key(prepared_key,length % 4);
}
/// Circular byte aligned mask/unmask (in place)
/**
* In place version of byte_mask_circ
*
* @see byte_mask_circ
*
* @param data Character buffer to read from and write to
*
* @param length Length of data
*
* @param prepared_key Prepared key to use.
*
* @return the prepared_key shifted to account for the input length
*/
inline size_t byte_mask_circ(uint8_t* data, size_t length, size_t prepared_key){
return byte_mask_circ(data,data,length,prepared_key);
}
} // namespace frame
} // namespace websocketpp
#endif //WEBSOCKETPP_FRAME_HPP
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