Allow leading zeroes in integers

The socket10kxfr uses serials with leading zeroes. A quick test showed
BIND and Knot both allow for leading zeroes too.

Author: k0ekk0ek

FORMAT.md

@@ -235,3 +235,5 @@ anything other than domain names and text strings, MUST not be quoted.
 * Some implementations (Knot, possibly PowerDNS) will silently split-up
   strings longer than 255 characters. Others (BIND, simdzone) will throw a
   syntax error.
+
+* Leading zeroes in integers appear to be allowed judging by the zone file generated for the [socket10kxfr](https://github.com/NLnetLabs/nsd/blob/86a6961f2ca64f169d7beece0ed8a5e1dd1cd302/tpkg/long/socket10kxfr.tdir/socket10kxfr.pre#L64) test in NSD. BIND and Knot (and the old parser in NSD) all parsed it without problems.

src/generic/number.h

@@ -15,11 +15,9 @@ static really_inline int32_t scan_int8(
 {
   uint32_t sum = (uint8_t)data[0] - '0';
 
-  if (sum > 9 || length > 3)
+  if (sum > 9 || !length || length > 3)
     return 0;
 
-  uint32_t non_zero = (sum != 0) | (length == 1);
-
   for (size_t count=1; count < length; count++) {
     const uint8_t digit = (uint8_t)data[count] - '0';
     sum = sum * 10 + digit;
@@ -28,7 +26,7 @@ static really_inline int32_t scan_int8(
   }
 
   *number = (uint8_t)sum;
-  return sum <= 255u && non_zero;
+  return sum <= 255u;
 }
 
 nonnull((1,3))
@@ -37,11 +35,9 @@ static really_inline int32_t scan_int16(
 {
   uint32_t sum = (uint8_t)data[0] - '0';
 
-  if (sum > 9 || length > 5)
+  if (sum > 9 || !length || length > 5)
     return 0;
 
-  uint32_t non_zero = (sum != 0) | (length == 1);
-
   for (size_t count=1; count < length; count++) {
     const uint8_t digit = (uint8_t)data[count] - '0';
     sum = sum * 10 + digit;
@@ -50,7 +46,7 @@ static really_inline int32_t scan_int16(
   }
 
   *number = (uint16_t)sum;
-  return sum <= 65535u && non_zero;
+  return sum <= 65535u;
 }
 
 nonnull((1,3))
@@ -59,11 +55,9 @@ static really_inline int32_t scan_int32(
 {
   uint64_t sum = (uint8_t)data[0] - '0';
 
-  if (sum > 9 || length > 10)
+  if (sum > 9 || !length || length > 10)
     return 0;
 
-  uint32_t non_zero = (sum != 0) | (length == 1);
-
   for (size_t count=1; count < length; count++) {
     const uint8_t digit = (uint8_t)data[count] - '0';
     sum = sum * 10 + digit;
@@ -72,7 +66,7 @@ static really_inline int32_t scan_int32(
   }
 
   *number = (uint32_t)sum;
-  return sum <= 4294967295u && non_zero;
+  return sum <= 4294967295u;
 }
 
 nonnull_all

tests/time.c

@@ -51,7 +51,7 @@ void time_stamp_syntax(void **state)
     // one second over maximum value
     { "4294967296", 0, ZONE_SYNTAX_ERROR },
     // starts with zero
-    { "01", 0, ZONE_SYNTAX_ERROR },
+    { "01", 1, ZONE_SUCCESS },
     // Time specified as YYYYMMDDHHmmSS
     // bad number of digits
     { "202301010101", 0, ZONE_SYNTAX_ERROR },