From: Christian Heller <c.heller@plomlompom.de>
Date: Wed, 25 Jan 2017 23:28:22 +0000 (+0100)
Subject: Commit of work done so far.
X-Git-Url: https://plomlompom.com/repos/%7B%7Bdb.prefix%7D%7D/%7B%7B%20web_path%20%7D%7D/decks/day?a=commitdiff_plain;h=07d3257fab88d61d28bee7202b8041576912900e;p=url-catcher

Commit of work done so far.
---

diff --git a/url_catcher.py b/url_catcher.py
new file mode 100644
index 0000000..ac4b7a7
--- /dev/null
+++ b/url_catcher.py
@@ -0,0 +1,147 @@
+import bottle
+import validators
+import html
+import os
+import os.path
+import time
+import json
+import smtplib
+import email.mime.text
+import tempfile
+import shutil
+
+slowdown_reset = 60 * 60 * 24
+ips_dir = 'ips'
+lists_dir = 'lists'
+captchas_dir = 'captchas'
+customizations_path = 'customizations.json'
+messages = {
+    'internalServerError': 'Internal server error.',
+    'badPageName': 'Bad page name.',
+    'wrongCaptcha': 'Wrong captcha.',
+    'invalidURL': 'Invalid URL.',
+    'recordedURL': 'Recorded URL: ',
+    'pleaseWait': 'Too many attempts from your IP. Wait this many seconds: ',
+    'mailSubject': '[url_catcher.py] New URL submitted',
+    'mailBodyPage': 'New URL submitted for page: ',
+    'mailBodyURL': 'URL is: ',
+}
+mail_config = {
+    'from': 'foo@example.org',
+    'to': 'bar@example.org',
+}
+if os.path.isfile(customizations_path):
+    customizations_file = open(customizations_path)
+    customizations = json.load(customizations_file)
+    customizations_file.close()
+    for key in customizations['translations']:
+        messages[key] = customizations['translations'][key]
+    for key in customizations['mailConfig']:
+        mail_config[key] = customizations['mailConfig'][key]
+    if 'slowdownReset' in customizations:
+        slowdown_reset = customizations['slowdownReset']
+os.makedirs(ips_dir, exist_ok=True)
+os.makedirs(lists_dir, exist_ok=True)
+
+
+def atomic_write(path, content, mode):
+    """Atomic write/append to file."""
+    _, tmpPath = tempfile.mkstemp()
+    if 'a' == mode:
+        shutil.copy2(path, tmpPath)
+    f = open(tmpPath, mode)
+    f.write(content)
+    f.flush()
+    os.fsync(f.fileno())
+    f.close()
+    os.rename(tmpPath, path)
+
+
+def send_mail(page, url):
+    """Send mail telling about page URL list update."""
+    body = messages['mailBodyPage'] + page + '\n' + messages['mailBodyURL'] + \
+        url
+    msg = email.mime.text.MIMEText(body)
+    msg['Subject'] = messages['mailSubject']
+    msg['From'] = mail_config['from']
+    msg['To'] = mail_config['to']
+    s = smtplib.SMTP('localhost')
+    s.send_message(msg)
+    s.quit()
+
+
+@bottle.error(500)
+def internal_error(error):
+    """If trouble, don't leak bottle.py's detailed error description."""
+    return messages['internalServerError']
+
+
+@bottle.post('/uwsgi/post_link')
+def post_link():
+    """Record URL if all sane, send mail to curator."""
+
+    # Slow down repeat requests.
+    now = int(time.time())
+    start_date = now
+    attempts = 0
+    rewrite = True
+    ip = bottle.request.environ.get('REMOTE_ADDR')
+    ip_file_path = ips_dir + '/' + ip
+    try:
+        if os.path.isfile(ip_file_path):
+            ip_file = open(ip_file_path, 'r')
+            ip_data = ip_file.readlines()
+            ip_file.close()
+            old_start_date = int(ip_data[0])
+            if old_start_date + slowdown_reset > now:
+                attempts = int(ip_data[1])
+                start_date = old_start_date
+                wait_period = 2**attempts
+                if start_date + wait_period > now:
+                    limit = min(start_date + wait_period,
+                        start_date + slowdown_reset)
+                    rewrite = False
+                    remaining_wait = limit - now
+                    msg = messages['pleaseWait'] + str(remaining_wait)
+                    return bottle.HTTPResponse(msg, 429,
+                        {'Retry-After': str(remaining_wait)})
+                attempts += 1 
+    except:
+        raise
+    finally:
+        if rewrite:
+            atomic_write(ip_file_path,
+                str(start_date) + '\n' + str(attempts), 'w')
+
+    # Derive page / page file name.
+    page = bottle.request.forms.get('page')
+    if '\0' in page or '/' in page or '.' in page or len(page.encode()) > 255:
+        return bottle.HTTPResponse(messages['badPageName'], 400)
+
+    # Test captcha.
+    captcha_file = open(captchas_dir + '/' + page, 'r')
+    captcha_correct = captcha_file.readline().rstrip()
+    captcha_file.close()
+    captcha_input = bottle.request.forms.get('captcha')
+    if captcha_correct != captcha_input:
+        return bottle.HTTPResponse(messages['wrongCaptcha'], 400)
+
+    # Record URL.
+    url = bottle.request.forms.get('url')
+    if not validators.url(url):
+        return bottle.HTTPResponse(messages['invalidURL'], 400)
+    send_mail(page, url)
+    atomic_write(lists_dir + '/' + page, url + '\n', 'a')
+    url_html = html.escape(url)
+
+    # Response body.
+    return messages['recordedURL'] + url_html
+
+
+bottle.debug(True)
+# Non-uWSGI mode.
+if __name__ == '__main__':
+    bottle.run(host='localhost', port=8080)
+# uWSGI mode.
+else:
+    app = application = bottle.default_app()