Hi, Justin.
I’ve reproduced the relevant code below. It’s almost exactly the simplepost.c
example Christian supplies in his tutorial.
https://www.gnu.org/software/libmicrohttpd/tutorial.html#simplepost_002ec The
biggest changes are that 1) I put in debugging writes, 2) I tried to override
the Content Type header from application/json to
application/x-www-form-urlencoded.
I’ve highlighted the relevant parts in yellow. In my main routine,
MHD_start_daemon is passed answer_to_connection as the callback routine. In
answer_to_connection MHD_create_post_processor is called. It returned a null
because application/json is not supported.
I’m getting the impression from other posts that I should not use
MHD_create_post_processor, but create my own processor of post requests. There
should be a hook that is called when pieces of the request body arrive, but I
haven’t found that hook.
Does your JSON-handling code use MHD_create_post_processor?
Regards, Rick
static int
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* incoming_encoding; // Interesting. Apparently, we point to a
// string that they have allocated and keep ahold of.
LogMessage("In answer_to_connection. Method = \"%s\"", method);
if (NULL == *con_cls) {
LogMessage("con_cls points to a NULL.");
struct connection_info_struct *con_info;
con_info = malloc (sizeof (struct connection_info_struct));
if (NULL == con_info) return MHD_NO;
con_info->answerstring = NULL;
if (0 == strcmp (method, "POST")) {
LogMessage("Method is POST.");
incoming_encoding = MHD_lookup_connection_value(connection,
MHD_HEADER_KIND,
MHD_HTTP_HEADER_CONTENT_TYPE);
LogMessage("Content Type before I changed it was \"%s\"",
incoming_encoding);
MHD_set_connection_value(connection,
MHD_HEADER_KIND,
MHD_HTTP_HEADER_CONTENT_TYPE,
MHD_HTTP_POST_ENCODING_FORM_URLENCODED);
incoming_encoding = NULL;
incoming_encoding = MHD_lookup_connection_value(connection,
MHD_HEADER_KIND,
MHD_HTTP_HEADER_CONTENT_TYPE);
LogMessage("And after I supposedly changed the content type, the c t it
had was \"%s\"", incoming_encoding);
con_info->postprocessor =
MHD_create_post_processor (connection, POSTBUFFERSIZE,
iterate_post, (void *) con_info);
if (NULL == con_info->postprocessor) {
LogMessage("con_info->postprocessor is null");
free (con_info);
return MHD_NO;
}
con_info->connectiontype = POST;
} else {
LogMessage("Method is GET.");
con_info->connectiontype = GET;
}
*con_cls = (void *) con_info;
return MHD_YES;
}
if (0 == strcmp (method, "GET")) {
LogMessage("Method is GET.");
LogMessage("About to send askpage page.");
return send_page (connection, askpage);
}
if (0 == strcmp (method, "POST")) {
LogMessage("Method is POST.");
struct connection_info_struct *con_info = *con_cls;
if (*upload_data_size != 0) {
MHD_post_process (con_info->postprocessor, upload_data,
*upload_data_size);
*upload_data_size = 0;
return MHD_YES;
} else if (NULL != con_info->answerstring) {
LogMessage("About to send con_info->answerstring page.");
return send_page (connection, con_info->answerstring);
}
}
LogMessage("About to send errorpage page.");
return send_page (connection, errorpage);
}
int main(int argc, char** argv) {
int portNum;
char portStr[10];
char outputDir[80];
char logFile[80];
char logPath[200];
struct MHD_Daemon* d;
GetCmdLineStr(argc, argv, "-o", "???", outputDir, sizeof(outputDir) );
GetCmdLineStr(argc, argv, "-l", "???", logFile, sizeof(logFile ) );
if (!strcmp(outputDir, "???") || !strcmp(logFile, "???") ) {
printf("Must supply -o outputDir and -l logFile on the command
line.\n");
return 1;
}
GetCmdLineStr(argc, argv, "-p", "???", portStr, sizeof(portStr) );
if (!strcmp(portStr, "???") ) {
printf("Must supply -p portStr on the command line.\n");
return 1;
}
strcpy(logPath, outputDir);
strcat(logPath, "/");
strcat(logPath, logFile);
portNum = atoi(portStr);
SetAppName("webcxn");
SetLogFileName(logPath);
SetLoggingOn(TRUE);
LogMessage("Webcxn starting");
LogMessage("Webcxn will listen on port number %d", portNum);
d = MHD_start_daemon (MHD_USE_SELECT_INTERNALLY, portNum, NULL, NULL,
&answer_to_connection, NULL,
MHD_OPTION_NOTIFY_COMPLETED, request_completed,
NULL, MHD_OPTION_END);
if (d == NULL) {
LogMessage("Failed to start the daemon.");
return 1;
}
LogMessage("About to \"pause\" waiting while our daemon does things.");
pause();
LogMessage("Came out of the pause. Signal received?");
MHD_stop_daemon(d);
return 0;
}
From: libmicrohttpd <[email protected]> On
Behalf Of Justin Graves
Sent: Friday, February 22, 2019 10:12 AM
To: [email protected]; libmicrohttpd development and user mailinglist
<[email protected]>
Subject: [EXTERNAL] Re: [libmicrohttpd] Can handle Content-Type =
application/json ?
We are running libmicrohttpd in an API which uses JSON in both request and
response bodies almost exclusively with no issue. We do also use form data. If
the client sends a body with "application/json" as the "Content-Type" header,
we will see whatever they sent via MHD_get_connection_values.
I have just verified this, using libmicrohttp v0.9.62, by sending a request
with a "Content-Type" header of "application/json", then using
MHD_get_connection_values with MHD_HEADER_KIND, and it gives me a key of
"Content-Type" exactly once with a value of "application/json".
Perhaps providing example code related to your header parsing would help?
-
Justin Graves
On Feb 22, 2019, 3:02 AM -0600, Hedin, Richard (InfoSys)
<[email protected]<mailto:[email protected]>>, wrote:
Gentlepeople:
I am using libmicrohttpd to make, naturally, a web server. The client wants to
send me a post request with a content type of “application/json”.
Libmicrohttpd doesn’t seem to support application/json. Only
"application/x-www-form-urlencoded" and "multipart/form-data". I tried using
MHD_set_connection_value as the source code suggested, but it doesn’t work. I
suspect it doesn’t replace the existing Content-Type key, but adds a header to
the end.
Does libmicrohttpd just not work for this case? I don’t feel I can tell my
client not to send me application/json. It’s such an obvious and commonly
accepted format.
Ideas?
Regards, Rick
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