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-rw-r--r--security/nss/lib/util/derdec.c189
1 files changed, 189 insertions, 0 deletions
diff --git a/security/nss/lib/util/derdec.c b/security/nss/lib/util/derdec.c
new file mode 100644
index 0000000000..2e3312b231
--- /dev/null
+++ b/security/nss/lib/util/derdec.c
@@ -0,0 +1,189 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "secder.h"
+#include "secerr.h"
+
+static PRUint32
+der_indefinite_length(unsigned char *buf, unsigned char *end)
+{
+ PRUint32 len, ret, dataLen;
+ unsigned char tag, lenCode;
+ int dataLenLen;
+
+ len = 0;
+ while (1) {
+ if ((buf + 2) > end) {
+ return (0);
+ }
+
+ tag = *buf++;
+ lenCode = *buf++;
+ len += 2;
+
+ if ((tag == 0) && (lenCode == 0)) {
+ return (len);
+ }
+
+ if (lenCode == 0x80) { /* indefinite length */
+ ret = der_indefinite_length(buf, end); /* recurse to find length */
+ if (ret == 0)
+ return 0;
+ len += ret;
+ buf += ret;
+ } else { /* definite length */
+ if (lenCode & 0x80) {
+ /* Length of data is in multibyte format */
+ dataLenLen = lenCode & 0x7f;
+ switch (dataLenLen) {
+ case 1:
+ dataLen = buf[0];
+ break;
+ case 2:
+ dataLen = (buf[0] << 8) | buf[1];
+ break;
+ case 3:
+ dataLen = ((unsigned long)buf[0] << 16) | (buf[1] << 8) | buf[2];
+ break;
+ case 4:
+ dataLen = ((unsigned long)buf[0] << 24) |
+ ((unsigned long)buf[1] << 16) | (buf[2] << 8) | buf[3];
+ break;
+ default:
+ PORT_SetError(SEC_ERROR_BAD_DER);
+ return SECFailure;
+ }
+ } else {
+ /* Length of data is in single byte */
+ dataLen = lenCode;
+ dataLenLen = 0;
+ }
+
+ /* skip this item */
+ buf = buf + dataLenLen + dataLen;
+ len = len + dataLenLen + dataLen;
+ }
+ }
+}
+
+/*
+** Capture the next thing in the buffer.
+** Returns the length of the header and the length of the contents.
+*/
+static SECStatus
+der_capture(unsigned char *buf, unsigned char *end,
+ int *header_len_p, PRUint32 *contents_len_p)
+{
+ unsigned char *bp;
+ unsigned char whole_tag;
+ PRUint32 contents_len;
+ int tag_number;
+
+ if ((buf + 2) > end) {
+ *header_len_p = 0;
+ *contents_len_p = 0;
+ if (buf == end)
+ return SECSuccess;
+ return SECFailure;
+ }
+
+ bp = buf;
+
+ /* Get tag and verify that it is ok. */
+ whole_tag = *bp++;
+ tag_number = whole_tag & DER_TAGNUM_MASK;
+
+ /*
+ * XXX This code does not (yet) handle the high-tag-number form!
+ */
+ if (tag_number == DER_HIGH_TAG_NUMBER) {
+ PORT_SetError(SEC_ERROR_BAD_DER);
+ return SECFailure;
+ }
+
+ if ((whole_tag & DER_CLASS_MASK) == DER_UNIVERSAL) {
+ /* Check that the universal tag number is one we implement. */
+ switch (tag_number) {
+ case DER_BOOLEAN:
+ case DER_INTEGER:
+ case DER_BIT_STRING:
+ case DER_OCTET_STRING:
+ case DER_NULL:
+ case DER_OBJECT_ID:
+ case DER_SEQUENCE:
+ case DER_SET:
+ case DER_PRINTABLE_STRING:
+ case DER_T61_STRING:
+ case DER_IA5_STRING:
+ case DER_VISIBLE_STRING:
+ case DER_UTC_TIME:
+ case 0: /* end-of-contents tag */
+ break;
+ default:
+ PORT_SetError(SEC_ERROR_BAD_DER);
+ return SECFailure;
+ }
+ }
+
+ /*
+ * Get first byte of length code (might contain entire length, might not).
+ */
+ contents_len = *bp++;
+
+ /*
+ * If the high bit is set, then the length is in multibyte format,
+ * or the thing has an indefinite-length.
+ */
+ if (contents_len & 0x80) {
+ int bytes_of_encoded_len;
+
+ bytes_of_encoded_len = contents_len & 0x7f;
+ contents_len = 0;
+
+ switch (bytes_of_encoded_len) {
+ case 4:
+ contents_len |= *bp++;
+ contents_len <<= 8;
+ /* fallthru */
+ case 3:
+ contents_len |= *bp++;
+ contents_len <<= 8;
+ /* fallthru */
+ case 2:
+ contents_len |= *bp++;
+ contents_len <<= 8;
+ /* fallthru */
+ case 1:
+ contents_len |= *bp++;
+ break;
+
+ case 0:
+ contents_len = der_indefinite_length(bp, end);
+ if (contents_len)
+ break;
+ /* fallthru */
+ default:
+ PORT_SetError(SEC_ERROR_BAD_DER);
+ return SECFailure;
+ }
+ }
+
+ if ((bp + contents_len) > end) {
+ /* Ran past end of buffer */
+ PORT_SetError(SEC_ERROR_BAD_DER);
+ return SECFailure;
+ }
+
+ *header_len_p = (int)(bp - buf);
+ *contents_len_p = contents_len;
+
+ return SECSuccess;
+}
+
+SECStatus
+DER_Lengths(SECItem *item, int *header_len_p, PRUint32 *contents_len_p)
+{
+ return (der_capture(item->data, &item->data[item->len], header_len_p,
+ contents_len_p));
+}