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I am facing some problem with GPRS Project. I am sending request to server through GPRS and receiving responce from the server. I have used AVR ATmega32 micro controller and SIM900 GSM/GPRS Module from simcom. I can send HTTP Request Header Successfully to the server, but getting Bad Request response every time. I have wrote program in AVR Studio 6.2. here I have attached Response of Server received on GPRS.

  AT
OK
AT+CSMINS?
+CSMINS: 0,1

OK
AT+CREG?
+CREG: 0,1

OK
AT+CGATT?
+CGATT: 1

OK
AT+CIPSHUT
SHUT OK
AT+CIPSTATUS
OK

STATE:IP INITIAL
AT+CIPMUX=0
OK
AT+CSTT="idea gprs"
OK
AT+CIICR
OK
AT+CIFSR
10.112.37.103
AT+CIPSTART= "TCP","198.136.54.34","80"
OK

CONNECT OK
AT+CIPSEND
> GET /httptest.php?data1=value1 HTTP/1.1
 Host: http://exqure.com


SEND OK
HTTP/1.1 400 Bad Request
Date: Thu, 18 Jun 2015 12:19:34 GMT
Server: Apache
Content-Length: 226
Connection: close
Content-Type: text/html; charset=iso-8859-1

<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
                                                  <html><head>
                                                              <title>400 Bad Request</title>
                 </head><body>
                              <h1>Bad Request</h1>
                                                  <p>Your browser sent a request that this server could not understand.<br />
                                                  </p>
                                                      </body></html>

I want to under stand that where I am going wrong? What is the correct format for HTTP header request?

Here is my Code :

//////////////////////////////////////////////////////////////////////////
//          SEND DATA
//////////////////////////////////////////////////////////////////////////
    LCD_ClearScreen();
    LCD_goto_XY(1,1);
    LCD_Print("Sending DATA");
    _delay_ms(1000);
    LCD_ClearScreen();
    r=SIM300SendDATA(0,"/httptest.php?data1=value1","http://exqure.com");
    if (r==SIM300_FAIL)
    {


    }

int8_t  SIM300SendDATA(uint8_t *Method,char *PATH,char *HOST)
{
    UFlushBuffer();
    //UWriteString(num);
    char cmd[25]="AT+CIPSEND",DataToSend[255];
    //char GET2[255]="";
    //char CRLF[4]="\r\n\r\n";
    //Send Command
    SIM300Cmd(cmd);

    _delay_ms(200);
    uint8_t len = SIM300GPRSWaitForResponse(1000);
    if(len)
    {
        if (!Method)
        {
            sprintf(DataToSend, "GET %s HTTP/1.1\r\n Host: %s\r\n\r\n", PATH, HOST);
        }
        else
        {
            sprintf(DataToSend, "POST %s HTTP/1.1\r\n Host: %s\r\n", PATH,HOST);
        }
    }
    else
    {
        return SIM300_TIMEOUT;
    }


    UWriteString(DataToSend);
    //UWriteString(GET2);
    //UWriteString(CRLF);
    UWriteData(0x1A);

    len=SIM300WaitForResponse(1000);

    if(len==0)
    return SIM300_TIMEOUT;

    sim300_buffer[len-1]='\0';

    if(strncasecmp(sim300_buffer+2,"CMGS:",5)==0)
    {
        UFlushBuffer();

        return SIM300_OK;
    }
    else
    {
        UFlushBuffer();
        return SIM300_FAIL;
    }
}
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  • \$\begingroup\$ Is the script on your server expecting the data to be URL encoded or form encoded? You're passing it as URL encoded and I haven't done much with PHP but think the default is form encoded. \$\endgroup\$ – PeterJ Jun 18 '15 at 12:47
3
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I solved the problem. :) The problem was with Extra "Space" in header.

sprintf(DataToSend, "GET %s HTTP/1.1\r\n Host: %s\r\n\r\n", PATH, HOST);

I removed that space:

sprintf(DataToSend, "GET %s HTTP/1.1\r\nHost: %s\r\n\r\n", PATH, HOST);

and then problem get resolved. here is the response from server:

HTTP/1.1 200 OK
Date: Fri, 19 Jun 2015 03:38:14 GMT
Server: Apache
X-Powered-By: PHP/5.4.34
Cache-Control: no-store, no-cache, must-revalidate, post-check=0, pre-check=0
Pragma: no-cache
Last-Modified: Fri, 19 Jun 2015 03:38:14 GMT
Vary: Accept-Encoding,User-Agent
Content-Length: 87
Content-Type: text/plain

This is REQUEST Data
data1:value1
This is GET Data
data1:value1
This is POS
           HTTP/1.1 200 OK
Date: Fri, 19 Jun 2015 03:38:14 GMT
Server: Apache
X-Powered-By: PHP/5.4.34
Cache-Control: no-store, no-cache, must-revalidate, post-check=0, pre-check=0
Pragma: no-cache
Last-Modified: Fri, 19 Jun 2015 03:38:14 GMT
Vary: Accept-Encoding,User-Agent
Content-Length: 87
Content-Type: text/plain

This is REQUEST Data
data1:value1
This is GET Data
data1:value1
This is POS
           T Data

Thanks guys.

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2
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My best guess: the Host header's value should be a host name, not a URL. In your example, it should probably be exqure.com instead of http://exqure.com.

In terms of code, the offending line would be:

SIM300SendDATA(0,"/httptest.php?data1=value1","http://exqure.com")

...which should probably be changed into:

SIM300SendDATA(0,"/httptest.php?data1=value1","exqure.com")
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