python解析web访问日志

Question

我正在尝试使用以下正则表达式解析 Web 访问日志

pattern = re.compile(r"""(?x)^
    (?P<remote_host>\S+)            \s+         # host %h
    \S+                             \s+         # indent %l (unused)
    (?P<remote_user>\S+)            \s+         # user %u
    \[(?P<time_received>.*?)\]      \s+         # time %t
    "(?P<request>.*?)"              \s+         # request "%r"
    (?P<status>[0-9]+)              \s+         # status %>s
    (?P<response_bytes_clf>\S+)     (?:\s+      # size %b (careful, can be '-')
    "(?P<referrer>[^"?\s]*[^"]*)"   \s+         # referrer "%{Referer}i"
    "(?P<user_agent>[^"]*)"         (?:\s+      # user agent "%{User-agent}i"
    "[^"]*"                         )?)?        # optional argument (unused)
$""")

def get_structured_access_log(access_log):
    return pattern.match(access_log).groupdict()

但有些日志行包含如下恶意请求：

190.2.7.178 - - [21/Dec/2011:05:47:03 +0000] "GET /gnu3/index.php?doc=../../../../../../../proc/self/environ%00 HTTP/1.1" 404 273 "-" "<?php system(\"id\"); ?>"
190.2.7.178 - - [21/Dec/2011:05:47:04 +0000] "GET /gnu/index.php?doc=../../../../../../../proc/self/environ%00 HTTP/1.1" 404 271 "-" "<?php system(\"id\"); ?>"
190.2.7.178 - - [21/Dec/2011:05:47:04 +0000] "GET /phpgwapi/setup/tables_update.inc.php?appdir=../../../../../../../proc/self/environ%00 HTTP/1.1" 404 286 "-" "<?php system(\"id\"); ?>"
190.2.7.178 - - [21/Dec/2011:05:47:05 +0000] "GET /forum/install.php?phpbb_root_dir=../../../../../../../proc/self/environ%00 HTTP/1.1" 404 274 "-" "<?php system(\"id\"); ?>"
190.2.7.178 - - [21/Dec/2011:05:47:06 +0000] "GET /includes/calendar.php?phpc_root_path=../../../../../../../proc/self/environ%00 HTTP/1.1" 404 275 "-" "<?php system(\"id\"); ?>"
190.2.7.178 - - [21/Dec/2011:05:47:06 +0000] "GET /includes/setup.php?phpc_root_path=../../../../../../../proc/self/environ%00 HTTP/1.1" 404 273 "-" "<?php system(\"id\"); ?>"
190.2.7.178 - - [21/Dec/2011:05:47:07 +0000] "GET /inc/authform.inc.php?path_pre=../../../../../../../proc/self/environ%00 HTTP/1.1" 404 275 "-" "<?php system(\"id\"); ?>"
190.2.7.178 - - [21/Dec/2011:05:47:07 +0000] "GET /include/authform.inc.php?path_pre=../../../../../../../proc/self/environ%00 HTTP/1.1" 404 278 "-" "<?php system(\"id\"); ?>"
190.2.7.178 - - [21/Dec/2011:05:47:08 +0000] "GET /index.php?nic=../../../../../../../proc/self/environ%00 HTTP/1.1" 200 4399 "-" "<?php system(\"id\"); ?>"
190.2.7.178 - - [21/Dec/2011:05:47:11 +0000] "GET /index.php?sec=../../../../../../../proc/self/environ%00 HTTP/1.1" 200 4399 "-" "<?php system(\"id\"); ?>"

这些请求用上面的正则解析失败，其他正常的web请求解析成功。

以下是一些成功解析的访问日志：

123.125.71.79 - - [28/Apr/2012:08:12:57 +0100] "GET /robots.txt HTTP/1.1" 404 268 "-" "Mozilla/5.0 (compatible; Baiduspider/2.0; +http://www.baidu.com/search/spider.html)"
157.56.95.126 - - [28/Apr/2012:10:23:02 +0100] "GET /robots.txt HTTP/1.1" 404 268 "-" "msnbot/2.0b (+http://search.msn.com/msnbot.htm)"
157.56.95.126 - - [28/Apr/2012:10:23:02 +0100] "GET / HTTP/1.1" 200 4399 "-" "msnbot/2.0b (+http://search.msn.com/msnbot.htm)"
110.75.173.193 - - [28/Apr/2012:11:57:26 +0100] "GET / HTTP/1.1" 200 4399 "-" "Yahoo! Slurp China"

异常错误信息：

'NoneType' object has no attribute 'groupdict'

如何修复正则表达式，使其也可以解析这些复杂的请求？

Answer 1

使用re.match 将返回一个对应的匹配对象，如果字符串与模式不匹配，则返回None。

在第一个示例数据中，这是包含转义双引号 "<?php system(\"id\"); ?>" 的最后一部分

如果您使用非双引号匹配的否定字符类并且想要断言字符串的结尾，那么[^"]* 将不会超过(\"id 中的第一个双引号

您可以通过替换否定字符类以匹配此部分中的双引号"(?P<user_agent>[^"]*)" 来匹配除新行之外的任何字符.*?

您的模式可能如下所示：

(?x)^
    (?P<remote_host>\S+)            \s+         # host %h
    \S+                             \s+         # indent %l (unused)
    (?P<remote_user>\S+)            \s+         # user %u
    \[(?P<time_received>.*?)\]      \s+         # time %t
    "(?P<request>.*?)"              \s+         # request "%r"
    (?P<status>[0-9]+)              \s+         # status %>s
    (?P<response_bytes_clf>\S+)     (?:\s+      # size %b (careful, can be '-')
    "(?P<referrer>[^"?\s]*[^"]*)"   \s+         # referrer "%{Referer}i"
    "(?P<user_agent>.*?  )"         (?:\s+      # user agent "%{User-agent}i"
    "[^"]*"                         )?)?        # optional argument (unused)
$

Regex demo