Web Server on MicroPython
为了在MicroPython上实现Web服务，找了几个框架，最终选择tinyweb。
tinyweb主要是小巧、符合编程习惯、做好错误处理、实现了HTTP 1.0基本功能等。相关信息如下：
- 项目: https://github.com/belyalov/tinyweb
- 源码: https://github.com/belyalov/tinyweb/blob/master/tinyweb/server.py
- 版本: e92546054b905de46f42157282677f56764fb2f0
但是tinyweb采用logging做log记录，而logging依赖的库有点多，于是改为使用ulooger。修改后的源码如下：
"""
Tiny Web - pretty simple and powerful web server for tiny platforms like ESP8266 / ESP32
MIT license
(C) Konstantin Belyalov 2017-2018
- project: https://github.com/belyalov/tinyweb
- source code: https://github.com/belyalov/tinyweb/blob/master/tinyweb/server.py
- version: e92546054b905de46f42157282677f56764fb2f0
edit: replace logging with ulogger
"""
import ulogger
import uasyncio as asyncio
import uasyncio.core
import ujson as json
import gc
import uos as os
import sys
import uerrno as errno
import usocket as socket
#log = logging.getLogger('WEB')
class UtcClock(ulogger.BaseClock):
def __call__(self) -> str:
# UTC date time: (year, month, mday, hour, minute, second, weekday, yearday)
dt = time.gmtime()
return f'{dt[0]}{dt[1]:02d}{dt[2]:02d}_{dt[3]:02d}{dt[4]:02d}{dt[5]:02d}'
handler_to_term = ulogger.Handler(
level=ulogger.INFO,
colorful=True,
fmt="&(time)%[&(level)%][&(name)%]: &(msg)%",
clock=UtcClock(),
direction=ulogger.TO_TERM,
)
handler_to_file = ulogger.Handler(
level=ulogger.INFO,
fmt="&(time)%[&(level)%][&(name)%]: &(msg)%",
clock=UtcClock(),
direction=ulogger.TO_FILE,
file_name="tinyweb.log",
max_file_size=102400 # max for 100KB
)
logger = ulogger.Logger(
name = __name__,
handlers = (
handler_to_term,
handler_to_file
)
)
type_gen = type((lambda: (yield))())
# uasyncio v3 is shipped with MicroPython 1.13, and contains some subtle
# but breaking changes. See also https://github.com/peterhinch/micropython-async/blob/master/v3/README.md
IS_UASYNCIO_V3 = hasattr(asyncio, "__version__") and asyncio.__version__ >= (3,)
def urldecode_plus(s):
"""Decode urlencoded string (including '+' char).
Returns decoded string
"""
s = s.replace('+', ' ')
arr = s.split('%')
res = arr[0]
for it in arr[1:]:
if len(it) >= 2:
res += chr(int(it[:2], 16)) + it[2:]
elif len(it) == 0:
res += '%'
else:
res += it
return res
def parse_query_string(s):
"""Parse urlencoded string into dict.
Returns dict
"""
res = {}
pairs = s.split('&')
for p in pairs:
vals = [urldecode_plus(x) for x in p.split('=', 1)]
if len(vals) == 1:
res[vals[0]] = ''
else:
res[vals[0]] = vals[1]
return res
class HTTPException(Exception):
"""HTTP protocol exceptions"""
def __init__(self, code=400):
self.code = code
class request:
"""HTTP Request class"""
def __init__(self, _reader):
self.reader = _reader
self.headers = {}
self.method = b''
self.path = b''
self.query_string = b''
async def read_request_line(self):
"""Read and parse first line (AKA HTTP Request Line).
Function is generator.
Request line is something like:
GET /something/script?param1=val1 HTTP/1.1
"""
while True:
rl = await self.reader.readline()
# skip empty lines
if rl == b'\r\n' or rl == b'\n':
continue
break
rl_frags = rl.split()
if len(rl_frags) != 3:
raise HTTPException(400)
self.method = rl_frags[0]
url_frags = rl_frags[1].split(b'?', 1)
self.path = url_frags[0]
if len(url_frags) > 1:
self.query_string = url_frags[1]
async def read_headers(self, save_headers=[]):
"""Read and parse HTTP headers until \r\n\r\n:
Optional argument 'save_headers' controls which headers to save.
This is done mostly to deal with memory constrains.
Function is generator.
HTTP headers could be like:
Host: google.com
Content-Type: blah
\r\n
"""
while True:
gc.collect()
line = await self.reader.readline()
if line == b'\r\n':
break
frags = line.split(b':', 1)
if len(frags) != 2:
raise HTTPException(400)
if frags[0] in save_headers:
self.headers[frags[0]] = frags[1].strip()
async def read_parse_form_data(self):
"""Read HTTP form data (payload), if any.
Function is generator.
Returns:
- dict of key / value pairs
- None in case of no form data present
"""
# TODO: Probably there is better solution how to handle
# request body, at least for simple urlencoded forms - by processing
# chunks instead of accumulating payload.
gc.collect()
if b'Content-Length' not in self.headers:
return {}
# Parse payload depending on content type
if b'Content-Type' not in self.headers:
# Unknown content type, return unparsed, raw data
return {}
size = int(self.headers[b'Content-Length'])
if size > self.params['max_body_size'] or size < 0:
raise HTTPException(413)
data = await self.reader.readexactly(size)
# Use only string before ';', e.g:
# application/x-www-form-urlencoded; charset=UTF-8
ct = self.headers[b'Content-Type'].split(b';', 1)[0]
try:
if ct == b'application/json':
return json.loads(data)
elif ct == b'application/x-www-form-urlencoded':
return parse_query_string(data.decode())
except ValueError:
# Re-generate exception for malformed form data
raise HTTPException(400)
class response:
"""HTTP Response class"""
def __init__(self, _writer):
self.writer = _writer
self.send = _writer.awrite
self.code = 200
self.version = '1.0'
self.headers = {}
async def _send_headers(self):
"""Compose and send:
- HTTP request line
- HTTP headers following by \r\n.
This function is generator.
P.S.
Because of usually we have only a few HTTP headers (2-5) it doesn't make sense
to send them separately - sometimes it could increase latency.
So combining headers together and send them as single "packet".
"""
# Request line
hdrs = 'HTTP/{} {} MSG\r\n'.format(self.version, self.code)
# Headers
for k, v in self.headers.items():
hdrs += '{}: {}\r\n'.format(k, v)
hdrs += '\r\n'
# Collect garbage after small mallocs
gc.collect()
await self.send(hdrs)
async def error(self, code, msg=None):
"""Generate HTTP error response
This function is generator.
Arguments:
code - HTTP response code
Example:
# Not enough permissions. Send HTTP 403 - Forbidden
await resp.error(403)
"""
self.code = code
if msg:
self.add_header('Content-Length', len(msg))
await self._send_headers()
if msg:
await self.send(msg)
async def redirect(self, location, msg=None):
"""Generate HTTP redirect response to 'location'.
Basically it will generate HTTP 302 with 'Location' header
Arguments:
location - URL to redirect to
Example:
# Redirect to /something
await resp.redirect('/something')
"""
self.code = 302
self.add_header('Location', location)
if msg:
self.add_header('Content-Length', len(msg))
await self._send_headers()
if msg:
await self.send(msg)
def add_header(self, key, value):
"""Add HTTP response header
Arguments:
key - header name
value - header value
Example:
resp.add_header('Content-Encoding', 'gzip')
"""
self.headers[key] = value
def add_access_control_headers(self):
"""Add Access Control related HTTP response headers.
This is required when working with RestApi (JSON requests)
"""
self.add_header('Access-Control-Allow-Origin', self.params['allowed_access_control_origins'])
self.add_header('Access-Control-Allow-Methods', self.params['allowed_access_control_methods'])
self.add_header('Access-Control-Allow-Headers', self.params['allowed_access_control_headers'])
async def start_html(self):
"""Start response with HTML content type.
This function is generator.
Example:
await resp.start_html()
await resp.send('<html><h1>Hello, world!</h1></html>')
"""
self.add_header('Content-Type', 'text/html')
await self._send_headers()
async def send_file(self, filename, content_type=None, content_encoding=None, max_age=2592000, buf_size=128):
"""Send local file as HTTP response.
This function is generator.
Arguments:
filename - Name of file which exists in local filesystem
Keyword arguments:
content_type - Filetype. By default - None means auto-detect.
max_age - Cache control. How long browser can keep this file on disk.
By default - 30 days
Set to 0 - to disable caching.
Example 1: Default use case:
await resp.send_file('images/cat.jpg')
Example 2: Disable caching:
await resp.send_file('static/index.html', max_age=0)
Example 3: Override content type:
await resp.send_file('static/file.bin', content_type='application/octet-stream')
"""
try:
# Get file size
stat = os.stat(filename)
slen = str(stat[6])
self.add_header('Content-Length', slen)
# Find content type
if content_type:
self.add_header('Content-Type', content_type)
# Add content-encoding, if any
if content_encoding:
self.add_header('Content-Encoding', content_encoding)
# Since this is static content is totally make sense
# to tell browser to cache it, however, you can always
# override it by setting max_age to zero
self.add_header('Cache-Control', 'max-age={}, public'.format(max_age))
with open(filename) as f:
await self._send_headers()
gc.collect()
buf = bytearray(min(stat[6], buf_size))
while True:
size = f.readinto(buf)
if size == 0:
break
await self.send(buf, sz=size)
except OSError as e:
# special handling for ENOENT / EACCESS
if e.args[0] in (errno.ENOENT, errno.EACCES):
raise HTTPException(404)
else:
raise
async def restful_resource_handler(req, resp, param=None):
"""Handler for RESTful API endpoins"""
# Gather data - query string, JSON in request body...
data = await req.read_parse_form_data()
# Add parameters from URI query string as well
# This one is actually for simply development of RestAPI
if req.query_string != b'':
data.update(parse_query_string(req.query_string.decode()))
# Call actual handler
_handler, _kwargs = req.params['_callmap'][req.method]
# Collect garbage before / after handler execution
gc.collect()
if param:
res = _handler(data, param, **_kwargs)
else:
res = _handler(data, **_kwargs)
gc.collect()
# Handler result could be:
# 1. generator - in case of large payload
# 2. string - just string :)
# 2. dict - meaning client what tinyweb to convert it to JSON
# it can also return error code together with str / dict
# res = {'blah': 'blah'}
# res = {'blah': 'blah'}, 201
if isinstance(res, type_gen):
# Result is generator, use chunked response
# NOTICE: HTTP 1.0 by itself does not support chunked responses, so, making workaround:
# Response is HTTP/1.1 with Connection: close
resp.version = '1.1'
resp.add_header('Connection', 'close')
resp.add_header('Content-Type', 'application/json')
resp.add_header('Transfer-Encoding', 'chunked')
resp.add_access_control_headers()
await resp._send_headers()
# Drain generator
for chunk in res:
chunk_len = len(chunk.encode('utf-8'))
await resp.send('{:x}\r\n'.format(chunk_len))
await resp.send(chunk)
await resp.send('\r\n')
gc.collect()
await resp.send('0\r\n\r\n')
else:
if type(res) == tuple:
resp.code = res[1]
res = res[0]
elif res is None:
raise Exception('Result expected')
# Send response
if type(res) is dict:
res_str = json.dumps(res)
else:
res_str = res
resp.add_header('Content-Type', 'application/json')
resp.add_header('Content-Length', str(len(res_str)))
resp.add_access_control_headers()
await resp._send_headers()
await resp.send(res_str)
class webserver:
def __init__(self, request_timeout=3, max_concurrency=3, backlog=16, debug=False):
"""Tiny Web Server class.
Keyword arguments:
request_timeout - Time for client to send complete request
after that connection will be closed.
max_concurrency - How many connections can be processed concurrently.
It is very important to limit this number because of
memory constrain.
Default value depends on platform
backlog - Parameter to socket.listen() function. Defines size of
pending to be accepted connections queue.
Must be greater than max_concurrency
debug - Whether send exception info (text + backtrace)
to client together with HTTP 500 or not.
"""
self.loop = asyncio.get_event_loop()
self.request_timeout = request_timeout
self.max_concurrency = max_concurrency
self.backlog = backlog
self.debug = debug
self.explicit_url_map = {}
self.catch_all_handler = None
self.parameterized_url_map = {}
# Currently opened connections
self.conns = {}
# Statistics
self.processed_connections = 0
def _find_url_handler(self, req):
"""Helper to find URL handler.
Returns tuple of (function, opts, param) or (None, None) if not found.
"""
# First try - lookup in explicit (non parameterized URLs)
if req.path in self.explicit_url_map:
return self.explicit_url_map[req.path]
# Second try - strip last path segment and lookup in another map
idx = req.path.rfind(b'/') + 1
path2 = req.path[:idx]
if len(path2) > 0 and path2 in self.parameterized_url_map:
# Save parameter into request
req._param = req.path[idx:].decode()
return self.parameterized_url_map[path2]
if self.catch_all_handler:
return self.catch_all_handler
# No handler found
return (None, None)
async def _handle_request(self, req, resp):
await req.read_request_line()
# Find URL handler
req.handler, req.params = self._find_url_handler(req)
if not req.handler:
# No URL handler found - read response and issue HTTP 404
await req.read_headers()
raise HTTPException(404)
# req.params = params
# req.handler = han
resp.params = req.params
# Read / parse headers
await req.read_headers(req.params['save_headers'])
async def _handler(self, reader, writer):
"""Handler for TCP connection with
HTTP/1.0 protocol implementation
"""
gc.collect()
try:
req = request(reader)
resp = response(writer)
# Read HTTP Request with timeout
await asyncio.wait_for(self._handle_request(req, resp),
self.request_timeout)
# OPTIONS method is handled automatically
if req.method == b'OPTIONS':
resp.add_access_control_headers()
# Since we support only HTTP 1.0 - it is important
# to tell browser that there is no payload expected
# otherwise some webkit based browsers (Chrome)
# treat this behavior as an error
resp.add_header('Content-Length', '0')
await resp._send_headers()
return
# Ensure that HTTP method is allowed for this path
if req.method not in req.params['methods']:
raise HTTPException(405)
# Handle URL
gc.collect()
if hasattr(req, '_param'):
await req.handler(req, resp, req._param)
else:
await req.handler(req, resp)
# Done here
except (asyncio.CancelledError, asyncio.TimeoutError):
pass
except OSError as e:
# Do not send response for connection related errors - too late :)
# P.S. code 32 - is possible BROKEN PIPE error (TODO: is it true?)
if e.args[0] not in (errno.ECONNABORTED, errno.ECONNRESET, 32):
try:
await resp.error(500)
except Exception as e:
#log.exc(e, "")
logger.error(f'OSError: {e}')
except HTTPException as e:
try:
await resp.error(e.code)
except Exception as e:
#log.exc(e)
logger.error(f'HTTPException: {e}')
except Exception as e:
# Unhandled expection in user's method
#log.error(req.path.decode())
#log.exc(e, "")
logger.error(f'Unhandled expection. URL: {req.path.decode()}, exception: {e}')
try:
await resp.error(500)
# Send exception info if desired
if self.debug:
sys.print_exception(e, resp.writer.s)
except Exception as e:
pass
finally:
await writer.aclose()
# Max concurrency support -
# if queue is full schedule resume of TCP server task
if len(self.conns) == self.max_concurrency:
self.loop.create_task(self._server_coro)
# Delete connection, using socket as a key
del self.conns[id(writer.s)]
def add_route(self, url, f, **kwargs):
"""Add URL to function mapping.
Arguments:
url - url to map function with
f - function to map
Keyword arguments:
methods - list of allowed methods. Defaults to ['GET', 'POST']
save_headers - contains list of HTTP headers to be saved. Case sensitive. Default - empty.
max_body_size - Max HTTP body size (e.g. POST form data). Defaults to 1024
allowed_access_control_headers - Default value for the same name header. Defaults to *
allowed_access_control_origins - Default value for the same name header. Defaults to *
"""
if url == '' or '?' in url:
raise ValueError('Invalid URL')
# Initial params for route
params = {'methods': ['GET'],
'save_headers': [],
'max_body_size': 1024,
'allowed_access_control_headers': '*',
'allowed_access_control_origins': '*',
}
params.update(kwargs)
params['allowed_access_control_methods'] = ', '.join(params['methods'])
# Convert methods/headers to bytestring
params['methods'] = [x.encode() for x in params['methods']]
params['save_headers'] = [x.encode() for x in params['save_headers']]
# If URL has a parameter
if url.endswith('>'):
idx = url.rfind('<')
path = url[:idx]
idx += 1
param = url[idx:-1]
if path.encode() in self.parameterized_url_map:
raise ValueError('URL exists')
params['_param_name'] = param
self.parameterized_url_map[path.encode()] = (f, params)
if url.encode() in self.explicit_url_map:
raise ValueError('URL exists')
self.explicit_url_map[url.encode()] = (f, params)
def add_resource(self, cls, url, **kwargs):
"""Map resource (RestAPI) to URL
Arguments:
cls - Resource class to map to
url - url to map to class
kwargs - User defined key args to pass to the handler.
Example:
class myres():
def get(self, data):
return {'hello': 'world'}
app.add_resource(myres, '/api/myres')
"""
methods = []
callmap = {}
# Create instance of resource handler, if passed as just class (not instance)
try:
obj = cls()
except TypeError:
obj = cls
# Get all implemented HTTP methods and make callmap
for m in ['GET', 'POST', 'PUT', 'PATCH', 'DELETE']:
fn = m.lower()
if hasattr(obj, fn):
methods.append(m)
callmap[m.encode()] = (getattr(obj, fn), kwargs)
self.add_route(url, restful_resource_handler,
methods=methods,
save_headers=['Content-Length', 'Content-Type'],
_callmap=callmap)
def catchall(self):
"""Decorator for catchall()
Example:
@app.catchall()
def catchall_handler(req, resp):
response.code = 404
await response.start_html()
await response.send('<html><body><h1>My custom 404!</h1></html>\n')
"""
params = {'methods': [b'GET'], 'save_headers': [], 'max_body_size': 1024, 'allowed_access_control_headers': '*', 'allowed_access_control_origins': '*'}
def _route(f):
self.catch_all_handler = (f, params)
return f
return _route
def route(self, url, **kwargs):
"""Decorator for add_route()
Example:
@app.route('/')
def index(req, resp):
await resp.start_html()
await resp.send('<html><body><h1>Hello, world!</h1></html>\n')
"""
def _route(f):
self.add_route(url, f, **kwargs)
return f
return _route
def resource(self, url, method='GET', **kwargs):
"""Decorator for add_resource() method
Examples:
@app.resource('/users')
def users(data):
return {'a': 1}
@app.resource('/messages/<topic_id>')
async def index(data, topic_id):
yield '{'
yield '"topic_id": "{}",'.format(topic_id)
yield '"message": "test",'
yield '}'
"""
def _resource(f):
self.add_route(url, restful_resource_handler,
methods=[method],
save_headers=['Content-Length', 'Content-Type'],
_callmap={method.encode(): (f, kwargs)})
return f
return _resource
async def _tcp_server(self, host, port, backlog):
"""TCP Server implementation.
Opens socket for accepting connection and
creates task for every new accepted connection
"""
addr = socket.getaddrinfo(host, port, 0, socket.SOCK_STREAM)[0][-1]
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.setblocking(False)
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
sock.bind(addr)
sock.listen(backlog)
try:
while True:
if IS_UASYNCIO_V3:
yield uasyncio.core._io_queue.queue_read(sock)
else:
yield asyncio.IORead(sock)
csock, caddr = sock.accept()
csock.setblocking(False)
# Start handler / keep it in the map - to be able to
# shutdown gracefully - by close all connections
self.processed_connections += 1
hid = id(csock)
handler = self._handler(asyncio.StreamReader(csock),
asyncio.StreamWriter(csock, {}))
self.conns[hid] = handler
self.loop.create_task(handler)
# In case of max concurrency reached - temporary pause server:
# 1. backlog must be greater than max_concurrency, otherwise
# client will got "Connection Reset"
# 2. Server task will be resumed whenever one active connection finished
if len(self.conns) == self.max_concurrency:
# Pause
yield False
except asyncio.CancelledError:
return
finally:
sock.close()
def run(self, host="127.0.0.1", port=8081, loop_forever=True):
"""Run Web Server. By default it runs forever.
Keyword arguments:
host - host to listen on. By default - localhost (127.0.0.1)
port - port to listen on. By default - 8081
loop_forever - run loo.loop_forever(), otherwise caller must run it by itself.
"""
self._server_coro = self._tcp_server(host, port, self.backlog)
self.loop.create_task(self._server_coro)
if loop_forever:
self.loop.run_forever()
def shutdown(self):
"""Gracefully shutdown Web Server"""
asyncio.cancel(self._server_coro)
for hid, coro in self.conns.items():
asyncio.cancel(coro)使用时，其实也有不少东西需要注意。
- 处理POST请求的方法，其注解需要设置
save_headers = ['Content-Length','Content-Type']，才能获取到请求的参数。例如：
app = tinyweb.webserver()
@app.route('/save', methods = ['POST'], save_headers = ['Content-Length','Content-Type'])
async def save(request, response):
params = await request.read_parse_form_data()
await response.send(params)- 一个方法处理多个请求链接，加多行注解即可。例如：
app = tinyweb.webserver()
@app.route('/')
@app.route('/index')
async def index(request, response):
await response.send("Hello world!")- 如果需要浏览器或对方客户端不要缓存，设置响应头即可。相关代码：
response.add_header('Cache-Control', 'no-cache') # for HTTP 1.1
response.add_header('Pragma', 'no-cache') # for HTTP 1.0
response.add_header('Expires', '0') # for proxies- Web服务的
max_concurrency不要设置太大，以降低内存占用。 - 更多的示例，可参考官方文档。