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Re: [libmicrohttpd] not getting a keep-alive session from MHD
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From: |
Christian Grothoff |
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Subject: |
Re: [libmicrohttpd] not getting a keep-alive session from MHD |
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Date: |
Mon, 28 Jun 2021 20:33:54 +0200 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 |
Hi tz,
You're answering too early. Try (for minimalistic test, not for good style):
static enum MHD_Result
answer_to_connection (void *cls, struct MHD_Connection *connection,
const char *url, const char *method,
const char *version, const char *upload_data,
size_t *upload_data_size, void **con_cls)
{
if (NULL == *con_cls)
{
*con_cls = "foo";
return MHD_YES;
}
// continue as before
That should do the trick. And yes, the API is counter-intuitive here,
especially for simple GET calls. The reason is that the first request
is for responding to 'Expect: 100 continue' and error replies _only_.
Which I guess for GET is quite odd. But once you handle POSTs and start
to keep state in *con_cls, it'll be more natural.
Happy hacking!
Christian
On 6/28/21 5:49 PM, tz@objectiveapps.net wrote:
> Hello,
>
> I've compiled one of the first MHD examples and I'm struggeling how to
> get a keep-alive session. From my understanding, MHD should always
> respond with Connection: keep-alive, as long as not getting a
> Connection: close in the request. Here is my code:
>
> --------------------------
> #include <sys/types.h>
> #ifndef _WIN32
> #include <sys/select.h>
> #include <sys/socket.h>
> #else
> #include <winsock2.h>
> #endif
> #include <string.h>
> #include <microhttpd.h>
> #include <stdio.h>
>
> #define PORT 8888
>
> static enum MHD_Result
> answer_to_connection (void *cls, struct MHD_Connection *connection,
> const char *url, const char *method,
> const char *version, const char *upload_data,
> size_t *upload_data_size, void **con_cls)
> {
> const char *page = "<html><body>Hello, browser!</body></html>";
> struct MHD_Response *response;
> enum MHD_Result ret;
> (void) cls; /* Unused. Silent compiler warning. */
> (void) url; /* Unused. Silent compiler warning. */
> (void) method; /* Unused. Silent compiler warning. */
> (void) version; /* Unused. Silent compiler warning. */
> (void) upload_data; /* Unused. Silent compiler warning. */
> (void) upload_data_size; /* Unused. Silent compiler warning. */
> (void) con_cls; /* Unused. Silent compiler warning. */
>
> response =
> MHD_create_response_from_buffer (strlen (page), (void *) page,
> MHD_RESPMEM_PERSISTENT);
> MHD_add_response_header(response, MHD_HTTP_HEADER_CONNECTION,
> "keep-alive");
> ret = MHD_queue_response (connection, MHD_HTTP_OK, response);
> MHD_destroy_response (response);
> return ret;
> }
>
> int main (void)
> {
> struct MHD_Daemon *daemon;
> daemon = MHD_start_daemon (MHD_USE_THREAD_PER_CONNECTION,
> PORT, NULL, NULL,
> &answer_to_connection, NULL,
> MHD_OPTION_END);
> if (NULL == daemon)
> return 1;
> (void) getchar ();
> MHD_stop_daemon (daemon);
> return 0;
> }
> --------------------------
>
>
> I'm calling the server from curl with the following command:
>
>> curl -v 192.168.178.70:8888 -H "Connection: keep-alive"
>
> Curl output is as follows:
>
>
>> GET / HTTP/1.1
>> Host: 192.168.178.70:8888
>> User-Agent: curl/7.66.0
>> Accept: */*
>> Connection: keep-alive
>>
>
> < HTTP/1.1 200 OK
> < Connection: close
> < Content-Length: 41
> < Date: Mon, 28 Jun 2021 15:44:19 GMT
> <
> * Closing connection 0
>
>
>
> As you can see, Curl asks for a keep-alive connection, MHD answers with
> Connection: close. Im getting the same result when using a browser
> (chrome) and inspecting the packets.
>
> Obviously, I'm doing something wrong. But what?
>
> Thanks in advance,
> Thomas
>
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