ne_get_response_header - Man Page

functions to access response headers and trailers

Synopsis

#include <ne_request.h>

const char *ne_get_response_header(ne_request *request, const char *name);

const char *ne_get_response_trailer(ne_request *req, const char *name);

void *ne_response_header_iterate(ne_request *request, void *cursor, const char **name, const char **value);

void *ne_response_trailer_iterate(ne_request *request, void *cursor, const char **name, const char **value);

To retrieve the value of a response header field, the ne_get_response_header function can be used, and is given the name of the header to return. If multiple HTTP response headers are received with the same name, their values are combined together in a comma-separated list.

To retrieve the value of a header from a chunked response trailer section (sent after, rather than before, the response body), ne_get_response_trailer can be used. This function otherwise has the same semantics as ne_get_response_header. Note that trailer fields are used rarely and should be interpreted with care, see RFC 9110 §6.5^[1].

To iterate over all the response headers returned, the ne_response_header_iterate function can be used. This function takes a cursor parameter which should be NULL to retrieve the first header. The function stores the name and value of the next header header in the name and value parameters, and returns a new cursor pointer which can be passed to ne_response_header_iterate to retrieve the next header.

The ne_response_trailer_iterate function has the same semantics as ne_response_header_iterate except it operates on the response trailer fields rather than the header section.

Return Value

ne_get_response_header and ne_get_response_trailer each return a string, or NULL if no header or trailer field with that name was found. The return value pointer is valid only until the next call to ne_begin_request or ne_request_destroy for the same request.

Likewise, the cursor, names, and values returned by ne_response_header_iterate or ne_response_trailer_iterate are only valid until the next call to ne_begin_request or until the request object is destroyed.

Examples

The following code will output the value of the Last-Modified header for a resource:

ne_request *req = ne_request_create(sess, "GET", "/foo.txt");
if (ne_request_dispatch(req) == NE_OK) {
    const char *mtime = ne_get_response_header(req, "Last-Modified");
    if (mtime) {
        printf("/foo.txt has last-modified value %s\n", mtime);
    }
}
ne_request_destroy(req);

History

ne_get_response_trailer and ne_response_trailer_iterate are available in neon 0.37.0 and later. In older releases, trailer fields were merged with normal response headers and could be accessed using ne_get_response_header or ne_response_header_iterate.