utility.cpp File Reference

Various helpful templates, classes and functions. More...

#include <config.h>
#include <cstdio>
#include <cstring>
#include <cctype>
#include <cstdint>
#include <cassert>
#include <exception>
#include <stdexcept>
#include "utility.h"

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Functions
static const char *	title_adjusted (const char *title)
int	compare_title_order (const std::string &astr, const std::string &bstr)
	Compare titles, ignoring 'a', 'an', or 'the'. More...
static int	count_words (const char *start, const char *end)
	Count words. More...
bool	compare_person_or_title (const std::string &astr, const std::string &bstr)
	Compare an artist's name, which might be a person's name or a band. More...
std::string	makeIdentity (std::string s)
	Remove whitespace and other desireable characters, and make all lowercase for use as an ID. More...
std::vector< std::string >	split_string (const std::string &value)
	Split a string to words. More...
std::vector< std::string >	split_string (const std::string &value, const std::string separator, const bool include_empty_last)
	Split a string on a fixed pattern. More...
std::string	join_strings (const std::vector< std::string > &list, const std::string joiner)
	Join strings together. More...
lamerkey_t	compute_crc (const char *data, lamerkey_t divisor, lamerkey_t remainder)
	Compute a key from a string using a CRC algorithm. More...
lamerkey_t	create_key_from_string (const char *source)
	Generate a key from a string. More...
char *	lamer_cipher (const char *keystr, const char *item)
	Encipher or decipher an item based on a key. More...
std::string	lamer_cipher (const std::string &keystr, const std::string &item)

Variables
static const lamerkey_t	lamer_crc_generator = 0xae060ed2
	Symmetrical cipher using a text string as a key. More...
static const int	lamer_keybits = sizeof (lamerkey_t) * 8 - 1

Detailed Description

Various helpful templates, classes and functions.

• pianod

  Author

  Perette Barella

  Date

  2014-12-08

  Copyright

  Copyright 2014-2021 Devious Fish. All rights reserved.

Function Documentation

compare_person_or_title()

bool compare_person_or_title	(	const std::string &	astr,
		const std::string &	bstr
	)

Compare an artist's name, which might be a person's name or a band.

If it's a title, it may have 'a', 'an', or 'the', or maybe not. If it's a person, it may be /first last/ or /last, first/.

Parameters

astr	First title.
bstr	Second title.

Returns

true if values are equivalent, false if not.

Warning

Because this function guesses type of name by looking at the parameters, int return would not be sort-consistent. Thus, return type bool.

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compare_title_order()

int compare_title_order	(	const std::string &	astr,
		const std::string &	bstr
	)

Compare titles, ignoring 'a', 'an', or 'the'.

Parameters

astr	First title.
bstr	Second title.

Returns

< 0 if astr < bstr; 0 if equal; >0 if astr > bstr.

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compute_crc()

lamerkey_t compute_crc	(	const char *	data,
		lamerkey_t	divisor,
		lamerkey_t	remainder
	)

Compute a key from a string using a CRC algorithm.

If VARIABLE_SIZE_DIVISORS is set, the CRC length is determined dynamically by the value in the divisor. Otherwise, it is determined by the length of the generator set in constants above.

Parameters

data	The string to use to generate the key.
divisor	The generator/divisor for performing the CRC.
remainder	For unit testing; set to 0 for generating keys. For test purposes, reinvoke this function pass the function's result for remainder. The result should be 0; if not, it's broken.

Returns

The computed key.

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count_words()

static int count_words ( const char *  start, const char *  end  )

static

Count words.

Parameters

start	Start of string to count.
end	End of string to count.

Returns

Number of words between start and end.

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create_key_from_string()

lamerkey_t create_key_from_string

(

const char *

source

)

Generate a key from a string.

Parameters

source

The string.

Returns

The key.

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join_strings()

std::string join_strings	(	const std::vector< std::string > &	list,
		const std::string	joiner
	)

Join strings together.

Parameters

list	The strings to join.
joiner	The string to insert between list strings.

Returns

The assembled string.

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lamer_cipher() [1/2]

char* lamer_cipher	(	const char *	keystr,
		const char *	item
	)

Encipher or decipher an item based on a key.

Parameters

keystr	The string to use to generate a key.
item	The string to encipher or decipher.

Returns

The enciphered/deciphered string, freshly malloced; or NULL on error. Original strings are unmodified.

Warning

Allocates space on the heap for the returned string. Caller must free() this when done with the string.

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lamer_cipher() [2/2]

std::string lamer_cipher	(	const std::string &	keystr,
		const std::string &	item
	)

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makeIdentity()

std::string makeIdentity

(

std::string

s

)

Remove whitespace and other desireable characters, and make all lowercase for use as an ID.

split_string() [1/2]

std::vector<std::string> split_string

(

const std::string &

value

)

Split a string to words.

Mid-word punctuation is retained.

• "Don't stop thinking" -> "Don't", "stop", "thinking"
• "'Lyin' Eyes" -> "Lyin", "eyes"

  Parameters

  value

  The string to split.

  Returns

  Words.

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split_string() [2/2]

std::vector<std::string> split_string	(	const std::string &	value,
		const std::string	separator,
		const bool	include_empty_last
	)

Split a string on a fixed pattern.

Parameters

value	The string to split.
separator	The pattern for splitting the string. It is removed from the result strings.
include_empty_last	If false, then if the separator occurs at end of string, then the null space following it is omitted from the results.

Returns

1 or more strings.

title_adjusted()

static const char* title_adjusted ( const char *  title )

inlinestatic

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Variable Documentation

lamer_crc_generator

const lamerkey_t lamer_crc_generator = 0xae060ed2

static

Symmetrical cipher using a text string as a key.

Author

Perette Barella

Date

2014-03-11

Copyright

Copyright 2012-2014 Devious Fish. All rights reserved.

This is a simplistic cipher intended to be difficult enough to inconvenience hand deciphering, but nothing truly secure. In short: Enough to keep the riff-raff out.

Usernames cannot be changed in pianod. The user's name will be used to generate the key by feeding it through a 32-bit CRC generator. Note that a 32-bit generator yields 31 bits of CRC. We will then encipher the password symetrically with the key/CRC as follows:

For each character, starting at the beginning:
XOR the character with the least significant bits of
the CRC as follows:
0x01–0x1f (000x xxxx): Assert(0), or do nothing.
0x20–0x3f (001x xxxx): XOR 5 bits
0x40–0x7f (01xx xxxx): XOR 6 bits
0x80–0xff (1xxx xxxx), XOR 7 bits of the CRC.
Rotate right the CRC by the number of bits "consumed".

This is certainly not NSA quality, and there are hazards of inventing your own encryption system; but given the inherent insecurity of anyone being able to strategically add printf ("%s's password is %s\n", user->password, user->name) and recompiling, this is adequate. It is, after all, only a music server.

lamer_keybits

const int lamer_keybits = sizeof (lamerkey_t) * 8 - 1

static