// See the file "COPYING" in the main distribution directory for copyright.

#pragma once

#include "zeek/analyzer/protocol/pia/PIA.h"
#include "zeek/analyzer/protocol/ssl/events.bif.h"
#include "zeek/analyzer/protocol/tcp/TCP.h"

namespace binpac {
namespace SSL {
class SSL_Conn;
}
} // namespace binpac

namespace binpac {
namespace TLSHandshake {
class Handshake_Conn;
}
} // namespace binpac

namespace zeek::analyzer::ssl {

class SSL_Analyzer final : public analyzer::tcp::TCP_ApplicationAnalyzer {
    // let binpac forward encrypted TLS application data to us.
    friend class binpac::SSL::SSL_Conn;

public:
    explicit SSL_Analyzer(Connection* conn);
    ~SSL_Analyzer() override;

    // Overridden from Analyzer.
    void Done() override;
    void DeliverStream(int len, const u_char* data, bool orig) override;
    void Undelivered(uint64_t seq, int len, bool orig) override;

    void SendHandshake(uint16_t raw_tls_version, const u_char* begin, const u_char* end, bool orig);

    // Tell the analyzer that encryption has started.
    void StartEncryption();
    // Get the TLS version that the server chose. 0 if not yet known.
    uint16_t GetNegotiatedVersion() const;

    // Overridden from analyzer::tcp::TCP_ApplicationAnalyzer.
    void EndpointEOF(bool is_orig) override;

    static analyzer::Analyzer* Instantiate(Connection* conn) { return new SSL_Analyzer(conn); }

    /**
     * Set the secret that should be used to derive keys for the
     * connection. (For TLS 1.2 this is the pre-master secret)
     *
     * Please note that these functions currently are hardcoded to only work with a single TLS 1.2
     * ciphersuite (TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384).
     *
     * @param secret The secret to set
     */
    void SetSecret(const StringVal& secret);

    /**
     * Set the secret that should be used to derive keys for the
     * connection. (For TLS 1.2 this is the pre-master secret)
     *
     * Please note that these functions currently are hardcoded to only work with a single TLS 1.2
     * ciphersuite (TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384).
     *
     * @param len Length of the secret bytes
     *
     * @param data Pointer to the secret bytes
     */
    void SetSecret(size_t len, const u_char* data);

    /**
     * Set the decryption keys that should be used to decrypt
     * TLS application data in the connection.
     *
     * Please note that these functions currently are hardcoded to only work with a single TLS 1.2
     * ciphersuite (TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384).
     *
     * @param keys The key buffer as derived via TLS PRF (for
     * AES_GCM this should be 72 bytes in length)
     */
    void SetKeys(const StringVal& keys);

    /**
     * Set the decryption keys that should be used to decrypt
     * TLS application data in the connection.
     *
     * Please note that these functions currently are hardcoded to only work with a single TLS 1.2
     * ciphersuite (TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384).
     *
     * @param keys The key buffer as derived via TLS PRF (for
     * AES_GCM this should be 72 bytes in length)
     */
    void SetKeys(const std::vector<u_char> newkeys);

    /**
     * Check if the connection is flipped--meaning that the TLS client is the responder of the
     * connection.
     *
     * @return True if connection is flipped.
     */
    bool GetFlipped();

protected:
    /**
     * Try to decrypt TLS application data from a packet. Requires secret or keys to be set prior.
     *
     * Please note that these functions currently are hardcoded to only work with a single TLS 1.2
     * ciphersuite (TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384).
     *
     * @param len Length of the encrypted bytes to decrypt
     *
     * @param data Pointer to the encrypted bytes to decrypt
     *
     * @param is_orig Direction of the connection
     *
     * @param content_type Content type as given in the TLS packet
     *
     * @param raw_tls_version Raw TLS version as given in the TLS packets
     *
     * @return True if decryption succeeded and data was forwarded.
     */
    bool TryDecryptApplicationData(int len, const u_char* data, bool is_orig, uint8_t content_type,
                                   uint16_t raw_tls_version);

    /**
     * TLS 1.2 pseudo random function (PRF) used to expand the pre-master secret and derive keys.
     * The seed is obtained by concatenating rnd1 and rnd2.
     *
     * Please note that these functions currently are hardcoded to only work with a single TLS 1.2
     * ciphersuite (TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384).
     *
     * @param secret Secret as defined in the TLS RFC
     *
     * @param label Label as defined in the TLS RFC
     *
     * @param First part of the seed
     *
     * @param rnd2 Second part of the seed
     *
     * @param rnd2_len Length of the second part of the seed
     *
     * @param requested_len Length indicating how many bytes should be derived
     *
     * @return The derived bytes, if the operation succeeds.
     */
    std::optional<std::vector<u_char>> TLS12_PRF(const std::string& secret, const std::string& label,
                                                 const std::string& rnd1, const std::string& rnd2,
                                                 size_t requested_len);

    /**
     * Forward decrypted TLS application data to child analyzers.
     *
     * @param data Data to forward
     *
     * @param is_orig Direction of the connection
     */
    void ForwardDecryptedData(const std::vector<u_char>& data, bool is_orig);

    binpac::SSL::SSL_Conn* interp;
    binpac::TLSHandshake::Handshake_Conn* handshake_interp;
    bool had_gap;

    // client and server sequence number, used for TLS 1.2 decryption
    int c_seq;
    int s_seq;
    // secret, for decryption
    std::string secret;
    // derived keys, for decryption
    std::vector<u_char> keys;
    // PIA, for decrypted data
    zeek::analyzer::pia::PIA_TCP* pia;
};

} // namespace zeek::analyzer::ssl
