Posting multipart form-data to a web server

[starter08]

Hi,
I have a C++ routine(client-side) which uploads an xml file to a web server by making a socket connection and sending all the post request through that socket.
On the server side I have a cgi script which receives all the data and creates a file in the specified directory.
If I am uploading only the file all works well, however I want to send data of other fields too (field1, field2 ..etc), this fails the post request and even the file is not uploaded.
I think it has something to do with the Boundary Strings that need to be sent with each part of the form-data.
However I am unable to understand how to do that.
Greatly appreciate any help.
Here is my code snippet for preparing the post request for sending the form-data

int Send_to_DB_via_HTTP(char* Traveller_output_buffer, unsigned data_len, string fileName, string servIP, string url)
{
 
     int sock;                          /*  Socket descriptor */
        struct sockaddr_in echoServAddr;   /*  server address */
        unsigned short echoServPort;       /*  server port */
        char *echoString;                  /*  String to send to echo server */
        char echoBuffer[RCVBUFSIZE];       /* Buffer for echo string */
        unsigned int echoStringLen;        /* Length of string to echo */
        int bytesRcvd, totalBytesRcvd;     /* Bytes read in single recv()
                                                   and total bytes read */
    int                         first_form_len=0;
        int                         second_form_len=0;
    int                hidden_data_len=0;
    unsigned             count = 0;
    int    count1 = 0;
    int    count2 = 0;
    char buf[2000];
    int n;
    const char *m_servIP;
    const char *m_url;
    m_servIP = servIP.c_str();
    m_url = url.c_str();
    echoServPort = 80;
 
     /*Create a reliable, stream socket using TCP */
 
    if ((sock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0)
          cout << " socket () failed" << endl;
 
    /* Construct the server address structure */
 
    memset(&echoServAddr, 0, sizeof(echoServAddr));         /* Zero out structure */
    echoServAddr.sin_family         = PF_INET;              /* Internet address family */
    echoServAddr.sin_addr.s_addr = inet_addr(m_servIP);       /* Server IP address */
    echoServAddr.sin_port           = htons(echoServPort); /* Server port */
 
    /* Establish the connection to the echo server */
    int k;
    k = connect(sock, (struct sockaddr *) &echoServAddr, sizeof(echoServAddr));
 
    if (k < 0)
    {
          cout<< "Error Connecting to " << servIP << endl;
    return -1;
    }
    else
     cout << "Connection Successfull to " << servIP << endl;
 
     //Start the form off with the boundary string
    hidden_data_len += snprintf(
            &Buffer3[hidden_data_len],
            sizeof(Buffer3) - hidden_data_len,
            "%s%s\r\n",
            "--", BOUNDARY_STRING);
    hidden_data_len += snprintf(
                        &Buffer3[hidden_data_len],
                        sizeof(Buffer3) - (hidden_data_len),
                        "Content-Disposition: form-data;name=\"field1\"\r\n\r\n%s_auto_end\r\n",
                        syssn_no );
 
 
    //End of multi-part form
    hidden_data_len += snprintf(
                        &Buffer3[hidden_data_len],
                        sizeof(Buffer3) - (hidden_data_len),
                        "%s%s%s\r\n",
                        "--",BOUNDARY_STRING,"--" );
    first_form_len += snprintf(
                        &buffer1[first_form_len],
                        sizeof(buffer1) - first_form_len,
                        "%s%s\r\n",
                        "--",BOUNDARY_STRING );
    //Some random filename - must end in .dat because web server checks
    //This is the data portion of the form - the flat file will be sent in this section
    first_form_len += snprintf(
                        &buffer1[first_form_len],
                        sizeof(buffer1) - first_form_len,
                        "Content-Disposition: form-data; name=\"flat_file\"; filename=\"travellerdata.dat\"\r\n" );
 
    first_form_len += snprintf(
                        &buffer1[first_form_len],
                        sizeof(buffer1) - first_form_len,
                        "Content-Type: text/plain\r\n\r\n" );
 
 
    //Prepare the ending part of the form-data - this follows the flat file contents
    //Start the form off with the boundary string
    /*second_form_len += snprintf(
                        &buffer1[first_form_len+second_form_len],
                        sizeof(buffer1) - (first_form_len+second_form_len),
                        "%s%s\r\n",
                        "--",BOUNDARY_STRING );*/
 
 
    // Put together the headers for HTTP POST
    count = snprintf(
                       &buffer[0],
                       sizeof(buffer),
                       "POST %s HTTP/1.1\r\n",
                       m_url);
 
    count += snprintf(
                        &buffer[count],
                        sizeof(buffer) - count,
                        "Accept-Language: en-us\r\n" );
    count += snprintf(
                        &buffer[count],
                        sizeof(buffer) - count,
                        "Content-Type: multipart/form-data; boundary=%s\r\n",
                        BOUNDARY_STRING);
 
 
    count += snprintf(
                        &buffer[count],
                        sizeof(buffer) - count,
                        "User-Agent: Mozilla/3.01 (compatible)\r\n");
    count += snprintf(
                        &buffer[count],
                        sizeof(buffer) - count,
                        "Host: %s\r\n",
                        m_servIP);
 
 
    count += snprintf(
                        &buffer[count],
                        sizeof(buffer) - count,
                        "Pragma: no-cache\r\n" );
    count += snprintf(
                        &buffer[count],
                        sizeof(buffer) - count,
                        "Content-Length: %d\r\n",
                        data_len+first_form_len+second_form_len+hidden_data_len );
    count += snprintf(
                        &buffer[count],
                        sizeof(buffer) - count,
                        "\r\n" );
    //cout << buffer << endl;
   count1 += snprintf(
            &buffer2[count1],
            sizeof(buffer2) - count1,
            "%s%s\r\n",
                        "--",BOUNDARY_STRING);
 
   count1 += snprintf(
            &buffer2[count1],
            sizeof(buffer2) - count1,
            "Content-Disposition: form-data; \"\r\n");
   count1 += snprintf(
            &buffer2[count1],
            sizeof(buffer2) - count1,
            "Content-Type: text/html\r\n");
   count1 += snprintf(
            &buffer2[count1],
            sizeof(buffer2) - count1,
            "Content-Length: %d\r\n", data_len);
   count2 += snprintf(
            &buffer3[count2],
            sizeof(buffer3) - (count1+count2),
            "%s%s%s\r\n",
            "--",BOUNDARY_STRING, "--");
 
    string status;
 
    cout << "Sending Post Headers" << endl<< buffer << endl << "End Post Headers" << endl;
 
    //Send the "POST" header to the HTTP server.
    if (send(sock, buffer, count, 0) == -1) {
 
        //status = perror("send");
        cout << "Stats Worker: received socket error %d on header send\n" << endl;
        return -1;
    }
 
    cout << "Hidden Data" << endl<< Buffer3 << endl << "End Post Headers" << endl;
    if (send(sock, Buffer3, hidden_data_len, 0) == -1) {
 
        //status = perror("send");
        cout << "Stats Worker: received socket error %d on header send\n" << endl;
        return -1;
    }
    cout << "Now Sending first part of the form data BUFFER1" << endl << buffer1 << endl<< "End First Part"<< endl;
 
 
 
    if (send(sock, buffer1, first_form_len, 0) == -1) {
 
        //status = CK_Get_last_error();
        cout << "Stats Worker: received socket error on header send\n" << endl;
        return -1;
    }
 
    cout << "Now Sending file " << Traveller_output_buffer << endl;
    //Now send the flat file
    if (send(sock, Traveller_output_buffer, data_len, 0) == -1) {
 
        //status = CK_Get_last_error();
 
        cout << "Stats Worker: received socket error %d on message send\n" << endl;
        return -1;
    }
    cout << "Sending ending boundary string " << endl << buffer3 << endl;
    if (send(sock, buffer3, count2, 0) == -1) {
 
        //status = perror("send");
        cout << "Stats Worker: received socket error %d on header send\n" << endl;
        return -1;
    }
 
    //Send the last part of the form data to the HTTP server.
    /*if (send(sock, buffer1+first_form_len, second_form_len, 0) == -1) {
 
        //status = CK_Get_last_error();
        cout << "Stats Worker: received socket error %d on header send\n" << endl;
        return -1;
    }*/
 
    //Receive server response
 
    n = recv(sock, buf, 2000, 0);
    //cout << "Server Response is " << endl << buf << endl;
    if(n < 0)
    {
        cout << "Upload Failed" << endl;
        return -1;
    }
 
    // Make sure this is a HTTP header
    if (!strstr(buf, "HTTP")) {
 
        cout << "Stats Worker: response doesn't contain HTTP\n";
        return -1;
    }
 
    if (n < 0) {
 
        cout << "Stats Worker: response status is " << n;
        return -1;
    }
 
        // while (n > 0) {
     //printf(buf);
            if(!strstr(buf, Successful_Upload))
         {
        cout << "Traveller Upload Failed. Server Responded " << buf;
        return -1;
        }
         else
        {
         cout << "Traveller Upload Successfull. \n Server Response is \n" << buf;
         //return 0;
        }
            //n = recv(sock, buf, 10480, 0);
         //}
 //remove("newtravellerdata.dat");
//close(sock);
}
 

If required I can upload the server side cgi too.

Thanks,
Mohit

[starter08]

Hi,
Can anybody help me out.
This is the whole output that I am trying to send through a post request

POST http://192.168.2.5/upload.cgi HTTP/1.1
Accept-Language: en-us
Content-Type: multipart/form-data; boundary=---------------------------7d2b119100532
User-Agent: Mozilla/3.01 (compatible)
Host: 192.168.2.5
Pragma: no-cache
Content-Length: 717
 
-----------------------------7d2b119100532
Content-Disposition: form-data; name="field1"
 
5107115015_auto_end
-----------------------------7d2b119100532
Content-Disposition: form-data; name="flat_file"; filename="travellerdata.dat"
Content-Type: text/plain
 
<SYSSN>5107115015</SYSSN>
<HDD slot="0">
    <serial>DA40P7C003P5</serial>
    <model>MAW3300NC</model>
    <firmware>0104</firmware>
</HDD>
<network>
    <adapter slot="1">
        <interface slot="1">
            <mac>00:E0:81:4B:8F:FD</mac>
        </interface>
    </adapter>
</network>
<BIOS>
    <revision></revision>
    <date>06/23/06</date>
</BIOS>
<CPU_count>4</CPU_count>
<CPU slot="0">
    <serial>00020F120000000000000000</serial>
</CPU>
-----------------------------7d2b119100532--
 

however I receive the following response back from the server

Server Response is
HTTP/1.1 200 OK
Date: Fri, 26 Sep 2008 05:13:55 GMT
Server: Apache/2.2.3 (Debian) PHP/5.2.0-8+etch10
Transfer-Encoding: chunked
Content-Type: text/html; charset=UTF-8

f3
<h1>Software error:</h1>
<pre>Malformed multipart POST
</pre>
<p>
For help, please send mail to the webmaster (<a href="mailto:webmaster@localhost">webmaster@localh ost</a>), giving this error message
and the time and date of the error.

</p>