The encoding of negative ASN1 INTEGERs and the conversion of BNs to negative
[openssl.git] / crypto / asn1 / a_enum.c
index 3654039..9239ecc 100644 (file)
 #include "cryptlib.h"
 #include <openssl/asn1.h>
 
-/* Support for ASN1 ENUMERATED type: based on a_int.c */
+/* 
+ * Code for ENUMERATED type: identical to INTEGER apart from a different tag.
+ * for comments on encoding see a_int.c
+ */
 
 int i2d_ASN1_ENUMERATED(ASN1_ENUMERATED *a, unsigned char **pp)
        {
        int pad=0,ret,r,i,t;
-       unsigned char *p,*pt,*n,pb=0;
+       unsigned char *p,*n,pb=0;
 
        if ((a == NULL) || (a->data == NULL)) return(0);
        t=a->type;
@@ -75,16 +78,21 @@ int i2d_ASN1_ENUMERATED(ASN1_ENUMERATED *a, unsigned char **pp)
                {
                ret=a->length;
                i=a->data[0];
-               if ((t == V_ASN1_ENUMERATED) && (i > 127))
-                       {
+               if ((t == V_ASN1_ENUMERATED) && (i > 127)) {
                        pad=1;
                        pb=0;
+               } else if(t == V_ASN1_NEG_ENUMERATED) {
+                       if(i>128) {
+                               pad=1;
+                               pb=0xFF;
+                       } else if(i == 128) {
+                               for(i = 1; i < a->length; i++) if(a->data[i]) {
+                                               pad=1;
+                                               pb=0xFF;
+                                               break;
+                               }
                        }
-               else if ((t == V_ASN1_NEG_ENUMERATED) && (i>128))
-                       {
-                       pad=1;
-                       pb=0xFF;
-                       }
+               }
                ret+=pad;
                }
        r=ASN1_object_size(0,ret,V_ASN1_ENUMERATED);
@@ -100,14 +108,24 @@ int i2d_ASN1_ENUMERATED(ASN1_ENUMERATED *a, unsigned char **pp)
                memcpy(p,a->data,(unsigned int)a->length);
                p+=a->length;
                }
-       else
-               {
-               n=a->data;
-               pt=p;
-               for (i=a->length; i>0; i--)
-                       *(p++)= (*(n++)^0xFF)+1;
-               if (!pad) *pt|=0x80;
+       else {
+               /* Begin at the end of the encoding */
+               n=a->data + a->length - 1;
+               p += a->length - 1;
+               i = a->length;
+               /* Copy zeros to destination as long as source is zero */
+               while(!*n) {
+                       *(p--) = 0;
+                       n--;
+                       i--;
                }
+               /* Complement and increment next octet */
+               *(p--) = ((*(n--)) ^ 0xff) + 1;
+               i--;
+               /* Complement any octets left */
+               for(;i > 0; i--) *(p--) = *(n--) ^ 0xff;
+               p += a->length;
+       }
 
        *pp=p;
        return(r);
@@ -156,16 +174,30 @@ ASN1_ENUMERATED *d2i_ASN1_ENUMERATED(ASN1_ENUMERATED **a, unsigned char **pp,
        if (*p & 0x80) /* a negative number */
                {
                ret->type=V_ASN1_NEG_ENUMERATED;
-               if (*p == 0xff)
-                       {
+               if ((*p == 0xff) && (len != 1)) {
                        p++;
                        len--;
-                       }
-               for (i=(int)len; i>0; i--)
-                       *(to++)= (*(p++)^0xFF)+1;
                }
-       else
-               {
+               i = len;
+               p += i - 1;
+               to += i - 1;
+               while((!*p) && i) {
+                       *(to--) = 0;
+                       i--;
+                       p--;
+               }
+               if(!i) {
+                       *s = 1;
+                       s[len] = 0;
+                       p += len;
+                       len++;
+               } else {
+                       *(to--) = (*(p--) ^ 0xff) + 1;
+                       i--;
+                       for(;i > 0; i--) *(to--) = *(p--) ^ 0xff;
+                       p += len;
+               }
+       } else {
                ret->type=V_ASN1_ENUMERATED;
                if ((*p == 0) && (len != 1))
                        {
@@ -174,7 +206,7 @@ ASN1_ENUMERATED *d2i_ASN1_ENUMERATED(ASN1_ENUMERATED **a, unsigned char **pp,
                        }
                memcpy(s,p,(int)len);
                p+=len;
-               }
+       }
 
        if (ret->data != NULL) Free((char *)ret->data);
        ret->data=s;
@@ -222,7 +254,6 @@ int ASN1_ENUMERATED_set(ASN1_ENUMERATED *a, long v)
                d>>=8;
                }
        j=0;
-       if (v < 0) a->data[j++]=0;
        for (k=i-1; k >=0; k--)
                a->data[j++]=buf[k];
        a->length=j;
@@ -272,7 +303,8 @@ ASN1_ENUMERATED *BN_to_ASN1_ENUMERATED(BIGNUM *bn, ASN1_ENUMERATED *ai)
                ASN1err(ASN1_F_BN_TO_ASN1_ENUMERATED,ERR_R_NESTED_ASN1_ERROR);
                goto err;
                }
-       ret->type=V_ASN1_ENUMERATED;
+       if(bn->neg) ret->type = V_ASN1_NEG_ENUMERATED;
+       else ret->type=V_ASN1_ENUMERATED;
        j=BN_num_bits(bn);
        len=((j == 0)?0:((j/8)+1));
        ret->data=(unsigned char *)Malloc(len+4);
@@ -289,5 +321,6 @@ BIGNUM *ASN1_ENUMERATED_to_BN(ASN1_ENUMERATED *ai, BIGNUM *bn)
 
        if ((ret=BN_bin2bn(ai->data,ai->length,bn)) == NULL)
                ASN1err(ASN1_F_ASN1_ENUMERATED_TO_BN,ASN1_R_BN_LIB);
+       if(ai->type == V_ASN1_NEG_ENUMERATED) bn->neg = 1;
        return(ret);
        }