RemoteAuthentication.h

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/*
 * Copyright (c) 2018 https://www.thecoderscorner.com (Dave Cherry).
 * This product is licensed under an Apache license, see the LICENSE file in the top-level directory.
 */
 
#ifndef _REMOTE_AUTHENTICATION_H_
#define _REMOTE_AUTHENTICATION_H_
 
#include <EepromAbstraction.h>
#include "tcUtil.h"
 
#ifndef MAX_PIN_LENGTH
#define MAX_PIN_LENGTH 16
#endif
 
#ifndef CLIENT_DESC_SIZE
#define CLIENT_DESC_SIZE 16
#endif
 
#define UUID_KEY_SIZE 40
#define TOTAL_KEY_SIZE (UUID_KEY_SIZE + CLIENT_DESC_SIZE)
 
enum AuthenticationManagerType: uint8_t {
    AUTHENTICATION_NONE, AUTHENTICATION_IN_EEPROM, AUTHENTICATION_IN_FLASH
};
 
class AuthenticationManager {
private:
    AuthenticationManagerType authenticationManagerType;
public:
    explicit AuthenticationManager(AuthenticationManagerType authType) : authenticationManagerType(authType) {}
 
    AuthenticationManagerType getAuthenticationManagerType() { return authenticationManagerType; }
 
    virtual bool addAdditionalUUIDKey(const char* connectionName, const char* uuid)=0;
 
    virtual bool isAuthenticated(const char* connectionName, const char* authResponse)=0;
 
    virtual bool doesPinMatch(const char* pinAttempt)=0;
};
 
class EepromAuthenticatorManager : public AuthenticationManager {
private:
    EepromAbstraction *eeprom;
    EepromPosition romStart;
    uint16_t magicKey;
    uint8_t  numberOfEntries;
public:
    explicit EepromAuthenticatorManager(uint8_t numOfEntries = 6) : AuthenticationManager(AUTHENTICATION_IN_EEPROM) {
        eeprom = nullptr;
        romStart = 0;
        this->magicKey = 0;
        this->numberOfEntries = numOfEntries;
    }
 
    void initialise(EepromAbstraction* eeprom, EepromPosition start, uint16_t magicKey = 0x9B32);
 
    void resetAllKeys();
 
    void changePin(const char* newPin);
 
    void copyPinToBuffer(char* buffer, int size);
 
    void copyKeyNameToBuffer(int idx, char* buffer, int bufSize);
 
    bool addAdditionalUUIDKey(const char* connectionName, const char* uuid) override;
 
    bool isAuthenticated(const char* connectionName, const char* authResponse) override;
 
    bool doesPinMatch(const char* pinAttempt) override;
 
    int getNumberOfEntries() const {
        return numberOfEntries;
    }
private:
    // finds the slot (or an empty slot) or if neither are found returns -1
    int findSlotFor(const char* name);
 
    // helper to calculate the eeprom position from an index.
    EepromPosition eepromOffset(int i) const {
        return romStart + 2 + (i * TOTAL_KEY_SIZE);
    }
};
 
class NoAuthenticationManager : public AuthenticationManager {
public:
    NoAuthenticationManager() : AuthenticationManager(AUTHENTICATION_NONE) { }
 
    bool addAdditionalUUIDKey(const char* /*connectionName*/, const char* /*uuid*/) override { return true; }
 
    bool isAuthenticated(const char* /*connectionName*/, const char* /*authResponse*/) override { return true; }
 
    bool doesPinMatch(const char*) override { return true; }
};
 
struct AuthBlock {
    char name[CLIENT_DESC_SIZE];
    char uuid[UUID_KEY_SIZE];
};
 
class ReadOnlyAuthenticationManager : public AuthenticationManager {
private:
    const AuthBlock* authBlocksPgm;
    int numberOfEntries;
    const char* pgmActualPin;
public:
    ReadOnlyAuthenticationManager(const AuthBlock* authBlocksPgm, int numberOfEntries, const char* pgmActualPin)
      : AuthenticationManager(AUTHENTICATION_IN_FLASH) {
        this->authBlocksPgm = authBlocksPgm;
        this->numberOfEntries = numberOfEntries;
        this->pgmActualPin = pgmActualPin;
    }
 
    explicit ReadOnlyAuthenticationManager(const char* pgmActualPin)  : AuthenticationManager(AUTHENTICATION_IN_FLASH) {
        this->authBlocksPgm = nullptr;
        this->numberOfEntries = 0;
        this->pgmActualPin = pgmActualPin;
    }
 
    bool addAdditionalUUIDKey(const char* /*connectionName*/, const char* /*uuid*/) override { return false; }
 
    bool isAuthenticated(const char* connectionName, const char* authResponse) override;
 
    bool doesPinMatch(const char* pinAttempt) override {
        return strcmp_P(pgmActualPin, pinAttempt) == 0;
    }
};
 
#endif //_REMOTE_AUTHENTICATION_H_