Re: Last Call: draft-ietf-hip-dns (Host Identity Protocol (HIP) Domain Name System (DNS) Extensions) to Experimental RFC

[Stephane Bortzmeyer <[e-mail]>]

On Tue, May 29, 2007 at 08:23:49AM +0300,
 Pekka Savola <[e-mail]> wrote 
 a message of 187 lines which said:

> 5) HIP wire format vs zone representation
..
> I may me misunderstanding this, but doesn't that imply that the
> authoritative DNS servers must implement Base16 and Base64 decoding support
> so that they can convert from BaseXX to the on-the-wire format?

First, there is traditionally no obligation, for a name server, to
support the zone file format. Many name servers take their data from
something else (a database, or a file with a different format). It is
not even clear if it was a good idea to specify one zone file format
in RFC 1035, since it is not "on the wire".

Second, a name server already needs a specific parser for each
resource record type. It does not seem it is different or more
complicated to parse Base64 than it is to parse a LOC record. See the
code in BIND's lib/dns/rdata/generic directory.

Some resource record types already require knowledge of Base 64, such
as CERT (RFC 4398) or DNSKEY (RFC 4034).

For fun, I included here the LOC parsing code of nsd :-)

/*
 * Parses a specific part of rdata.
 *
 * Returns:
 *
 *	number of elements parsed
 *	zero on error
 *
 */
uint16_t *
zparser_conv_loc(region_type *region, char *str)
{
	uint16_t *r;
	uint32_t *p;
	int i;
	int deg, min, secs;	/* Secs is stored times 1000.  */
	uint32_t lat = 0, lon = 0, alt = 0;
	/* encoded defaults: version=0 sz=1m hp=10000m vp=10m */
	uint8_t vszhpvp[4] = {0, 0x12, 0x16, 0x13};
	char *start;
	double d;
			

	for(;;) {
		deg = min = secs = 0;
		
		/* Degrees */
		if (*str == '\0') {
			zc_error_prev_line("unexpected end of LOC data");
			return NULL;
		}

		if (!parse_int(str, &str, &deg, "degrees", 0, 180))
			return NULL;
		if (!isspace(*str)) {
			zc_error_prev_line("space expected after degrees");
			return NULL;
		}
		++str;
		
		/* Minutes? */
		if (isdigit(*str)) {
			if (!parse_int(str, &str, &min, "minutes", 0, 60))
				return NULL;
			if (!isspace(*str)) {
				zc_error_prev_line("space expected after minutes");
				return NULL;
			}
			++str;
		}
		
		/* Seconds? */
		if (isdigit(*str)) {
			start = str;
			if (!parse_int(str, &str, &i, "seconds", 0, 60)) {
				return NULL;
			}

			if (*str == '.' && !parse_int(str + 1, &str, &i, "seconds fraction", 0, 999)) {
				return NULL;
			}

			if (!isspace(*str)) {
				zc_error_prev_line("space expected after seconds");
				return NULL;
			}

			if (sscanf(start, "%lf", &d) != 1) {
				zc_error_prev_line("error parsing seconds");
			}

			if (d < 0.0 || d > 60.0) {
				zc_error_prev_line("seconds not in range 0.0 .. 60.0");
			}

			secs = (int) (d * 1000.0 + 0.5);
			++str;
		}
		
		switch(*str) {
		case 'N':
		case 'n':
			lat = ((uint32_t)1<<31) + (deg * 3600000 + min * 60000 + secs);
			break;
		case 'E':
		case 'e':
			lon = ((uint32_t)1<<31) + (deg * 3600000 + min * 60000 + secs);
			break;
		case 'S':
		case 's':
			lat = ((uint32_t)1<<31) - (deg * 3600000 + min * 60000 + secs);
			break;
		case 'W':
		case 'w':
			lon = ((uint32_t)1<<31) - (deg * 3600000 + min * 60000 + secs);
			break;
		default:
			zc_error_prev_line("invalid latitude/longtitude");
			return NULL;
		}
		++str;
		
		if (lat != 0 && lon != 0)
			break;

		if (!isspace(*str)) {
			zc_error_prev_line("space expected after latitude/longitude");
			return NULL;
		}
		++str;
	}

	/* Altitude */
	if (*str == '\0') {
		zc_error_prev_line("unexpected end of LOC data");
		return NULL;
	}

	if (!isspace(*str)) {
		zc_error_prev_line("space expected before altitude");
		return NULL;
	}
	++str;

	start = str;

	/* Sign */
	if (*str == '+' || *str == '-') {
		++str;
	}

	/* Meters of altitude... */
	(void)strtol(str, &str, 10);
	switch(*str) {
	case ' ':
	case '\0':
	case 'm':
		break;
	case '.':
		if (!parse_int(str + 1, &str, &i, "altitude fraction", 0, 99)) {
			return NULL;
		}
		if (!isspace(*str) && *str != '\0' && *str != 'm') {
			zc_error_prev_line("altitude fraction must be a number");
			return NULL;
		}
		break;
	default:
		zc_error_prev_line("altitude must be expressed in meters");
		return NULL;
	}
	if (!isspace(*str) && *str != '\0')
		++str;

	if (sscanf(start, "%lf", &d) != 1) {
		zc_error_prev_line("error parsing altitude");
	}
	
	alt = (uint32_t) (10000000.0 + d * 100 + 0.5);

	if (!isspace(*str) && *str != '\0') {
		zc_error_prev_line("unexpected character after altitude");
		return NULL;
	}

	/* Now parse size, horizontal precision and vertical precision if any */
	for(i = 1; isspace(*str) && i <= 3; i++) {
		vszhpvp[i] = precsize_aton(str + 1, &str);

		if (!isspace(*str) && *str != '\0') {
			zc_error_prev_line("invalid size or precision");
			return NULL;
		}
	}

	/* Allocate required space... */
	r = alloc_rdata(region, 16);
	p = (uint32_t *) (r + 1);

	memmove(p, vszhpvp, 4);
	write_uint32(p + 1, lat);
	write_uint32(p + 2, lon);
	write_uint32(p + 3, alt);

	return r;
}

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