esp-httpd README

This is the demonstration project for the small but powerful libesphttpd webserver for ESP8266(EX) chips. It is an example of how to make a module that can have the AP it connects to configured over a webbrowser. It also illustrates multiple flash layouts and some OTA update functionality.

ABOUT THE WEBSERVER

The Good (aka: what's awesome)

• Supports multiple connections, for eg simultaneous html/css/js/images downloading
• Static files stored in flash, in an (optionally compressed) RO filesystem
• Pluggable using external cgi routines
• Simple template engine for mixed c and html things
• Usable as an embedded library - should be easy to drop into your existing projects
• Includes websocket support

The Bad (aka: what can be improved)

• Not built for speediness, although it's reasonable fast.
• Built according to what I remember of the HTTP protocol, not according to the RFCs. Should work with most modern browsers, though.
• No support for https.

The Ugly (aka: bugs, misbehaviour)

• Possible buffer overflows (usually not remotely exploitable) due to no os_snprintf This can be theoretically remedied by either Espressif including an os_snprintf in their libs or by using some alternate printf lib, like elm-chans xprintf

SOURCE OF THIS CODE

The official esphttpd repo lives at http://git.spritesserver.nl/esphttpd.git/ and http://git.spritesserver.nl/libesphttpd.git/ . If you're a fan of Github, you can also peruse the official mirror at https://github.com/Spritetm/esphttpd and https://github.com/Spritetm/libesphttpd . If you want to discuss this code, there is a subforum at esp8266.com: http://www.esp8266.com/viewforum.php?f=34 .

ABOUT THE EXAMPLE

When you flash the example into an ESP8266(EX) module, you get a small webserver with a few example pages. If you've already connected your module to your WLAN before, it'll keep those settings. When you haven't or the settings are wrong, keep GPIO0 for >5 seconds. The module will reboot into its STA+AP mode. Connect a computer to the newly formed access point and browse to http://192.168.4.1/wifi in order to connect the module to your WiFi network. The example also allows you to control a LED that's connected to GPIO2.

BUILDING EVERYTHING

For this, you need an environment that can compile ESP8266 firmware. Environments for this still are in flux at the moment, but I'm using esp-open-sdk: https://github.com/pfalcon/esp-open-sdk . You probably also need an UNIX-like system; I'm working on Debian Linux myself.

To manage the paths to all this, you can source a small shell fragment into your current session. For example, I source a file with these contents:

export PATH=${PWD}/esp-open-sdk/xtensa-lx106-elf/bin:$PATH
export SDK_BASE=${PWD}/esp-open-sdk/sdk
export ESPTOOL=${PWD}/esptool/esptool.py
export ESPPORT=/dev/ttyUSB0
export ESPBAUD=460800

Actual setup of the SDK and toolchain is out of the scope of this document, so I hope this helps you enough to set up your own if you haven't already.

If you have that, you can clone out the source code: git clone http://git.spritesserver.nl/esphttpd.git/

This project makes use of heatshrink, which is a git submodule. To fetch the code:

cd esphttpd
git submodule init
git submodule update

Now, build the code:

make

Depending on the way you built it, esp-open-sdk sometimes patches Espressifs SDK, needing a slightly different compiling process. If this is needed, you will get errors during compiling complaining about uint8_t being undeclared. If this happens, try building like this:

make USE_OPENSDK=yes

You can also edit the Makefile to change this more permanently.

After the compile process, flash the code happens in 2 steps. First the code itself gets flashed. Reset the module into bootloader mode and enter 'make flash'.

The 2nd step is to pack the static files the webserver will serve and flash that. Reset the module into bootloader mode again and enter make htmlflash.

You should have a working webserver now.

WRITING CODE FOR THE WEBSERVER

See programming.md

CHANGE FROM SDK 0.9.3 (and earlier) TO SDK 0.9.4 (and later):

Change all occurences of espconn_sent(connData->conn, (uint8 *)buff, len); to httpdSend(connData, buff, len) please. The reason for this is that you can't do multiple espconn_sent calls serially anymore, so httpd needs to buffer the writes now. This is only needed in your own code; the code that comes with httpd already has this changed.