/*********************************************************************************************************
* Software License Agreement (BSD License)                                                               *
* Author: Sebastien Decugis <sdecugis@freediameter.net>							 *
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* Copyright (c) 2013, WIDE Project and NICT								 *
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#include "fdproto-internal.h"

/* This file contains helpers functions to be reused as callbacks in the struct dict_type_data structure.
There are three callbacks there:

 - type_encode    :
 - type_interpret :
 	  Those two callbacks allow to manipulate more natural structures of data in the code, and to 
	map transparently these natural structures with the AVP-encoded format by calling the functions
	msg_avp_value_encode or msg_avp_value_interpret.
 - type_dump : 
 	  This callback if provided gives a more human-readable debug information.

 */

/****************************/
/*    Address  AVP  type    */
/****************************/

/* The interpret and encode functions work with a "struct sockaddr_storage" pointer for mapping 
the contents of the AVP */

int fd_dictfct_Address_encode(void * data, union avp_value * avp_value)
{
	sSS * ss = (sSS *) data;
	uint16_t AddressType = 0;
	size_t	size = 0;
	unsigned char * buf = NULL;
	
	TRACE_ENTRY("%p %p", data, avp_value);
	CHECK_PARAMS( data && avp_value  );
	
	switch (ss->ss_family) {
		case AF_INET:
			{
				/* We are encoding an IP address */
				sSA4 * sin = (sSA4 *)ss;
				
				AddressType = 1;/* see http://www.iana.org/assignments/address-family-numbers/ */
				size = 6;	/* 2 for AddressType + 4 for data */
				
				CHECK_MALLOC(  buf = malloc(size)  );
				
				/* may not work because of alignment: *(uint32_t *)(buf+2) = htonl(sin->sin_addr.s_addr); */
				memcpy(buf + 2, &sin->sin_addr.s_addr, 4);
			}
			break;
				
		case AF_INET6:
			{
				/* We are encoding an IPv6 address */
				sSA6 * sin6 = (sSA6 *)ss;
				
				AddressType = 2;/* see http://www.iana.org/assignments/address-family-numbers/ */
				size = 18;	/* 2 for AddressType + 16 for data */
				
				CHECK_MALLOC(  buf = malloc(size)  );
				
				/* The order is already good here */
				memcpy(buf + 2, &sin6->sin6_addr.s6_addr, 16);
			}
			break;
				
		default:
			CHECK_PARAMS( AddressType = 0 );
	}
	
	*(uint16_t *)buf = htons(AddressType);

	avp_value->os.len = size;
	avp_value->os.data = buf;
	
	return 0;
}

int fd_dictfct_Address_interpret(union avp_value * avp_value, void * interpreted)
{
	uint16_t AddressType = 0;
	unsigned char * buf;
	
	TRACE_ENTRY("%p %p", avp_value, interpreted);
	
	CHECK_PARAMS( avp_value && interpreted && (avp_value->os.len >= 2)  );
	
	AddressType = ntohs(*(uint16_t *)avp_value->os.data);
	buf = &avp_value->os.data[2];
	
	switch (AddressType) {
		case 1 /* IP */:
			{
				sSA4 * sin = (sSA4 *)interpreted;
				
				CHECK_PARAMS(  avp_value->os.len == 6  );
				
				sin->sin_family = AF_INET;
				/* sin->sin_addr.s_addr = ntohl( * (uint32_t *) buf); -- may not work because of bad alignment */
				memcpy(&sin->sin_addr.s_addr, buf, 4);
			}
			break;
				
		case 2 /* IP6 */:
			{
				sSA6 * sin6 = (sSA6 *)interpreted;
				
				CHECK_PARAMS(  avp_value->os.len == 18  );
				
				sin6->sin6_family = AF_INET6;
				memcpy(&sin6->sin6_addr.s6_addr, buf, 16);
			}
			break;
				
		default:
			CHECK_PARAMS( AddressType = 0 );
	}
	
	return 0;
}

/* Dump the content of an Address AVP */
char * fd_dictfct_Address_dump(union avp_value * avp_value)
{
	char * ret;
	#define STR_LEN	1024
	union {
		sSA	sa;
		sSS	ss;
		sSA4	sin;
		sSA6	sin6;
	} s;
	uint16_t fam;
	
	memset(&s, 0, sizeof(s));
	
	CHECK_MALLOC_DO( ret = malloc(STR_LEN), return NULL );
	
	/* The first two octets represent the address family, http://www.iana.org/assignments/address-family-numbers/ */
	if (avp_value->os.len < 2) {
		snprintf(ret, STR_LEN, "[invalid length: %zd]", avp_value->os.len);
		return ret;
	}
	
	/* Following octets are the address in network byte order already */
	fam = avp_value->os.data[0] << 8 | avp_value->os.data[1];
	switch (fam) {
		case 1:
			/* IP */
			s.sa.sa_family = AF_INET;
			if (avp_value->os.len != 6) {
				snprintf(ret, STR_LEN, "[invalid IP length: %zd]", avp_value->os.len);
				return ret;
			}
			memcpy(&s.sin.sin_addr.s_addr, avp_value->os.data + 2, 4);
			break;
		case 2:
			/* IP6 */
			s.sa.sa_family = AF_INET6;
			if (avp_value->os.len != 18) {
				snprintf(ret, STR_LEN, "[invalid IP6 length: %zd]", avp_value->os.len);
				return ret;
			}
			memcpy(&s.sin6.sin6_addr.s6_addr, avp_value->os.data + 2, 16);
			break;
		default:
			snprintf(ret, STR_LEN, "[unsupported family: 0x%hx]", fam);
			return ret;
	}
	
	{
		int rc = getnameinfo(&s.sa, sSAlen(&s.sa), ret, STR_LEN, NULL, 0, NI_NUMERICHOST);
		if (rc)
			snprintf(ret, STR_LEN, "%s", (char *)gai_strerror(rc));
	}
	
	return ret;
}



/*******************************/
/*    UTF8String  AVP  type    */
/*******************************/

/* Dump the AVP in a natural human-readable format */
char * fd_dictfct_UTF8String_dump(union avp_value * avp_value)
{
#define TRUNC_LEN	42 /* avoid very long strings */
	char * ret = strndup((char *)avp_value->os.data, TRUNC_LEN); 
	if (ret && (*ret != '\0')) {
		/* We sanitize the returned string to avoid UTF8 boundary problem.
		We do this whether the string is trucated at TRUNC_LEN or not, to avoid potential problem
		with malformed AVP */

		char * end = strchr(ret, '\0');
		
		while (end > ret) {
			end--;
			char b = *end;
			/* after the position pointed by end, we have only \0s */
			if ((b & 0x80) == 0) {
				break; /* this is a single byte char, no problem */
			} else {
				/* this byte is start or cont. of multibyte sequence, as we do not know the next byte we need to delete it. */
				*end = '\0';
				if (b & 0x40)
					break; /* This was a start byte, we can stop the loop */
			}
		}
	}	
	return ret;
}


/*******************************/
/*    Time  AVP  type    */
/*******************************/

/* The interpret and encode functions work with a "time_t" pointer for mapping 
the contents of the AVP */

/* Unix Epoch starts 1970-01-01, NTP 0 is at 1900-01-01 */
#define DIFF_EPOCH_TO_NTP ((365*(1970-1900) + 17ul) * 24 * 60 * 60)

static int diameter_string_to_time_t(const char *str, size_t len, time_t *result) {
    time_t time_stamp;
    CHECK_PARAMS(len == 4);
   
    time_stamp = (((unsigned long)(str[0]&0xff))<<24) + ((str[1]&0xff)<<16) + ((str[2]&0xff)<<8) + ((str[3]&0xff));
    time_stamp -= DIFF_EPOCH_TO_NTP;
#ifdef FIX__NEEDED_FOR_YEAR_2036_AND_LATER
/* NTP overflows in 2036; after that, values start at zero again */
#define NTP_OVERFLOW_CORRECTION (0x100000000ull)
    /* XXX: debug and find correct conversion */
    if (str[0] & 0x80 == 0x00) {
        time_stamp += NTP_OVERFLOW_CORRECTION;
    }
#endif
    *result = time_stamp;
    return 0;
}

static int time_t_to_diameter_string(time_t time_stamp, char **result) {
    uint64_t out = time_stamp;
    char *conv;
    /* XXX: 2036 fix */
    out += DIFF_EPOCH_TO_NTP;
    CHECK_PARAMS( (out & 0xffffffff00000000) == 0);

    CHECK_MALLOC(conv=(char *)malloc(5));
    
    conv[0] = (out>>24) & 0xff;
    conv[1] = (out>>16) & 0xff;
    conv[2] = (out>> 8) & 0xff;
    conv[3] =  out      & 0xff;
    conv[4] = '\0';
    *result = conv;
    return 0;
}

int fd_dictfct_Time_encode(void * data, union avp_value * avp_value)
{
	char * buf;
	size_t len;
	
	TRACE_ENTRY("%p %p", data, avp_value);
	CHECK_PARAMS( data && avp_value  );
	
	CHECK_FCT( time_t_to_diameter_string( *((time_t *)data), &buf) );
	/* FIXME: return len from the function above? */ len = 4;
	
	avp_value->os.len = len;
	avp_value->os.data = buf;
	return 0;
}

int fd_dictfct_Time_interpret(union avp_value * avp_value, void * interpreted)
{
	TRACE_ENTRY("%p %p", avp_value, interpreted);
	
	CHECK_PARAMS( avp_value && interpreted );
	
	return diameter_string_to_time_t(avp_value->os.data, avp_value->os.len, interpreted);
}

char * fd_dictfct_Time_dump(union avp_value * avp_value)
{
	char * ret;
	CHECK_MALLOC_DO( ret = malloc(STR_LEN), return NULL );
	if (avp_value->os.len != 4) {
		snprintf(ret, STR_LEN, "[invalid length: %zd]", avp_value->os.len);
		return ret;
	}
	/* TODO: display the time as human-readable */
	snprintf(ret, STR_LEN, "[TODO Time dump: 0x%02hhx%02hhx%02hhx%02hhx]", avp_value->os.data[0], avp_value->os.data[1], avp_value->os.data[2], avp_value->os.data[3]);
	return ret;
}