| /* 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)); |
| } |