RTMPdump（libRTMP）源代码分析 4：连接第一步——握手（Hand Shake）

static intHandShake(RTMP * r, int FP9HandShake){  int i, offalg = 0;  int dhposClient = 0;  int digestPosClient = 0;  int encrypted = r->Link.protocol & RTMP_FEATURE_ENC;  RC4_handle keyIn = 0;  RC4_handle keyOut = 0;  int32_t *ip;  uint32_t uptime;  uint8_t clientbuf[RTMP_SIG_SIZE + 4], *clientsig=clientbuf+4;  uint8_t serversig[RTMP_SIG_SIZE], client2[RTMP_SIG_SIZE], *reply;  uint8_t type;  getoff *getdh = NULL, *getdig = NULL;  if (encrypted || r->Link.SWFSize)    FP9HandShake = TRUE;  else//普通的    FP9HandShake = FALSE;  r->Link.rc4keyIn = r->Link.rc4keyOut = 0;  if (encrypted)    {      clientsig[-1] = 0x06;/* 0x08 is RTMPE as well */      offalg = 1;    }  else//0x03代表RTMP协议的版本（客户端要求的）//数组竟然能有“-1”下标//C0中的字段(1B)    clientsig[-1] = 0x03;  uptime = htonl(RTMP_GetTime());  //void *memcpy(void *dest, const void *src, int n);  //由src指向地址为起始地址的连续n个字节的数据复制到以dest指向地址为起始地址的空间内  //把uptime的前4字节（其实一共就4字节）数据拷贝到clientsig指向的地址中  //C1中的字段(4B)  memcpy(clientsig, &uptime, 4);  if (FP9HandShake)    {      /* set version to at least 9.0.115.0 */      if (encrypted){  clientsig[4] = 128;  clientsig[6] = 3;}      else        {  clientsig[4] = 10;  clientsig[6] = 45;}      clientsig[5] = 0;      clientsig[7] = 2;      RTMP_Log(RTMP_LOGDEBUG, "%s: Client type: %02X", __FUNCTION__, clientsig[-1]);      getdig = digoff[offalg];      getdh  = dhoff[offalg];    }  else    {//void *memset(void *s, int ch, size_t n);将s中前n个字节替换为ch并返回s；//将clientsig[4]开始的4个字节替换为0//这是C1的字段      memset(&clientsig[4], 0, 4);    }  /* generate random data */#ifdef _DEBUG  //将clientsig+8开始的1528个字节替换为0（这是一种简单的方法）  //这是C1中的random字段  memset(clientsig+8, 0, RTMP_SIG_SIZE-8);#else  //实际中使用rand()循环生成1528字节的伪随机数  ip = (int32_t *)(clientsig+8);  for (i = 2; i < RTMP_SIG_SIZE/4; i++)    *ip++ = rand();#endif  /* set handshake digest */  if (FP9HandShake)    {      if (encrypted){  /* generate Diffie-Hellmann parameters */  r->Link.dh = DHInit(1024);  if (!r->Link.dh)    {      RTMP_Log(RTMP_LOGERROR, "%s: Couldn't initialize Diffie-Hellmann!",  __FUNCTION__);      return FALSE;    }  dhposClient = getdh(clientsig, RTMP_SIG_SIZE);  RTMP_Log(RTMP_LOGDEBUG, "%s: DH pubkey position: %d", __FUNCTION__, dhposClient);  if (!DHGenerateKey((DH *)r->Link.dh))    {      RTMP_Log(RTMP_LOGERROR, "%s: Couldn't generate Diffie-Hellmann public key!",  __FUNCTION__);      return FALSE;    }  if (!DHGetPublicKey((DH *)r->Link.dh, &clientsig[dhposClient], 128))    {      RTMP_Log(RTMP_LOGERROR, "%s: Couldn't write public key!", __FUNCTION__);      return FALSE;    }}      digestPosClient = getdig(clientsig, RTMP_SIG_SIZE);/* reuse this value in verification */      RTMP_Log(RTMP_LOGDEBUG, "%s: Client digest offset: %d", __FUNCTION__,  digestPosClient);      CalculateDigest(digestPosClient, clientsig, GenuineFPKey, 30,      &clientsig[digestPosClient]);      RTMP_Log(RTMP_LOGDEBUG, "%s: Initial client digest: ", __FUNCTION__);      RTMP_LogHex(RTMP_LOGDEBUG, clientsig + digestPosClient,     SHA256_DIGEST_LENGTH);    }#ifdef _DEBUG  RTMP_Log(RTMP_LOGDEBUG, "Clientsig: ");  RTMP_LogHex(RTMP_LOGDEBUG, clientsig, RTMP_SIG_SIZE);#endif  //发送数据报C0+C1  //从clientsig-1开始发，长度1536+1，两个包合并  //握手----------------  r->dlg->AppendCInfo("建立连接：第1次连接。发送握手数据C0+C1");  //-----------------------------  if (!WriteN(r, (char *)clientsig-1, RTMP_SIG_SIZE + 1))    return FALSE;  //读取数据报，长度1，存入type  //是服务器的S0，表示服务器使用的RTMP版本  if (ReadN(r, (char *)&type, 1) != 1)/* 0x03 or 0x06 */    return FALSE;  //握手----------------  r->dlg->AppendCInfo("建立连接：第1次连接。接收握手数据S0");  //-----------------------------  RTMP_Log(RTMP_LOGDEBUG, "%s: Type Answer   : %02X", __FUNCTION__, type);  //客户端要求的版本和服务器提供的版本不同  if (type != clientsig[-1])    RTMP_Log(RTMP_LOGWARNING, "%s: Type mismatch: client sent %d, server answered %d",__FUNCTION__, clientsig[-1], type);  //握手----------------  r->dlg->AppendCInfo("建立连接：第1次连接。成功接收握手数据S0，服务器和客户端版本相同");  //-----------------------------  //客户端和服务端随机序列长度是否相同  //握手----------------  r->dlg->AppendCInfo("建立连接：第1次连接。接收握手数据S1");  //-----------------------------  if (ReadN(r, (char *)serversig, RTMP_SIG_SIZE) != RTMP_SIG_SIZE)    return FALSE;  /* decode server response */  //把serversig的前四个字节赋值给uptime  memcpy(&uptime, serversig, 4);  //大端转小端  uptime = ntohl(uptime);  RTMP_Log(RTMP_LOGDEBUG, "%s: Server Uptime : %d", __FUNCTION__, uptime);  RTMP_Log(RTMP_LOGDEBUG, "%s: FMS Version   : %d.%d.%d.%d", __FUNCTION__, serversig[4],      serversig[5], serversig[6], serversig[7]);  if (FP9HandShake && type == 3 && !serversig[4])    FP9HandShake = FALSE;#ifdef _DEBUG  RTMP_Log(RTMP_LOGDEBUG, "Server signature:");  RTMP_LogHex(RTMP_LOGDEBUG, serversig, RTMP_SIG_SIZE);#endif  if (FP9HandShake)    {      uint8_t digestResp[SHA256_DIGEST_LENGTH];      uint8_t *signatureResp = NULL;      /* we have to use this signature now to find the correct algorithms for getting the digest and DH positions */      int digestPosServer = getdig(serversig, RTMP_SIG_SIZE);      if (!VerifyDigest(digestPosServer, serversig, GenuineFMSKey, 36)){  RTMP_Log(RTMP_LOGWARNING, "Trying different position for server digest!");  offalg ^= 1;  getdig = digoff[offalg];  getdh  = dhoff[offalg];  digestPosServer = getdig(serversig, RTMP_SIG_SIZE);  if (!VerifyDigest(digestPosServer, serversig, GenuineFMSKey, 36))    {      RTMP_Log(RTMP_LOGERROR, "Couldn't verify the server digest");/* continuing anyway will probably fail */      return FALSE;    }}      /* generate SWFVerification token (SHA256 HMAC hash of decompressed SWF, key are the last 32 bytes of the server handshake) */      if (r->Link.SWFSize){  const char swfVerify[] = { 0x01, 0x01 };  char *vend = r->Link.SWFVerificationResponse+sizeof(r->Link.SWFVerificationResponse);  memcpy(r->Link.SWFVerificationResponse, swfVerify, 2);  AMF_EncodeInt32(&r->Link.SWFVerificationResponse[2], vend, r->Link.SWFSize);  AMF_EncodeInt32(&r->Link.SWFVerificationResponse[6], vend, r->Link.SWFSize);  HMACsha256(r->Link.SWFHash, SHA256_DIGEST_LENGTH,     &serversig[RTMP_SIG_SIZE - SHA256_DIGEST_LENGTH],     SHA256_DIGEST_LENGTH,     (uint8_t *)&r->Link.SWFVerificationResponse[10]);}      /* do Diffie-Hellmann Key exchange for encrypted RTMP */      if (encrypted){  /* compute secret key */  uint8_t secretKey[128] = { 0 };  int len, dhposServer;  dhposServer = getdh(serversig, RTMP_SIG_SIZE);  RTMP_Log(RTMP_LOGDEBUG, "%s: Server DH public key offset: %d", __FUNCTION__,    dhposServer);  len = DHComputeSharedSecretKey((DH *)r->Link.dh, &serversig[dhposServer],  128, secretKey);  if (len < 0)    {      RTMP_Log(RTMP_LOGDEBUG, "%s: Wrong secret key position!", __FUNCTION__);      return FALSE;    }  RTMP_Log(RTMP_LOGDEBUG, "%s: Secret key: ", __FUNCTION__);  RTMP_LogHex(RTMP_LOGDEBUG, secretKey, 128);  InitRC4Encryption(secretKey,    (uint8_t *) & serversig[dhposServer],    (uint8_t *) & clientsig[dhposClient],    &keyIn, &keyOut);}      reply = client2;#ifdef _DEBUG      memset(reply, 0xff, RTMP_SIG_SIZE);#else      ip = (int32_t *)reply;      for (i = 0; i < RTMP_SIG_SIZE/4; i++)        *ip++ = rand();#endif      /* calculate response now */      signatureResp = reply+RTMP_SIG_SIZE-SHA256_DIGEST_LENGTH;      HMACsha256(&serversig[digestPosServer], SHA256_DIGEST_LENGTH, GenuineFPKey, sizeof(GenuineFPKey), digestResp);      HMACsha256(reply, RTMP_SIG_SIZE - SHA256_DIGEST_LENGTH, digestResp, SHA256_DIGEST_LENGTH, signatureResp);      /* some info output */      RTMP_Log(RTMP_LOGDEBUG,  "%s: Calculated digest key from secure key and server digest: ",  __FUNCTION__);      RTMP_LogHex(RTMP_LOGDEBUG, digestResp, SHA256_DIGEST_LENGTH);#ifdef FP10      if (type == 8 )        {  uint8_t *dptr = digestResp;  uint8_t *sig = signatureResp;  /* encrypt signatureResp */          for (i=0; i<SHA256_DIGEST_LENGTH; i+=8)    rtmpe8_sig(sig+i, sig+i, dptr[i] % 15);        }#if 0      else if (type == 9))        {  uint8_t *dptr = digestResp;  uint8_t *sig = signatureResp;  /* encrypt signatureResp */          for (i=0; i<SHA256_DIGEST_LENGTH; i+=8)            rtmpe9_sig(sig+i, sig+i, dptr[i] % 15);        }#endif#endif      RTMP_Log(RTMP_LOGDEBUG, "%s: Client signature calculated:", __FUNCTION__);      RTMP_LogHex(RTMP_LOGDEBUG, signatureResp, SHA256_DIGEST_LENGTH);    }  else    {//直接赋值      reply = serversig;#if 0      uptime = htonl(RTMP_GetTime());      memcpy(reply+4, &uptime, 4);#endif    }#ifdef _DEBUG  RTMP_Log(RTMP_LOGDEBUG, "%s: Sending handshake response: ",    __FUNCTION__);  RTMP_LogHex(RTMP_LOGDEBUG, reply, RTMP_SIG_SIZE);#endif  //把reply中的1536字节数据发送出去  //对应C2  //握手----------------  r->dlg->AppendCInfo("建立连接：第1次连接。发送握手数据C2");  //-----------------------------  if (!WriteN(r, (char *)reply, RTMP_SIG_SIZE))    return FALSE;  /* 2nd part of handshake */  //读取1536字节数据到serversig  //握手----------------  r->dlg->AppendCInfo("建立连接：第1次连接。读取握手数据S2");  //-----------------------------  if (ReadN(r, (char *)serversig, RTMP_SIG_SIZE) != RTMP_SIG_SIZE)    return FALSE;#ifdef _DEBUG  RTMP_Log(RTMP_LOGDEBUG, "%s: 2nd handshake: ", __FUNCTION__);  RTMP_LogHex(RTMP_LOGDEBUG, serversig, RTMP_SIG_SIZE);#endif  if (FP9HandShake)    {      uint8_t signature[SHA256_DIGEST_LENGTH];      uint8_t digest[SHA256_DIGEST_LENGTH];      if (serversig[4] == 0 && serversig[5] == 0 && serversig[6] == 0  && serversig[7] == 0){  RTMP_Log(RTMP_LOGDEBUG,      "%s: Wait, did the server just refuse signed authentication?",      __FUNCTION__);}      RTMP_Log(RTMP_LOGDEBUG, "%s: Server sent signature:", __FUNCTION__);      RTMP_LogHex(RTMP_LOGDEBUG, &serversig[RTMP_SIG_SIZE - SHA256_DIGEST_LENGTH],     SHA256_DIGEST_LENGTH);      /* verify server response */      HMACsha256(&clientsig[digestPosClient], SHA256_DIGEST_LENGTH, GenuineFMSKey, sizeof(GenuineFMSKey), digest);      HMACsha256(serversig, RTMP_SIG_SIZE - SHA256_DIGEST_LENGTH, digest, SHA256_DIGEST_LENGTH, signature);      /* show some information */      RTMP_Log(RTMP_LOGDEBUG, "%s: Digest key: ", __FUNCTION__);      RTMP_LogHex(RTMP_LOGDEBUG, digest, SHA256_DIGEST_LENGTH);#ifdef FP10      if (type == 8 )        {  uint8_t *dptr = digest;  uint8_t *sig = signature;  /* encrypt signature */          for (i=0; i<SHA256_DIGEST_LENGTH; i+=8)    rtmpe8_sig(sig+i, sig+i, dptr[i] % 15);        }#if 0      else if (type == 9)        {  uint8_t *dptr = digest;  uint8_t *sig = signature;  /* encrypt signatureResp */          for (i=0; i<SHA256_DIGEST_LENGTH; i+=8)            rtmpe9_sig(sig+i, sig+i, dptr[i] % 15);        }#endif#endif      RTMP_Log(RTMP_LOGDEBUG, "%s: Signature calculated:", __FUNCTION__);      RTMP_LogHex(RTMP_LOGDEBUG, signature, SHA256_DIGEST_LENGTH);      if (memcmp  (signature, &serversig[RTMP_SIG_SIZE - SHA256_DIGEST_LENGTH],   SHA256_DIGEST_LENGTH) != 0){  RTMP_Log(RTMP_LOGWARNING, "%s: Server not genuine Adobe!", __FUNCTION__);  return FALSE;}      else{  RTMP_Log(RTMP_LOGDEBUG, "%s: Genuine Adobe Flash Media Server", __FUNCTION__);}      if (encrypted){  char buff[RTMP_SIG_SIZE];  /* set keys for encryption from now on */  r->Link.rc4keyIn = keyIn;  r->Link.rc4keyOut = keyOut;  /* update the keystreams */  if (r->Link.rc4keyIn)    {      RC4_encrypt((RC4_KEY *)r->Link.rc4keyIn, RTMP_SIG_SIZE, (uint8_t *) buff);    }  if (r->Link.rc4keyOut)    {      RC4_encrypt((RC4_KEY *)r->Link.rc4keyOut, RTMP_SIG_SIZE, (uint8_t *) buff);    }}    }  else    {//int memcmp(const void *buf1, const void *buf2, unsigned int count); 当buf1=buf2时，返回值=0//比较serversig和clientsig是否相等//握手----------------r->dlg->AppendCInfo("建立连接：第1次连接。比较握手数据签名");//-----------------------------      if (memcmp(serversig, clientsig, RTMP_SIG_SIZE) != 0){//握手----------------r->dlg->AppendCInfo("建立连接：第1次连接。握手数据签名不匹配！");//-----------------------------  RTMP_Log(RTMP_LOGWARNING, "%s: client signature does not match!",      __FUNCTION__);}    }  //握手----------------  r->dlg->AppendCInfo("建立连接：第1次连接。握手成功");  //-----------------------------  RTMP_Log(RTMP_LOGDEBUG, "%s: Handshaking finished....", __FUNCTION__);  return TRUE;}

rtmpdump源代码（Linux）：http://download.csdn.net/detail/leixiaohua1020/6376561

rtmpdump源代码（VC 2005 工程）：http://download.csdn.net/detail/leixiaohua1020/6563163