rtsp.c

一个简单的RTSP客户端实现源码

	int bytesRead = 0; // because we've already read the first byte
	unsigned bytesReadNow  = 0;
	fSocketNum = socketNum;

	if (responseBufferSize == 0) return 0; // just in case...
	*(responseBuffer) = '\0';

	while (bytesRead < (int)responseBufferSize) 
	{
		lastToCheck = NULL;
		if(blockUntilReadable(fSocketNum)<=0)
		{
			fprintf(stderr,"socket is unreadable\n");
			break;
		}
		bytesReadNow = recv(fSocketNum,(unsigned char*)(responseBuffer+bytesRead),1, 0);
		if (bytesReadNow != 1) 
		{
			fprintf(stderr,"RTSP response was truncated\n");
			break;
		}
		bytesRead++;
    
  
		lastToCheck = responseBuffer+bytesRead-4;
		if (lastToCheck < responseBuffer) continue;
		p = lastToCheck;
		if (*p == '\r' && *(p+1) == '\n' &&
						*(p+2) == '\r' && *(p+3) == '\n') 
		{
			*(responseBuffer+bytesRead)= '\0';
			// Before returning, trim any \r or \n from the start:
			while (*responseBuffer == '\r' || *responseBuffer == '\n'||*responseBuffer!=0x52) 
			{
				++responseBuffer;
				--bytesRead;
			}
			if(*responseBuffer == 0x52)//&&responseBuffer[1]=='T'&&responseBuffer[2]=='S'&&responseBuffer[3]=='P')
				return bytesRead;

		}
	}
	return bytesRead;
}
/////////////////////
char* parseSDPLine(char* inputLine)
{
	char *ptr;
	for (ptr = inputLine; *ptr != '\0'; ++ptr) 
	{
		if (*ptr == '\r' || *ptr == '\n') 
		{
			++ptr;
			while (*ptr == '\r' || *ptr == '\n') ++ptr;
			if (ptr[0] == '\0') ptr = NULL; // special case for end
			break;
		}
	}

	if (inputLine[0] == '\r' || inputLine[0] == '\n') return ptr;
	if (strlen(inputLine) < 2 || inputLine[1] != '='
		    || inputLine[0] < 'a' || inputLine[0] > 'z') 
	{
		fprintf(stderr,"Invalid SDP line \n");
		return NULL;
	}

	return ptr;
}

char * parseSDPAttribute_rtpmap(char* sdpLine,unsigned* rtpTimestampFrequency,unsigned *fnumChannels) 
{
	unsigned rtpmapPayloadFormat;
	unsigned numChannels = 1;
	char* codecName = strDupSize(sdpLine); // ensures we have enough space
	if (sscanf(sdpLine, "a=rtpmap: %u %[^/]/%u/%u",
			&rtpmapPayloadFormat, codecName, rtpTimestampFrequency,
			&numChannels) == 4
		|| sscanf(sdpLine, "a=rtpmap: %u %[^/]/%u",
			&rtpmapPayloadFormat, codecName, rtpTimestampFrequency) == 3
		|| sscanf(sdpLine, "a=rtpmap: %u %s",
			&rtpmapPayloadFormat, codecName) == 2) 
	{
		*fnumChannels = numChannels;  
		return strDup(codecName);

	}
	free(codecName);

	return NULL;
}

char * parseSDPAttribute_control(char* sdpLine) 
{
  
	char* controlPath = strDupSize(sdpLine); // ensures we have enough space
	if (sscanf(sdpLine, "a=control:%s", controlPath) == 1) 
	{
		return strDup(controlPath);
	}
	free(controlPath);

	return NULL;
}

int parseSDPAttribute_range(char* sdpLine) 
{
	int parseSuccess = -1;
	char playEndTime[32];
	char temp[32];
	int index = 0;
	int j = 0;
	unsigned long endtime = 0;
	char *endstr;
	int k;
	int i,num;
	if (sscanf(sdpLine, "a=range:npt=0-  %s", playEndTime)==1) 
	{
		parseSuccess = 0;
		for(index = 0;index<strlen(playEndTime);index++)
		{
			if(playEndTime[index]!='.')
			{
				temp[j] = playEndTime[index];
				j++;
			}
			else
			{
				for(k=index+1;k<strlen(playEndTime);k++)
				{
					temp[j] = playEndTime[k];
					j++;
					PotPos++;
				}
				break;
			}

		}
		temp[j] = '\0';
		
		
		endtime = strtoul(temp,&endstr,10);

		if (endtime > fMaxPlayEndTime) 
		{
			if(PotPos>=3)
			{
				num = 1;
				for(i = 0;i<PotPos-3;i++)
				{
					num = 10*num;
				}
				fMaxPlayEndTime = endtime/num;
			}
			else
			{
				num = 1;
				for(i = 0;i<3-PotPos;i++)
				{
					num = 10*num;
				}
				fMaxPlayEndTime = endtime*num;
			}
			PotPos = 1000;
			
		}
		fprintf(stderr,"fMaxPlayEndTime is %lu\n",fMaxPlayEndTime);
	}

	return parseSuccess;
}


char * parseSDPAttribute_fmtp(char* sdpLine) 
{
	char* lineCopy;
	char* line;
	char* valueStr;
	char* c;
	do 
	{
		if (strncmp(sdpLine, "a=fmtp:", 7) != 0) break; 
		sdpLine += 7;
		while (isdigit(*sdpLine)) ++sdpLine;

		lineCopy = strDup(sdpLine); 
		line = lineCopy;
		for (c = line; *c != '\0'; ++c) *c = tolower(*c);
    
		while (*line != '\0' && *line != '\r' && *line != '\n') 
		{
			valueStr = strDupSize(line);
			if (sscanf(line, " config = %[^; \t\r\n]", valueStr) == 1) 
			{
				free(lineCopy);
				
				return strDup(valueStr);
      			}
      			free(valueStr);

			while (*line != '\0' && *line != '\r' && *line != '\n'&& *line != ';') ++line;
			while (*line == ';') ++line;
		}
		free(lineCopy);
	} while (0);
	return NULL;
}


struct MediaAttribute * GetMediaAttrbute(struct MediaAttribute *Attribute,struct MediaSubsession * subsession,int subsessionNum)
{
	struct MediaSubsession *mediasub;
	int len = 0;
	mediasub = subsession;
	while(subsessionNum>0)
	{
		if(strcmp(mediasub->fCodecName,"MP4V-ES") == 0)
		{	
			Attribute->fVideoFrequency = mediasub->frtpTimestampFrequency;
			Attribute->fVideoPayloadFormat = mediasub->fRTPPayloadFormat;
			len = strlen(mediasub->fConfig);
			memcpy(Attribute->fConfigAsc,mediasub->fConfig,len);
			a_hex(mediasub->fConfig,Attribute->fConfigHex,len);
			Attribute->fConfigHexLen = len/2;
			parse_vovod(Attribute->fConfigHex,Attribute->fConfigHexLen,&(Attribute->fVideoFrameRate),&(Attribute->fTimeIncBits),&(Attribute->fVideoWidth),&(Attribute->fVideoHeight));
			
			Attribute->fixed_vop_rate = fixed_vop_rate;
			VFrameRate = Attribute->fVideoFrameRate;
		}
		else if(strcmp(mediasub->fCodecName,"MPA") == 0||strcmp(mediasub->fCodecName,"mpeg4-generic") == 0)
		{	
			Attribute->fAudioFrequency = mediasub->frtpTimestampFrequency;
			Attribute->fAudioPayloadFormat = mediasub->fRTPPayloadFormat;
			Attribute->fTrackNum = mediasub->fNumChannels;
		}	
		mediasub = mediasub->fNext;
		subsessionNum--;
	}
	return Attribute;
}

struct MediaSubsession * initializeWithSDP(char* sdpDescription,int *SubsessionNum)
{
 

	int Num = 0;
	char*  sdpLine = sdpDescription;
	char* nextSDPLine = NULL;
	struct MediaSubsession *fSubsessionsHead;
	struct MediaSubsession *fSubsessionsTail;
	struct MediaSubsession* subsession;
	char* mediumName;
	char * CodecName;
	char * ControlPath;
	char *Config;
	unsigned payloadFormat;
	if (sdpDescription == NULL) return NULL;
	fSubsessionsHead = fSubsessionsTail = NULL;
	while (1) 
	{
		if ((nextSDPLine = parseSDPLine(sdpLine)) == NULL)
		{
			return NULL;		
		}
		if (sdpLine[0] == 'm') 
		{
			Num++;
			break;
		}
		sdpLine = nextSDPLine;
		if (sdpLine == NULL) break; // there are no m= lines at all 
		if (!parseSDPAttribute_range(sdpLine)) continue;//check a=range:npt=
	}
    
	while (sdpLine != NULL) 
	{
		subsession = (struct MediaSubsession*)malloc(sizeof(struct MediaSubsession));
		if (subsession == NULL) 
		{
			fprintf(stderr,"Unable to create new MediaSubsession\n");
			return NULL;
		}

		if (fSubsessionsTail == NULL) 
		{
			fSubsessionsHead = fSubsessionsTail = subsession;
		} 
		else 
		{
			fSubsessionsTail->fNext = subsession;
			subsession->fNext = NULL;
			fSubsessionsTail = subsession;
			
		}

		mediumName = strDupSize(sdpLine);
    
		if (sscanf(sdpLine, "m=%s %hu RTP/AVP %u",mediumName, &subsession->fClientPortNum, &payloadFormat) != 3
			|| payloadFormat > 127) 
		{
			fprintf(stderr,"Bad SDP line\n");
			free(mediumName);
			return NULL;
		}
    
		subsession->fMediumName = strDup(mediumName);
		free(mediumName);
		subsession->fRTPPayloadFormat = payloadFormat;
		

		while (1) 
		{
			sdpLine = nextSDPLine;//a=rtpmap...
			if (sdpLine == NULL) break; // we've reached the end
			if ((nextSDPLine = parseSDPLine(sdpLine)) == NULL)
			{
				*SubsessionNum = Num;
				return fSubsessionsHead;			
				//下移一行
			}

			if (sdpLine[0] == 'm') 
			{
				Num ++;
				break; // we've reached the next subsession
			}
			// Check for various special SDP lines that we understand:
			CodecName = strDupSize(sdpLine);
			if ((CodecName = parseSDPAttribute_rtpmap(sdpLine,&(subsession->frtpTimestampFrequency),&(subsession->fNumChannels)))!=NULL)
			{
				subsession->fCodecName = strDup(CodecName);
				if(strcmp(CodecName,"MP4V-ES") == 0)
				{	
					VTimestampFrequency = subsession->frtpTimestampFrequency;
					VPayloadType = subsession->fRTPPayloadFormat;
				}
				else if(strcmp(CodecName,"MPA") == 0||strcmp(CodecName,"mpeg4-generic") == 0)
				{	
					ATimestampFrequency = subsession->frtpTimestampFrequency;
					APayloadType = subsession->fRTPPayloadFormat;
				}
				free(CodecName);
				continue;
			}
			ControlPath = strDupSize(sdpLine);
			if ((ControlPath = parseSDPAttribute_control(sdpLine))!=NULL)
			{
				subsession->fControlPath = strDup(ControlPath);
				free(ControlPath);
				continue;
			}
			Config = strDupSize(sdpLine);
			if ((Config = parseSDPAttribute_fmtp(sdpLine))!=NULL)
			{
				subsession->fConfig = strDup(Config);
				free(Config);
				continue;
			}
		}
	}
	
	*SubsessionNum = Num;
	return fSubsessionsHead;
  
}
int blockUntilwriteable(int socket)//, struct timeval* timeout)
{
	int result = -1;
	static unsigned numFds;
	fd_set wd_set;
	do 
	{
		FD_ZERO(&wd_set);
		if (socket < 0) break;
		FD_SET((unsigned) socket, &wd_set);
		numFds = socket+1;
		
		result = select(numFds, NULL, &wd_set, NULL,0);// timeout);
		if (result == 0)
		{
			break; // this is OK - timeout occurred
		}
		else if(result <= 0) 
		{
			fprintf(stderr, "select() error\n ");
			break;
		}

		if (!FD_ISSET(socket, &wd_set)) 
		{
			fprintf(stderr, "select() error - !FD_ISSET\n");
			break;
		}
	} while (0);
	return result;
};

int blockUntilReadable(int socket)//, struct timeval* timeout) 
{
	fd_set rd_set;
	int result = -1;
	static unsigned numFds;
	
	do 
	{
		FD_ZERO(&rd_set);
		if (socket < 0) break;
		FD_SET((unsigned) socket, &rd_set);
		numFds = socket+1;
		result = select(numFds, &rd_set, NULL, NULL,0);
		if (result == 0) 
		{
			break; // this is OK - timeout occurred
		} 
		else if (result <= 0) 
		{
			fprintf(stderr, "select() error\n ");
			break;
		}
    
		if (!FD_ISSET(socket, &rd_set)) 
		{
			fprintf(stderr, "select() error - !FD_ISSET\n");
			break;
		}	
	} while (0);

	return result;
}


int getSDPDescriptionFromURL(int socketNum,char* url,char* Description)
{
	int fSocketNum;
	char *readBuffer;//[MAX_READBUFSIZE+1]; 
	char* readBuf;

	int bytesRead;

	char* cmdFmt ="DESCRIBE %s RTSP/1.0\r\nCSeq: %d\r\nAccept: application/sdp\r\n%s\r\n";
	unsigned cmdSize = 0;										
  	char* cmd = NULL;
	char* firstLine;
	char* nextLineStart;
	unsigned responseCode;
	int contentLength = -1;
	char* lineStart;  
	unsigned numExtraBytesNeeded;
	char* ptr;
	int bytesRead2;
	
	readBuffer = (char *)malloc((MAX_READBUFSIZE+1)*sizeof(char));
	if(readBuffer == NULL)
	{
		fprintf(stderr,"failed to alloc the memory\n");
    		return -1;
	}
	memset(readBuffer,0,MAX_READBUFSIZE+1);
	readBuf =readBuffer;
	
	//fprintf(stderr,"start alloc cmd\n");
	cmdSize = strlen(cmdFmt) + strlen(url) + 20 /* max int len */+ strlen(UserAgentHeaderStr);
	cmd = (char *)malloc((cmdSize+1)*sizeof(char));
	if(cmd ==NULL)
	{
		fprintf(stderr,"failed to alloc the memory\n");
    		free(readBuffer);
    		return -1;
	}
	//fprintf(stderr,"alloc cmd successful\n");
	memset(cmd,0,cmdSize+1);
	fSocketNum = socketNum;
	do 
	{  
 
		// Send the DESCRIBE command:
		//fprintf(stderr,"Send the DESCRIBE command\n");
		sprintf(cmd, cmdFmt,url,++fCSeq,UserAgentHeaderStr);

    //发送description 请求
		
		//fprintf(stderr,"start blockUntilwriteable\n");
  		if(blockUntilwriteable(fSocketNum)<=0)
  		{ 
  			fprintf(stderr,"socket is unwriteable\n");
  			break;
  		}
  		//fprintf(stderr,"start send\n");
  		if (send(fSocketNum, cmd, strlen(cmd), 0)<0) 
		{
			fprintf(stderr,"DESCRIBE send() failed\n ");
			break;
		}
		//fprintf(stderr,"DESCRIBE send() successful\n");
			// Get the response from the server:
		//fprintf(stderr,"Get the response from the server\n");
		bytesRead = getResponse(fSocketNum,readBuf, MAX_READBUFSIZE);
		if (bytesRead <= 0) break;
		
		//fprintf(stderr,"DESCRIBE response-%d:\n%s\n",fCSeq,readBuf);
		//Received DESCRIBE response
    
		// Inspect the first line to check whether it's a result code that
		// we can handle.

		firstLine = readBuf;
		nextLineStart = getLine(firstLine);
		if (sscanf(firstLine, "%*s%u", &responseCode) != 1) 
		{
			fprintf(stderr,"no response code in line\n");
			break;
		}
		if (responseCode != 200) 
		{
			fprintf(stderr,"cannot handle DESCRIBE response\n");
			break;
		}

		// Skip every subsequent header line, until we see a blank line
		// The remaining data is assumed to be the SDP descriptor that we want.
		// We should really do some checking on the headers here - e.g., to
		// check for "Content-type: application/sdp", "Content-base",
		// "Content-location", "CSeq", etc. #####
		//fprintf(stderr,"start get Content-Length\n");
		while (1) 
		{
			lineStart = nextLineStart;
			if (lineStart == NULL||lineStart[0] == '\0') break;

			nextLineStart = getLine(lineStart);
			if (sscanf(lineStart, "Content-Length: %d", &contentLength) == 1
				|| sscanf(lineStart, "Content-length: %d", &contentLength) == 1) 
			if(contentLength>0)
			{
				if (contentLength < 0) 
				{
					fprintf(stderr,"Bad Content-length\n");
					break;
				}
				// Use the remaining data as the SDP descr, but first, check
				// the "Content-length:" header (if any) that we saw.  We may need to
				// read more data, or we may have extraneous data in the buffer.
				//bodyStart = nextLineStart;
				// We saw a "Content-length:" header
				
				//numBodyBytes = &readBuf[bytesRead] - bodyStart;
				//if (contentLength > (int)numBodyBytes) 
				//{
				// We need to read more data.  First, make sure we have enough
				// space for it:
				numExtraBytesNeeded = contentLength;// - numBodyBytes;
			
				// Keep reading more data until we have enough:
				bytesRead = 0;
				//fprintf(stderr,"start recv %d\n",contentLength);
				while (numExtraBytesNeeded > 0) 
				{
					if(blockUntilReadable(fSocketNum)<=0)
    					{
    						fprintf(stderr,"socket is unreadable\n");
    						break;