lwIP  2.1.0
Lightweight IP stack


#define LWIP_HTTPD_CGI   0
#define LWIP_HTTPD_CGI_SSI   0
#define LWIP_HTTPD_SSI   0
#define LWIP_HTTPD_SSI_RAW   0
#define HTTPD_SERVER_AGENT   "lwIP/" LWIP_VERSION_STRING " (http://savannah.nongnu.org/projects/lwip)"
#define HTTPD_USE_MEM_POOL   0
#define LWIP_HTTPD_SUPPORT_V09   1
#define HTTPD_FSDATA_FILE   "fsdata.c"

Detailed Description

Macro Definition Documentation



Default: Tags are sent from struct http_state and are therefore volatile



Set this to 1 to enable timing each file sent



Enable https support?


#define HTTPD_FSDATA_FILE   "fsdata.c"

Filename (including path) to use as FS data file



Maximum retries before the connection is aborted/closed.

  • number of times pcb->poll is called -> default is 4*500ms = 2s;
  • reset when pcb->sent is called



The poll delay is X*500ms



HTTPD_PRECALCULATED_CHECKSUM==1: include precompiled checksums for predefined (MSS-sized) chunks of the files to prevent having to calculate the checksums at runtime.


#define HTTPD_SERVER_AGENT   "lwIP/" LWIP_VERSION_STRING " (http://savannah.nongnu.org/projects/lwip)"

This string is passed in the HTTP header as "Server: "



The server port for HTTPD to use



The https server port for HTTPD to use



Priority for tcp pcbs created by HTTPD (very low by default). Lower priorities get killed first when running out of memory.


#define HTTPD_USE_MEM_POOL   0

Set this to 1 to use a memp pool for allocating struct http_state instead of the heap. If enabled, you'll need to define MEMP_NUM_PARALLEL_HTTPD_CONNS (and MEMP_NUM_PARALLEL_HTTPD_SSI_CONNS for SSI) to set the size of the pool(s).



Set this to 1 to call tcp_abort when tcp_close fails with memory error. This can be used to prevent consuming all memory in situations where the HTTP server has low priority compared to other communication.


#define LWIP_HTTPD_CGI   0

Set this to 1 to support CGI (old style).

This old style CGI support works by registering an array of URLs and associated CGI handler functions (http_set_cgi_handlers). This list is scanned just before fs_open is called from request handling. The handler can return a new URL that is used internally by the httpd to load the returned page (passed to fs_open).

Use this CGI type e.g. to execute specific actions and return a page that does not depend on the CGI parameters.


#define LWIP_HTTPD_CGI_SSI   0

Set this to 1 to support CGI (new style).

This new style CGI support works by calling a global function (tCGIHandler) for all URLs that are found. fs_open is called first and the URL can not be written by the CGI handler. Instead, this handler gets passed the http file state, an object where it can store information derived from the CGI URL or parameters. This file state is later passed to SSI, so the SSI code can return data depending on CGI input.

Use this CGI handler if you want CGI information passed on to SSI.



Set this to 1 and provide the functions:

  • "int fs_open_custom(struct fs_file *file, const char *name)" Called first for every opened file to allow opening files that are not included in fsdata(_custom).c
  • "void fs_close_custom(struct fs_file *file)" Called to free resources allocated by fs_open_custom().



Set this to 1 to support fs_read() to dynamically read file data. Without this (default=off), only one-block files are supported, and the contents must be ready after fs_open().



Set this to 1 if you want to include code that creates HTTP headers at runtime. Default is off: HTTP headers are then created statically by the makefsdata tool. Static headers mean smaller code size, but the (readonly) fsdata will grow a bit as every file includes the HTTP header.



Set this to 1 to include an application state argument per file that is opened. This allows to keep a state per connection/file.



LWIP_HTTPD_FS_ASYNC_READ==1: support asynchronous read operations (fs_read_async returns FS_READ_DELAYED and calls a callback when finished).



Set this to 1 to kill the oldest connection when running out of memory for 'struct http_state' or 'struct http_ssi_state'. ATTENTION: This puts all connections on a linked list, so may be kind of slow.



Defines the maximum length of a HTTP request line (up to the first CRLF, copied from pbuf into this a global buffer when pbuf- or packet-queues are received - otherwise the input pbuf is used directly)



This is the size of a static buffer used when URIs end with '/'. In this buffer, the directory requested is concatenated with all the configured default file names. Set to 0 to disable checking default filenames on non-root directories.



Set this to 1 to send URIs without extension without headers (who uses this at all??)



Maximum length of the filename to send as response to a POST request, filled in by the application when a POST is finished.



Number of (TCP payload-) bytes (in pbufs) to enqueue to parse and incoming request (up to the first double-newline)



Number of rx pbufs to enqueue to parse an incoming request (up to the first newline)


#define LWIP_HTTPD_SSI   0

Set this to 1 to support SSI (Server-Side-Includes)

In contrast to other http servers, this only calls a preregistered callback function (

See also
http_set_ssi_handler) for each tag (in the format of ) encountered in SSI-enabled pages. SSI-enabled pages must have one of the predefined SSI-enabled file extensions. All files with one of these extensions are parsed when sent.

A downside of the current SSI implementation is that persistent connections don't work, as the file length is not known in advance (and httpd currently relies on the Content-Length header for persistent connections).

To save memory, the maximum tag length is limited (

See also
LWIP_HTTPD_MAX_TAG_NAME_LEN). To save memory, the maximum insertion string length is limited (
LWIP_HTTPD_MAX_TAG_INSERT_LEN). If this is not enought, LWIP_HTTPD_SSI_MULTIPART can be used.



Set this to 0 to prevent parsing the file extension at runtime to decide if a file should be scanned for SSI tags or not. Default is 1 (file extensions are checked using the g_pcSSIExtensions array) Set to 2 to override this runtime test function.

This is enabled by default, but if you only use a newer version of makefsdata supporting the "-ssi" option, this info is already present in



Set this to 0 to not send the SSI tag (default is on, so the tag will be sent in the HTML page



LWIP_HTTPD_SSI_MULTIPART==1: SSI handler function is called with 2 more arguments indicating a counter for insert string that are too long to be inserted at once: the SSI handler function must then set 'next_tag_part' which will be passed back to it in the next call.


#define LWIP_HTTPD_SSI_RAW   0

Set this to 1 to implement an SSI tag handler callback that gets a const char* to the tag (instead of an index into a pre-registered array of known tags) If this is 0, the SSI handler callback function is only called pre-registered tags.



Set this to 1 to enable HTTP/1.1 persistent connections. ATTENTION: If the generated file system includes HTTP headers, these must include the "Connection: keep-alive" header (pass argument "-11" to makefsdata).



Set this to one to show error pages when parsing a request fails instead of simply closing the connection.



Set this to 1 to support HTTP POST



Set this to 1 to support HTTP request coming in in multiple packets/pbufs


#define LWIP_HTTPD_SUPPORT_V09   1

Set this to 0 to drop support for HTTP/0.9 clients (to save some bytes)



Set this to 1 to enable timing each file sent