Add srt caller mode and stream encryption support. (#4088)

Add srt caller mode and stream encryption support.
1. Support srt caller mode, realize srt proxy pull stream proxy push
stream;
url parameter format such as: srt://127.0.0.1:9000?streamid=#!
::r=live/test11
2. Support srt stream encrypted transmission in caller and listener
mode.

---------

Co-authored-by: xiongguangjie <xiong_panda@163.com>

srt/Crypto.hpp

@@ -0,0 +1,102 @@
+#ifndef ZLMEDIAKIT_SRT_CRYPTO_H
+#define ZLMEDIAKIT_SRT_CRYPTO_H
+#include <stdint.h>
+#include <vector>
+
+#include "Network/Buffer.h"
+#include "Network/sockutil.h"
+#include "Util/logger.h"
+
+#include "Common.hpp"
+#include "HSExt.hpp"
+#include "Packet.hpp"
+
+namespace SRT {
+
+class CryptoContext : public std::enable_shared_from_this<CryptoContext> {
+public:
+    using Ptr = std::shared_ptr<CryptoContext>;
+    CryptoContext(const std::string& passparase, uint8_t kk, KeyMaterial::Ptr packet = nullptr);
+    virtual ~CryptoContext() = default;
+
+    virtual void refresh();
+    virtual std::string generateWarppedKey();
+
+    virtual BufferLikeString::Ptr encrypt(uint32_t pkt_seq_no, const char *buf, int len) = 0;
+    virtual BufferLikeString::Ptr decrypt(uint32_t pkt_seq_no, const char *buf, int len) = 0;
+    virtual uint8_t getCipher() const = 0;
+
+protected:
+    virtual void loadFromKeyMaterial(KeyMaterial::Ptr packet);
+    virtual bool generateKEK();
+    BufferLikeString::Ptr generateIv(uint32_t pkt_seq_no);
+
+private:
+
+public:
+    std::string _passparase;
+
+    uint8_t _kk = SRT::KeyMaterial::KEY_BASED_ENCRYPTION_EVEN_SEK;
+
+    BufferLikeString _kek;
+    const uint32_t   _iter  = 2048;
+
+    size_t           _slen = 16;
+    BufferLikeString _salt;
+
+    size_t           _klen = 16;
+    BufferLikeString _sek;
+};
+
+class AesCtrCryptoContext : public CryptoContext {
+public:
+    using Ptr = std::shared_ptr<AesCtrCryptoContext>;
+    AesCtrCryptoContext(const std::string& passparase, uint8_t kk, KeyMaterial::Ptr packet = nullptr);
+    virtual ~AesCtrCryptoContext() = default;
+
+    uint8_t getCipher() const  override {
+        return KeyMaterial::CIPHER_AES_CTR;
+    }
+
+    BufferLikeString::Ptr encrypt(uint32_t pkt_seq_no, const char *buf, int len) override;
+    BufferLikeString::Ptr decrypt(uint32_t pkt_seq_no, const char *buf, int len) override;
+
+};
+
+
+class Crypto : public std::enable_shared_from_this<Crypto>{
+public:
+    using Ptr = std::shared_ptr<Crypto>;
+    Crypto(const std::string& passparase);
+    virtual ~Crypto() = default;
+
+    HSExtKeyMaterial::Ptr generateKeyMaterialExt(uint16_t extension_type);
+    KeyMaterialPacket::Ptr takeAwayAnnouncePacket();
+
+    bool loadFromKeyMaterial(KeyMaterial::Ptr packet);
+
+    // for encryption
+    std::string _passparase;
+
+    //The recommended KM Refresh Period is after 2^25 packets encrypted with the same SEK are sent. 
+    const uint32_t _refresh_period  = 1 <<25;
+    const uint32_t _re_announcement_period = (1 <<25) - 4000;
+
+    uint32_t _pkt_count = 0;
+    KeyMaterialPacket::Ptr _re_announce_pkt;
+
+    CryptoContext::Ptr  _ctx_pair[2];    /* Even(0)/Odd(1) crypto contexts */
+    uint32_t _ctx_idx = 0;
+
+    BufferLikeString::Ptr encrypt(DataPacket::Ptr pkt, const char *buf, int len);
+    BufferLikeString::Ptr decrypt(DataPacket::Ptr pkt, const char *buf, int len);
+
+private:
+
+    CryptoContext::Ptr createCtx(int cipher, const std::string& passparase, uint8_t kk, KeyMaterial::Ptr packet = nullptr);
+    KeyMaterialPacket::Ptr generateAnnouncePacket(CryptoContext::Ptr ctx);
+};
+
+} // namespace SRT
+
+#endif // ZLMEDIAKIT_SRT_CRYPTO_H