python - 如何从 CGI 脚本发送响应头和状态

Question

我正在使用 CGIHTTPServer.py用于创建简单的 CGI 服务器。如果某些操作出错，我希望我的 CGI 脚本处理响应代码。我该怎么做？

我的 CGI 脚本中的代码片段。

if authmxn.authenticate():
     stats = Stats()
     print "Content-Type: application/json"
     print 'Status: 200 OK'
     print

     print json.dumps(stats.getStats())
 else:
     print 'Content-Type: application/json'
     print 'Status: 403 Forbidden'
     print
     print json.dumps({'msg': 'request is not authenticated'})

来自请求处理程序的一些片段，

def run_cgi(self):
'''
    rest of code
'''
    if not os.path.exists(scriptfile):
        self.send_error(404, "No such CGI script (%s)" % `scriptname`)
        return
    if not os.path.isfile(scriptfile):
        self.send_error(403, "CGI script is not a plain file (%s)" %
                        `scriptname`)
        return
    ispy = self.is_python(scriptname)
    if not ispy:
        if not (self.have_fork or self.have_popen2):
            self.send_error(403, "CGI script is not a Python script (%s)" %
                            `scriptname`)
            return
        if not self.is_executable(scriptfile):
            self.send_error(403, "CGI script is not executable (%s)" %
                            `scriptname`)
            return

    if not self.have_fork:
        # Since we're setting the env in the parent, provide empty
        # values to override previously set values
        for k in ('QUERY_STRING', 'REMOTE_HOST', 'CONTENT_LENGTH',
                  'HTTP_USER_AGENT', 'HTTP_COOKIE'):
            env.setdefault(k, "")

    self.send_response(200, "Script output follows") # overrides the headers

    decoded_query = query.replace('+', ' ')

Answer 1

可以实现对覆盖 HTTP 状态行的 Status: code message header 的支持(HTTP 响应的第一行，例如 HTTP/1.0 200 OK) .这需要:

1. 对 CGIHTTPRequestHandler 进行子类化，以诱使其将 CGI 脚本的输出写入 StringIO 对象，而不是直接写入套接字。
2. 然后，在 CGI 脚本完成后，使用 Status: header 中提供的值更新 HTTP 状态行。

这是一个 hack，但还不错，不需要修补标准库代码。

import BaseHTTPServer
import SimpleHTTPServer

from CGIHTTPServer import CGIHTTPRequestHandler
from cStringIO import StringIO

class BufferedCGIHTTPRequestHandler(CGIHTTPRequestHandler):
    def setup(self):
        """
        Arrange for CGI response to be buffered in a StringIO rather than
        sent directly to the client.
        """
        CGIHTTPRequestHandler.setup(self)
        self.original_wfile = self.wfile
        self.wfile = StringIO()
        # prevent use of os.dup(self.wfile...) forces use of subprocess instead
        self.have_fork = False

    def run_cgi(self):
        """
        Post-process CGI script response before sending to client.
        Override HTTP status line with value of "Status:" header, if set.
        """
        CGIHTTPRequestHandler.run_cgi(self)
        self.wfile.seek(0)
        headers = []
        for line in self.wfile:
            headers.append(line)    # includes new line character
            if line.strip() == '':  # blank line signals end of headers
                body = self.wfile.read()
                break
            elif line.startswith('Status:'):
                # Use status header to override premature HTTP status line.
                # Header format is: "Status: code message"
                status = line.split(':')[1].strip()
                headers[0] = '%s %s' % (self.protocol_version, status)

        self.original_wfile.write(''.join(headers))
        self.original_wfile.write(body)


def test(HandlerClass = BufferedCGIHTTPRequestHandler,
         ServerClass = BaseHTTPServer.HTTPServer):
    SimpleHTTPServer.test(HandlerClass, ServerClass)

if __name__ == '__main__':
    test()

不用说，这可能不是最好的方法，您应该看看非 CGIHTTPServer 解决方案，例如一个微型框架，例如 bottle ，合适的网络服务器(根据内存，不建议将 CGIHTTPServer 用于生产用途)、fastcgi 或 WSGI - 仅举几个选项。