diff options
Diffstat (limited to 'nss/lib/util/derdec.c')
| -rw-r--r-- | nss/lib/util/derdec.c | 189 |
1 files changed, 189 insertions, 0 deletions
diff --git a/nss/lib/util/derdec.c b/nss/lib/util/derdec.c new file mode 100644 index 0000000..2e3312b --- /dev/null +++ b/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)); +} |