Re: [lwip-users] Pulling data from a server using HTTP with lwIP

[Mikael Eiman]

For the HTTP basics, have a look at 
http://www.w3.org/Protocols/rfc2616/rfc2616-sec5.html#sec5

(Ok, not the most recent version of the spec, but this bit is still valid)

Notably, this is a minimum valid request for HTTP/1.1:

GET /pub/WWW/TheProject.html HTTP/1.1
Host: www.w3.org
<empty line>

You must provide a Host header, and end the headers with an empty line. For 
HTTP/1.0 you can omit the Host header, if you have to.

regards,
        Mikael


> 13 nov 2014 kl. 13:52 skrev Robert Wood <address@hidden>:
> 
> Well, I am certainly no expert on HTTP, *but*, if I look at how things work 
> with my computer, when it requests a packet from my board there is only the 
> SYN, SYN ACK, ACK handshake before the computer sends the GET command.
> 
> Now, when my board is the client, the issue I have is not [yet] whether the 
> GET is working properly.
> 
> What is happening when lwIP board is client and desktop is server:
> 
> If I establish a connection from the board to the desktop and do not send a 
> GET request, then lwIP does the SYN, SYN ACK, ACK handshake just fine.
> 
> If I add the [potentially incorrect] GET request, the SYNN is sent, the SYN 
> ACK is received, but my board running lwIP does not send the ACK out to the 
> desktop.
> 
> You may well be totally correct that my GET line is incomplete, I cannot find 
> any details on exactly how it should be, but I don't think that is the main 
> issue at the moment. I'm happy to be told I'm talking nonsense though.
> 
> Thanks!
> 
> 
> 
> On 13/11/14 11:21, Simon Goldschmidt wrote:
>> Robert Wood wrote:
>>> Hmmmm. I seem to be wrong, It *does* send out the ACK. I took out these
>>> lines:
>>> strcpy(GetString,"GET /index.html HTTP/1.1\r\n");
>>> netconn_write(xNetConn,GetString,sizeof(GetString),NETCONN_NOCOPY);
>> 
>> As you seem to be trying to implement a HTTP client: are you familiar with 
>> the HTTP protocol? I'm not sure the single line is enough for HTTP 1.1 (it 
>> should be for 0.9), but at least you need a double line-break to inform the 
>> server that this is the end of the HTTP header.
>> 
>> I'd suggest reading a bit more on  HTTP.
>> 
>> Simon
>> 
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> 
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