Commit 861c53c6 authored by Tao Bao's avatar Tao Bao

Refactor asn1_decoder functions into a class.

Test: mmma bootable/recovery
Test: recovery_unit_test passes.
Test: recovery_component_test passes.
Change-Id: If0bf25993158eaebeedff55ba4f4dd0f6e5f937d
parent 5b2bf90e
......@@ -14,178 +14,145 @@
* limitations under the License.
*/
#include <malloc.h>
#include <stdint.h>
#include <string.h>
#include "asn1_decoder.h"
#include <stdint.h>
typedef struct asn1_context {
size_t length;
const uint8_t* p;
int app_type;
} asn1_context_t;
static const int kMaskConstructed = 0xE0;
static const int kMaskTag = 0x7F;
static const int kMaskAppType = 0x1F;
static const int kTagOctetString = 0x04;
static const int kTagOid = 0x06;
static const int kTagSequence = 0x30;
static const int kTagSet = 0x31;
static const int kTagConstructed = 0xA0;
asn1_context_t* asn1_context_new(const uint8_t* buffer, size_t length) {
asn1_context_t* ctx = (asn1_context_t*) calloc(1, sizeof(asn1_context_t));
if (ctx == NULL) {
return NULL;
}
ctx->p = buffer;
ctx->length = length;
return ctx;
}
void asn1_context_free(asn1_context_t* ctx) {
free(ctx);
int asn1_context::peek_byte() const {
if (length_ <= 0) {
return -1;
}
return *p_;
}
static inline int peek_byte(asn1_context_t* ctx) {
if (ctx->length <= 0) {
return -1;
}
return *ctx->p;
}
int asn1_context::get_byte() {
if (length_ <= 0) {
return -1;
}
static inline int get_byte(asn1_context_t* ctx) {
if (ctx->length <= 0) {
return -1;
}
int byte = *ctx->p;
ctx->p++;
ctx->length--;
return byte;
int byte = *p_;
p_++;
length_--;
return byte;
}
static inline bool skip_bytes(asn1_context_t* ctx, size_t num_skip) {
if (ctx->length < num_skip) {
return false;
}
ctx->p += num_skip;
ctx->length -= num_skip;
return true;
bool asn1_context::skip_bytes(size_t num_skip) {
if (length_ < num_skip) {
return false;
}
p_ += num_skip;
length_ -= num_skip;
return true;
}
static bool decode_length(asn1_context_t* ctx, size_t* out_len) {
int num_octets = get_byte(ctx);
if (num_octets == -1) {
return false;
}
if ((num_octets & 0x80) == 0x00) {
*out_len = num_octets;
return 1;
}
num_octets &= kMaskTag;
if ((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(ctx);
if (byte == -1) {
return false;
}
length <<= 8;
length += byte;
}
*out_len = length;
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_t* asn1_constructed_get(asn1_context_t* ctx) {
int type = get_byte(ctx);
if (type == -1 || (type & kMaskConstructed) != kTagConstructed) {
return NULL;
}
size_t length;
if (!decode_length(ctx, &length) || length > ctx->length) {
return NULL;
}
asn1_context_t* app_ctx = asn1_context_new(ctx->p, length);
app_ctx->app_type = type & kMaskAppType;
return app_ctx;
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_constructed_skip_all(asn1_context_t* ctx) {
int byte = peek_byte(ctx);
while (byte != -1 && (byte & kMaskConstructed) == kTagConstructed) {
skip_bytes(ctx, 1);
size_t length;
if (!decode_length(ctx, &length) || !skip_bytes(ctx, length)) {
return false;
}
byte = peek_byte(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;
}
return byte != -1;
byte = peek_byte();
}
return byte != -1;
}
int asn1_constructed_type(asn1_context_t* ctx) {
return ctx->app_type;
int asn1_context::asn1_constructed_type() const {
return app_type_;
}
asn1_context_t* asn1_sequence_get(asn1_context_t* ctx) {
if ((get_byte(ctx) & kMaskTag) != kTagSequence) {
return NULL;
}
size_t length;
if (!decode_length(ctx, &length) || length > ctx->length) {
return NULL;
}
return asn1_context_new(ctx->p, length);
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_t* asn1_set_get(asn1_context_t* ctx) {
if ((get_byte(ctx) & kMaskTag) != kTagSet) {
return NULL;
}
size_t length;
if (!decode_length(ctx, &length) || length > ctx->length) {
return NULL;
}
return asn1_context_new(ctx->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_sequence_next(asn1_context_t* ctx) {
size_t length;
if (get_byte(ctx) == -1 || !decode_length(ctx, &length) || !skip_bytes(ctx, length)) {
return false;
}
return true;
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_oid_get(asn1_context_t* ctx, const uint8_t** oid, size_t* length) {
if (get_byte(ctx) != kTagOid) {
return false;
}
if (!decode_length(ctx, length) || *length == 0 || *length > ctx->length) {
return false;
}
*oid = ctx->p;
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_octet_string_get(asn1_context_t* ctx, const uint8_t** octet_string, size_t* length) {
if (get_byte(ctx) != kTagOctetString) {
return false;
}
if (!decode_length(ctx, length) || *length == 0 || *length > ctx->length) {
return false;
}
*octet_string = ctx->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;
}
......@@ -14,23 +14,42 @@
* limitations under the License.
*/
#ifndef ASN1_DECODER_H_
#define ASN1_DECODER_H_
#include <stdint.h>
typedef struct asn1_context asn1_context_t;
asn1_context_t* asn1_context_new(const uint8_t* buffer, size_t length);
void asn1_context_free(asn1_context_t* ctx);
asn1_context_t* asn1_constructed_get(asn1_context_t* ctx);
bool asn1_constructed_skip_all(asn1_context_t* ctx);
int asn1_constructed_type(asn1_context_t* ctx);
asn1_context_t* asn1_sequence_get(asn1_context_t* ctx);
asn1_context_t* asn1_set_get(asn1_context_t* ctx);
bool asn1_sequence_next(asn1_context_t* seq);
bool asn1_oid_get(asn1_context_t* ctx, const uint8_t** oid, size_t* length);
bool asn1_octet_string_get(asn1_context_t* ctx, const uint8_t** octet_string, size_t* length);
class asn1_context {
public:
asn1_context(const uint8_t* buffer, size_t length) : p_(buffer), length_(length), app_type_(0) {}
int asn1_constructed_type() const;
asn1_context* asn1_constructed_get();
bool asn1_constructed_skip_all();
asn1_context* asn1_sequence_get();
asn1_context* asn1_set_get();
bool asn1_sequence_next();
bool asn1_oid_get(const uint8_t** oid, size_t* length);
bool asn1_octet_string_get(const uint8_t** octet_string, size_t* length);
private:
static constexpr int kMaskConstructed = 0xE0;
static constexpr int kMaskTag = 0x7F;
static constexpr int kMaskAppType = 0x1F;
static constexpr int kTagOctetString = 0x04;
static constexpr int kTagOid = 0x06;
static constexpr int kTagSequence = 0x30;
static constexpr int kTagSet = 0x31;
static constexpr int kTagConstructed = 0xA0;
int peek_byte() const;
int get_byte();
bool skip_bytes(size_t num_skip);
bool decode_length(size_t* out_len);
const uint8_t* p_;
size_t length_;
int app_type_;
};
#endif /* ASN1_DECODER_H_ */
This diff is collapsed.
......@@ -66,48 +66,50 @@ static bool read_pkcs7(const uint8_t* pkcs7_der, size_t pkcs7_der_len,
CHECK(sig_der != nullptr);
sig_der->clear();
asn1_context_t* ctx = asn1_context_new(pkcs7_der, pkcs7_der_len);
if (ctx == NULL) {
asn1_context ctx(pkcs7_der, pkcs7_der_len);
std::unique_ptr<asn1_context> pkcs7_seq(ctx.asn1_sequence_get());
if (pkcs7_seq == nullptr || !pkcs7_seq->asn1_sequence_next()) {
return false;
}
asn1_context_t* pkcs7_seq = asn1_sequence_get(ctx);
if (pkcs7_seq != NULL && asn1_sequence_next(pkcs7_seq)) {
asn1_context_t *signed_data_app = asn1_constructed_get(pkcs7_seq);
if (signed_data_app != NULL) {
asn1_context_t* signed_data_seq = asn1_sequence_get(signed_data_app);
if (signed_data_seq != NULL
&& asn1_sequence_next(signed_data_seq)
&& asn1_sequence_next(signed_data_seq)
&& asn1_sequence_next(signed_data_seq)
&& asn1_constructed_skip_all(signed_data_seq)) {
asn1_context_t *sig_set = asn1_set_get(signed_data_seq);
if (sig_set != NULL) {
asn1_context_t* sig_seq = asn1_sequence_get(sig_set);
if (sig_seq != NULL
&& asn1_sequence_next(sig_seq)
&& asn1_sequence_next(sig_seq)
&& asn1_sequence_next(sig_seq)
&& asn1_sequence_next(sig_seq)) {
const uint8_t* sig_der_ptr;
size_t sig_der_length;
if (asn1_octet_string_get(sig_seq, &sig_der_ptr, &sig_der_length)) {
sig_der->resize(sig_der_length);
std::copy(sig_der_ptr, sig_der_ptr + sig_der_length, sig_der->begin());
}
asn1_context_free(sig_seq);
}
asn1_context_free(sig_set);
}
asn1_context_free(signed_data_seq);
}
asn1_context_free(signed_data_app);
}
asn1_context_free(pkcs7_seq);
std::unique_ptr<asn1_context> signed_data_app(pkcs7_seq->asn1_constructed_get());
if (signed_data_app == nullptr) {
return false;
}
std::unique_ptr<asn1_context> signed_data_seq(signed_data_app->asn1_sequence_get());
if (signed_data_seq == nullptr ||
!signed_data_seq->asn1_sequence_next() ||
!signed_data_seq->asn1_sequence_next() ||
!signed_data_seq->asn1_sequence_next() ||
!signed_data_seq->asn1_constructed_skip_all()) {
return false;
}
std::unique_ptr<asn1_context> sig_set(signed_data_seq->asn1_set_get());
if (sig_set == nullptr) {
return false;
}
std::unique_ptr<asn1_context> sig_seq(sig_set->asn1_sequence_get());
if (sig_seq == nullptr ||
!sig_seq->asn1_sequence_next() ||
!sig_seq->asn1_sequence_next() ||
!sig_seq->asn1_sequence_next() ||
!sig_seq->asn1_sequence_next()) {
return false;
}
const uint8_t* sig_der_ptr;
size_t sig_der_length;
if (!sig_seq->asn1_octet_string_get(&sig_der_ptr, &sig_der_length)) {
return false;
}
asn1_context_free(ctx);
return !sig_der->empty();
sig_der->resize(sig_der_length);
std::copy(sig_der_ptr, sig_der_ptr + sig_der_length, sig_der->begin());
return true;
}
/*
......
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