'\" t
.\"     Title: ne_get_response_header
.\"    Author: 
.\" Generator: DocBook XSL Stylesheets vsnapshot <http://docbook.sf.net/>
.\"      Date: 03/20/2026
.\"    Manual: neon API reference
.\"    Source: neon
.\"  Language: English
.\"
.TH "NE_GET_RESPONSE_HEAD" "3" "03/20/2026" "neon" "neon API reference"
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.SH "NAME"
ne_get_response_header, ne_get_response_trailer, ne_response_header_iterate, ne_response_trailer_iterate \- functions to access response headers and trailers
.SH "SYNOPSIS"
.sp
.ft B
.nf
#include <ne_request\&.h>
.fi
.ft
.HP \w'const\ char\ *ne_get_response_header('u
.BI "const char *ne_get_response_header(ne_request\ *" "request" ", const\ char\ *" "name" ");"
.HP \w'const\ char\ *ne_get_response_trailer('u
.BI "const char *ne_get_response_trailer(ne_request\ *" "req" ", const\ char\ *" "name" ");"
.HP \w'void\ *ne_response_header_iterate('u
.BI "void *ne_response_header_iterate(ne_request\ *" "request" ", void\ *" "cursor" ", const\ char\ **" "name" ", const\ char\ **" "value" ");"
.HP \w'void\ *ne_response_trailer_iterate('u
.BI "void *ne_response_trailer_iterate(ne_request\ *" "request" ", void\ *" "cursor" ", const\ char\ **" "name" ", const\ char\ **" "value" ");"
.SH "DESCRIPTION"
.PP
To retrieve the value of a response header field, the
\fBne_get_response_header\fR
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\&.
.PP
To retrieve the value of a header from a chunked response trailer section (sent after, rather than before, the response body),
\fBne_get_response_trailer\fR
can be used\&. This function otherwise has the same semantics as
\fBne_get_response_header\fR\&. Note that trailer fields are used rarely and should be interpreted with care, see
\m[blue]\fBRFC 9110 \(sc6\&.5\fR\m[]\&\s-2\u[1]\d\s+2\&.
.PP
To iterate over all the response headers returned, the
\fBne_response_header_iterate\fR
function can be used\&. This function takes a
\fIcursor\fR
parameter which should be
NULL
to retrieve the first header\&. The function stores the name and value of the next header header in the
\fIname\fR
and
\fIvalue\fR
parameters, and returns a new cursor pointer which can be passed to
\fBne_response_header_iterate\fR
to retrieve the next header\&.
.PP
The
\fBne_response_trailer_iterate\fR
function has the same semantics as
\fBne_response_header_iterate\fR
except it operates on the response trailer fields rather than the header section\&.
.SH "RETURN VALUE"
.PP
\fBne_get_response_header\fR
and
\fBne_get_response_trailer\fR
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
\fBne_begin_request\fR
or
\fBne_request_destroy\fR
for the same request\&.
.PP
Likewise, the cursor, names, and values returned by
\fBne_response_header_iterate\fR
or
\fBne_response_trailer_iterate\fR
are only valid until the next call to
\fBne_begin_request\fR
or until the request object is destroyed\&.
.SH "EXAMPLES"
.PP
The following code will output the value of the
Last\-Modified
header for a resource:
.sp
.if n \{\
.RS 4
.\}
.nf
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\en", mtime);
    }
}
ne_request_destroy(req);
.fi
.if n \{\
.RE
.\}
.SH "HISTORY"
.PP
\fBne_get_response_trailer\fR
and
\fBne_response_trailer_iterate\fR
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
\fBne_get_response_header\fR
or
\fBne_response_header_iterate\fR\&.
.SH "SEE ALSO"
.PP
\fBne_request_create\fR(3),
\fBne_request_destroy\fR(3)\&.
.SH "COPYRIGHT"
.br
Copyright \(co 2001-2026 Joe Orton
.br
.SH "REFERENCES"
.IP " 1." 4
RFC 9110 \(sc6.5
.RS 4
\%https://www.rfc-editor.org/rfc/rfc9110.html#name-trailer-fields
.RE