是否可以将 keep-alive 与 boost::beast sync https 客户端一起使用？

Question

在使用同步 ssl 客户端时，是否可以将 http 1.1 keep-alive 与 boost beast 库一起使用？我有一个类似这样的过程：

使用 https 连接到 Web 服务器。发送初始请求，等待响应
select()/epoll()/etc on the https native socket handle
当本机句柄准备就绪时，我在 ssl_stream<beast::tcp_stream>.

第一个 http::read() 工作得很好。但是，当下次套接字准备就绪时，在套接字上发出 http::read() 时，我会遇到流结束异常。我想要的是让套接字在多个请求中保持活动状态。

代码并不算太复杂，但是是分段的：

         if( native_socket_for_https_connection_ready ) {                                                                                                                                                                                                                                                                                             
              boost::beast::http::response<boost::beast::http::dynamic_body> res;                                                                                                                                                                                                                                                                                                                                     
              boost::beast::http::read( m_HTTPSConnection, m_HTTPSBuffer, res, ec );                                                                                                                       
                                                                                                                                                                                                           
              std::cout << "Https Connection Response: " << res << std::endl;                                                                                                                              
              std::cout << "Keep-Alive Result: " << res.keep_alive() << std::endl;                                                                                                                         
                                                                                                                                                                                                           
              m_HTTPSBuffer.clear();                                                                                                                                                                       
          }

其中，m_HTTPSConnection是一个boost::beast::ssl_stream<boost::beast::tcp_stream>，m_HTTPSBuffer是一个flat_buffer。唯一的其他细节是本机套接字的提取。

我正在尝试使从安全套接字的读取适合未使用异步的遗留应用程序 I/O -- 我希望对 http::read() 的后续读取能够完成，而不是抛出异常。

Answer 1

服务器可能正在断开连接，例如当您的请求可能不确定 content-length，导致无法保持连接打开时（服务器如何知道请求不完整？）。

所以，想象一些更完整的代码：

1a。使用 https

连接到网络服务器

ssl::context ctx(ssl::context::sslv23);
beast::ssl_stream<beast::tcp_stream> s(ioc, ctx);
s.next_layer().connect({address_v4{{34, 227, 133, 25}}, 443});
s.handshake(ssl::stream_base::handshake_type::client);

1b。发送初始请求

http::request<http::string_body> req(http::verb::post, "/post", 10,
                                     R"~({"data":42})~");
req.set(http::field::host, "httpbin.org");
req.keep_alive(true); // no difference on HTTP/1.1+
req.prepare_payload();
write(s, req);

2。然后等待响应(select/epoll):

std::future<void> ready = s.next_layer().socket().async_wait(
    net::socket_base::wait_type::wait_read, net::use_future);
ready.wait();

(obviously, this can be done by external code based on the native_handle() instead)

3。在流上发布阅读

http::response<http::dynamic_body> res;
beast::flat_buffer                 buf;
http::read(s, buf, res);

一切正常：

Live On Coliru

#include <boost/asio.hpp>
#include <boost/asio/ssl.hpp>
#include <boost/beast.hpp>
#include <boost/beast/ssl.hpp>
#include <iostream>

namespace net   = boost::asio;
namespace beast = boost::beast;
namespace http  = beast::http;
namespace ssl   = net::ssl;
using boost::system::error_code;
using net::ip::address_v4;
using net::ip::tcp;

using namespace std::chrono_literals;
using std::this_thread::sleep_for;
static auto now = std::chrono::steady_clock::now;

int main() {
    net::thread_pool ioc;

    // connection to web server using https
    ssl::context ctx(ssl::context::sslv23);
    beast::ssl_stream<beast::tcp_stream> s(ioc, ctx);
    s.next_layer().connect({address_v4{{34, 227, 133, 25}}, 443});
    s.handshake(ssl::stream_base::handshake_type::client);

    for (auto demo_end = now() + 1s; now() <= demo_end; sleep_for(10ms)) {
        // send an initial request
        http::request<http::string_body> req(http::verb::post, "/post", 10,
                                             R"~({"data":42})~");
        req.set(http::field::host, "httpbin.org");
        req.keep_alive(true); // no difference on HTTP/1.1+
        req.prepare_payload();
        write(s, req);

        // wait for a response
        // (obviously, this can be done by external code based on the
        // native_handle() instead)
        std::future<void> ready = s.next_layer().socket().async_wait(
            net::socket_base::wait_type::wait_read, net::use_future);
        ready.wait();

        // issue read on the stream
        http::response<http::dynamic_body> res;
        beast::flat_buffer                 buf;
        http::read(s, buf, res);

        std::cout << "Https Connection Response: " << res << std::endl;
        std::cout << "Keep-Alive Result: " << res.keep_alive() << std::endl;
        if (!res.keep_alive())
            break;
    }

    // bye
    ioc.join();
}

版画

Https Connection Response: HTTP/1.1 200 OK
Date: Thu, 03 Mar 2022 16:42:50 GMT
Content-Type: application/json
Content-Length: 321
Connection: keep-alive
Server: gunicorn/19.9.0
Access-Control-Allow-Origin: *
Access-Control-Allow-Credentials: true
{
  "args": {}, 
  "data": "{\"data\":42}", 
  "files": {}, 
  "form": {}, 
  "headers": {
    "Content-Length": "11", 
    "Host": "httpbin.org", 
    "X-Amzn-Trace-Id": "Root=1-6220f00a-124910e0751e35dd54340615"
  }, 
  "json": {
    "data": 42
  }, 
  "origin": "173.203.57.63", 
  "url": "https://httpbin.org/post"
}

Keep-Alive Result: 1
Https Connection Response: HTTP/1.1 200 OK
Date: Thu, 03 Mar 2022 16:42:50 GMT
Content-Type: application/json
Content-Length: 321
Connection: keep-alive
Server: gunicorn/19.9.0
Access-Control-Allow-Origin: *
Access-Control-Allow-Credentials: true
{
  "args": {}, 
  "data": "{\"data\":42}", 
  "files": {}, 
  "form": {}, 
  "headers": {
    "Content-Length": "11", 
    "Host": "httpbin.org", 
    "X-Amzn-Trace-Id": "Root=1-6220f00a-5fa263b33e2cc5937d6204a5"
  }, 
  "json": {
    "data": 42
  }, 
  "origin": "173.203.57.63", 
  "url": "https://httpbin.org/post"
}

Keep-Alive Result: 1
Https Connection Response: HTTP/1.1 200 OK
Date: Thu, 03 Mar 2022 16:42:50 GMT
Content-Type: application/json
Content-Length: 321
Connection: keep-alive
Server: gunicorn/19.9.0
Access-Control-Allow-Origin: *
Access-Control-Allow-Credentials: true
{
  "args": {}, 
  "data": "{\"data\":42}", 
  "files": {}, 
  "form": {}, 
  "headers": {
    "Content-Length": "11", 
    "Host": "httpbin.org", 
    "X-Amzn-Trace-Id": "Root=1-6220f00a-0430cdac1b7924210e9ea13d"
  }, 
  "json": {
    "data": 42
  }, 
  "origin": "173.203.57.63", 
  "url": "https://httpbin.org/post"
}

Keep-Alive Result: 1
Https Connection Response: HTTP/1.1 200 OK
Date: Thu, 03 Mar 2022 16:42:50 GMT
Content-Type: application/json
Content-Length: 321
Connection: keep-alive
Server: gunicorn/19.9.0
Access-Control-Allow-Origin: *
Access-Control-Allow-Credentials: true
{
  "args": {}, 
  "data": "{\"data\":42}", 
  "files": {}, 
  "form": {}, 
  "headers": {
    "Content-Length": "11", 
    "Host": "httpbin.org", 
    "X-Amzn-Trace-Id": "Root=1-6220f00a-7683e03c727619fc5e5db850"
  }, 
  "json": {
    "data": 42
  }, 
  "origin": "173.203.57.63", 
  "url": "https://httpbin.org/post"
}

Keep-Alive Result: 1
Https Connection Response: HTTP/1.1 200 OK
Date: Thu, 03 Mar 2022 16:42:50 GMT
Content-Type: application/json
Content-Length: 321
Connection: keep-alive
Server: gunicorn/19.9.0
Access-Control-Allow-Origin: *
Access-Control-Allow-Credentials: true
{
  "args": {}, 
  "data": "{\"data\":42}", 
  "files": {}, 
  "form": {}, 
  "headers": {
    "Content-Length": "11", 
    "Host": "httpbin.org", 
    "X-Amzn-Trace-Id": "Root=1-6220f00a-5c733376197f2e0d68afb4c8"
  }, 
  "json": {
    "data": 42
  }, 
  "origin": "173.203.57.63", 
  "url": "https://httpbin.org/post"
}

Keep-Alive Result: 1
Https Connection Response: HTTP/1.1 200 OK
Date: Thu, 03 Mar 2022 16:42:50 GMT
Content-Type: application/json
Content-Length: 321
Connection: keep-alive
Server: gunicorn/19.9.0
Access-Control-Allow-Origin: *
Access-Control-Allow-Credentials: true
{
  "args": {}, 
  "data": "{\"data\":42}", 
  "files": {}, 
  "form": {}, 
  "headers": {
    "Content-Length": "11", 
    "Host": "httpbin.org", 
    "X-Amzn-Trace-Id": "Root=1-6220f00a-604db5aa0f4abccc4c721740"
  }, 
  "json": {
    "data": 42
  }, 
  "origin": "173.203.57.63", 
  "url": "https://httpbin.org/post"
}

Keep-Alive Result: 1
Https Connection Response: HTTP/1.1 200 OK
Date: Thu, 03 Mar 2022 16:42:50 GMT
Content-Type: application/json
Content-Length: 321
Connection: keep-alive
Server: gunicorn/19.9.0
Access-Control-Allow-Origin: *
Access-Control-Allow-Credentials: true
{
  "args": {}, 
  "data": "{\"data\":42}", 
  "files": {}, 
  "form": {}, 
  "headers": {
    "Content-Length": "11", 
    "Host": "httpbin.org", 
    "X-Amzn-Trace-Id": "Root=1-6220f00a-3ea4400e52caa293041cd83f"
  }, 
  "json": {
    "data": 42
  }, 
  "origin": "173.203.57.63", 
  "url": "https://httpbin.org/post"
}

Keep-Alive Result: 1
Https Connection Response: HTTP/1.1 200 OK
Date: Thu, 03 Mar 2022 16:42:51 GMT
Content-Type: application/json
Content-Length: 321
Connection: keep-alive
Server: gunicorn/19.9.0
Access-Control-Allow-Origin: *
Access-Control-Allow-Credentials: true
{
  "args": {}, 
  "data": "{\"data\":42}", 
  "files": {}, 
  "form": {}, 
  "headers": {
    "Content-Length": "11", 
    "Host": "httpbin.org", 
    "X-Amzn-Trace-Id": "Root=1-6220f00b-05d2949e37556119199d2627"
  }, 
  "json": {
    "data": 42
  }, 
  "origin": "173.203.57.63", 
  "url": "https://httpbin.org/post"
}

Keep-Alive Result: 1
Https Connection Response: HTTP/1.1 200 OK
Date: Thu, 03 Mar 2022 16:42:51 GMT
Content-Type: application/json
Content-Length: 321
Connection: keep-alive
Server: gunicorn/19.9.0
Access-Control-Allow-Origin: *
Access-Control-Allow-Credentials: true
{
  "args": {}, 
  "data": "{\"data\":42}", 
  "files": {}, 
  "form": {}, 
  "headers": {
    "Content-Length": "11", 
    "Host": "httpbin.org", 
    "X-Amzn-Trace-Id": "Root=1-6220f00b-57e377492da2d9f26c205699"
  }, 
  "json": {
    "data": 42
  }, 
  "origin": "173.203.57.63", 
  "url": "https://httpbin.org/post"
}

Keep-Alive Result: 1
Https Connection Response: HTTP/1.1 200 OK
Date: Thu, 03 Mar 2022 16:42:51 GMT
Content-Type: application/json
Content-Length: 321
Connection: keep-alive
Server: gunicorn/19.9.0
Access-Control-Allow-Origin: *
Access-Control-Allow-Credentials: true
{
  "args": {}, 
  "data": "{\"data\":42}", 
  "files": {}, 
  "form": {}, 
  "headers": {
    "Content-Length": "11", 
    "Host": "httpbin.org", 
    "X-Amzn-Trace-Id": "Root=1-6220f00b-526a207d11c3aa9d231ec537"
  }, 
  "json": {
    "data": 42
  }, 
  "origin": "173.203.57.63", 
  "url": "https://httpbin.org/post"
}

Keep-Alive Result: 1
Https Connection Response: HTTP/1.1 200 OK
Date: Thu, 03 Mar 2022 16:42:51 GMT
Content-Type: application/json
Content-Length: 321
Connection: keep-alive
Server: gunicorn/19.9.0
Access-Control-Allow-Origin: *
Access-Control-Allow-Credentials: true
{
  "args": {}, 
  "data": "{\"data\":42}", 
  "files": {}, 
  "form": {}, 
  "headers": {
    "Content-Length": "11", 
    "Host": "httpbin.org", 
    "X-Amzn-Trace-Id": "Root=1-6220f00b-64f2d0df238d5d14388390db"
  }, 
  "json": {
    "data": 42
  }, 
  "origin": "173.203.57.63", 
  "url": "https://httpbin.org/post"
}

Keep-Alive Result: 1
Https Connection Response: HTTP/1.1 200 OK
Date: Thu, 03 Mar 2022 16:42:51 GMT
Content-Type: application/json
Content-Length: 321
Connection: keep-alive
Server: gunicorn/19.9.0
Access-Control-Allow-Origin: *
Access-Control-Allow-Credentials: true
{
  "args": {}, 
  "data": "{\"data\":42}", 
  "files": {}, 
  "form": {}, 
  "headers": {
    "Content-Length": "11", 
    "Host": "httpbin.org", 
    "X-Amzn-Trace-Id": "Root=1-6220f00b-1612613c2520b2a908706e58"
  }, 
  "json": {
    "data": 42
  }, 
  "origin": "173.203.57.63", 
  "url": "https://httpbin.org/post"
}

Keep-Alive Result: 1
Https Connection Response: HTTP/1.1 200 OK
Date: Thu, 03 Mar 2022 16:42:51 GMT
Content-Type: application/json
Content-Length: 321
Connection: keep-alive
Server: gunicorn/19.9.0
Access-Control-Allow-Origin: *
Access-Control-Allow-Credentials: true
{
  "args": {}, 
  "data": "{\"data\":42}", 
  "files": {}, 
  "form": {}, 
  "headers": {
    "Content-Length": "11", 
    "Host": "httpbin.org", 
    "X-Amzn-Trace-Id": "Root=1-6220f00b-00d80af2769dbc023e8ab652"
  }, 
  "json": {
    "data": 42
  }, 
  "origin": "173.203.57.63", 
  "url": "https://httpbin.org/post"
}

Keep-Alive Result: 1
Https Connection Response: HTTP/1.1 200 OK
Date: Thu, 03 Mar 2022 16:42:51 GMT
Content-Type: application/json
Content-Length: 321
Connection: keep-alive
Server: gunicorn/19.9.0
Access-Control-Allow-Origin: *
Access-Control-Allow-Credentials: true
{
  "args": {}, 
  "data": "{\"data\":42}", 
  "files": {}, 
  "form": {}, 
  "headers": {
    "Content-Length": "11", 
    "Host": "httpbin.org", 
    "X-Amzn-Trace-Id": "Root=1-6220f00b-505398b91878748a45d04795"
  }, 
  "json": {
    "data": 42
  }, 
  "origin": "173.203.57.63", 
  "url": "https://httpbin.org/post"
}

Keep-Alive Result: 1
Https Connection Response: HTTP/1.1 200 OK
Date: Thu, 03 Mar 2022 16:42:51 GMT
Content-Type: application/json
Content-Length: 321
Connection: keep-alive
Server: gunicorn/19.9.0
Access-Control-Allow-Origin: *
Access-Control-Allow-Credentials: true
{
  "args": {}, 
  "data": "{\"data\":42}", 
  "files": {}, 
  "form": {}, 
  "headers": {
    "Content-Length": "11", 
    "Host": "httpbin.org", 
    "X-Amzn-Trace-Id": "Root=1-6220f00b-087616e737a56957076e0a9c"
  }, 
  "json": {
    "data": 42
  }, 
  "origin": "173.203.57.63", 
  "url": "https://httpbin.org/post"
}

Keep-Alive Result: 1
Https Connection Response: HTTP/1.1 200 OK
Date: Thu, 03 Mar 2022 16:42:51 GMT
Content-Type: application/json
Content-Length: 321
Connection: keep-alive
Server: gunicorn/19.9.0
Access-Control-Allow-Origin: *
Access-Control-Allow-Credentials: true
{
  "args": {}, 
  "data": "{\"data\":42}", 
  "files": {}, 
  "form": {}, 
  "headers": {
    "Content-Length": "11", 
    "Host": "httpbin.org", 
    "X-Amzn-Trace-Id": "Root=1-6220f00b-31987540136993062764c373"
  }, 
  "json": {
    "data": 42
  }, 
  "origin": "173.203.57.63", 
  "url": "https://httpbin.org/post"
}

Keep-Alive Result: 1
Https Connection Response: HTTP/1.1 200 OK
Date: Thu, 03 Mar 2022 16:42:51 GMT
Content-Type: application/json
Content-Length: 321
Connection: keep-alive
Server: gunicorn/19.9.0
Access-Control-Allow-Origin: *
Access-Control-Allow-Credentials: true
{
  "args": {}, 
  "data": "{\"data\":42}", 
  "files": {}, 
  "form": {}, 
  "headers": {
    "Content-Length": "11", 
    "Host": "httpbin.org", 
    "X-Amzn-Trace-Id": "Root=1-6220f00b-37efb18d7fdc07ef1d4051cf"
  }, 
  "json": {
    "data": 42
  }, 
  "origin": "173.203.57.63", 
  "url": "https://httpbin.org/post"
}

Keep-Alive Result: 1
Https Connection Response: HTTP/1.1 200 OK
Date: Thu, 03 Mar 2022 16:42:51 GMT
Content-Type: application/json
Content-Length: 321
Connection: keep-alive
Server: gunicorn/19.9.0
Access-Control-Allow-Origin: *
Access-Control-Allow-Credentials: true
{
  "args": {}, 
  "data": "{\"data\":42}", 
  "files": {}, 
  "form": {}, 
  "headers": {
    "Content-Length": "11", 
    "Host": "httpbin.org", 
    "X-Amzn-Trace-Id": "Root=1-6220f00b-666c753e62ff049e375253d3"
  }, 
  "json": {
    "data": 42
  }, 
  "origin": "173.203.57.63", 
  "url": "https://httpbin.org/post"
}

Keep-Alive Result: 1
Https Connection Response: HTTP/1.1 200 OK
Date: Thu, 03 Mar 2022 16:42:51 GMT
Content-Type: application/json
Content-Length: 321
Connection: keep-alive
Server: gunicorn/19.9.0
Access-Control-Allow-Origin: *
Access-Control-Allow-Credentials: true
{
  "args": {}, 
  "data": "{\"data\":42}", 
  "files": {}, 
  "form": {}, 
  "headers": {
    "Content-Length": "11", 
    "Host": "httpbin.org", 
    "X-Amzn-Trace-Id": "Root=1-6220f00b-524b4fea230a31273a1264e6"
  }, 
  "json": {
    "data": 42
  }, 
  "origin": "173.203.57.63", 
  "url": "https://httpbin.org/post"
}

Keep-Alive Result: 1
Https Connection Response: HTTP/1.1 200 OK
Date: Thu, 03 Mar 2022 16:42:51 GMT
Content-Type: application/json
Content-Length: 321
Connection: keep-alive
Server: gunicorn/19.9.0
Access-Control-Allow-Origin: *
Access-Control-Allow-Credentials: true
{
  "args": {}, 
  "data": "{\"data\":42}", 
  "files": {}, 
  "form": {}, 
  "headers": {
    "Content-Length": "11", 
    "Host": "httpbin.org", 
    "X-Amzn-Trace-Id": "Root=1-6220f00b-4352dd83652fa4d74d8910e8"
  }, 
  "json": {
    "data": 42
  }, 
  "origin": "173.203.57.63", 
  "url": "https://httpbin.org/post"
}

Keep-Alive Result: 1
Https Connection Response: HTTP/1.1 200 OK
Date: Thu, 03 Mar 2022 16:42:51 GMT
Content-Type: application/json
Content-Length: 321
Connection: keep-alive
Server: gunicorn/19.9.0
Access-Control-Allow-Origin: *
Access-Control-Allow-Credentials: true
{
  "args": {}, 
  "data": "{\"data\":42}", 
  "files": {}, 
  "form": {}, 
  "headers": {
    "Content-Length": "11", 
    "Host": "httpbin.org", 
    "X-Amzn-Trace-Id": "Root=1-6220f00b-36f9eb3918e3fbf215e0c5a7"
  }, 
  "json": {
    "data": 42
  }, 
  "origin": "173.203.57.63", 
  "url": "https://httpbin.org/post"
}

Keep-Alive Result: 1

This file can be also found using the Coliru command line: cat /Archive2/c2/f4e2478d335b42/main.cpp

是否可以将 keep-alive 与 boost::beast sync https 客户端一起使用？

Is it possible to use keep-alive with boost::beast sync https client?

c++

https

boost

boost-asio

boost-beast