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librtmp协议分析---RTMP_SendPacket函数
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接下來我們分析RTMP_SendPacket函數(shù)。我們先了解一下rtmp的消息格式chunk。
RTMP的head組成
Chunk basic header：?
Chunk Data
總結(jié)如下圖所示：
6.1.2 塊消息頭
6.1.2.1 類型0
時間戳：3 字節(jié)
時間戳增量：3 字節(jié)
6.1.3. 擴展時間戳
代碼分析如下：
[cpp] ?view plaincopy print?
int ?RTMP_SendPacket(RTMP?*r,?RTMPPacket?*packet,? int ?queue)?? {?? ????const ?RTMPPacket?*prevPacket?=?r->m_vecChannelsOut[packet->m_nChannel];?? ????uint32_t?last?=?0;?? ????int ?nSize;?? ????int ?hSize,?cSize;?? ????char ?*header,?*hptr,?*hend,?hbuf[RTMP_MAX_HEADER_SIZE],?c;?? ????uint32_t?t;?? ????char ?*buffer,?*tbuf?=?NULL,?*toff?=?NULL;?? ????int ?nChunkSize;?? ????int ?tlen;?? ?? ?????? ?????? ????? ? ? ? ?? ????if ?(prevPacket?&&?packet->m_headerType?!=?RTMP_PACKET_SIZE_LARGE)?? ????{?? ?????????? ?????????? ?????????? ?????????? ?????????? ????????if ?(prevPacket->m_nBodySize?==?packet->m_nBodySize&&?prevPacket->m_packetType?==?packet->m_packetType?? ????????&&?packet->m_headerType?==?RTMP_PACKET_SIZE_MEDIUM)?? ????????????packet->m_headerType?=?RTMP_PACKET_SIZE_SMALL;?? ?? ?????????? ?????????? ????????if ?(prevPacket->m_nTimeStamp?==?packet->m_nTimeStamp?&&?packet->m_headerType?==?RTMP_PACKET_SIZE_SMALL)?? ????????????packet->m_headerType?=?RTMP_PACKET_SIZE_MINIMUM;?? ????????last?=?prevPacket->m_nTimeStamp;?? ????}?? ?? ?????? ????if ?(packet->m_headerType?>?3)? ?? ????{?? ????????RTMP_Log(RTMP_LOGERROR,?"sanity?failed!!?trying?to?send?header?of?type:?0x%02x." ,?(unsigned? char )packet->m_headerType);?? ????????return ?FALSE;?? ????}?? ?? ?????? ?????? ?????? ????nSize?=?packetSize[packet->m_headerType];?? ????hSize?=?nSize;?? ????cSize?=?0;?? ?????? ????t?=?packet->m_nTimeStamp?-?last;?? ?? ????if ?(packet->m_body)?? ????{?? ?????????? ????????header?=?packet->m_body?-?nSize;?? ?????????? ????????hend?=?packet->m_body;?? ?????????? ????}?? ????else ?? ????{?? ????????header?=?hbuf?+?6;?? ????????hend?=?hbuf?+?sizeof (hbuf);?? ????}?? ?? ????if ?(packet->m_nChannel?>?319) ?? ????????cSize?=?2;?? ????else ? if ?(packet->m_nChannel?>?63) ?? ????????cSize?=?1;?? ?????? ????if ?(cSize)?? ????{?? ????????header?-=?cSize;?? ????????hSize?+=?cSize;?? ????}?? ?? ?????? ?????? ????if ?(nSize?>?1?&&?t?>=?0xffffff)?? ????{?? ????????header?-=?4;?? ????????hSize?+=?4;?? ????}?? ?? ????hptr?=?header;?? ????c?=?packet->m_headerType?<<?6;?? ?? ?????? ????switch ?(cSize)?? ????{?? ????case ?0: ?? ????????c?|=?packet->m_nChannel;?? ????????break ;?? ????case ?1: ?? ????????break ;?? ????case ?2: ?? ????????c?|=?1;?? ????????break ;?? ????}?? ????*hptr++?=?c;?? ?? ?????? ????if ?(cSize)?? ????{?? ????????int ?tmp?=?packet->m_nChannel?-?64; ?? ????????*hptr++?=?tmp?&?0xff;?? ????????if ?(cSize?==?2) ?? ????????????*hptr++?=?tmp?>>?8;?? ????}?? ?? ????if ?(nSize?>?1) ?? ????{?? ?????????? ????????hptr?=?AMF_EncodeInt24(hptr,?hend,?t?>?0xffffff???0xffffff?:?t);?? ????}?? ?? ????if ?(nSize?>?4) ?? ????{?? ?????????? ????????hptr?=?AMF_EncodeInt24(hptr,?hend,?packet->m_nBodySize);?? ????????*hptr++?=?packet->m_packetType;?? ????}?? ?????? ????if ?(nSize?>?8)?? ????????hptr?+=?EncodeInt32LE(hptr,?packet->m_nInfoField2);?? ?? ????if ?(nSize?>?1?&&?t?>=?0xffffff) ?? ????????hptr?=?AMF_EncodeInt32(hptr,?hend,?t);?? ?? ?????? ?????? ????nSize?=?packet->m_nBodySize;?? ????buffer?=?packet->m_body;?? ????nChunkSize?=?r->m_outChunkSize;?? ?? ????RTMP_Log(RTMP_LOGDEBUG2,?"%s:?fd=%d,?size=%d" ,?__FUNCTION__,?r->m_sb.sb_socket,?nSize);?? ?????? ????if ?(r->Link.protocol?&?RTMP_FEATURE_HTTP)?? ????{?? ?????????? ?????????? ?????????? ?????????? ????????int ?chunks?=?(nSize?+?nChunkSize?-?1)?/?nChunkSize;?? ????????if ?(chunks?>?1) ?? ????????{?? ?????????????? ?????????????? ?????????????? ?????????????? ????????????tlen?=?chunks?*?(cSize?+?1)?+?nSize?+?hSize;?? ????????????tbuf?=?malloc(tlen);?? ????????????if ?(!tbuf)?? ????????????????return ?FALSE;?? ????????????toff?=?tbuf;?? ????????}?? ????}?? ?? ?????? ????while ?(nSize?+?hSize)?? ????{?? ????????int ?wrote;?? ?? ????????if ?(nSize?<?nChunkSize) ?? ????????????nChunkSize?=?nSize;?? ?? ????????RTMP_LogHexString(RTMP_LOGDEBUG2,?(uint8_t?*)header,?hSize);?? ????????RTMP_LogHexString(RTMP_LOGDEBUG2,?(uint8_t?*)buffer,?nChunkSize);?? ?????????? ?????????? ????????if ?(tbuf)?? ????????{?? ?????????????? ?????????????? ????????????memcpy(toff,?header,?nChunkSize?+?hSize);?? ????????????toff?+=?nChunkSize?+?hSize;?? ????????}?? ????????else ?? ????????{?? ?????????????? ????????????wrote?=?WriteN(r,?header,?nChunkSize?+?hSize);?? ????????????if ?(!wrote)?? ????????????????return ?FALSE;?? ????????}?? ????????nSize?-=?nChunkSize;?? ????????buffer?+=?nChunkSize;?? ????????hSize?=?0;?? ?? ?????????? ????????if ?(nSize?>?0)?? ????????{?? ????????????header?=?buffer?-?1;?? ????????????hSize?=?1;?? ????????????if ?(cSize)?? ????????????{?? ????????????????header?-=?cSize;?? ????????????????hSize?+=?cSize;?? ????????????}?? ????????????*header?=?(0xc0?|?c);?? ????????????if ?(cSize)?? ????????????{?? ????????????????int ?tmp?=?packet->m_nChannel?-?64;?? ????????????????header[1]?=?tmp?&?0xff;?? ????????????????if ?(cSize?==?2)?? ????????????????????header[2]?=?tmp?>>?8;?? ????????????}?? ????????}?? ????}?? ????if ?(tbuf)?? ????{?? ????????int ?wrote?=?WriteN(r,?tbuf,?toff?-?tbuf);?? ????????free(tbuf);?? ????????tbuf?=?NULL;?? ????????if ?(!wrote)?? ????????????return ?FALSE;?? ????}?? ?? ?????? ????if ?(packet->m_packetType?==?0x14)?? ????{?? ????????AVal?method;?? ????????char ?*ptr;?? ????????ptr?=?packet->m_body?+?1;?? ????????AMF_DecodeString(ptr,?&method);?? ????????RTMP_Log(RTMP_LOGDEBUG,?"Invoking?%s" ,?method.av_val);?? ?????????? ????????if ?(queue)?? ????????{?? ????????????int ?txn;?? ????????????ptr?+=?3?+?method.av_len;?? ????????????txn?=?(int )AMF_DecodeNumber(ptr);?? ????????????AV_queue(&r->m_methodCalls,?&r->m_numCalls,?&method,?txn);?? ????????}?? ????}?? ?? ????if ?(!r->m_vecChannelsOut[packet->m_nChannel])?? ????r->m_vecChannelsOut[packet->m_nChannel]?=?malloc(sizeof (RTMPPacket));?? ????memcpy(r->m_vecChannelsOut[packet->m_nChannel],?packet,?sizeof (RTMPPacket));?? ????return ?TRUE;?? }??
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