fix padding for certs

Reference: /n/atom/patch/applied/x509pad
Date: Fri Mar 21 01:40:58 CET 2014
Signed-off-by: quanstro@quanstro.net

--- /sys/src/libsec/port/x509.c	Fri Mar 21 01:40:50 2014
+++ /sys/src/libsec/port/x509.c	Fri Mar 21 01:40:52 2014
@@ -665,16 +665,15 @@
 			switch(elem.val.tag) {
 			case VOctets:
 				newans = catbytes(ans, elem.val.u.octetsval);
+				freevalfields(&elem.val);
 				freebytes(ans);
 				ans = newans;
 				break;
 
 			case VEOC:
-				if(length != -1) {
-					p = pold;
-					err = ASN_EINVAL;
-				}
-				goto cloop_done;
+				if(length == -1)
+					goto cloop_done;
+				/* no break */
 
 			default:
 				p = pold;
@@ -683,7 +682,10 @@
 			}
 		}
 cloop_done:
-		;
+		if(err != ASN_OK){
+			freebytes(ans);
+			ans = nil;
+		}
 	}
 	*pp = p;
 	*pbytes = ans;
@@ -736,7 +738,9 @@
 			else
 				lve = mkel(elem, lve);
 		}
-		if(err == ASN_OK) {
+		if(err != ASN_OK)
+			freeelist(lve);
+		else {
 			/* reverse back to original order */
 			while(lve != nil) {
 				lveold = lve;
@@ -977,8 +981,8 @@
 				memmove(p, bb->data, bb->len);
 			p += bb->len;
 		}
-			else
-				err = ASN_EINVAL;
+		else
+			err = ASN_EINVAL;
 		break;
 
 	case NULLTAG:
@@ -1598,7 +1602,6 @@
 static Ints7 oid_sha1WithRSAEncryption ={7, 1, 2, 840, 113549, 1, 1, 5 };
 static Ints7 oid_sha1WithRSAEncryptionOiw ={6, 1, 3, 14, 3, 2, 29 };
 static Ints7 oid_sha256WithRSAEncryption ={7, 1, 2, 840, 113549, 1, 1, 11 };
-static Ints7 oid_shaWithRSASignatureOiw ={6, 1, 3, 14, 3, 2, 15 };
 static Ints7 oid_md5 ={6, 1, 2, 840, 113549, 2, 5, 0 };
 static Ints *alg_oid_tab[NUMALGS+1] = {
 	(Ints*)&oid_rsaEncryption,
@@ -2036,25 +2039,31 @@
 	return nil;
 }
 
-static mpint*
-pkcs1pad(Bytes *b, mpint *modulus)
+mpint*
+pkcs1padbuf(uchar *buf, int len, mpint *modulus)
 {
 	int n = (mpsignif(modulus)+7)/8;
 	int pm1, i;
 	uchar *p;
 	mpint *mp;
 
-	pm1 = n - 1 - b->len;
+	pm1 = n - 1 - len;
 	p = (uchar*)emalloc(n);
 	p[0] = 0;
 	p[1] = 1;
 	for(i = 2; i < pm1; i++)
 		p[i] = 0xFF;
 	p[pm1] = 0;
-	memcpy(&p[pm1+1], b->data, b->len);
+	memcpy(&p[pm1+1], buf, len);
 	mp = betomp(p, n, nil);
 	free(p);
 	return mp;
+}
+
+static mpint*
+pkcs1pad(Bytes *b, mpint *modulus)
+{
+	return pkcs1padbuf(b->data, b->len, modulus);
 }
 
 RSApriv*