Use more efficient way to locate end of an ASN1 structure.

[openssl.git] / crypto / asn1 / tasn_dec.c

diff --git a/crypto/asn1/tasn_dec.c b/crypto/asn1/tasn_dec.c
index 46df79519f8e17a9176c0d12933a6b29ec438c5e..39a9d5a9aab472959d46cda1f1bd06317513b39a 100644 (file)
--- a/crypto/asn1/tasn_dec.c
+++ b/crypto/asn1/tasn_dec.c
@@ -66,6 +66,7 @@
 #include <openssl/err.h>
 
 static int asn1_check_eoc(const unsigned char **in, long len);
+static int asn1_find_end(const unsigned char **in, long len, char inf);
 
 static int asn1_collect(BUF_MEM *buf, const unsigned char **in, long len,
                                char inf, int tag, int aclass);
@@ -848,7 +849,7 @@ static int asn1_d2i_ex_primitive(ASN1_VALUE **pval,
                /* If indefinite length constructed find the real end */
                if (inf)
                        {
-                       if (!asn1_collect(NULL, &p, plen, inf, -1, -1))
+                       if (!asn1_find_end(&p, plen, inf))
                                 goto err;
                        len = p - cont;
                        }
@@ -1053,12 +1054,66 @@ int asn1_ex_c2i(ASN1_VALUE **pval, const unsigned char *cont, int len,
        return ret;
        }
 
+
+/* This function finds the end of an ASN1 structure when passed its maximum
+ * length, whether it is indefinite length and a pointer to the content.
+ * This is more efficient than calling asn1_collect because it does not
+ * recurse on each indefinite length header.
+ */
+
+static int asn1_find_end(const unsigned char **in, long len, char inf)
+       {
+       int expected_eoc;
+       long plen;
+       const unsigned char *p = *in, *q;
+       /* If not indefinite length constructed just add length */
+       if (inf == 0)
+               {
+               *in += len;
+               return 1;
+               }
+       expected_eoc = 1;
+       /* Indefinite length constructed form. Find the end when enough EOCs
+        * are found. If more indefinite length constructed headers
+        * are encountered increment the expected eoc count otherwise just
+        * skip to the end of the data.
+        */
+       while (len > 0)
+               {
+               if(asn1_check_eoc(&p, len))
+                       {
+                       expected_eoc--;
+                       if (expected_eoc == 0)
+                               break;
+                       len -= 2;
+                       continue;
+                       }
+               q = p;
+               /* Just read in a header: only care about the length */
+               if(!asn1_check_tlen(&plen, NULL, NULL, &inf, NULL, &p, len,
+                               -1, 0, 0, NULL))
+                       {
+                       ASN1err(ASN1_F_ASN1_FIND_END, ERR_R_NESTED_ASN1_ERROR);
+                       return 0;
+                       }
+               if (inf)
+                       expected_eoc++;
+               else
+                       p += plen;
+               len -= p - q;
+               }
+       if (expected_eoc)
+               {
+               ASN1err(ASN1_F_ASN1_FIND_END, ASN1_R_MISSING_EOC);
+               return 0;
+               }
+       *in = p;
+       return 1;
+       }
 /* This function collects the asn1 data from a constructred string
  * type into a buffer. The values of 'in' and 'len' should refer
  * to the contents of the constructed type and 'inf' should be set
- * if it is indefinite length. If 'buf' is NULL then we just want
- * to find the end of the current structure: useful for indefinite
- * length constructed stuff.
+ * if it is indefinite length.
  */
 
 static int asn1_collect(BUF_MEM *buf, const unsigned char **in, long len,