header.c 2.35 KB
/**
 * \file
 * Interface implementation for HTTP header class.
 *
 * \author	Georg Hopp
 *
 * \copyright
 * Copyright (C) 2012  Georg Hopp
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <stdlib.h>
#include <string.h>
#include <ctype.h>

#include "class.h"
#include "interface/class.h"

#include "http/header.h"

/**
 * SDBM hashing algorithm:
 *
 * this algorithm was created for sdbm (a public-domain reimplementation of
 * ndbm) database library. it was found to do well in scrambling bits,
 * causing better distribution of the keys and fewer splits. it also happens
 * to be a good general hashing function with good distribution. the actual
 * function is hash(i) = hash(i - 1) * 65599 + str[i]; what is included below
 * is the faster version used in gawk. [there is even a faster, duff-device
 * version] the magic constant 65599 was picked out of thin air while
 * experimenting with different constants, and turns out to be a prime. this
 * is one of the algorithms used in berkeley db (see sleepycat) and elsewhere. 
 */
static
inline
unsigned long
sdbm(unsigned char * str)
{
	unsigned long hash = 0;
	int c;

	while ((c = tolower(*str++)))
		hash = c + (hash << 6) + (hash << 16) - hash;

	return hash;
}

static
void
ctor(void * _this, va_list * params) {
	HttpHeader this = _this;
	char * name;
	char * value;

	name  = va_arg(* params, char *);
	value = va_arg(* params, char *);
	
	this->name = malloc(strlen(name) + 1);
	strcpy(this->name, name);

	this->hash = sdbm((unsigned char *)name);

	this->value = malloc(strlen(value) + 1);
	strcpy(this->value, value);
}

static
void
dtor(void * _this)
{
	HttpHeader this = _this;

	free(this->name);
	free(this->value);
}

INIT_IFACE(Class, ctor, dtor, NULL);
CREATE_CLASS(HttpHeader, NULL, IFACE(Class));

// vim: set ts=4 sw=4: