/*
The MIT License (MIT)

Copyright (c) 2013-2015 SRS(simple-rtmp-server)

Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
the Software, and to permit persons to whom the Software is furnished to do so,
subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/

#ifndef SRS_RTMP_PROTOCOL_HANDSHKAE_HPP
#define SRS_RTMP_PROTOCOL_HANDSHKAE_HPP

/*
#include <srs_rtmp_handshake.hpp>
*/

#include <srs_core.hpp>

class ISrsProtocolReaderWriter;
class SrsComplexHandshake;
class SrsHandshakeBytes;
class SrsStream;

#ifdef SRS_AUTO_SSL

// for openssl.
#include <openssl/hmac.h>

namespace _srs_internal
{
    // the digest key generate size.
    #define SRS_OpensslHashSize 512
    extern u_int8_t SrsGenuineFMSKey[];
    extern u_int8_t SrsGenuineFPKey[];
    int openssl_HMACsha256(const void* key, int key_size, const void* data, int data_size, void* digest);
    int openssl_generate_key(char* public_key, int32_t size);
    
    /**
    * the DH wrapper.
    */
    class SrsDH
    {
    private:
        DH* pdh;
    public:
        SrsDH();
        virtual ~SrsDH();
    public:
        /**
        * initialize dh, generate the public and private key.
        * @param ensure_128bytes_public_key whether ensure public key is 128bytes,
        *       sometimes openssl generate 127bytes public key.
        *       default to false to donot ensure.
        */
        virtual int initialize(bool ensure_128bytes_public_key = false);
        /**
        * copy the public key.
        * @param pkey the bytes to copy the public key.
        * @param pkey_size the max public key size, output the actual public key size.
        *       user should never ignore this size.
        * @remark, when ensure_128bytes_public_key, the size always 128.
        */
        virtual int copy_public_key(char* pkey, int32_t& pkey_size);
        /**
        * generate and copy the shared key.
        * generate the shared key with peer public key.
        * @param ppkey peer public key.
        * @param ppkey_size the size of ppkey.
        * @param skey the computed shared key.
        * @param skey_size the max shared key size, output the actual shared key size.
        *       user should never ignore this size.
        */
        virtual int copy_shared_key(const char* ppkey, int32_t ppkey_size, char* skey, int32_t& skey_size);
    private:
        virtual int do_initialize();
    };
    /**
    * the schema type.
    */
    enum srs_schema_type 
    {
        srs_schema_invalid = 2,
        
        /**
        * key-digest sequence
        */
        srs_schema0 = 0,
        
        /**
        * digest-key sequence
        * @remark, FMS requires the schema1(digest-key), or connect failed.
        */
        // 
        srs_schema1 = 1,
    };
    
    /**
    * 764bytes key structure
    *     random-data: (offset)bytes
    *     key-data: 128bytes
    *     random-data: (764-offset-128-4)bytes
    *     offset: 4bytes
    * @see also: http://blog.csdn.net/win_lin/article/details/13006803
    */
    class key_block
    {
    public:
        // (offset)bytes
        char* random0;
        int random0_size;
        
        // 128bytes
        char key[128];
        
        // (764-offset-128-4)bytes
        char* random1;
        int random1_size;
        
        // 4bytes
        int32_t offset;
    public:
        key_block();
        virtual ~key_block();
    public:
        // parse key block from c1s1.
        // if created, user must free it by srs_key_block_free
        // @stream contains c1s1_key_bytes the key start bytes
        int parse(SrsStream* stream);
    private:
        // calc the offset of key,
        // the key->offset cannot be used as the offset of key.
        int calc_valid_offset();
    };
    
    /**
    * 764bytes digest structure
    *     offset: 4bytes
    *     random-data: (offset)bytes
    *     digest-data: 32bytes
    *     random-data: (764-4-offset-32)bytes
    * @see also: http://blog.csdn.net/win_lin/article/details/13006803
    */
    class digest_block
    {
    public:
        // 4bytes
        int32_t offset;
        
        // (offset)bytes
        char* random0;
        int random0_size;
        
        // 32bytes
        char digest[32];
        
        // (764-4-offset-32)bytes
        char* random1;
        int random1_size;
    public:
        digest_block();
        virtual ~digest_block();
    public:
        // parse digest block from c1s1.
        // if created, user must free it by srs_digest_block_free
        // @stream contains c1s1_digest_bytes the digest start bytes
        int parse(SrsStream* stream);
    private:
        // calc the offset of digest,
        // the key->offset cannot be used as the offset of digest.
        int calc_valid_offset();
    };
    
    class c1s1;
    
    /**
    * the c1s1 strategy, use schema0 or schema1.
    * the template method class to defines common behaviors,
    * while the concrete class to implements in schema0 or schema1.
    */
    class c1s1_strategy
    {
    protected:
        key_block key;
        digest_block digest;
    public:
        c1s1_strategy();
        virtual ~c1s1_strategy();
    public:
        /**
        * get the scema.
        */
        virtual srs_schema_type schema() = 0;
        /**
        * get the digest.
        */
        virtual char* get_digest();
        /**
        * get the key.
        */
        virtual char* get_key();
        /**
        * copy to bytes.
        * @param size must be 1536.
        */
        virtual int dump(c1s1* owner, char* _c1s1, int size);
        /**
        * server: parse the c1s1, discovery the key and digest by schema.
        * use the c1_validate_digest() to valid the digest of c1.
        */
        virtual int parse(char* _c1s1, int size) = 0;
    public:
        /**
        * client: create and sign c1 by schema.
        * sign the c1, generate the digest.
        *         calc_c1_digest(c1, schema) {
        *            get c1s1-joined from c1 by specified schema
        *            digest-data = HMACsha256(c1s1-joined, FPKey, 30)
        *            return digest-data;
        *        }
        *        random fill 1536bytes c1 // also fill the c1-128bytes-key
        *        time = time() // c1[0-3]
        *        version = [0x80, 0x00, 0x07, 0x02] // c1[4-7]
        *        schema = choose schema0 or schema1
        *        digest-data = calc_c1_digest(c1, schema)
        *        copy digest-data to c1
        */
        virtual int c1_create(c1s1* owner);
        /**
        * server: validate the parsed c1 schema
        */
        virtual int c1_validate_digest(c1s1* owner, bool& is_valid);
        /**
        * server: create and sign the s1 from c1.
        *       // decode c1 try schema0 then schema1
        *       c1-digest-data = get-c1-digest-data(schema0)
        *       if c1-digest-data equals to calc_c1_digest(c1, schema0) {  
        *           c1-key-data = get-c1-key-data(schema0)  
        *           schema = schema0
        *       } else {  
        *           c1-digest-data = get-c1-digest-data(schema1)  
        *           if c1-digest-data not equals to calc_c1_digest(c1, schema1) {
        *               switch to simple handshake.  
        *               return  
        *           }
        *           c1-key-data = get-c1-key-data(schema1)  
        *           schema = schema1
        *       }
        * 
        *       // generate s1
        *       random fill 1536bytes s1
        *       time = time() // c1[0-3]
        *       version = [0x04, 0x05, 0x00, 0x01] // s1[4-7]
        *       s1-key-data=shared_key=DH_compute_key(peer_pub_key=c1-key-data)
        *       get c1s1-joined by specified schema
        *       s1-digest-data = HMACsha256(c1s1-joined, FMSKey, 36)
        *       copy s1-digest-data and s1-key-data to s1.
        * @param c1, to get the peer_pub_key of client.
        */
        virtual int s1_create(c1s1* owner, c1s1* c1);
        /**
        * server: validate the parsed s1 schema
        */
        virtual int s1_validate_digest(c1s1* owner, bool& is_valid);
    public:
        /**
        * calc the digest for c1
        */
        virtual int calc_c1_digest(c1s1* owner, char*& c1_digest);
        /**
        * calc the digest for s1
        */
        virtual int calc_s1_digest(c1s1* owner, char*& s1_digest);
        /**
        * copy whole c1s1 to bytes.
        * @param size must always be 1536 with digest, and 1504 without digest.
        */
        virtual int copy_to(c1s1* owner, char* bytes, int size, bool with_digest) = 0;
        /**
        * copy time and version to stream.
        */
        virtual void copy_time_version(SrsStream* stream, c1s1* owner);
        /**
        * copy key to stream.
        */
        virtual void copy_key(SrsStream* stream);
        /**
        * copy digest to stream.
        */
        virtual void copy_digest(SrsStream* stream, bool with_digest);
    };
    
    /**
    * c1s1 schema0
    *     key: 764bytes
    *     digest: 764bytes
    */
    class c1s1_strategy_schema0 : public c1s1_strategy
    {
    public:
        c1s1_strategy_schema0();
        virtual ~c1s1_strategy_schema0();
    public:
        virtual srs_schema_type schema();
        virtual int parse(char* _c1s1, int size);
    public:
        virtual int copy_to(c1s1* owner, char* bytes, int size, bool with_digest);
    };
    
    /**
    * c1s1 schema1
    *     digest: 764bytes
    *     key: 764bytes
    */
    class c1s1_strategy_schema1 : public c1s1_strategy
    {
    public:
        c1s1_strategy_schema1();
        virtual ~c1s1_strategy_schema1();
    public:
        virtual srs_schema_type schema();
        virtual int parse(char* _c1s1, int size);
    public:
        virtual int copy_to(c1s1* owner, char* bytes, int size, bool with_digest);
    };

    /**
    * c1s1 schema0
    *     time: 4bytes
    *     version: 4bytes
    *     key: 764bytes
    *     digest: 764bytes
    * c1s1 schema1
    *     time: 4bytes
    *     version: 4bytes
    *     digest: 764bytes
    *     key: 764bytes
    * @see also: http://blog.csdn.net/win_lin/article/details/13006803
    */
    class c1s1
    {
    public:
        // 4bytes
        int32_t time;
        // 4bytes
        int32_t version;
        // 764bytes+764bytes
        c1s1_strategy* payload;
    public:
        c1s1();
        virtual ~c1s1();
    public:
        /**
        * get the scema.
        */
        virtual srs_schema_type schema();
        /**
        * get the digest key.
        */
        virtual char* get_digest();
        /**
        * get the key.
        */
        virtual char* get_key();
    public:
        /**
        * copy to bytes.
        * @param size, must always be 1536.
        */
        virtual int dump(char* _c1s1, int size);
        /**
        * server: parse the c1s1, discovery the key and digest by schema.
        * @param size, must always be 1536.
        * use the c1_validate_digest() to valid the digest of c1.
        * use the s1_validate_digest() to valid the digest of s1.
        */
        virtual int parse(char* _c1s1, int size, srs_schema_type _schema);
    public:
        /**
        * client: create and sign c1 by schema.
        * sign the c1, generate the digest.
        *         calc_c1_digest(c1, schema) {
        *            get c1s1-joined from c1 by specified schema
        *            digest-data = HMACsha256(c1s1-joined, FPKey, 30)
        *            return digest-data;
        *        }
        *        random fill 1536bytes c1 // also fill the c1-128bytes-key
        *        time = time() // c1[0-3]
        *        version = [0x80, 0x00, 0x07, 0x02] // c1[4-7]
        *        schema = choose schema0 or schema1
        *        digest-data = calc_c1_digest(c1, schema)
        *        copy digest-data to c1
        */
        virtual int c1_create(srs_schema_type _schema);
        /**
        * server: validate the parsed c1 schema
        */
        virtual int c1_validate_digest(bool& is_valid);
    public:
        /**
        * server: create and sign the s1 from c1.
        *       // decode c1 try schema0 then schema1
        *       c1-digest-data = get-c1-digest-data(schema0)
        *       if c1-digest-data equals to calc_c1_digest(c1, schema0) {  
        *           c1-key-data = get-c1-key-data(schema0)  
        *           schema = schema0
        *       } else {  
        *           c1-digest-data = get-c1-digest-data(schema1)  
        *           if c1-digest-data not equals to calc_c1_digest(c1, schema1) {
        *               switch to simple handshake.  
        *               return  
        *           }
        *           c1-key-data = get-c1-key-data(schema1)  
        *           schema = schema1
        *       }
        * 
        *       // generate s1
        *       random fill 1536bytes s1
        *       time = time() // c1[0-3]
        *       version = [0x04, 0x05, 0x00, 0x01] // s1[4-7]
        *       s1-key-data=shared_key=DH_compute_key(peer_pub_key=c1-key-data)
        *       get c1s1-joined by specified schema
        *       s1-digest-data = HMACsha256(c1s1-joined, FMSKey, 36)
        *       copy s1-digest-data and s1-key-data to s1.
        */
        virtual int s1_create(c1s1* c1);
        /**
        * server: validate the parsed s1 schema
        */
        virtual int s1_validate_digest(bool& is_valid);
    };
    
    /**
    * the c2s2 complex handshake structure.
    * random-data: 1504bytes
    * digest-data: 32bytes
    * @see also: http://blog.csdn.net/win_lin/article/details/13006803
    */
    class c2s2
    {
    public:
        char random[1504];
        char digest[32];
    public:
        c2s2();
        virtual ~c2s2();
    public:
        /**
        * copy to bytes.
        * @param size, must always be 1536.
        */
        virtual int dump(char* _c2s2, int size);
        /**
        * parse the c2s2
        * @param size, must always be 1536.
        */
        virtual int parse(char* _c2s2, int size);
    public:
        /**
        * create c2.
        * random fill c2s2 1536 bytes
        * 
        * // client generate C2, or server valid C2
        * temp-key = HMACsha256(s1-digest, FPKey, 62)
        * c2-digest-data = HMACsha256(c2-random-data, temp-key, 32)
        */
        virtual int c2_create(c1s1* s1);
        
        /**
        * validate the c2 from client.
        */
        virtual int c2_validate(c1s1* s1, bool& is_valid);
    public:
        /**
        * create s2.
        * random fill c2s2 1536 bytes
        * 
        * // server generate S2, or client valid S2
        * temp-key = HMACsha256(c1-digest, FMSKey, 68)
        * s2-digest-data = HMACsha256(s2-random-data, temp-key, 32)
        */
        virtual int s2_create(c1s1* c1);
        
        /**
        * validate the s2 from server.
        */
        virtual int s2_validate(c1s1* c1, bool& is_valid);
    };
}

#endif

/**
* simple handshake.
* user can try complex handshake first, 
* rollback to simple handshake if error ERROR_RTMP_TRY_SIMPLE_HS
*/
class SrsSimpleHandshake
{
public:
    SrsSimpleHandshake();
    virtual ~SrsSimpleHandshake();
public:
    /**
    * simple handshake.
    */
    virtual int handshake_with_client(SrsHandshakeBytes* hs_bytes, ISrsProtocolReaderWriter* io);
    virtual int handshake_with_server(SrsHandshakeBytes* hs_bytes, ISrsProtocolReaderWriter* io);
};

/**
* rtmp complex handshake,
* @see also crtmp(crtmpserver) or librtmp,
* @see also: http://blog.csdn.net/win_lin/article/details/13006803
*/
class SrsComplexHandshake
{
public:
    SrsComplexHandshake();
    virtual ~SrsComplexHandshake();
public:
    /**
    * complex hanshake.
    * @return user must:
    *     continue connect app if success,
    *     try simple handshake if error is ERROR_RTMP_TRY_SIMPLE_HS,
    *     otherwise, disconnect
    */
    virtual int handshake_with_client(SrsHandshakeBytes* hs_bytes, ISrsProtocolReaderWriter* io);
    virtual int handshake_with_server(SrsHandshakeBytes* hs_bytes, ISrsProtocolReaderWriter* io);
};

#endif
