HTTPS 请求的持久连接

该库LuaSocket（在示例代码中使用）不支持持久性 http(s) 连接。因此，不能免除最小痛苦，必须使用其他一些库。

例如，您可以使用Lua-cURL：

local curl = require "cURL"

local function main()

  local e = curl.easy()

  -- включает подробный вывод о ходе соединения
  e:setopt_verbose(true)

  e:setopt_url("https://httpbin.org/get")
  e:perform() -- выполняет загрузку и НЕ закрывает соединение

  -- отключает переиспользование соединений
  e:setopt_forbid_reuse(true)

  e:setopt_url("https://httpbin.org/ip")
  e:perform() -- выполняет загрузку и закрывает соединение

  e:close()
end

main()

相反，在这个库中，默认情况下连接不会关闭并被重用（即使在调用之后e:close），在这里您需要使用特殊的CURLOPT_FORBID_REUSE选项来断开连接（如果需要）。

在日志中可以观察到打开/重用/关闭连接的整个过程：

*   Trying 23.22.14.18...
* Connected to httpbin.org (23.22.14.18) port 443 (#0)
* ALPN, offering http/1.1
* Cipher selection: ALL:!EXPORT:!EXPORT40:!EXPORT56:!aNULL:!LOW:!RC4:@STRENGTH
* successfully set certificate verify locations:
*   CAfile: /etc/ssl/certs/ca-certificates.crt
  CApath: /etc/ssl/certs
* NPN, negotiated HTTP1.1
* SSL connection using TLSv1.2 / ECDHE-RSA-AES256-GCM-SHA384
* ALPN, server did not agree to a protocol
* Server certificate:
*    subject: OU=Domain Control Validated; OU=EssentialSSL Wildcard; CN=*.httpbin.org
*    start date: Jan 12 00:00:00 2016 GMT
*    expire date: Jan 19 23:59:59 2017 GMT
*    subjectAltName: httpbin.org matched
*    issuer: C=GB; ST=Greater Manchester; L=Salford; O=COMODO CA Limited; CN=COMODO RSA Domain Validation Secure Server CA
*    SSL certificate verify ok.
> GET /get HTTP/1.1
Host: httpbin.org
Accept: */*

{
  "args": {}, 
  "headers": {
    "Accept": "*/*", 
    "Host": "httpbin.org"
  }, 
  "origin": "xx.xx.xx.xx", 
  "url": "https://httpbin.org/get"
}
< HTTP/1.1 200 OK
< Server: nginx
< Date: Tue, 04 Oct 2016 19:46:13 GMT
< Content-Type: application/json
< Content-Length: 154
< Connection: keep-alive
< Access-Control-Allow-Origin: *
< Access-Control-Allow-Credentials: true
< 
* Connection #0 to host httpbin.org left intact
* Found bundle for host httpbin.org: 0x95eac28 [can pipeline]
* Re-using existing connection! (#0) with host httpbin.org
* Connected to httpbin.org (23.22.14.18) port 443 (#0)
> GET /ip HTTP/1.1
Host: httpbin.org
Accept: */*

{
  "origin": "xx.xx.xx.xx"
}
< HTTP/1.1 200 OK
< Server: nginx
< Date: Tue, 04 Oct 2016 19:46:13 GMT
< Content-Type: application/json
< Content-Length: 33
< Connection: keep-alive
< Access-Control-Allow-Origin: *
< Access-Control-Allow-Credentials: true
< 
* Closing connection 0

执行第一个请求后curl，报告连接保持打开状态：

Connection #0 to host httpbin.org left intact

在执行第二个请求之前，它找到它并愉快地重用它：

Found bundle for host httpbin.org: 0x95eac28 [can pipeline]
Re-using existing connection! (#0) with host httpbin.org

但是在第二次请求之后，由于在第二次请求之前的例子中有禁止重用连接，所以关闭了：

Closing connection 0

在套接字上：

require("socket")
require("ssl")
-----

local params = {
   mode = "client",
   protocol = "tlsv1",
   verify = "none",
   options = { "all", "no_sslv2", "no_sslv3", "no_ticket", "no_compression" } 
}
-----------------------------

local url = 'https://httpbin.org/get'

local host, file = url:match("://(.+)(/.+)")
local headers = "HTTP/1.1\nHost: "..host.."\nConnection: keep-alive\n\n"
local conn = socket.tcp()
conn:connect(host, 443)

conn = ssl.wrap(conn, params)
conn:dohandshake()
conn:send( "GET ".. file.." "..headers )
--
    local  len, s, status = 0
    local str, answer = "",""
    while true do
          s, status = conn:receive('*l') 
          if s==nil or status =="closed" then   break end
          str=str..s..'\n'
          if s:find("Content%-Length")  then  len = s:match("Content%-Length:%s?(%d+)")   end
          if s=="" then 
              answer, status = conn:receive(len)      break 
          end
    end
    print(str)
    print(answer)   

conn:close()