inets httpd cgi脚本:如何检索json数据? [英] inets httpd cgi script: How do you retrieve json data?

问题描述

我尝试过的cgi脚本无法从我的inets httpd服务器检索json数据.

The cgi scripts that I have tried are unable to retrieve json data from my inets httpd server.

为了在cgi脚本中检索json数据，您需要能够读取请求的正文，其中包含以下内容:

In order to retrieve json data in a cgi script, you need to be able to read the body of the request, which will contain something like:

{"a": 1, "b": 2}

使用perl cgi脚本，我可以这样读取请求的正文:

With a perl cgi script, I can read the body of a request like this:

my $cgi = CGI->new;
my $req_body = $cgi->param('POSTDATA');

我认为这是读取服务器通过管道传递到脚本的stdin的间接方法，因为在python cgi脚本中，我必须编写:

I assume that is an indirect way of reading what the server pipes to the script's stdin because in a python cgi script I have to write:

req_body = sys.stdin.read()

当我从apache服务器请求cgi脚本时，我的perl和python cgi脚本可以成功地从apache获取json数据.但是，当我从inets httpd服务器请求相同的cgi脚本时，我的perl cgi脚本不读取请求正文，并且python cgi脚本挂起，然后服务器超时.我的cgi脚本能够从inets httpd服务器检索格式为"a=1&b=2"的数据-在这种情况下，perl和python中的cgi设施会自动为我解析数据，因此无需尝试要读取请求的正文，我只需访问cgi创建的结构.

When I request a cgi script from an apache server, my perl and python cgi scripts can successfully get the json data from apache. But when I request the same cgi scripts from my inets httpd server, my perl cgi script reads nothing for the request body, and my python cgi script hangs then the server times out. My cgi scripts are able to retrieve data formatted as "a=1&b=2" from an inets httpd server--in that case the cgi facilities in both perl and python automatically parse the data for me, so instead of trying to read the body of the request, I just access the structures that cgi created.

这是我的httpd服务器配置(server.conf):

Here is my httpd sever configuration (server.conf):

[
  {modules, [
    mod_alias,
    mod_actions,
    mod_esi,
    mod_cgi,
    mod_get,
    mod_log
  ]},
  {bind_address, "localhost"}, 
  {port,0},
  {server_name,"httpd_test"},
  {server_root,"/Users/7stud/erlang_programs/inets_proj"},
  {document_root,"./htdocs"},
  {script_alias, {"/cgi-bin/", "/Users/7stud/erlang_programs/inets_proj/cgi-bin/"} },
  {erl_script_alias, {"/erl", [mymod]} },
  {erl_script_nocache, true},
  {error_log, "./errors.log"},
  {transfer_log, "./requests.log"}
].

我使用以下程序(s.erl)启动我的httpd服务器:

I start my httpd server with this program (s.erl):

-module(s).
-compile(export_all).

%Need to look up port with httpd:info(Server)

ensure_inets_start() ->
    case inets:start() of
        ok -> ok;
        {error,{already_started,inets}} -> ok
    end.

start() ->
    ok = ensure_inets_start(),

    {ok, Server} = inets:start(httpd, 
        [{proplist_file, "./server.conf"}]
    ),
    Server.

stop(Server) ->
    ok = inets:stop(httpd, Server).

我的cgi脚本(1.py):

#!/usr/bin/env python3

import json
import cgi
import cgitb
cgitb.enable()  #errors to browser
import sys

sys.stdout.write("Content-Type: text/html")
sys.stdout.write("\r\n\r\n")

#print("<div>hello</div>")

req_body = sys.stdin.read()
my_dict = json.loads(req_body)

if my_dict:
    a = my_dict.get("a", "Not found")
    b = my_dict.get("b", "Not found")
    total = a + b
    print("<div>Got json: {}</div>".format(my_dict) )
    print("<div>a={}, b={}, total={}</div>".format(a, b, total))
else:
    print("<div>Couldn't read json data.</div>")

我的cgi脚本(1.pl):

#!/usr/bin/env perl

use strict;
use warnings;
use 5.020;
use autodie;
use Data::Dumper;
use CGI;
use CGI::Carp qw(fatalsToBrowser);
use JSON;

my $q = CGI->new;

print $q->header,
      $q->start_html("Test Page"),
      $q->h1("Results:"),
      $q->div("json=$json"),
      $q->end_html;

在终端窗口中启动服务器:

Server startup in terminal window:

~/erlang_programs/inets_proj$ erl
Erlang/OTP 20 [erts-9.2] [source] [64-bit] [smp:4:4] [ds:4:4:10] [async-threads:10] [hipe] [kernel-poll:false]
Eshell V9.2  (abort with ^G)

1> c(s).              
s.erl:2: Warning: export_all flag enabled - all functions will be exported
{ok,s}

2> Server = s:start().
<0.86.0>

3> httpd:info(Server).
[{mime_types,[{"htm","text/html"},{"html","text/html"}]},
 {server_name,"httpd_test"},
 {erl_script_nocache,true},
 {script_alias,{"/cgi-bin/",
                "/Users/7stud/erlang_programs/inets_proj/cgi-bin/"}},
 {bind_address,{127,0,0,1}},
 {modules,[mod_alias,mod_actions,mod_esi,mod_cgi,mod_get,
           mod_log]},
 {server_root,"/Users/7stud/erlang_programs/inets_proj"},
 {erl_script_alias,{"/erl",[mymod]}},
 {port,51301},
 {transfer_log,<0.93.0>},
 {error_log,<0.92.0>},
 {document_root,"./htdocs"}]
4> 

卷曲请求:

$ curl -v \
> -H 'Content-Type: application/json' \
> --data '{"a": 1, "b": 2}' \
> http://localhost:51301/cgi-bin/1.py

*   Trying ::1...
* TCP_NODELAY set
* Connection failed
* connect to ::1 port 51301 failed: Connection refused
*   Trying 127.0.0.1...
* TCP_NODELAY set
* Connected to localhost (127.0.0.1) port 51301 (#0)
> POST /cgi-bin/1.py HTTP/1.1
> Host: localhost:51301
> User-Agent: curl/7.58.0
> Accept: */*
> Content-Type: application/json
> Content-Length: 16
> 
* upload completely sent off: 16 out of 16 bytes

===== hangs for about 5 seconds ====

< HTTP/1.1 504 Gateway Time-out
< Date: Thu, 08 Mar 2018 11:02:27 GMT
< Content-Type: text/html
< Server: inets/6.4.5
* no chunk, no close, no size. Assume close to signal end
< 
* Closing connection 0
$ 

我的目录结构:

~/erlang_programs$ tree inets_proj/
inets_proj/
├── apache_cl.erl
├── cgi-bin
│   ├── 1.pl
│   └── 1.py
├── cl.beam
├── cl.erl
├── errors.log
├── htdocs
│   └── file1.txt
├── mylog.log
├── mymod.beam
├── mymod.erl
├── old_server.conf
├── old_server3.conf
├── old_server4.conf
├── requests.log
├── s.beam
├── s.erl
├── server.conf
└── urlencoded_post_cl.erl

推荐答案

我为cgi规范挖了RFC，内容为:

I dug up the RFC for the cgi spec, which says:

RFC 3875                    CGI Version 1.1                 October 2004


4.2.  Request Message-Body

   Request data is accessed by the script in a system-defined method;
   unless defined otherwise, this will be by reading the 'standard
   input' file descriptor or file handle.

      Request-Data   = [ request-body ] [ extension-data ]
      request-body   = <CONTENT_LENGTH>OCTET
      extension-data = *OCTET

   A request-body is supplied with the request if the CONTENT_LENGTH is
   not NULL.  The server MUST make at least that many bytes available
   for the script to read.  The server MAY signal an end-of-file
   condition after CONTENT_LENGTH bytes have been read or it MAY supply
   extension data.  Therefore, the script MUST NOT attempt to read more
   than CONTENT_LENGTH bytes, even if more data is available.  However,
   it is not obliged to read any of the data.

我不知道扩展数据是什么，但关键是:

I don't understand what extension data is, but the key line is:

[cgi]脚本绝不能尝试读取超过CONTENT_LENGTH 字节，即使有更多数据可用.

the [cgi] script MUST NOT attempt to read more than CONTENT_LENGTH bytes, even if more data is available.

如果我更改python脚本以读取内容长度，而不是尝试读取整个stdin文件(直到收到eof信号才停止读取)，然后我的python cgi脚本成功检索了json我的inets httpd服务器中的数据.

If I alter my python script to read in the content length rather than trying to read in the whole stdin file--which doesn't stop reading until it gets an eof signal--then my python cgi script successfully retrieves the json data from my inets httpd server.

#!/usr/bin/env python3

import json
import sys
import os

content_len = int(os.environ["CONTENT_LENGTH"])

req_body = sys.stdin.read(content_len)
my_dict = json.loads(req_body)

sys.stdout.write("Content-Type: text/html")
sys.stdout.write("\r\n\r\n")

if my_dict:
    a = my_dict.get("a", "Not found")
    b = my_dict.get("b", "Not found")
    total = a + b
    print("<div>Content-Length={}</div".format(content_len))
    print("<div>Got json: {}</div>".format(my_dict) )
    print("<div>a={}, b={}, total={}</div>".format(a, b, total))
else:
    print("<div>Couldn't read json data.</div>")

'''
form = cgi.FieldStorage()

if "a" not in form:
    print("<H1>Error:</H1>")
    print("<div>'a' not in form</div>")
else:
    print("<p>a:{}</p>".format( form["a"].value) )


if "b" not in form:
    print("<H1>Error:</H1>")
    print("<div>'b' not in form</div>")
else:
    print("<p>b:{}</p>".format(form["b"].value) )
'''

服务器信息:

4> httpd:info(Server).
[{mime_types,[{"htm","text/html"},{"html","text/html"}]},
 {server_name,"httpd_test"},
 {erl_script_nocache,true},
 {script_alias,{"/cgi-bin/",
                "/Users/7stud/erlang_programs/inets_proj/cgi-bin/"}},
 {bind_address,{127,0,0,1}},
 {modules,[mod_alias,mod_actions,mod_esi,mod_cgi,mod_get,
           mod_log]},
 {server_root,"/Users/7stud/erlang_programs/inets_proj"},
 {erl_script_alias,{"/erl",[mymod]}},
 {port,65451},
 {transfer_log,<0.93.0>},
 {error_log,<0.92.0>},
 {document_root,"./htdocs"}]
5> 

curl请求(请注意curl将自动计算内容长度并将其放入Content-Length标头中):

curl request (note that curl automatically calculates the content length and puts it in a Content-Length header):

~$ curl -v \
> -H 'Content-Type: application/json' \
> --data '{"a": 1, "b": 2}' \
> http://localhost:65451/cgi-bin/1.py

*   Trying ::1...
* TCP_NODELAY set
* Connection failed
* connect to ::1 port 65451 failed: Connection refused
*   Trying 127.0.0.1...
* TCP_NODELAY set
* Connected to localhost (127.0.0.1) port 65451 (#0)
> POST /cgi-bin/1.py HTTP/1.1
> Host: localhost:65451
> User-Agent: curl/7.58.0
> Accept: */*
> Content-Type: application/json
> Content-Length: 16
> 
* upload completely sent off: 16 out of 16 bytes
< HTTP/1.1 200 OK
< Date: Fri, 09 Mar 2018 04:36:42 GMT
< Server: inets/6.4.5
< Transfer-Encoding: chunked
< Content-Type: text/html
< 
<div>Content-Length=16</div
<div>Got json: {'a': 1, 'b': 2}</div>
<div>a=1, b=2, total=3</div>
* Connection #0 to host localhost left intact
~$ 

这是我使用inets httpd(1.pl)的perl脚本:

Here's the perl script that I got work with inets httpd (1.pl):

#!/usr/bin/env perl

use strict;
use warnings;
use 5.020;
use autodie;
use Data::Dumper;
use JSON;

if (my $content_len = $ENV{CONTENT_LENGTH}) {

    read(STDIN, my $json, $content_len);
    my $href = decode_json($json);
    my $a = $href->{a};
    my $b = $href->{b};

    print 'Content-type: text/html';
    print "\r\n\r\n";
    print "<div>a=$a</div>";
    print "<div>b=$b</div>";

    #my $q = CGI->new; #Doesn't work with inets httpd server
    #my $q = CGI->new(''); #Doesn't try to read from stdin, do does work.

    #  print $q->header,
    #    $q->start_html("Test Page"),
    #    $q->div("json=$json"),
    #    $q->div("a=$a"),
    #    $q->div("b=$b"),
    #    $q->div("total=$total"),
    #    $q->end_html;
} 
else {
    my $error = "Could not read json: No Content-Length header in request.";
    print 'Content-type: text/html';
    print "\r\n\r\n";
    print "<div>$error</div>";


    #   my $q = CGI->new;
    #   print $q->header,
    #         $q->start_html("Test Page"),
    #         $q->h1($error),
    #         $q->end_html;
}

我无法让perl的CGI模块与读取STDIN一起使用. perlmonks的善良灵魂帮助我解决了这个问题:

I couldn't get perl's CGI module to work in conjunction with reading from STDIN. A kind soul at perlmonks helped me solve that one:

my $q = CGI->new('');

空白字符串告诉CGI-> new不要从stdin读取并解析数据.

The blank string tells CGI->new not to read from stdin and parse the data.

这篇关于inets httpd cgi脚本:如何检索json数据?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！