http proxy - receive problem

This is a discussion on http proxy - receive problem within the Linux Programming forums, part of the Platform Specific Boards category; Hello, I have coded a http proxy in c that do the work very well. It wait for an connection ...

  1. #1
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    http proxy - receive problem

    Hello,

    I have coded a http proxy in c that do the work very well. It wait for an connection (http request), send it back to the browser and so on. But i can't receive *.gif's, *.jpg's .... Only what I see in the browser ist a "broken" image. The rest, such full html code, style sheets, received i completely. Anyone have an idea, where the problem can be?

    ...sry for the bad english.

    thx
    Last edited by laphoo; 05-13-2004 at 07:43 PM.

  2. #2
    Registered User linuxdude's Avatar
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    maybe the types you are recieving have to be typcasted or maybe tructuated to meet your requirments. Obviously something is happening between the server and you. Some of data is being damaged somehow. Do you have any ideas now?

  3. #3
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    Do you mean the Accept header part:

    Accept: image/png,image/jpeg,image/gif;q=0.2,*/*;q=0.1

    ...it will correct send and received.

  4. #4
    End Of Line Hammer's Avatar
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    Post a snippet of the code that does the reading/writing on the socket.
    When all else fails, read the instructions.
    If you're posting code, use code tags: [code] /* insert code here */ [/code]

  5. #5
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    buffer size for each array == 5000 chars
    pSock // return socket from local server
    bSock // return socket from accept
    tSock // reuurn socket from connected target

    Code:
    while(1)
    	{
    		if((bSock = accept(pSock, (struct sockaddr*)&client, &clientSize)) == -1)
    		{
    			fprintf(stdout, "error: proxy - accept()\n");
    			continue;
    		}
    		
    		if((childId = fork()) == 0)
    		{
    			close(pSock);
    		
    			fprintf(stdout, "Connection from: %s:%d [successfully]\n",
    				inet_ntoa(client.sin_addr.s_addr), htons(client.sin_port));
    			
    			memset(&recvBuf, 0x00, sizeof(recvBuf));
    			
    			if((recvBytes = recv(bSock, (char*)recvBuf, sizeof(recvBuf) - 1, 0)) == -1)
    			{
    				fprintf(stdout, "error: client - recv()\n");
    				return -4;
    			}
    			recvBuf[recvBytes] = '\0';
    		
    			if(verbose == 0)
    			{
    				fprintf(stdout, "< RECEIVING HTTP HEADER >");
    				fprintf(stdout, "\n%s\n", recvBuf);
    			}
    
    			memset(&sendBuf, 0x00, sizeof(sendBuf));
    			
    			if(ParseHttpHeader(recvBuf, the.hdrRef, sendBuf) < 0)
    				return -5;
    
    			if((tSock = SetupTargetServer(the.hdrHost)) < 0)
    				return -6;
    
    			if(verbose == 0)
    			{
    				fprintf(stdout, "< SENDING HTTP HEADER >");
    				fprintf(stdout, "\n%s\n", sendBuf);
    			}
    
    			if(send(tSock, (char*)sendBuf, strlen(sendBuf), 0) == -1)
    			{
    				fprintf(stdout, "error: target - send()\n");
    				return -7;
    			}
    		
    			while(1)
    			{
    				memset(&htmlBuf, 0x00, sizeof(htmlBuf));
    
    				if((recvBytes = recv(tSock, (char*)htmlBuf, sizeof(htmlBuf) - 1, 0)) == -1)
    				{
    					fprintf(stdout, "error: target - recv()\n");
    					return -8;
    				}
    				htmlBuf[recvBytes] = '\0';
    				
    				if(send(bSock, (char*)htmlBuf, strlen(htmlBuf), 0) == -1)
    				{
    					printf("error: client - send()\n");
    					return -9;
    				}
    			}
    			close(tSock);
    			close(bSock);
    			exit(EXIT_FAILURE);
    		}
    		else
    		{
    			if(childId < 0)
    			{
    				fprintf(stdout, "error: fork()\n");
    				exit(EXIT_FAILURE);
    			}
    			else
    			{
    				close(bSock);
    			}
    		}
    	}

  6. #6
    End Of Line Hammer's Avatar
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    >>if(send(bSock, (char*)htmlBuf, strlen(htmlBuf), 0) == -1)
    Is this part sending the image ? If so, it won't work too well, strcpy() isn't the correct function to use. Only the recvBytes variable knows how many bytes you've got in the buffer.
    When all else fails, read the instructions.
    If you're posting code, use code tags: [code] /* insert code here */ [/code]

  7. #7
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    Yes it is...do you mean, in correct form this:

    if(send(bSock, (char*)htmlBuf, strlen(recvBytes), 0) == -1)

    that I must put the recvBytes variable into strlen?

  8. #8
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    strlen() will count from the start of the buffer up to the first byte that have value \0 (0x00). It is designed to work with text strings, like words and sentences, not the internals of a GIF image. There is most likely many \0 bytes scatter throughout the image file, which will confuse your code completely. You should be sending all parts of the image, so I guess you'd want to go with something like
    >>if(send(bSock, (char*)htmlBuf, recvBytes, 0) == -1)
    When all else fails, read the instructions.
    If you're posting code, use code tags: [code] /* insert code here */ [/code]

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