HTTP

Provides high-performance HTTP/1.1 server functionality built on libevpl.

The libevpl HTTP server is very minimalist in its current form, but it allows HTTP to be transmitted over arbitrary supported protocols possibly with zero-copy transfer.

Overview

libevpl’s HTTP support provides:

  • HTTP/1.1 server - Handle GET, POST, PUT, DELETE, HEAD requests
  • Streaming - Support for chunked transfer encoding and content-length
  • Zero-copy - Use iovecs for efficient data transfer
  • Header manipulation - Add custom request/response headers
  • Multiple protocols - Run HTTP over TCP, XLIO, or RDMA

Supported methods: GET, HEAD, POST, PUT, DELETE

Types

struct evpl_http_agent

Opaque structure representing an HTTP agent (per event loop).

struct evpl_http_server

Opaque structure representing an HTTP server attached to a listener.

struct evpl_http_request

Opaque structure representing an individual HTTP request/response.

enum evpl_http_notify_type

HTTP event notifications:

Type Description
EVPL_HTTP_NOTIFY_RECEIVE_DATA Request body data available
EVPL_HTTP_NOTIFY_RECEIVE_COMPLETE Request fully received
EVPL_HTTP_NOTIFY_WANT_DATA Server ready for more response data
EVPL_HTTP_NOTIFY_RESPONSE_COMPLETE Response fully sent

enum evpl_http_request_type

HTTP request methods:

  • EVPL_HTTP_REQUEST_TYPE_GET
  • EVPL_HTTP_REQUEST_TYPE_HEAD
  • EVPL_HTTP_REQUEST_TYPE_POST
  • EVPL_HTTP_REQUEST_TYPE_PUT
  • EVPL_HTTP_REQUEST_TYPE_DELETE
  • EVPL_HTTP_REQUEST_TYPE_UNKNOWN

Callback Types

evpl_http_notify_callback_t 

typedef void (*evpl_http_notify_callback_t)(
    struct evpl                *evpl,
    struct evpl_http_agent     *agent,
    struct evpl_http_request   *request,
    enum evpl_http_notify_type  notify_type,
    enum evpl_http_request_type request_type,
    const char                 *uri,
    void                       *notify_data,
    void                       *private_data);

Callback invoked for HTTP events on a specific request.

Parameters:

  • evpl - Event loop
  • agent - HTTP agent
  • request - HTTP request
  • notify_type - Type of notification
  • request_type - HTTP method (GET, POST, etc.)
  • uri - Request URI
  • notify_data - Request-specific data (from dispatch callback)
  • private_data - User context (from dispatch callback)

evpl_http_dispatch_callback_t 

typedef void (*evpl_http_dispatch_callback_t)(
    struct evpl                 *evpl,
    struct evpl_http_agent      *agent,
    struct evpl_http_request    *request,
    evpl_http_notify_callback_t *notify_callback,
    void                       **notify_data,
    void                        *private_data);

Callback invoked when a new HTTP request arrives (routing/dispatch).

Parameters:

  • evpl - Event loop
  • agent - HTTP agent
  • request - New HTTP request
  • notify_callback - [OUT] Set notification callback for this request
  • notify_data - [OUT] Set request-specific context
  • private_data - Server context

Functions

Agent Management

evpl_http_init 

struct evpl_http_agent *evpl_http_init(struct evpl *evpl);

Create an HTTP agent for an event loop.

Parameters:

  • evpl - Event loop

Returns: HTTP agent, or NULL on failure

Note: One agent per event loop.

evpl_http_destroy 

void evpl_http_destroy(struct evpl_http_agent *agent);

Destroy an HTTP agent. All servers must be detached first.

Parameters:

  • agent - Agent to destroy

Server Management

evpl_http_attach 

struct evpl_http_server *evpl_http_attach(
    struct evpl_http_agent       *agent,
    struct evpl_listener         *listener,
    evpl_http_dispatch_callback_t dispatch_callback,
    void                         *private_data);

Attach an HTTP server to a listener.

Parameters:

  • agent - HTTP agent
  • listener - Network listener
  • dispatch_callback - Request dispatch callback
  • private_data - Server context

Returns: HTTP server handle, or NULL on failure

evpl_http_server_destroy 

void evpl_http_server_destroy(
    struct evpl_http_agent  *agent,
    struct evpl_http_server *server);

Detach and destroy an HTTP server.

Parameters:

  • agent - HTTP agent
  • server - Server to destroy

Request Information

evpl_http_request_type 

enum evpl_http_request_type evpl_http_request_type(
    struct evpl_http_request *request);

Get the HTTP method of a request.

Returns: Request type enum

evpl_http_request_type_to_string 

const char *evpl_http_request_type_to_string(
    struct evpl_http_request *request);

Get the HTTP method as a string.

Returns: Method string (“GET”, “POST”, etc.)

evpl_http_request_url 

const char *evpl_http_request_url(
    struct evpl_http_request *request,
    int                      *len);

Get the request URI.

Parameters:

  • request - HTTP request
  • len - [OUT] URI length (optional, can be NULL)

Returns: URI string

evpl_http_request_header 

const char *evpl_http_request_header(
    struct evpl_http_request *request,
    const char               *name);

Get a request header value.

Parameters:

  • request - HTTP request
  • name - Header name (case-insensitive)

Returns: Header value, or NULL if not present

Request Body

evpl_http_request_get_data_avail 

uint64_t evpl_http_request_get_data_avail(
    struct evpl_http_request *request);

Get the number of bytes available to read from request body.

Returns: Available bytes

evpl_http_request_get_datav 

int evpl_http_request_get_datav(
    struct evpl              *evpl,
    struct evpl_http_request *request,
    struct evpl_iovec        *iov,
    int                       length);

Read request body data into iovecs.

Parameters:

  • evpl - Event loop
  • request - HTTP request
  • iov - [OUT] Iovec to receive data
  • length - Maximum bytes to read

Returns: Number of bytes read

Response Headers

evpl_http_request_add_header 

void evpl_http_request_add_header(
    struct evpl_http_request *request,
    const char               *name,
    const char               *value);

Add a response header.

Parameters:

  • request - HTTP request
  • name - Header name
  • value - Header value

Response Body

evpl_http_server_set_response_length 

void evpl_http_server_set_response_length(
    struct evpl_http_request *request,
    uint64_t                  content_length);

Set the response Content-Length.

Parameters:

  • request - HTTP request
  • content_length - Response body size in bytes

Note: Call before sending data.

evpl_http_server_set_response_chunked 

void evpl_http_server_set_response_chunked(
    struct evpl_http_request *request);

Enable chunked transfer encoding for the response.

Parameters:

  • request - HTTP request

Use case: When response size is not known in advance.

evpl_http_request_add_datav 

void evpl_http_request_add_datav(
    struct evpl_http_request *request,
    struct evpl_iovec        *iov,
    int                       niov);

Add response body data.

Parameters:

  • request - HTTP request
  • iov - Iovecs containing response data
  • niov - Number of iovecs

evpl_http_server_dispatch_default 

void evpl_http_server_dispatch_default(
    struct evpl_http_request *request,
    int                       status);

Send a default response with a status code.

Parameters:

  • request - HTTP request
  • status - HTTP status code (200, 404, 500, etc.)

Use case: Quick responses for errors or simple status pages.

See Also