aper: Rework aper_get_length to gain lb & ub information

This should help aper_put_length() to take proper decisions on the way
to encode the length, since the range alone is not enough.
A contraint of lb=1 ub=65536 would yield a range=65536, but according to
ITU-T X.691 11.9 it shouldn't be encoded using nsnnwn since that only
applies in case ub<65536.
As a result, it would end up encoding/decoding it using 2 bytes while it
should use only 1.

Related: #94

skeletons/ANY_aper.c

@@ -132,7 +132,7 @@ ANY_decode_aper(const asn_codec_ctx_t *opt_codec_ctx,
         int ret;
 
         /* Get the PER length */
-        raw_len = aper_get_length(pd, -1, 0, &repeat);
+        raw_len = aper_get_length(pd, -1, -1, 0, &repeat);
         if(raw_len < 0) RETURN(RC_WMORE);
         if(raw_len == 0 && st->buf) break;
 

skeletons/INTEGER_aper.c

@@ -129,7 +129,7 @@ INTEGER_decode_aper(const asn_codec_ctx_t *opt_codec_ctx,
         int ret;
 
         /* Get the PER length */
-        len = aper_get_length(pd, -1, -1, &repeat);
+        len = aper_get_length(pd, -1, -1, -1, &repeat);
         if(len < 0) ASN__DECODE_STARVED;
 
         p = REALLOC(st->buf, st->size + len + 1);

skeletons/OCTET_STRING_aper.c

@@ -173,9 +173,10 @@ OCTET_STRING_decode_aper(const asn_codec_ctx_t *opt_codec_ctx,
         /* Get the PER length */
         if (csiz->upper_bound - csiz->lower_bound == 0)
             /* Indefinite length case */
-            raw_len = aper_get_length(pd, -1, csiz->effective_bits, &repeat);
+            raw_len = aper_get_length(pd, -1, -1, csiz->effective_bits, &repeat);
         else
-            raw_len = aper_get_length(pd, csiz->upper_bound - csiz->lower_bound + 1, csiz->effective_bits, &repeat);
+            raw_len = aper_get_length(pd, csiz->lower_bound, csiz->upper_bound,
+                                      csiz->effective_bits, &repeat);
         if(raw_len < 0) RETURN(RC_WMORE);
         raw_len += csiz->lower_bound;
 

skeletons/OPEN_TYPE_aper.c

@@ -146,7 +146,7 @@ OPEN_TYPE_aper_unknown_type_discard_bytes (asn_per_data_t *pd) {
     rv.code = RC_FAIL;
 
     do {
-        bytes = aper_get_length(pd, -1, -1, &repeat);
+        bytes = aper_get_length(pd, -1, -1, -1, &repeat);
         if (bytes > 10 * ASN_DUMMY_BYTES)
         {
             return rv;
@@ -171,4 +171,3 @@ OPEN_TYPE_aper_unknown_type_discard_bytes (asn_per_data_t *pd) {
      return rv;
 #undef ASN_DUMMY_BYTES
 }
-

skeletons/aper_opentype.c

@@ -25,7 +25,7 @@ aper_open_type_get_simple(const asn_codec_ctx_t *ctx,
 	ASN_DEBUG("Getting open type %s...", td->name);
 
 	do {
-	        chunk_bytes = aper_get_length(pd, -1, -1, &repeat);
+	        chunk_bytes = aper_get_length(pd, -1, -1, -1, &repeat);
 		if(chunk_bytes < 0) {
 			FREEMEM(buf);
 			ASN__DECODE_STARVED;

skeletons/aper_support.c

@@ -17,13 +17,17 @@ aper_get_align(asn_per_data_t *pd) {
 }
 
 ssize_t
-aper_get_length(asn_per_data_t *pd, int range, int ebits, int *repeat) {
+aper_get_length(asn_per_data_t *pd, ssize_t lb, ssize_t ub,
+		int ebits, int *repeat) {
+	int constrained = (lb >= 0) && (ub >= 0);
 	ssize_t value;
 
 	*repeat = 0;
 
-	if (range <= 65536 && range >= 0)
+	if (constrained && ub < 65536) {
+		int range = ub - lb + 1;
 		return aper_get_nsnnwn(pd, range);
+	}
 
 	if (aper_get_align(pd) < 0)
 		return -1;
@@ -59,7 +63,7 @@ aper_get_nslength(asn_per_data_t *pd) {
 		return length;
 	} else {
 		int repeat;
-		length = aper_get_length(pd, -1, -1, &repeat);
+		length = aper_get_length(pd, -1, -1, -1, &repeat);
 		if(length >= 0 && !repeat) return length;
 		return -1; /* Error, or do not support >16K extensions */
 	}

skeletons/aper_support.h

@@ -16,7 +16,7 @@ extern "C" {
  * X.691 (08/2015) #11.9 "General rules for encoding a length determinant"
  * Get the length "n" from the Aligned PER stream.
  */
-ssize_t aper_get_length(asn_per_data_t *pd, int range,
+ssize_t aper_get_length(asn_per_data_t *pd, ssize_t lb, ssize_t ub,
                         int effective_bound_bits, int *repeat);
 
 /*

skeletons/constr_SET_OF_aper.c

@@ -141,8 +141,11 @@ SET_OF_decode_aper(const asn_codec_ctx_t *opt_codec_ctx,
     do {
         int i;
         if(nelems < 0) {
-            nelems = aper_get_length(pd, ct ? ct->upper_bound - ct->lower_bound + 1 : -1,
-                                     ct ? ct->effective_bits : -1, &repeat);
+            if (ct)
+                nelems = aper_get_length(pd, ct->lower_bound, ct->upper_bound,
+                                         ct->effective_bits, &repeat);
+            else
+                nelems = aper_get_length(pd, -1, -1, -1, &repeat);
             ASN_DEBUG("Got to decode %d elements (eff %d)",
                       (int)nelems, (int)(ct ? ct->effective_bits : -1));
             if(nelems < 0) ASN__DECODE_STARVED;

tests/tests-skeletons/check-APER-support.c

@@ -36,7 +36,7 @@ static size_t get(asn_per_outp_t *po, ssize_t lb, ssize_t ub) {
     size_t length = 0;
     int repeat = 0;
     do {
-        ssize_t n = aper_get_length(&data, ub - lb + 1, -1, &repeat);
+        ssize_t n = aper_get_length(&data, lb, ub, -1, &repeat);
         fprintf(stderr, "  get = %zu +%zd\n", length, n);
         assert(n >= 0);
         length += n;