summaryrefslogtreecommitdiffstats
path: root/otautil/asn1_decoder.cpp
diff options
context:
space:
mode:
Diffstat (limited to 'otautil/asn1_decoder.cpp')
-rw-r--r--otautil/asn1_decoder.cpp156
1 files changed, 156 insertions, 0 deletions
diff --git a/otautil/asn1_decoder.cpp b/otautil/asn1_decoder.cpp
new file mode 100644
index 000000000..2d81a6e13
--- /dev/null
+++ b/otautil/asn1_decoder.cpp
@@ -0,0 +1,156 @@
+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "private/asn1_decoder.h"
+
+int asn1_context::peek_byte() const {
+ if (length_ == 0) {
+ return -1;
+ }
+ return *p_;
+}
+
+int asn1_context::get_byte() {
+ if (length_ == 0) {
+ return -1;
+ }
+
+ int byte = *p_;
+ p_++;
+ length_--;
+ return byte;
+}
+
+bool asn1_context::skip_bytes(size_t num_skip) {
+ if (length_ < num_skip) {
+ return false;
+ }
+ p_ += num_skip;
+ length_ -= num_skip;
+ return true;
+}
+
+bool asn1_context::decode_length(size_t* out_len) {
+ int num_octets = get_byte();
+ if (num_octets == -1) {
+ return false;
+ }
+ if ((num_octets & 0x80) == 0x00) {
+ *out_len = num_octets;
+ return true;
+ }
+ num_octets &= kMaskTag;
+ if (static_cast<size_t>(num_octets) >= sizeof(size_t)) {
+ return false;
+ }
+ size_t length = 0;
+ for (int i = 0; i < num_octets; ++i) {
+ int byte = get_byte();
+ if (byte == -1) {
+ return false;
+ }
+ length <<= 8;
+ length += byte;
+ }
+ *out_len = length;
+ return true;
+}
+
+/**
+ * Returns the constructed type and advances the pointer. E.g. A0 -> 0
+ */
+asn1_context* asn1_context::asn1_constructed_get() {
+ int type = get_byte();
+ if (type == -1 || (type & kMaskConstructed) != kTagConstructed) {
+ return nullptr;
+ }
+ size_t length;
+ if (!decode_length(&length) || length > length_) {
+ return nullptr;
+ }
+ asn1_context* app_ctx = new asn1_context(p_, length);
+ app_ctx->app_type_ = type & kMaskAppType;
+ return app_ctx;
+}
+
+bool asn1_context::asn1_constructed_skip_all() {
+ int byte = peek_byte();
+ while (byte != -1 && (byte & kMaskConstructed) == kTagConstructed) {
+ skip_bytes(1);
+ size_t length;
+ if (!decode_length(&length) || !skip_bytes(length)) {
+ return false;
+ }
+ byte = peek_byte();
+ }
+ return byte != -1;
+}
+
+int asn1_context::asn1_constructed_type() const {
+ return app_type_;
+}
+
+asn1_context* asn1_context::asn1_sequence_get() {
+ if ((get_byte() & kMaskTag) != kTagSequence) {
+ return nullptr;
+ }
+ size_t length;
+ if (!decode_length(&length) || length > length_) {
+ return nullptr;
+ }
+ return new asn1_context(p_, length);
+}
+
+asn1_context* asn1_context::asn1_set_get() {
+ if ((get_byte() & kMaskTag) != kTagSet) {
+ return nullptr;
+ }
+ size_t length;
+ if (!decode_length(&length) || length > length_) {
+ return nullptr;
+ }
+ return new asn1_context(p_, length);
+}
+
+bool asn1_context::asn1_sequence_next() {
+ size_t length;
+ if (get_byte() == -1 || !decode_length(&length) || !skip_bytes(length)) {
+ return false;
+ }
+ return true;
+}
+
+bool asn1_context::asn1_oid_get(const uint8_t** oid, size_t* length) {
+ if (get_byte() != kTagOid) {
+ return false;
+ }
+ if (!decode_length(length) || *length == 0 || *length > length_) {
+ return false;
+ }
+ *oid = p_;
+ return true;
+}
+
+bool asn1_context::asn1_octet_string_get(const uint8_t** octet_string, size_t* length) {
+ if (get_byte() != kTagOctetString) {
+ return false;
+ }
+ if (!decode_length(length) || *length == 0 || *length > length_) {
+ return false;
+ }
+ *octet_string = p_;
+ return true;
+}