Civetweb API Reference
mg_response_header_start( conn, status );
mg_response_header_add( conn, header, value, value_len );
mg_response_header_add_lines( conn, http1_headers );
mg_response_header_send( conn );
Parameters
| Parameter | Type | Description |
|---|---|---|
conn |
struct mg_connection * |
The server is sending a response to this connection |
status |
int |
HTTP status code to send (100-599) |
header |
const char * |
HTTP header name |
value |
const char * |
HTTP header value |
value_len |
int |
Length of HTTP header value. -1 will use the entire value string. |
http1_headers |
const char * |
String in format “Key: Value\r\nKey2: Value2” |
Return Value
| Type | Description |
int |
An integer indicating success (>=0) or failure (<0). |
-1 |
Error: Invalid parameter (e.g., NULL pointer or value out of range) |
-2 |
Error: Invalid connection type. These functions must only be used in web server request handlers. |
-3 |
Error: Invalid connection status. These functions must be used before mg_send() or mg_printf() functions. |
-4 |
Error: Too many headers. The total number of header lines is limited to MG_MAX_HEADERS (default: 64). |
-5 |
Error: Out of memory. |
Description
The mg_response_header_* family of functions can be used to send HTTP response headers from a web server handler function.
Do not use it for HTTP clients or websockets. When using mg_response_header_* functions, they must be used to send all HTTP headers - combining mg_response_header_* functions and mg_send_*/mg_write/mg_printf to send HTTP headers is not possible.
After sending HTTP headers, HTTP body data is still sent using mg_write/mg_printf.
All mg_response_header_* functions must be used prior to any call to mg_write/mg_printf, in the following order:
1) mg_response_header_start (once)
2) mg_response_header_add (0 - 64 times), alternatively mg_response_header_add_lines. The preferred function is mg_response_header_add. The function mg_response_header_add_lines can process HTTP/1.x formatted header lines and is used for compatibility.
3) mg_response_header_send (once)
4) mg_write or mg_printf (multiple) to send the HTTP body
Using mg_response_header_* functions will allow a request handler to process HTTP/1.x and HTTP/2 requests, in contrast to sending HTTP headers directly using mg_printf/mg_write.