RTMPdump（libRTMP）源代码分析 3 AMF编码

#include "stdafx.h"/* 本文件主要包含了对AMF对象的操作 *------------------------------------- *AMF数据类型： *Type  Byte code *Number 0x00 *Boolean 0x01 *String 0x02 *Object 0x03 *MovieClip 0x04 *Null  0x05 *Undefined 0x06 *Reference 0x07 *MixedArray 0x08 *EndOfObject 0x09 *Array   0x0a *Date   0x0b *LongString 0x0c *Unsupported 0x0d *Recordset  0x0e *XML   0x0f *TypedObject (Class instance) 0x10 *AMF3 data 0×11 *-------------------------------------- *应用举例： *0.Number这里指的是double类型，数据用8字节表示，比如十六进制00 40 10 00 00 00 00 00 00就表示的是一个double数4.0 *1.Boolean对应的是.net中的bool类型，数据使用1字节表示，和C语言差不多，使用00表示false，使用01表示true。比如十六进制01 01就表示true。 *2.String相当于.net中的string类型，String所占用的空间有1个类型标识字节和2个表示字符串UTF8长度的字节加上字符串UTF8格式的内容组成。 *  比如十六进制03 00 08 73 68 61 6E 67 67 75 61表示的就是字符串，该字符串长8字节，字符串内容为73 68 61 6E 67 67 75 61，对应的就是“shanggua”。 *3.Object在对应的就是Hashtable，内容由UTF8字符串作为Key，其他AMF类型作为Value，该对象由3个字节：00 00 09来表示结束。 *5.Null就是空对象，该对象只占用一个字节，那就是Null对象标识0x05。 *6.Undefined 也是只占用一个字节0x06。 *8.MixedArray相当于Hashtable，与3不同的是该对象定义了Hashtable的大小。 */#include <string.h>#include <assert.h>#include <stdlib.h>#include "rtmp_sys.h"#include "amf.h"#include "log.h"#include "bytes.h"static const AMFObjectProperty AMFProp_Invalid = { {0, 0}, AMF_INVALID };static const AVal AV_empty = { 0, 0 };//大端Big-Endian//低地址存放最高有效位（MSB），既高位字节排放在内存的低地址端，低位字节排放在内存的高地址端。//符合人脑逻辑，与计算机逻辑不同//网络字节序 Network Order:TCP/IP各层协议将字节序定义为Big-Endian，因此TCP/IP协议中使//用的字节序通常称之为网络字节序。//主机序 Host Orader:它遵循Little-Endian规则。所以当两台主机之间要通过TCP/IP协议进行通//信的时候就需要调用相应的函数进行主机序（Little-Endian）和网络序（Big-Endian）的转换。/*AMF数据采用 Big-Endian（大端模式），主机采用Little-Endian（小端模式） */unsigned shortAMF_DecodeInt16(const char *data){  unsigned char *c = (unsigned char *) data;  unsigned short val;  val = (c[0] << 8) | c[1];//转换  return val;}unsigned intAMF_DecodeInt24(const char *data){  unsigned char *c = (unsigned char *) data;  unsigned int val;  val = (c[0] << 16) | (c[1] << 8) | c[2];  return val;}unsigned intAMF_DecodeInt32(const char *data){  unsigned char *c = (unsigned char *)data;  unsigned int val;  val = (c[0] << 24) | (c[1] << 16) | (c[2] << 8) | c[3];  return val;}voidAMF_DecodeString(const char *data, AVal *bv){  bv->av_len = AMF_DecodeInt16(data);  bv->av_val = (bv->av_len > 0) ? (char *)data + 2 : NULL;}voidAMF_DecodeLongString(const char *data, AVal *bv){  bv->av_len = AMF_DecodeInt32(data);  bv->av_val = (bv->av_len > 0) ? (char *)data + 4 : NULL;}doubleAMF_DecodeNumber(const char *data){  double dVal;#if __FLOAT_WORD_ORDER == __BYTE_ORDER#if __BYTE_ORDER == __BIG_ENDIAN  memcpy(&dVal, data, 8);#elif __BYTE_ORDER == __LITTLE_ENDIAN  unsigned char *ci, *co;  ci = (unsigned char *)data;  co = (unsigned char *)&dVal;  co[0] = ci[7];  co[1] = ci[6];  co[2] = ci[5];  co[3] = ci[4];  co[4] = ci[3];  co[5] = ci[2];  co[6] = ci[1];  co[7] = ci[0];#endif#else#if __BYTE_ORDER == __LITTLE_ENDIAN /* __FLOAT_WORD_ORER == __BIG_ENDIAN */  unsigned char *ci, *co;  ci = (unsigned char *)data;  co = (unsigned char *)&dVal;  co[0] = ci[3];  co[1] = ci[2];  co[2] = ci[1];  co[3] = ci[0];  co[4] = ci[7];  co[5] = ci[6];  co[6] = ci[5];  co[7] = ci[4];#else /* __BYTE_ORDER == __BIG_ENDIAN && __FLOAT_WORD_ORER == __LITTLE_ENDIAN */  unsigned char *ci, *co;  ci = (unsigned char *)data;  co = (unsigned char *)&dVal;  co[0] = ci[4];  co[1] = ci[5];  co[2] = ci[6];  co[3] = ci[7];  co[4] = ci[0];  co[5] = ci[1];  co[6] = ci[2];  co[7] = ci[3];#endif#endif  return dVal;}intAMF_DecodeBoolean(const char *data){  return *data != 0;}char *AMF_EncodeInt16(char *output, char *outend, short nVal){  if (output+2 > outend)    return NULL;  output[1] = nVal & 0xff;  output[0] = nVal >> 8;  return output+2;}//3字节的int数据进行AMF编码，AMF采用大端模式char *AMF_EncodeInt24(char *output, char *outend, int nVal){  if (output+3 > outend)    return NULL;  //倒过来  output[2] = nVal & 0xff;  output[1] = nVal >> 8;  output[0] = nVal >> 16;  //返回指针指向编码后数据的尾部  return output+3;}char *AMF_EncodeInt32(char *output, char *outend, int nVal){  if (output+4 > outend)    return NULL;  output[3] = nVal & 0xff;  output[2] = nVal >> 8;  output[1] = nVal >> 16;  output[0] = nVal >> 24;  return output+4;}char *AMF_EncodeString(char *output, char *outend, const AVal *bv){  if ((bv->av_len < 65536 && output + 1 + 2 + bv->av_len > outend) || output + 1 + 4 + bv->av_len > outend)    return NULL;  if (bv->av_len < 65536)    {      *output++ = AMF_STRING;      output = AMF_EncodeInt16(output, outend, bv->av_len);    }  else    {      *output++ = AMF_LONG_STRING;      output = AMF_EncodeInt32(output, outend, bv->av_len);    }  memcpy(output, bv->av_val, bv->av_len);  output += bv->av_len;  return output;}char *AMF_EncodeNumber(char *output, char *outend, double dVal){  if (output+1+8 > outend)    return NULL;  *output++ = AMF_NUMBER; /* type: Number */#if __FLOAT_WORD_ORDER == __BYTE_ORDER#if __BYTE_ORDER == __BIG_ENDIAN  memcpy(output, &dVal, 8);#elif __BYTE_ORDER == __LITTLE_ENDIAN  {    unsigned char *ci, *co;    ci = (unsigned char *)&dVal;    co = (unsigned char *)output;    co[0] = ci[7];    co[1] = ci[6];    co[2] = ci[5];    co[3] = ci[4];    co[4] = ci[3];    co[5] = ci[2];    co[6] = ci[1];    co[7] = ci[0];  }#endif#else#if __BYTE_ORDER == __LITTLE_ENDIAN /* __FLOAT_WORD_ORER == __BIG_ENDIAN */  {    unsigned char *ci, *co;    ci = (unsigned char *)&dVal;    co = (unsigned char *)output;    co[0] = ci[3];    co[1] = ci[2];    co[2] = ci[1];    co[3] = ci[0];    co[4] = ci[7];    co[5] = ci[6];    co[6] = ci[5];    co[7] = ci[4];  }#else /* __BYTE_ORDER == __BIG_ENDIAN && __FLOAT_WORD_ORER == __LITTLE_ENDIAN */  {    unsigned char *ci, *co;    ci = (unsigned char *)&dVal;    co = (unsigned char *)output;    co[0] = ci[4];    co[1] = ci[5];    co[2] = ci[6];    co[3] = ci[7];    co[4] = ci[0];    co[5] = ci[1];    co[6] = ci[2];    co[7] = ci[3];  }#endif#endif  return output+8;}char *AMF_EncodeBoolean(char *output, char *outend, int bVal){  if (output+2 > outend)    return NULL;  *output++ = AMF_BOOLEAN;  *output++ = bVal ? 0x01 : 0x00;  return output;}char *AMF_EncodeNamedString(char *output, char *outend, const AVal *strName, const AVal *strValue){  if (output+2+strName->av_len > outend)    return NULL;  output = AMF_EncodeInt16(output, outend, strName->av_len);  memcpy(output, strName->av_val, strName->av_len);  output += strName->av_len;  return AMF_EncodeString(output, outend, strValue);}char *AMF_EncodeNamedNumber(char *output, char *outend, const AVal *strName, double dVal){  if (output+2+strName->av_len > outend)    return NULL;  output = AMF_EncodeInt16(output, outend, strName->av_len);  memcpy(output, strName->av_val, strName->av_len);  output += strName->av_len;  return AMF_EncodeNumber(output, outend, dVal);}char *AMF_EncodeNamedBoolean(char *output, char *outend, const AVal *strName, int bVal){  if (output+2+strName->av_len > outend)    return NULL;  output = AMF_EncodeInt16(output, outend, strName->av_len);  memcpy(output, strName->av_val, strName->av_len);  output += strName->av_len;  return AMF_EncodeBoolean(output, outend, bVal);}voidAMFProp_GetName(AMFObjectProperty *prop, AVal *name){  *name = prop->p_name;}voidAMFProp_SetName(AMFObjectProperty *prop, AVal *name){  prop->p_name = *name;}AMFDataTypeAMFProp_GetType(AMFObjectProperty *prop){  return prop->p_type;}doubleAMFProp_GetNumber(AMFObjectProperty *prop){  return prop->p_vu.p_number;}intAMFProp_GetBoolean(AMFObjectProperty *prop){  return prop->p_vu.p_number != 0;}voidAMFProp_GetString(AMFObjectProperty *prop, AVal *str){  *str = prop->p_vu.p_aval;}voidAMFProp_GetObject(AMFObjectProperty *prop, AMFObject *obj){  *obj = prop->p_vu.p_object;}intAMFProp_IsValid(AMFObjectProperty *prop){  return prop->p_type != AMF_INVALID;}char *AMFProp_Encode(AMFObjectProperty *prop, char *pBuffer, char *pBufEnd){  if (prop->p_type == AMF_INVALID)    return NULL;  if (prop->p_type != AMF_NULL && pBuffer + prop->p_name.av_len + 2 + 1 >= pBufEnd)    return NULL;  if (prop->p_type != AMF_NULL && prop->p_name.av_len)    {      *pBuffer++ = prop->p_name.av_len >> 8;      *pBuffer++ = prop->p_name.av_len & 0xff;      memcpy(pBuffer, prop->p_name.av_val, prop->p_name.av_len);      pBuffer += prop->p_name.av_len;    }  switch (prop->p_type)    {    case AMF_NUMBER:      pBuffer = AMF_EncodeNumber(pBuffer, pBufEnd, prop->p_vu.p_number);      break;    case AMF_BOOLEAN:      pBuffer = AMF_EncodeBoolean(pBuffer, pBufEnd, prop->p_vu.p_number != 0);      break;    case AMF_STRING:      pBuffer = AMF_EncodeString(pBuffer, pBufEnd, &prop->p_vu.p_aval);      break;    case AMF_NULL:      if (pBuffer+1 >= pBufEnd)        return NULL;      *pBuffer++ = AMF_NULL;      break;    case AMF_OBJECT:      pBuffer = AMF_Encode(&prop->p_vu.p_object, pBuffer, pBufEnd);      break;    default:      RTMP_Log(RTMP_LOGERROR, "%s, invalid type. %d", __FUNCTION__, prop->p_type);      pBuffer = NULL;    };  return pBuffer;}#define AMF3_INTEGER_MAX 268435455#define AMF3_INTEGER_MIN -268435456intAMF3ReadInteger(const char *data, int32_t *valp){  int i = 0;  int32_t val = 0;  while (i <= 2)    {    /* handle first 3 bytes */      if (data[i] & 0x80) {   /* byte used */   val <<= 7;  /* shift up */   val |= (data[i] & 0x7f); /* add bits */   i++; }      else {   break; }    }  if (i > 2)    {    /* use 4th byte, all 8bits */      val <<= 8;      val |= data[3];      /* range check */      if (val > AMF3_INTEGER_MAX) val -= (1 << 29);    }  else    {    /* use 7bits of last unparsed byte (0xxxxxxx) */      val <<= 7;      val |= data[i];    }  *valp = val;  return i > 2 ? 4 : i + 1;}intAMF3ReadString(const char *data, AVal *str){  int32_t ref = 0;  int len;  assert(str != 0);  len = AMF3ReadInteger(data, &ref);  data += len;  if ((ref & 0x1) == 0)    {    /* reference: 0xxx */      uint32_t refIndex = (ref >> 1);      RTMP_Log(RTMP_LOGDEBUG,   "%s, string reference, index: %d, not supported, ignoring!",   __FUNCTION__, refIndex);      return len;    }  else    {      uint32_t nSize = (ref >> 1);      str->av_val = (char *)data;      str->av_len = nSize;      return len + nSize;    }  return len;}intAMF3Prop_Decode(AMFObjectProperty *prop, const char *pBuffer, int nSize,  int bDecodeName){  int nOriginalSize = nSize;  AMF3DataType type;  prop->p_name.av_len = 0;  prop->p_name.av_val = NULL;  if (nSize == 0 || !pBuffer)    {      RTMP_Log(RTMP_LOGDEBUG, "empty buffer/no buffer pointer!");      return -1;    }  /* decode name */  if (bDecodeName)    {      AVal name;      int nRes = AMF3ReadString(pBuffer, &name);      if (name.av_len <= 0) return nRes;      prop->p_name = name;      pBuffer += nRes;      nSize -= nRes;    }  /* decode */  type = (AMF3DataType) *pBuffer++;  nSize--;  switch (type)    {    case AMF3_UNDEFINED:    case AMF3_NULL:      prop->p_type = AMF_NULL;      break;    case AMF3_FALSE:      prop->p_type = AMF_BOOLEAN;      prop->p_vu.p_number = 0.0;      break;    case AMF3_TRUE:      prop->p_type = AMF_BOOLEAN;      prop->p_vu.p_number = 1.0;      break;    case AMF3_INTEGER:      { int32_t res = 0; int len = AMF3ReadInteger(pBuffer, &res); prop->p_vu.p_number = (double)res; prop->p_type = AMF_NUMBER; nSize -= len; break;      }    case AMF3_DOUBLE:      if (nSize < 8) return -1;      prop->p_vu.p_number = AMF_DecodeNumber(pBuffer);      prop->p_type = AMF_NUMBER;      nSize -= 8;      break;    case AMF3_STRING:    case AMF3_XML_DOC:    case AMF3_XML:      { int len = AMF3ReadString(pBuffer, &prop->p_vu.p_aval); prop->p_type = AMF_STRING; nSize -= len; break;      }    case AMF3_DATE:      { int32_t res = 0; int len = AMF3ReadInteger(pBuffer, &res); nSize -= len; pBuffer += len; if ((res & 0x1) == 0)   {   /* reference */     uint32_t nIndex = (res >> 1);     RTMP_Log(RTMP_LOGDEBUG, "AMF3_DATE reference: %d, not supported!", nIndex);   } else   {     if (nSize < 8)       return -1;     prop->p_vu.p_number = AMF_DecodeNumber(pBuffer);     nSize -= 8;     prop->p_type = AMF_NUMBER;   } break;      }    case AMF3_OBJECT:      { int nRes = AMF3_Decode(&prop->p_vu.p_object, pBuffer, nSize, TRUE); if (nRes == -1)   return -1; nSize -= nRes; prop->p_type = AMF_OBJECT; break;      }    case AMF3_ARRAY:    case AMF3_BYTE_ARRAY:    default:      RTMP_Log(RTMP_LOGDEBUG, "%s - AMF3 unknown/unsupported datatype 0x%02x, @0x%08X",   __FUNCTION__, (unsigned char)(*pBuffer), pBuffer);      return -1;    }  return nOriginalSize - nSize;}//对AMF数据类型解析intAMFProp_Decode(AMFObjectProperty *prop, const char *pBuffer, int nSize,        int bDecodeName){  int nOriginalSize = nSize;  int nRes;  prop->p_name.av_len = 0;  prop->p_name.av_val = NULL;  if (nSize == 0 || !pBuffer)    {      RTMP_Log(RTMP_LOGDEBUG, "%s: Empty buffer/no buffer pointer!", __FUNCTION__);      return -1;    }  if (bDecodeName && nSize < 4)    {    /* at least name (length + at least 1 byte) and 1 byte of data */      RTMP_Log(RTMP_LOGDEBUG,   "%s: Not enough data for decoding with name, less than 4 bytes!",   __FUNCTION__);      return -1;    }  if (bDecodeName)    {      unsigned short nNameSize = AMF_DecodeInt16(pBuffer);      if (nNameSize > nSize - 2) {   RTMP_Log(RTMP_LOGDEBUG,       "%s: Name size out of range: namesize (%d) > len (%d) - 2",       __FUNCTION__, nNameSize, nSize);   return -1; }      AMF_DecodeString(pBuffer, &prop->p_name);      nSize -= 2 + nNameSize;      pBuffer += 2 + nNameSize;    }  if (nSize == 0)    {      return -1;    }  nSize--;  prop->p_type = (AMFDataType) *pBuffer++;  switch (prop->p_type)    { //Number数据类型    case AMF_NUMBER:      if (nSize < 8) return -1;      prop->p_vu.p_number = AMF_DecodeNumber(pBuffer);      nSize -= 8;      break;  //Boolean数据类型    case AMF_BOOLEAN:      if (nSize < 1) return -1;      prop->p_vu.p_number = (double)AMF_DecodeBoolean(pBuffer);      nSize--;      break;   //String数据类型    case AMF_STRING:      { unsigned short nStringSize = AMF_DecodeInt16(pBuffer); if (nSize < (long)nStringSize + 2)   return -1; AMF_DecodeString(pBuffer, &prop->p_vu.p_aval); nSize -= (2 + nStringSize); break;      }   //Object数据类型    case AMF_OBJECT:      { int nRes = AMF_Decode(&prop->p_vu.p_object, pBuffer, nSize, TRUE); if (nRes == -1)   return -1; nSize -= nRes; break;      }    case AMF_MOVIECLIP:      { RTMP_Log(RTMP_LOGERROR, "AMF_MOVIECLIP reserved!"); return -1; break;      }    case AMF_NULL:    case AMF_UNDEFINED:    case AMF_UNSUPPORTED:      prop->p_type = AMF_NULL;      break;    case AMF_REFERENCE:      { RTMP_Log(RTMP_LOGERROR, "AMF_REFERENCE not supported!"); return -1; break;      }    case AMF_ECMA_ARRAY:      { nSize -= 4; /* next comes the rest, mixed array has a final 0x000009 mark and names, so its an object */ nRes = AMF_Decode(&prop->p_vu.p_object, pBuffer + 4, nSize, TRUE); if (nRes == -1)   return -1; nSize -= nRes; prop->p_type = AMF_OBJECT; break;      }    case AMF_OBJECT_END:      { return -1; break;      }    case AMF_STRICT_ARRAY:      { unsigned int nArrayLen = AMF_DecodeInt32(pBuffer); nSize -= 4; nRes = AMF_DecodeArray(&prop->p_vu.p_object, pBuffer + 4, nSize,       nArrayLen, FALSE); if (nRes == -1)   return -1; nSize -= nRes; prop->p_type = AMF_OBJECT; break;      }    case AMF_DATE:      { RTMP_Log(RTMP_LOGDEBUG, "AMF_DATE"); if (nSize < 10)   return -1; prop->p_vu.p_number = AMF_DecodeNumber(pBuffer); prop->p_UTCoffset = AMF_DecodeInt16(pBuffer + 8); nSize -= 10; break;      }    case AMF_LONG_STRING:      { unsigned int nStringSize = AMF_DecodeInt32(pBuffer); if (nSize < (long)nStringSize + 4)   return -1; AMF_DecodeLongString(pBuffer, &prop->p_vu.p_aval); nSize -= (4 + nStringSize); prop->p_type = AMF_STRING; break;      }    case AMF_RECORDSET:      { RTMP_Log(RTMP_LOGERROR, "AMF_RECORDSET reserved!"); return -1; break;      }    case AMF_XML_DOC:      { RTMP_Log(RTMP_LOGERROR, "AMF_XML_DOC not supported!"); return -1; break;      }    case AMF_TYPED_OBJECT:      { RTMP_Log(RTMP_LOGERROR, "AMF_TYPED_OBJECT not supported!"); return -1; break;      }    case AMF_AVMPLUS:      { int nRes = AMF3_Decode(&prop->p_vu.p_object, pBuffer, nSize, TRUE); if (nRes == -1)   return -1; nSize -= nRes; prop->p_type = AMF_OBJECT; break;      }    default:      RTMP_Log(RTMP_LOGDEBUG, "%s - unknown datatype 0x%02x, @0x%08X", __FUNCTION__,   prop->p_type, pBuffer - 1);      return -1;    }  return nOriginalSize - nSize;}voidAMFProp_Dump(AMFObjectProperty *prop){  char strRes[256];  char str[256];  AVal name;  if (prop->p_type == AMF_INVALID)    {      RTMP_Log(RTMP_LOGDEBUG, "Property: INVALID");      return;    }  if (prop->p_type == AMF_NULL)    {      RTMP_Log(RTMP_LOGDEBUG, "Property: NULL");      return;    }  if (prop->p_name.av_len)    {      name = prop->p_name;    }  else    {      name.av_val = "no-name.";      name.av_len = sizeof("no-name.") - 1;    }  if (name.av_len > 18)    name.av_len = 18;  snprintf(strRes, 255, "Name: %18.*s, ", name.av_len, name.av_val);  if (prop->p_type == AMF_OBJECT)    {      RTMP_Log(RTMP_LOGDEBUG, "Property: <%sOBJECT>", strRes);      AMF_Dump(&prop->p_vu.p_object);      return;    }  switch (prop->p_type)    {    case AMF_NUMBER:      snprintf(str, 255, "NUMBER:\t%.2f", prop->p_vu.p_number);      break;    case AMF_BOOLEAN:      snprintf(str, 255, "BOOLEAN:\t%s",        prop->p_vu.p_number != 0.0 ? "TRUE" : "FALSE");      break;    case AMF_STRING:      snprintf(str, 255, "STRING:\t%.*s", prop->p_vu.p_aval.av_len,        prop->p_vu.p_aval.av_val);      break;    case AMF_DATE:      snprintf(str, 255, "DATE:\ttimestamp: %.2f, UTC offset: %d",        prop->p_vu.p_number, prop->p_UTCoffset);      break;    default:      snprintf(str, 255, "INVALID TYPE 0x%02x", (unsigned char)prop->p_type);    }  RTMP_Log(RTMP_LOGDEBUG, "Property: <%s%s>", strRes, str);}voidAMFProp_Reset(AMFObjectProperty *prop){  if (prop->p_type == AMF_OBJECT)    AMF_Reset(&prop->p_vu.p_object);  else    {      prop->p_vu.p_aval.av_len = 0;      prop->p_vu.p_aval.av_val = NULL;    }  prop->p_type = AMF_INVALID;}/* AMFObject */char *AMF_Encode(AMFObject *obj, char *pBuffer, char *pBufEnd){  int i;  if (pBuffer+4 >= pBufEnd)    return NULL;  *pBuffer++ = AMF_OBJECT;  for (i = 0; i < obj->o_num; i++)    {      char *res = AMFProp_Encode(&obj->o_props[i], pBuffer, pBufEnd);      if (res == NULL) {   RTMP_Log(RTMP_LOGERROR, "AMF_Encode - failed to encode property in index %d",       i);   break; }      else {   pBuffer = res; }    }  if (pBuffer + 3 >= pBufEnd)    return NULL;   /* no room for the end marker */  pBuffer = AMF_EncodeInt24(pBuffer, pBufEnd, AMF_OBJECT_END);  return pBuffer;}intAMF_DecodeArray(AMFObject *obj, const char *pBuffer, int nSize,  int nArrayLen, int bDecodeName){  int nOriginalSize = nSize;  int bError = FALSE;  obj->o_num = 0;  obj->o_props = NULL;  while (nArrayLen > 0)    {      AMFObjectProperty prop;      int nRes;      nArrayLen--;      nRes = AMFProp_Decode(&prop, pBuffer, nSize, bDecodeName);      if (nRes == -1) bError = TRUE;      else {   nSize -= nRes;   pBuffer += nRes;   AMF_AddProp(obj, &prop); }    }  if (bError)    return -1;  return nOriginalSize - nSize;}intAMF3_Decode(AMFObject *obj, const char *pBuffer, int nSize, int bAMFData){  int nOriginalSize = nSize;  int32_t ref;  int len;  obj->o_num = 0;  obj->o_props = NULL;  if (bAMFData)    {      if (*pBuffer != AMF3_OBJECT) RTMP_Log(RTMP_LOGERROR,     "AMF3 Object encapsulated in AMF stream does not start with AMF3_OBJECT!");      pBuffer++;      nSize--;    }  ref = 0;  len = AMF3ReadInteger(pBuffer, &ref);  pBuffer += len;  nSize -= len;  if ((ref & 1) == 0)    {    /* object reference, 0xxx */      uint32_t objectIndex = (ref >> 1);      RTMP_Log(RTMP_LOGDEBUG, "Object reference, index: %d", objectIndex);    }  else    /* object instance */    {      int32_t classRef = (ref >> 1);      AMF3ClassDef cd = { {0, 0}      };      AMFObjectProperty prop;      if ((classRef & 0x1) == 0) {   /* class reference */   uint32_t classIndex = (classRef >> 1);   RTMP_Log(RTMP_LOGDEBUG, "Class reference: %d", classIndex); }      else {   int32_t classExtRef = (classRef >> 1);   int i;   cd.cd_externalizable = (classExtRef & 0x1) == 1;   cd.cd_dynamic = ((classExtRef >> 1) & 0x1) == 1;   cd.cd_num = classExtRef >> 2;   /* class name */   len = AMF3ReadString(pBuffer, &cd.cd_name);   nSize -= len;   pBuffer += len;   /*std::string str = className; */   RTMP_Log(RTMP_LOGDEBUG,       "Class name: %s, externalizable: %d, dynamic: %d, classMembers: %d",       cd.cd_name.av_val, cd.cd_externalizable, cd.cd_dynamic,       cd.cd_num);   for (i = 0; i < cd.cd_num; i++)     {       AVal memberName;       len = AMF3ReadString(pBuffer, &memberName);       RTMP_Log(RTMP_LOGDEBUG, "Member: %s", memberName.av_val);       AMF3CD_AddProp(&cd, &memberName);       nSize -= len;       pBuffer += len;     } }      /* add as referencable object */      if (cd.cd_externalizable) {   int nRes;   AVal name = AVC("DEFAULT_ATTRIBUTE");   RTMP_Log(RTMP_LOGDEBUG, "Externalizable, TODO check");   nRes = AMF3Prop_Decode(&prop, pBuffer, nSize, FALSE);   if (nRes == -1)     RTMP_Log(RTMP_LOGDEBUG, "%s, failed to decode AMF3 property!",  __FUNCTION__);   else     {       nSize -= nRes;       pBuffer += nRes;     }   AMFProp_SetName(&prop, &name);   AMF_AddProp(obj, &prop); }      else {   int nRes, i;   for (i = 0; i < cd.cd_num; i++) /* non-dynamic */     {       nRes = AMF3Prop_Decode(&prop, pBuffer, nSize, FALSE);       if (nRes == -1)  RTMP_Log(RTMP_LOGDEBUG, "%s, failed to decode AMF3 property!",      __FUNCTION__);       AMFProp_SetName(&prop, AMF3CD_GetProp(&cd, i));       AMF_AddProp(obj, &prop);       pBuffer += nRes;       nSize -= nRes;     }   if (cd.cd_dynamic)     {       int len = 0;       do  {    nRes = AMF3Prop_Decode(&prop, pBuffer, nSize, TRUE);    AMF_AddProp(obj, &prop);    pBuffer += nRes;    nSize -= nRes;    len = prop.p_name.av_len;  }       while (len > 0);     } }      RTMP_Log(RTMP_LOGDEBUG, "class object!");    }  return nOriginalSize - nSize;}//解AMF编码的Object数据类型intAMF_Decode(AMFObject *obj, const char *pBuffer, int nSize, int bDecodeName){  int nOriginalSize = nSize;  int bError = FALSE;  /* if there is an error while decoding - try to at least find the end mark AMF_OBJECT_END */  obj->o_num = 0;  obj->o_props = NULL;  while (nSize > 0)    {      AMFObjectProperty prop;      int nRes;      if (nSize >=3 && AMF_DecodeInt24(pBuffer) == AMF_OBJECT_END) {   nSize -= 3;   bError = FALSE;   break; }      if (bError) {   RTMP_Log(RTMP_LOGERROR,       "DECODING ERROR, IGNORING BYTES UNTIL NEXT KNOWN PATTERN!");   nSize--;   pBuffer++;   continue; }   //解Object里的Property      nRes = AMFProp_Decode(&prop, pBuffer, nSize, bDecodeName);      if (nRes == -1) bError = TRUE;      else {   nSize -= nRes;   pBuffer += nRes;   AMF_AddProp(obj, &prop); }    }  if (bError)    return -1;  return nOriginalSize - nSize;}voidAMF_AddProp(AMFObject *obj, const AMFObjectProperty *prop){  if (!(obj->o_num & 0x0f))    obj->o_props = (AMFObjectProperty *)      realloc(obj->o_props, (obj->o_num + 16) * sizeof(AMFObjectProperty));  obj->o_props[obj->o_num++] = *prop;}intAMF_CountProp(AMFObject *obj){  return obj->o_num;}AMFObjectProperty *AMF_GetProp(AMFObject *obj, const AVal *name, int nIndex){  if (nIndex >= 0)    {      if (nIndex <= obj->o_num) return &obj->o_props[nIndex];    }  else    {      int n;      for (n = 0; n < obj->o_num; n++) {   if (AVMATCH(&obj->o_props[n].p_name, name))     return &obj->o_props[n]; }    }  return (AMFObjectProperty *)&AMFProp_Invalid;}voidAMF_Dump(AMFObject *obj){  int n;  RTMP_Log(RTMP_LOGDEBUG, "(object begin)");  for (n = 0; n < obj->o_num; n++)    {      AMFProp_Dump(&obj->o_props[n]);    }  RTMP_Log(RTMP_LOGDEBUG, "(object end)");}voidAMF_Reset(AMFObject *obj){  int n;  for (n = 0; n < obj->o_num; n++)    {      AMFProp_Reset(&obj->o_props[n]);    }  free(obj->o_props);  obj->o_props = NULL;  obj->o_num = 0;}/* AMF3ClassDefinition */voidAMF3CD_AddProp(AMF3ClassDef *cd, AVal *prop){  if (!(cd->cd_num & 0x0f))    cd->cd_props = (AVal *)realloc(cd->cd_props, (cd->cd_num + 16) * sizeof(AVal));  cd->cd_props[cd->cd_num++] = *prop;}AVal *AMF3CD_GetProp(AMF3ClassDef *cd, int nIndex){  if (nIndex >= cd->cd_num)    return (AVal *)&AV_empty;  return &cd->cd_props[nIndex];}
可参考文件：
AMF3 中文版介绍：http://download.csdn.net/detail/leixiaohua1020/6389977
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
RTMPdump（libRTMP） 源代码分析 3 AMF编码

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