/*
 *  Authentication helper functions.
 *
 *  Copyright (C) 2014 Andreas Steinmetz <ast@domdv.de>
 *
 *  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 2 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, write to the Free Software Foundation, Inc.,
 *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#include <string.h>
#include <stdint.h>
#include "auth.h"

#define MD5_SIZE	16
#define MD5_HEX		(MD5_SIZE<<1)
#define MD5(a)		uint8_t a[MD5_SIZE]

#define AUTH_SESS	0x13
#define AUTH_SESS_REPLY	0x14

#define AUTH_SUCCESS	0x00
#define AUTH_FAIL	0x01

#define TYPE_METHODS	0x00
#define TYPE_PLAIN	0x01
#define TYPE_RFC2069	0x03
#define TYPE_RFC2617	0x04

#define MAX_USER	32
#define MAX_PASS	32
#define MAX_REALM	64
#define MAX_NONCE	MD5_HEX
#define MAX_CNONCE	MD5_HEX
#define MAX_RESPONSE	MD5_HEX
#define MAX_QOP		8

#define URI		"/RedirectionService"
#define NC		"00000002"
#define QOP		"auth"
#define METHOD		"POST"

#define put_header(data,length,type)			\
do {							\
	*data++=AUTH_SESS;				\
	*data++=AUTH_SUCCESS;				\
	*data++=0;					\
	*data++=0;					\
	*data++=type;					\
	*data++=(unsigned char)(length);		\
	*data++=(unsigned char)(length>>8);		\
	*data++=(unsigned char)(length>>16);		\
	*data++=(unsigned char)(length>>24);		\
} while(0)

#define put_element(data,element)			\
do {							\
	int length=strlen(element);			\
	*data++=(unsigned char)length;			\
	memcpy(data,element,length);			\
	data+=length;					\
} while(0)

#define get_header(data,len,method,status)		\
do {							\
	if(data[0]!=AUTH_SESS_REPLY)goto out;		\
	status=data[1];					\
	if(data[4]!=method)goto out;			\
	len=data[8];					\
	len<<=8;					\
	len|=data[7];					\
	len<<=8;					\
	len|=data[6];					\
	len<<=8;					\
	len|=data[5];					\
} while(0)

#define get_element(data,len,element,max)		\
do {							\
	int blen=*data++;				\
	if(blen>--len||blen>max)goto out;		\
	memcpy(element,data,blen);			\
	element[blen]=0;				\
	data+=blen;					\
	len-=blen;					\
} while(0)

typedef struct
{
	uint32_t md5[4];
	uint32_t total;
	uint8_t bfr[64];
	uint8_t size;
} md5_ctx;

static void md5block(uint32_t *md5,uint8_t *block)
{
	register uint32_t a;
	register uint32_t b;
	register uint32_t c;
	register uint32_t d;
	uint32_t bfr[16];

	a=block[3];
	a<<=8;
	a+=block[2];
	a<<=8;
	a+=block[1];
	a<<=8;
	bfr[0]=a+block[0];

	a=block[7];
	a<<=8;
	a+=block[6];
	a<<=8;
	a+=block[5];
	a<<=8;
	bfr[1]=a+block[4];

	a=block[11];
	a<<=8;
	a+=block[10];
	a<<=8;
	a+=block[9];
	a<<=8;
	bfr[2]=a+block[8];

	a=block[15];
	a<<=8;
	a+=block[14];
	a<<=8;
	a+=block[13];
	a<<=8;
	bfr[3]=a+block[12];

	a=block[19];
	a<<=8;
	a+=block[18];
	a<<=8;
	a+=block[17];
	a<<=8;
	bfr[4]=a+block[16];

	a=block[23];
	a<<=8;
	a+=block[22];
	a<<=8;
	a+=block[21];
	a<<=8;
	bfr[5]=a+block[20];

	a=block[27];
	a<<=8;
	a+=block[26];
	a<<=8;
	a+=block[25];
	a<<=8;
	bfr[6]=a+block[24];

	a=block[31];
	a<<=8;
	a+=block[30];
	a<<=8;
	a+=block[29];
	a<<=8;
	bfr[7]=a+block[28];

	a=block[35];
	a<<=8;
	a+=block[34];
	a<<=8;
	a+=block[33];
	a<<=8;
	bfr[8]=a+block[32];

	a=block[39];
	a<<=8;
	a+=block[38];
	a<<=8;
	a+=block[37];
	a<<=8;
	bfr[9]=a+block[36];

	a=block[43];
	a<<=8;
	a+=block[42];
	a<<=8;
	a+=block[41];
	a<<=8;
	bfr[10]=a+block[40];

	a=block[47];
	a<<=8;
	a+=block[46];
	a<<=8;
	a+=block[45];
	a<<=8;
	bfr[11]=a+block[44];

	a=block[51];
	a<<=8;
	a+=block[50];
	a<<=8;
	a+=block[49];
	a<<=8;
	bfr[12]=a+block[48];

	a=block[55];
	a<<=8;
	a+=block[54];
	a<<=8;
	a+=block[53];
	a<<=8;
	bfr[13]=a+block[52];

	a=block[59];
	a<<=8;
	a+=block[58];
	a<<=8;
	a+=block[57];
	a<<=8;
	bfr[14]=a+block[56];

	a=block[63];
	a<<=8;
	a+=block[62];
	a<<=8;
	a+=block[61];
	a<<=8;
	bfr[15]=a+block[60];

	a=md5[0];
	b=md5[1];
	c=md5[2];
	d=md5[3];

	a+=bfr[0];
	a+=0xd76aa478;
	a+=d^(b&(c^d));
	a=(a<<7)|(a>>25);
	a+=b;
	d+=bfr[1];
	d+=0xe8c7b756;
	d+=c^(a&(b^c));
	d=(d<<12)|(d>>20);
	d+=a;
	c+=bfr[2];
	c+=0x242070db;
	c+=b^(d&(a^b));
	c=(c<<17)|(c>>15);
	c+=d;
	b+=bfr[3];
	b+=0xc1bdceee;
	b+=a^(c&(d^a));
	b=(b<<22)|(b>>10);
	b+=c;
	a+=bfr[4];
	a+=0xf57c0faf;
	a+=d^(b&(c^d));
	a=(a<<7)|(a>>25);
	a+=b;
	d+=bfr[5];
	d+=0x4787c62a;
	d+=c^(a&(b^c));
	d=(d<<12)|(d>>20);
	d+=a;
	c+=bfr[6];
	c+=0xa8304613;
	c+=b^(d&(a^b));
	c=(c<<17)|(c>>15);
	c+=d;
	b+=bfr[7];
	b+=0xfd469501;
	b+=a^(c&(d^a));
	b=(b<<22)|(b>>10);
	b+=c;
	a+=bfr[8];
	a+=0x698098d8;
	a+=d^(b&(c^d));
	a=(a<<7)|(a>>25);
	a+=b;
	d+=bfr[9];
	d+=0x8b44f7af;
	d+=c^(a&(b^c));
	d=(d<<12)|(d>>20);
	d+=a;
	c+=bfr[10];
	c+=0xffff5bb1;
	c+=b^(d&(a^b));
	c=(c<<17)|(c>>15);
	c+=d;
	b+=bfr[11];
	b+=0x895cd7be;
	b+=a^(c&(d^a));
	b=(b<<22)|(b>>10);
	b+=c;
	a+=bfr[12];
	a+=0x6b901122;
	a+=d^(b&(c^d));
	a=(a<<7)|(a>>25);
	a+=b;
	d+=bfr[13];
	d+=0xfd987193;
	d+=c^(a&(b^c));
	d=(d<<12)|(d>>20);
	d+=a;
	c+=bfr[14];
	c+=0xa679438e;
	c+=b^(d&(a^b));
	c=(c<<17)|(c>>15);
	c+=d;
	b+=bfr[15];
	b+=0x49b40821;
	b+=a^(c&(d^a));
	b=(b<<22)|(b>>10);
	b+=c;

	a+=bfr[1];
	a+=0xf61e2562;
	a+=c^(d&(b^c));
	a=(a<<5)|(a>>27);
	a+=b;
	d+=bfr[6];
	d+=0xc040b340;
	d+=b^(c&(a^b));
	d=(d<<9)|(d>>23);
	d+=a;
	c+=bfr[11];
	c+=0x265e5a51;
	c+=a^(b&(d^a));
	c=(c<<14)|(c>>18);
	c+=d;
	b+=bfr[0];
	b+=0xe9b6c7aa;
	b+=d^(a&(c^d));
	b=(b<<20)|(b>>12);
	b+=c;
	a+=bfr[5];
	a+=0xd62f105d;
	a+=c^(d&(b^c));
	a=(a<<5)|(a>>27);
	a+=b;
	d+=bfr[10];
	d+=0x02441453;
	d+=b^(c&(a^b));
	d=(d<<9)|(d>>23);
	d+=a;
	c+=bfr[15];
	c+=0xd8a1e681;
	c+=a^(b&(d^a));
	c=(c<<14)|(c>>18);
	c+=d;
	b+=bfr[4];
	b+=0xe7d3fbc8;
	b+=d^(a&(c^d));
	b=(b<<20)|(b>>12);
	b+=c;
	a+=bfr[9];
	a+=0x21e1cde6;
	a+=c^(d&(b^c));
	a=(a<<5)|(a>>27);
	a+=b;
	d+=bfr[14];
	d+=0xc33707d6;
	d+=b^(c&(a^b));
	d=(d<<9)|(d>>23);
	d+=a;
	c+=bfr[3];
	c+=0xf4d50d87;
	c+=a^(b&(d^a));
	c=(c<<14)|(c>>18);
	c+=d;
	b+=bfr[8];
	b+=0x455a14ed;
	b+=d^(a&(c^d));
	b=(b<<20)|(b>>12);
	b+=c;
	a+=bfr[13];
	a+=0xa9e3e905;
	a+=c^(d&(b^c));
	a=(a<<5)|(a>>27);
	a+=b;
	d+=bfr[2];
	d+=0xfcefa3f8;
	d+=b^(c&(a^b));
	d=(d<<9)|(d>>23);
	d+=a;
	c+=bfr[7];
	c+=0x676f02d9;
	c+=a^(b&(d^a));
	c=(c<<14)|(c>>18);
	c+=d;
	b+=bfr[12];
	b+=0x8d2a4c8a;
	b+=d^(a&(c^d));
	b=(b<<20)|(b>>12);
	b+=c;

	a+=bfr[5];
	a+=0xfffa3942;
	a+=b^c^d;
	a=(a<<4)|(a>>28);
	a+=b;
	d+=bfr[8];
	d+=0x8771f681;
	d+=a^b^c;
	d=(d<<11)|(d>>21);
	d+=a;
	c+=bfr[11];
	c+=0x6d9d6122;
	c+=d^a^b;
	c=(c<<16)|(c>>16);
	c+=d;
	b+=bfr[14];
	b+=0xfde5380c;
	b+=c^d^a;
	b=(b<<23)|(b>>9);
	b+=c;
	a+=bfr[1];
	a+=0xa4beea44;
	a+=b^c^d;
	a=(a<<4)|(a>>28);
	a+=b;
	d+=bfr[4];
	d+=0x4bdecfa9;
	d+=a^b^c;
	d=(d<<11)|(d>>21);
	d+=a;
	c+=bfr[7];
	c+=0xf6bb4b60;
	c+=d^a^b;
	c=(c<<16)|(c>>16);
	c+=d;
	b+=bfr[10];
	b+=0xbebfbc70;
	b+=c^d^a;
	b=(b<<23)|(b>>9);
	b+=c;
	a+=bfr[13];
	a+=0x289b7ec6;
	a+=b^c^d;
	a=(a<<4)|(a>>28);
	a+=b;
	d+=bfr[0];
	d+=0xeaa127fa;
	d+=a^b^c;
	d=(d<<11)|(d>>21);
	d+=a;
	c+=bfr[3];
	c+=0xd4ef3085;
	c+=d^a^b;
	c=(c<<16)|(c>>16);
	c+=d;
	b+=bfr[6];
	b+=0x04881d05;
	b+=c^d^a;
	b=(b<<23)|(b>>9);
	b+=c;
	a+=bfr[9];
	a+=0xd9d4d039;
	a+=b^c^d;
	a=(a<<4)|(a>>28);
	a+=b;
	d+=bfr[12];
	d+=0xe6db99e5;
	d+=a^b^c;
	d=(d<<11)|(d>>21);
	d+=a;
	c+=bfr[15];
	c+=0x1fa27cf8;
	c+=d^a^b;
	c=(c<<16)|(c>>16);
	c+=d;
	b+=bfr[2];
	b+=0xc4ac5665;
	b+=c^d^a;
	b=(b<<23)|(b>>9);
	b+=c;

	a+=bfr[0];
	a+=0xf4292244;
	a+=c^(b|~d);
	a=(a<<6)|(a>>26);
	a+=b;
	d+=bfr[7];
	d+=0x432aff97;
	d+=b^(a|~c);
	d=(d<<10)|(d>>22);
	d+=a;
	c+=bfr[14];
	c+=0xab9423a7;
	c+=a^(d|~b);
	c=(c<<15)|(c>>17);
	c+=d;
	b+=bfr[5];
	b+=0xfc93a039;
	b+=d^(c|~a);
	b=(b<<21)|(b>>11);
	b+=c;
	a+=bfr[12];
	a+=0x655b59c3;
	a+=c^(b|~d);
	a=(a<<6)|(a>>26);
	a+=b;
	d+=bfr[3];
	d+=0x8f0ccc92;
	d+=b^(a|~c);
	d=(d<<10)|(d>>22);
	d+=a;
	c+=bfr[10];
	c+=0xffeff47d;
	c+=a^(d|~b);
	c=(c<<15)|(c>>17);
	c+=d;
	b+=bfr[1];
	b+=0x85845dd1;
	b+=d^(c|~a);
	b=(b<<21)|(b>>11);
	b+=c;
	a+=bfr[8];
	a+=0x6fa87e4f;
	a+=c^(b|~d);
	a=(a<<6)|(a>>26);
	a+=b;
	d+=bfr[15];
	d+=0xfe2ce6e0;
	d+=b^(a|~c);
	d=(d<<10)|(d>>22);
	d+=a;
	c+=bfr[6];
	c+=0xa3014314;
	c+=a^(d|~b);
	c=(c<<15)|(c>>17);
	c+=d;
	b+=bfr[13];
	b+=0x4e0811a1;
	b+=d^(c|~a);
	b=(b<<21)|(b>>11);
	b+=c;
	a+=bfr[4];
	a+=0xf7537e82;
	a+=c^(b|~d);
	a=(a<<6)|(a>>26);
	a+=b;
	d+=bfr[11];
	d+=0xbd3af235;
	d+=b^(a|~c);
	d=(d<<10)|(d>>22);
	d+=a;
	c+=bfr[2];
	c+=0x2ad7d2bb;
	c+=a^(d|~b);
	c=(c<<15)|(c>>17);
	c+=d;
	b+=bfr[9];
	b+=0xeb86d391;
	b+=d^(c|~a);
	b=(b<<21)|(b>>11);
	b+=c;

	md5[0]+=a;
	md5[1]+=b;
	md5[2]+=c;
	md5[3]+=d;
}

static void md5init(register md5_ctx *ptr)
{
	ptr->total=ptr->size=0;
	ptr->md5[0]=0x67452301;
	ptr->md5[1]=0xefcdab89;
	ptr->md5[2]=0x98badcfe;
	ptr->md5[3]=0x10325476;
}

static void md5next(register uint8_t *data,register uint32_t length,
	register md5_ctx *ptr)
{
	register uint32_t i;

	ptr->total+=length;

	for(i=ptr->size;(i&63)&&length;length--)ptr->bfr[i++]=*data++;

	if(i==64)
	{
		i=0;
		md5block(ptr->md5,ptr->bfr);
	}

	for(;length>63;data+=64,length-=64)
		md5block(ptr->md5,data);

	for(;length;length--)ptr->bfr[i++]=*data++;

	ptr->size=(uint8_t)(i);
}

static void md5end(register uint8_t *result,register md5_ctx *ptr)
{
	register uint32_t i=ptr->size;

	ptr->bfr[i++]=0x80;
	if(i>56)
	{
		for(;i<64;i++)ptr->bfr[i]=0;
		i=0;
		md5block(ptr->md5,ptr->bfr);
	}
	for(;i<56;i++)ptr->bfr[i]=0;

	ptr->bfr[56]=(uint8_t)((ptr->total)<<3);
	ptr->bfr[57]=(uint8_t)((ptr->total)>>5);
	ptr->bfr[58]=(uint8_t)((ptr->total)>>13);
	ptr->bfr[59]=(uint8_t)((ptr->total)>>21);
	ptr->bfr[60]=(uint8_t)((ptr->total)>>29);
	ptr->bfr[61]=0;
	ptr->bfr[62]=0;
	ptr->bfr[63]=0;

	md5block(ptr->md5,ptr->bfr);

	result[ 0]=(uint8_t) (ptr->md5[0]);
	result[ 1]=(uint8_t)((ptr->md5[0])>>8);
	result[ 2]=(uint8_t)((ptr->md5[0])>>16);
	result[ 3]=(uint8_t)((ptr->md5[0])>>24);
	result[ 4]=(uint8_t) (ptr->md5[1]);
	result[ 5]=(uint8_t)((ptr->md5[1])>>8);
	result[ 6]=(uint8_t)((ptr->md5[1])>>16);
	result[ 7]=(uint8_t)((ptr->md5[1])>>24);
	result[ 8]=(uint8_t) (ptr->md5[2]);
	result[ 9]=(uint8_t)((ptr->md5[2])>>8);
	result[10]=(uint8_t)((ptr->md5[2])>>16);
	result[11]=(uint8_t)((ptr->md5[2])>>24);
	result[12]=(uint8_t) (ptr->md5[3]);
	result[13]=(uint8_t)((ptr->md5[3])>>8);
	result[14]=(uint8_t)((ptr->md5[3])>>16);
	result[15]=(uint8_t)((ptr->md5[3])>>24);
}

static void bin2hex(unsigned char *bin,int len,char *hex)
{
	while(len--)
	{
		*hex=*bin>>4;
		if(*hex>9)*hex+++='a'-10;
		else *hex+++='0';
		*hex=*bin++&0xf;
		if(*hex>9)*hex+++='a'-10;
		else *hex+++='0';
	}
	*hex=0;
}

int authenticate(int mode,char *user,char *pass,
	int (*io)(void *parm,unsigned char *data,int len,int mode),void *parm)
{
	int r=-1;
	int len;
	int status;
	int method;
	unsigned char *ptr;
	unsigned char bfr[512];
	char realm[MAX_REALM+1];
	char nonce[MAX_NONCE+1];
	char cnonce[MAX_CNONCE+1];
	char response[MAX_RESPONSE+1];
	char qop[MAX_QOP+1];
	char tmp[MD5_HEX+1];
	MD5(md5);
	md5_ctx ctx;

	if(strlen(user)>MAX_USER||strlen(pass)>MAX_PASS)return -1;

	ptr=bfr;
	put_header(ptr,0,TYPE_METHODS);
	if(io(parm,bfr,9,WRITE))goto out;

	if(io(parm,bfr,9,READ))goto out;
	get_header(bfr,len,TYPE_METHODS,status);
	if(status!=AUTH_SUCCESS)goto out;
	if(len>sizeof(bfr))goto out;
	if(io(parm,bfr,len,READ))goto out;

	for(method=0,ptr=bfr;len;len--)
	{
		if(!*ptr||*ptr>=sizeof(method)*8)return -1;
		method|=1<<*ptr++;
	}

	if(method&(1<<TYPE_RFC2617))method=TYPE_RFC2617;
	else if(method&(1<<TYPE_RFC2069))method=TYPE_RFC2069;
	else if(method&(1<<TYPE_PLAIN))method=TYPE_PLAIN;
	else goto out;

	switch(method)
	{
	case TYPE_PLAIN:
		len=strlen(user)+strlen(pass)+2;
		ptr=bfr;
		put_header(ptr,len,method);
		put_element(ptr,user);
		put_element(ptr,pass);
		break;

	case TYPE_RFC2069:
	case TYPE_RFC2617:
		len=strlen(user)+strlen(URI)+(method==TYPE_RFC2617?8:7);
		ptr=bfr;
		put_header(ptr,len,method);
		put_element(ptr,user);
		*ptr++=0;
		*ptr++=0;
		put_element(ptr,URI);
		*ptr++=0;
		*ptr++=0;
		*ptr++=0;
		*ptr=0;
		if(io(parm,bfr,len+9,WRITE))goto out;

		if(io(parm,bfr,9,READ))goto out;
		get_header(bfr,len,method,status);
		if(status!=AUTH_FAIL)goto out;
		if(len>sizeof(bfr))goto out;
		if(io(parm,bfr,len,READ))goto out;
		ptr=bfr;
		if(!len)goto out;
		get_element(ptr,len,realm,MAX_REALM);
		if(!len)goto out;
		get_element(ptr,len,nonce,MAX_NONCE);
		if(!len)*qop=0;
		else get_element(ptr,len,qop,MAX_QOP);

		if(method==TYPE_RFC2617)
		{
			if(strcmp(qop,QOP))goto out;
		}
		else if(*qop)goto out;

		if(io(parm,bfr,16,RANDOM))goto out;
		md5init(&ctx);
		md5next(bfr,16,&ctx);
		md5end(md5,&ctx);
		bin2hex(md5,MD5_SIZE,cnonce);

		md5init(&ctx);
		md5next((uint8_t *)user,strlen(user),&ctx);
		md5next((uint8_t *)":",1,&ctx);
		md5next((uint8_t *)realm,strlen(realm),&ctx);
		md5next((uint8_t *)":",1,&ctx);
		md5next((uint8_t *)pass,strlen(pass),&ctx);
		md5end(md5,&ctx);
		bin2hex(md5,MD5_SIZE,tmp);

		md5init(&ctx);
		md5next((uint8_t *)METHOD,strlen(METHOD),&ctx);
		md5next((uint8_t *)":",1,&ctx);
		md5next((uint8_t *)URI,strlen(URI),&ctx);
		md5end(md5,&ctx);
		bin2hex(md5,MD5_SIZE,response);

		md5init(&ctx);
		md5next((uint8_t *)tmp,strlen(tmp),&ctx);
		md5next((uint8_t *)":",1,&ctx);
		md5next((uint8_t *)nonce,strlen(nonce),&ctx);
		md5next((uint8_t *)":",1,&ctx);
		if(method==TYPE_RFC2617)
		{
			md5next((uint8_t *)NC,strlen(NC),&ctx);
			md5next((uint8_t *)":",1,&ctx);
			md5next((uint8_t *)cnonce,strlen(cnonce),&ctx);
			md5next((uint8_t *)":",1,&ctx);
			md5next((uint8_t *)qop,strlen(qop),&ctx);
			md5next((uint8_t *)":",1,&ctx);
		}
		md5next((uint8_t *)response,strlen(response),&ctx);
		md5end(md5,&ctx);
		bin2hex(md5,MD5_SIZE,response);

		len=strlen(user)+strlen(realm)+strlen(nonce)
			+strlen(URI)+strlen(cnonce)+strlen(NC)
			+strlen(response)+strlen(qop)+
			(method==TYPE_RFC2617?8:7);
		ptr=bfr;
		put_header(ptr,len,method);
		put_element(ptr,user);
		put_element(ptr,realm);
		put_element(ptr,nonce);
		put_element(ptr,URI);
		put_element(ptr,cnonce);
		put_element(ptr,NC);
		put_element(ptr,response);
		put_element(ptr,qop);
		break;

	default:goto out;
	}

	if(io(parm,bfr,len+9,WRITE))goto out;

	if(mode)
	{
		if(io(parm,bfr,9,READ))goto out;
		get_header(bfr,len,method,status);
		if(len>sizeof(bfr))goto out;
		if(io(parm,bfr,len,READ))goto out;

		if(status==AUTH_SUCCESS)r=0;
		else r=-2;
	}
	else r=0;

out:	memset(bfr,0,sizeof(bfr));

	return r;
}