CODEWITHSUNDEEP
clinuxhttpurl-parsing
rachit7
rachit7

Reputation: 141

How to read URLs containing question marks in C using microhttpd.h

I am trying to parse the URL in C using microhttpd library. 

daemon = MHD_start_daemon (MHD_USE_SELECT_INTERNALLY | MHD_USE_SSL, PORT, NULL, NULL, &answer_to_connection, NULL, MHD_OPTION_HTTPS_MEM_KEY, key_pem, MHD_OPTION_HTTPS_MEM_CERT, cert_pem, MHD_OPTION_END);

When I run the function MHD_start_daemon a call back function answer_to_connection is called.

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)
{
    printf("URL:%s\n", url);
}

One of the parameters of answer_to_connection is const char *url. The url variable contains the string after https://localhost:port example: for http://128.19.24.123:8888/cars/ferrari the url value will be /cars/ferrari

But in case of http://128.19.24.123:8888/cars?value=ferrari the url is printing only cars.

I want to print cars?value=ferrari. How can I do that?

There is a tutorial on microhttpd library at https://www.gnu.org/software/libmicrohttpd/tutorial.html

But I can't find any solution to this problem there.

Upvotes: 2

Views: 1996

Answers (2)

norm graham
norm graham

Reputation: 1

use MHD_get_connection_values to call your function, once for every name=value pair. Lets dumb it down into an example. First you have the URL, but not the parms. So, lets show how to get the name=value pairs. So, lets show this with an example. call via curl, with [bla.bla.bla?name1=value1&name2=value2] . Now, in your Answer_To_Connection(...), say we want to build a string, that looks like [name1=value1,name2=value2\0]. we call MHD_get_connection_values (ConnectionPtr, MHD_GET_ARGUMENT_KIND, &OurFunctionToCallForEach, bufferptr); In OurFunctionToCallForEach( void *bufferptr, MHD_VAlueKind k, const char *key, const char *value), we sprintf(strchr(bufferptr,'\0'), "%s=%s,", name, value); Anyway, it's a crude example, which will exercise any static code analysis, but does show the procedure. We make one call to MHD, MHD calls our function once for every name/value pair, and gives us the pointer we gave MHD.

Upvotes: 0

harmic
harmic

Reputation: 30597

CAVEAT EMPTOR: I have not used this library, this answer is based on a quick perusal of the API.

It looks like you can't access the whole original URL, because microhttpd parses it for you. Instead you access the individual query string values using MHD_lookup_connection_value, like this:

value = MHD_lookup_connection_value(connection, MHD_GET_ARGUMENT_KIND, "value");

That would return a pointer to the value of the query string argument, or null if not found.

You can also use MHD_get_connection_values to iterate over the query string components. In that case you would call it like this:

num = MHD_get_connection_values(connection, MHD_GET_ARGUMENT_KIND, iterator, cls);

iterator would be a callback function to receive the GET query arguments, one by one.

See also: the Handling requests section in the manual.

Upvotes: 3

Related Questions