/*
 * Copyright 2016 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 "avb_manager.h"

#include <string.h>
#include <uapi/err.h>

#include "secure_storage_interface.h"

#define DEBUG 0

const unsigned int kRollbackSlotMax = 32;

static const uint32_t kAvbVersion = 1;
static const char* kAvbRollbackFilename = "avb.rollback";
static const unsigned int kPermanentAttributesLengthMax = 2048;
static const char* kPermanentAttributesFilename = "avb.ppa";
static const char* kLockStateFile = "avb.lock_state";
static const unsigned int kStorageIdLengthMax = 64;

static const uint32_t kTypeMask = 0xF000;
static const unsigned int kTypeShift = 12;

// Helper function to get |filename| and |slot| and based on type flag
// in |raw_slot|. |filename| is assumed to be allocated with
// kStorageIdLengthMax bytes.
static int GetFilenameAndSlot(uint32_t raw_slot,
                              char filename[kStorageIdLengthMax],
                              uint32_t* slot) {
    // Upper 16 bits should not be set
    if (raw_slot & 0xFFFF0000) {
        TLOGE("Error: Slot value %u invalid\n", raw_slot);
        return ERR_NOT_VALID;
    }
    // Mask type flag from raw slot to get index
    *slot = raw_slot & ~kTypeMask;
    if (*slot >= kRollbackSlotMax) {
        TLOGE("Error: Slot value %u larger than supported %u\n", *slot,
              kRollbackSlotMax);
        return ERR_NOT_VALID;
    }
    // Choose correct file for rollback index type
    strcpy(filename, kAvbRollbackFilename);
    int index_type = (raw_slot & kTypeMask) >> kTypeShift;
    char postfix[4];
    snprintf(postfix, 4, ".%01X", index_type);
    strcat(filename, postfix);
    return NO_ERROR;
}

namespace avb {

void AvbManager::ReadRollbackIndex(const RollbackIndexRequest& request,
                                   RollbackIndexResponse* response) {
    uint32_t slot;
    char filename[kStorageIdLengthMax];
    if (GetFilenameAndSlot(request.get_slot(), filename, &slot) < 0) {
        response->set_error(AvbError::kInvalid);
        TLOGE("Error: Invalid slot value: %u\n", request.get_slot());
        return;
    }

    int rc = storage_->open(filename);
    if (rc < 0) {
        response->set_error(AvbError::kInternal);
        TLOGE("Error: failed to open file %s: %d\n", filename, rc);
        return;
    }
    uint64_t size;
    rc = storage_->get_file_size(&size);
    if (rc < 0) {
        response->set_error(AvbError::kInternal);
        TLOGE("Error: failed to get size of file %s: %d\n", filename, rc);
        return;
    }

    // If no valid rollback counter file is found, initialize to 0
    uint64_t rollback_counter;
    if (size < kRollbackSlotMax * sizeof(uint64_t)) {
        TLOGD("No valid rollback index file found. Initializing to 0\n");
        uint64_t write_buf[kRollbackSlotMax] = {0};
        rc = storage_->write(0, write_buf, sizeof(write_buf));
        rollback_counter = 0;
    } else {
        TLOGD("Rollback index file found\n");
        rc = storage_->read(sizeof(rollback_counter) * slot, &rollback_counter,
                            sizeof(rollback_counter));
    }

    if (rc < 0) {
        response->set_error(AvbError::kInternal);
        TLOGE("Error: reading storage object: %d\n", rc);
        return;
    }

    if (static_cast<size_t>(rc) < sizeof(rollback_counter)) {
        response->set_error(AvbError::kInternal);
        TLOGE("Error: invalid object size: %d\n", rc);
        return;
    }

    response->set_value(rollback_counter);
}

void AvbManager::WriteRollbackIndex(const RollbackIndexRequest& request,
                                    RollbackIndexResponse* response) {
    uint32_t slot;
    char filename[kStorageIdLengthMax];
    if (GetFilenameAndSlot(request.get_slot(), filename, &slot) < 0) {
        response->set_error(AvbError::kInvalid);
        TLOGE("Error: Invalid slot value: %u\n", request.get_slot());
        return;
    }

    int rc = storage_->open(filename);
    if (rc < 0) {
        response->set_error(AvbError::kInternal);
        TLOGE("Error: failed to open file %s: %d\n", filename, rc);
        return;
    }
    uint64_t size;
    rc = storage_->get_file_size(&size);
    if (rc < 0) {
        response->set_error(AvbError::kInternal);
        TLOGE("Error: failed to get size of file %s: %d\n", filename, rc);
        return;
    }

    // If no valid rollback counter file is found, initialize to 0
    uint64_t request_value = request.get_value();
    if (static_cast<size_t>(size) < kRollbackSlotMax * sizeof(uint64_t)) {
        TLOGD("No valid rollback index file found. Initializing to 0\n");
        uint64_t write_buf[kRollbackSlotMax] = {0};
        write_buf[slot] = request_value;
        rc = storage_->write(0, write_buf, sizeof(write_buf));
    } else {
        uint64_t rollback_counter;
        TLOGD("Found a rollback index file\n");
        rc = storage_->read(sizeof(rollback_counter) * slot, &rollback_counter,
                            sizeof(rollback_counter));

        // Write value to specified slot in file
        if (request_value < rollback_counter) {
            response->set_error(AvbError::kInvalid);
            TLOGE("Error: Requested write [%lu] is less than existing counter value "
                  "[%lu]\n",
                  static_cast<long unsigned>(request_value),
                  static_cast<long unsigned>(rollback_counter));
            response->set_value(rollback_counter);
            return;
        }
        rc = storage_->write(sizeof(request_value) * slot, &request_value,
                             sizeof(request_value));
    }

    if (rc < 0) {
        response->set_error(AvbError::kInternal);
        TLOGE("Error: accessing storage object [%d]\n", rc);
        return;
    }

    if (static_cast<size_t>(rc) < sizeof(request_value)) {
        response->set_error(AvbError::kInternal);
        TLOGE("Error: invalid object size [%d]\n", rc);
        return;
    }

    response->set_value(request_value);
}

void AvbManager::GetVersion(const GetVersionRequest& request,
                            GetVersionResponse* response) {
    response->set_version(kAvbVersion);
}

void AvbManager::ReadPermanentAttributes(
        const ReadPermanentAttributesRequest& request,
        ReadPermanentAttributesResponse* response) {
    int rc = storage_->open(kPermanentAttributesFilename);
    if (rc < 0) {
        response->set_error(AvbError::kInternal);
        TLOGE("Error: failed to open attributes file: %d\n", rc);
        return;
    }

    // Read permanent product attributes
    UniquePtr<uint8_t[]> attributes(new uint8_t[kPermanentAttributesLengthMax]);
    rc = storage_->read(0, attributes.get(), kPermanentAttributesLengthMax);
    if (rc <= 0) {
        response->set_error(AvbError::kInternal);
        TLOGE("Error: %s attributes file [%d]\n",
              rc == 0 ? "missing" : "accessing", rc);
        return;
    }
    uint32_t attributes_size = static_cast<uint32_t>(rc);
    response->set_attributes_buf(attributes.get(), attributes_size);
}

void AvbManager::WritePermanentAttributes(
        const WritePermanentAttributesRequest& request,
        WritePermanentAttributesResponse* response) {
    int rc = storage_->open(kPermanentAttributesFilename);
    if (rc < 0) {
        response->set_error(AvbError::kInternal);
        TLOGE("Error: failed to open attributes file: %d\n", rc);
        return;
    }
    uint64_t size;
    rc = storage_->get_file_size(&size);
    if (rc < 0) {
        response->set_error(AvbError::kInternal);
        TLOGE("Error: failed to get size of attributes file: %d\n", rc);
        return;
    }

    if (size) {
        response->set_error(AvbError::kInvalid);
        TLOGE("Error: Permanent attributes already set!\n");
        return;
    }
    // New file, write serialized permanent product attributes to storage
    uint32_t attributes_size = request.get_attributes_size();
    uint8_t* attributes = request.get_attributes_buf();
    rc = storage_->write(0, attributes, attributes_size);

    if (rc < 0 || static_cast<size_t>(rc) < attributes_size) {
        response->set_error(AvbError::kInternal);
        TLOGE("Error: accessing storage object [%d]\n", rc);
        return;
    }
}

void AvbManager::ReadLockState(const ReadLockStateRequest& request,
                               ReadLockStateResponse* response) {
    int rc = storage_->open(kLockStateFile);
    if (rc < 0) {
        response->set_error(AvbError::kInternal);
        TLOGE("Error: failed to open lock state file: %d\n", rc);
        return;
    }
    uint64_t size;
    rc = storage_->get_file_size(&size);
    if (rc < 0) {
        response->set_error(AvbError::kInternal);
        TLOGE("Error: failed to get size of lock state file: %d\n", rc);
        return;
    }

    uint8_t lock_state = 1;
    if (size == 0) {
        // No lock state found, assume initial state is locked and write it
        rc = storage_->write(0, &lock_state, sizeof(lock_state));
    } else {
        rc = storage_->read(0, &lock_state, sizeof(lock_state));
    }
    if (rc < 0 || static_cast<size_t>(rc) < sizeof(lock_state)) {
        response->set_error(AvbError::kInternal);
        TLOGE("Error: accessing storage object [%d]\n", rc);
        return;
    }
    response->set_lock_state(lock_state);
}

void AvbManager::WriteLockState(const WriteLockStateRequest& request,
                                WriteLockStateResponse* response) {
    // Only 0 and 1 are valid lock states
    uint8_t request_lock_state = request.get_lock_state();
    if (request_lock_state != 0 && request_lock_state != 1) {
        response->set_error(AvbError::kInvalid);
        TLOGE("Error: invalid lock state requested: %d\n", request_lock_state);
        return;
    }

    int rc = storage_->open(kLockStateFile);
    if (rc < 0) {
        response->set_error(AvbError::kInternal);
        TLOGE("Error: failed to open lock state file: %d\n", rc);
        return;
    }

    // Try to read existing lock state
    uint8_t stored_lock_state = 0xFF;
    storage_->read(0, &stored_lock_state, sizeof(stored_lock_state));

    // If no lock state file was found, or the device is changing lock state,
    // clear rollback index data
    if (stored_lock_state != request_lock_state) {
        if (DeleteRollbackIndexFiles() < 0) {
            response->set_error(AvbError::kInternal);
            TLOGE("Error: clearing rollback index data\n");
            return;
        }
    }

    // Write new lock state
    rc = storage_->write(0, &request_lock_state, sizeof(request_lock_state));
    if (rc < 0 || static_cast<size_t>(rc) < sizeof(request_lock_state)) {
        response->set_error(AvbError::kInternal);
        TLOGE("Error: accessing storage object [%d]\n", rc);
        return;
    }
}

// Rollback counters are stored in files avb.rollback.{0..F}. When a device
// changes lock state, data in rollback index files must be deleted.
int AvbManager::DeleteRollbackIndexFiles() {
    char filename[kStorageIdLengthMax];
    char postfix[4];
    int rc = NO_ERROR;

    for (unsigned int i = 0x0; i <= 0xF; ++i) {
        strcpy(filename, kAvbRollbackFilename);
        snprintf(postfix, 4, ".%01X", i);
        strcat(filename, postfix);
        int storage_rc = storage_->delete_file(filename);
        if (storage_rc < 0 && storage_rc != ERR_NOT_FOUND) {
            rc = storage_rc;
            TLOGE("Error: deleting file %s: %d\n", filename, rc);
            continue;
        }
    }
    return rc;
}

};  // namespace avb