| /* |
| * ASN.1 DER parsing |
| * Copyright (c) 2006, Jouni Malinen <j@w1.fi> |
| * |
| * This software may be distributed under the terms of the BSD license. |
| * See README for more details. |
| */ |
| |
| #include "includes.h" |
| |
| #include "common.h" |
| #include "asn1.h" |
| |
| int asn1_get_next(const u8 *buf, size_t len, struct asn1_hdr *hdr) |
| { |
| const u8 *pos, *end; |
| u8 tmp; |
| |
| os_memset(hdr, 0, sizeof(*hdr)); |
| pos = buf; |
| end = buf + len; |
| |
| hdr->identifier = *pos++; |
| hdr->class = hdr->identifier >> 6; |
| hdr->constructed = !!(hdr->identifier & (1 << 5)); |
| |
| if ((hdr->identifier & 0x1f) == 0x1f) { |
| hdr->tag = 0; |
| do { |
| if (pos >= end) { |
| wpa_printf(MSG_DEBUG, "ASN.1: Identifier " |
| "underflow"); |
| return -1; |
| } |
| tmp = *pos++; |
| wpa_printf(MSG_MSGDUMP, "ASN.1: Extended tag data: " |
| "0x%02x", tmp); |
| hdr->tag = (hdr->tag << 7) | (tmp & 0x7f); |
| } while (tmp & 0x80); |
| } else |
| hdr->tag = hdr->identifier & 0x1f; |
| |
| tmp = *pos++; |
| if (tmp & 0x80) { |
| if (tmp == 0xff) { |
| wpa_printf(MSG_DEBUG, "ASN.1: Reserved length " |
| "value 0xff used"); |
| return -1; |
| } |
| tmp &= 0x7f; /* number of subsequent octets */ |
| hdr->length = 0; |
| if (tmp > 4) { |
| wpa_printf(MSG_DEBUG, "ASN.1: Too long length field"); |
| return -1; |
| } |
| while (tmp--) { |
| if (pos >= end) { |
| wpa_printf(MSG_DEBUG, "ASN.1: Length " |
| "underflow"); |
| return -1; |
| } |
| hdr->length = (hdr->length << 8) | *pos++; |
| } |
| } else { |
| /* Short form - length 0..127 in one octet */ |
| hdr->length = tmp; |
| } |
| |
| if (end < pos || hdr->length > (unsigned int) (end - pos)) { |
| wpa_printf(MSG_DEBUG, "ASN.1: Contents underflow"); |
| return -1; |
| } |
| |
| hdr->payload = pos; |
| return 0; |
| } |
| |
| |
| int asn1_parse_oid(const u8 *buf, size_t len, struct asn1_oid *oid) |
| { |
| const u8 *pos, *end; |
| unsigned long val; |
| u8 tmp; |
| |
| os_memset(oid, 0, sizeof(*oid)); |
| |
| pos = buf; |
| end = buf + len; |
| |
| while (pos < end) { |
| val = 0; |
| |
| do { |
| if (pos >= end) |
| return -1; |
| tmp = *pos++; |
| val = (val << 7) | (tmp & 0x7f); |
| } while (tmp & 0x80); |
| |
| if (oid->len >= ASN1_MAX_OID_LEN) { |
| wpa_printf(MSG_DEBUG, "ASN.1: Too long OID value"); |
| return -1; |
| } |
| if (oid->len == 0) { |
| /* |
| * The first octet encodes the first two object |
| * identifier components in (X*40) + Y formula. |
| * X = 0..2. |
| */ |
| oid->oid[0] = val / 40; |
| if (oid->oid[0] > 2) |
| oid->oid[0] = 2; |
| oid->oid[1] = val - oid->oid[0] * 40; |
| oid->len = 2; |
| } else |
| oid->oid[oid->len++] = val; |
| } |
| |
| return 0; |
| } |
| |
| |
| int asn1_get_oid(const u8 *buf, size_t len, struct asn1_oid *oid, |
| const u8 **next) |
| { |
| struct asn1_hdr hdr; |
| |
| if (asn1_get_next(buf, len, &hdr) < 0 || hdr.length == 0) |
| return -1; |
| |
| if (hdr.class != ASN1_CLASS_UNIVERSAL || hdr.tag != ASN1_TAG_OID) { |
| wpa_printf(MSG_DEBUG, "ASN.1: Expected OID - found class %d " |
| "tag 0x%x", hdr.class, hdr.tag); |
| return -1; |
| } |
| |
| *next = hdr.payload + hdr.length; |
| |
| return asn1_parse_oid(hdr.payload, hdr.length, oid); |
| } |
| |
| |
| void asn1_oid_to_str(struct asn1_oid *oid, char *buf, size_t len) |
| { |
| char *pos = buf; |
| size_t i; |
| int ret; |
| |
| if (len == 0) |
| return; |
| |
| buf[0] = '\0'; |
| |
| for (i = 0; i < oid->len; i++) { |
| ret = os_snprintf(pos, buf + len - pos, |
| "%s%lu", |
| i == 0 ? "" : ".", oid->oid[i]); |
| if (ret < 0 || ret >= buf + len - pos) |
| break; |
| pos += ret; |
| } |
| buf[len - 1] = '\0'; |
| } |
| |
| |
| static u8 rotate_bits(u8 octet) |
| { |
| int i; |
| u8 res; |
| |
| res = 0; |
| for (i = 0; i < 8; i++) { |
| res <<= 1; |
| if (octet & 1) |
| res |= 1; |
| octet >>= 1; |
| } |
| |
| return res; |
| } |
| |
| |
| unsigned long asn1_bit_string_to_long(const u8 *buf, size_t len) |
| { |
| unsigned long val = 0; |
| const u8 *pos = buf; |
| |
| /* BER requires that unused bits are zero, so we can ignore the number |
| * of unused bits */ |
| pos++; |
| |
| if (len >= 2) |
| val |= rotate_bits(*pos++); |
| if (len >= 3) |
| val |= ((unsigned long) rotate_bits(*pos++)) << 8; |
| if (len >= 4) |
| val |= ((unsigned long) rotate_bits(*pos++)) << 16; |
| if (len >= 5) |
| val |= ((unsigned long) rotate_bits(*pos++)) << 24; |
| if (len >= 6) |
| wpa_printf(MSG_DEBUG, "X509: %s - some bits ignored " |
| "(BIT STRING length %lu)", |
| __func__, (unsigned long) len); |
| |
| return val; |
| } |