= nng_http_res_add_header(3http) // // Copyright 2018 Staysail Systems, Inc. // Copyright 2018 Capitar IT Group BV // // This document is supplied under the terms of the MIT License, a // copy of which should be located in the distribution where this // file was obtained (LICENSE.txt). A copy of the license may also be // found online at https://opensource.org/licenses/MIT. // == NAME nng_http_res_add_header - add HTTP response header == SYNOPSIS [source, c] ---- #include #include int nng_http_res_add_header(nng_http_res *res, const char *key, const char *val); ---- == DESCRIPTION The `nng_http_res_add_header()` adds an HTTP header for the response _res_ and the _key_ to the _val_. The _key_ and _val_ are copied. If a header with the value of _key_ already exists, then a comma and whitespace separate are appended to it, followed by _val_. If no such header already exists, then one is created with the value _val_. TIP: The HTTP specification requires that duplicate headers be treated identically to a single header with multiple comma-delimited values. TIP: See xref:nng_http_res_set_header.3http.adoc[`nng_http_res_set_header()`] if replacement of an existing header rather than appending to it is desired. The value of _key_ is case insensitive, and should not include the final colon in an HTTP header. For example, specifying `Host` or `hOSt` are equivalent, whereas the value `Host:` is not a legal header key. == RETURN VALUES This function returns 0 on success, and non-zero otherwise. == ERRORS [horizontal] `NNG_ENOMEM`:: Insufficient memory to perform the operation. `NNG_ENOTSUP`:: No support for HTTP in the library. == SEE ALSO [.text-left] xref:nng_http_res_alloc.3http.adoc[nng_http_res_alloc(3http)], xref:nng_http_res_del_header.3http.adoc[nng_http_res_del_header(3http)], xref:nng_http_res_get_header.3http.adoc[nng_http_res_get_header(3http)], xref:nng_http_res_set_header.3http.adoc[nng_http_res_set_header(3http)], xref:nng.7.adoc[nng(7)]