ubase64.c

/*
 * SPDX-License-Identifier: ISC
 * SPDX-URL: https://spdx.org/licenses/ISC.html
 *
 * Copyright (C) 2005-2012 Atheme Project (http://atheme.org/)
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * atheme-services: A collection of minimalist IRC services
 * ubase64.c: ircu base64 routines.
 */

#include <atheme.h>
#include "internal.h"

/*
 * base64touint() written 01/20/06 by jilles, for getting IP addresses.
 */

static const char ub64_alphabet[65] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789[]";
#define __ '\377'
static const char ub64_lookuptab[256] = {
__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, /* 0-15 */
__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, /* 16-31 */
__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, /* 32-47 */
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, __, __, __, __, __, __, /* 48-63 */
__, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, /* 64-79 */
15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 62, __, 63, __, __, /* 80-95 */
__, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, /* 96-111 */
41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, __, __, __, __, __, /* 112-127 */
__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __ };
#undef __

const char *
uinttobase64(char *buf, uint64_t v, int64_t count)
{
	buf[count] = '\0';

	while (count > 0)
	{
		buf[--count] = ub64_alphabet[v & 63];
		v >>= 6;
	}

	return buf;
}

unsigned int
base64touint(const char *buf)
{
	int bits;
	unsigned int v = 0;
	int count = 6;

	while (--count >= 0 && (bits = ub64_lookuptab[255 & *buf++]) != '\377')
		v = v << 6 | bits;
	return v;
}

void
decode_p10_ip(const char *b64, char ipstring[HOSTIPLEN + 1])
{
	struct in_addr ip;
	char buf[4];
	int i, j;
	size_t len;

	ipstring[0] = '\0';
	len = strlen(b64);
	if (len == 6)
	{
		ip.s_addr = ntohl(base64touint(b64));
		if (!inet_ntop(AF_INET, &ip, ipstring, HOSTIPLEN + 1))
			ipstring[0] = '\0';
	}
	else if (len == 24 || (len < 24 && strchr(b64, '_')))
	{
		/* why is this encoded in such a complicated manner? */
		i = 0;
		j = 0;
		while (b64[i] != '\0')
		{
			if (b64[i] == '_')
			{
				i++;
				if (j > HOSTIPLEN - 2)
					break;
				if (j == 0)
					ipstring[j++] = '0';
				if (b64[i] == '\0')
					ipstring[j++] = ':';
				ipstring[j++] = ':';
			}
			else
			{
				if (j > HOSTIPLEN - 5)
					break;
				if (j != 0)
					ipstring[j++] = ':';
				mowgli_strlcpy(buf, b64 + i, 4);
				i += strlen(buf);
				j += sprintf(ipstring + j, "%x", (uint16_t)base64touint(buf));
			}
		}
		ipstring[j] = '\0';
	}
}

/* vim:cinoptions=>s,e0,n0,f0,{0,}0,^0,=s,ps,t0,c3,+s,(2s,us,)20,*30,gs,hs
 * vim:ts=8
 * vim:sw=8
 * vim:noexpandtab
 */