cURL 版本 7.64 上的 curl_multi 出现“无法解析主机”错误
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【中文标题】cURL 版本 7.64 上的 curl_multi 出现“无法解析主机”错误【英文标题】："Could not resolve host" error with curl_multi on cURL version 7.64 【发布时间】：2019-07-13 06:59:45 【问题描述】：当我在 curl_multi 上下文中调用 curl_error($ch) 时，我得到“无法解析主机”，但 errno 为 0，并且请求也成功完成（我从远程服务器获得了预期的响应)。
curl_multi 组中的所有请求都出现此错误，只有第一个请求除外，没有任何错误消息！
（例如 curl_multi 附加了 10 个子请求，只有第一个请求不会出错，其他 9 个会出错）
重现问题的代码
<?php
$url = "https://www.example.com";
$options = array(
CURLOPT_RETURNTRANSFER => true, // don't echo page
CURLOPT_VERBOSE =>true,
);
$cm = curl_multi_init();
// step 1 of 3 (adding requests)
//request 1
$ch1 = curl_init( $url );
$verboseH1 = fopen('php://temp', 'w+');
$options[CURLOPT_STDERR] = $verboseH1;
curl_setopt_array( $ch1, $options);
curl_multi_add_handle($cm, $ch1);
//request 2
$ch2 = curl_init( $url );
$verboseH2 = fopen('php://temp', 'w+');
$options[CURLOPT_STDERR] = $verboseH2;
curl_setopt_array( $ch2, $options);
curl_multi_add_handle($cm, $ch2);
//request 3
$ch3 = curl_init( $url );
$verboseH3 = fopen('php://temp', 'w+');
$options[CURLOPT_STDERR] = $verboseH3;
curl_setopt_array( $ch3, $options);
curl_multi_add_handle($cm, $ch3);
// step 2 of 3 (executing requests in parallel)
// for more information about these strange loops , check http://php.net/manual/en/function.curl-multi-init.php#115055
$active = null;
do
$mrc = curl_multi_exec($cm, $active);
while ($mrc == CURLM_CALL_MULTI_PERFORM);
while ($active && $mrc == CURLM_OK)
if (curl_multi_select($cm) == -1)
usleep(100);
do
$mrc = curl_multi_exec($cm, $active);
while ($mrc == CURLM_CALL_MULTI_PERFORM);
// step 3 of 3 (getting results)
echo "<h1>Requet 1</h1>\n";
echo "errmsg1: '" . curl_error($ch1) . "'\n";
rewind($verboseH1);
echo "verbose1:\n" . stream_get_contents( $verboseH1) . "\n";
echo "===============================================================\n";
echo "<h1>Requet 2</h1>\n";
echo "errmsg2: '" . curl_error($ch2) . "'\n";
rewind($verboseH2);
echo "verbose2:\n" . stream_get_contents( $verboseH2) . "\n";
echo "===============================================================\n";
echo "<h1>Requet 3</h1>\n";
echo "errmsg3: '" . curl_error($ch3) . "'\n";
rewind($verboseH3);
echo "verbose3:\n" . stream_get_contents( $verboseH3) . "\n";
exit;
这段代码的输出
<h1>Requet 1</h1>
errmsg1: ''
verbose1:
* Expire in 0 ms for 6 (transfer 0x2b750f0)
* Expire in 1 ms for 1 (transfer 0x2b750f0)
* Expire in 0 ms for 1 (transfer 0x2b750f0)
* Expire in 0 ms for 1 (transfer 0x2b750f0)
* Trying 93.184.216.34...
* TCP_NODELAY set
* Expire in 149999 ms for 3 (transfer 0x2b750f0)
* Expire in 200 ms for 4 (transfer 0x2b750f0)
* Connected to www.example.com (93.184.216.34) port 443 (#0)
* ALPN, offering h2
* ALPN, offering http/1.1
* Cipher selection: ALL:!EXPORT:!EXPORT40:!EXPORT56:!aNULL:!LOW:!RC4:@STRENGTH
* successfully set certificate verify locations:
* CAfile: /etc/pki/tls/certs/ca-bundle.crt
CApath: none
* SSL connection using TLSv1.2 / ECDHE-RSA-AES128-GCM-SHA256
* ALPN, server accepted to use h2
* Server certificate:
* subject: C=US; ST=California; L=Los Angeles; O=Internet Corporation for Assigned Names and Numbers; OU=Technology; CN=www.example.org
* start date: Nov 28 00:00:00 2018 GMT
* expire date: Dec 2 12:00:00 2020 GMT
* subjectAltName: host "www.example.com" matched cert's "www.example.com"
* issuer: C=US; O=DigiCert Inc; CN=DigiCert SHA2 Secure Server CA
* SSL certificate verify ok.
* Using HTTP2, server supports multi-use
* Connection state changed (HTTP/2 confirmed)
* Copying HTTP/2 data in stream buffer to connection buffer after upgrade: len=0
* Using Stream ID: 1 (easy handle 0x2b750f0)
> GET / HTTP/2
Host: www.example.com
Accept: */*
* Connection state changed (MAX_CONCURRENT_STREAMS == 100)!
< HTTP/2 200
< cache-control: max-age=604800
< content-type: text/html; charset=UTF-8
< date: Tue, 19 Feb 2019 17:01:16 GMT
< etag: "1541025663+ident"
< expires: Tue, 26 Feb 2019 17:01:16 GMT
< last-modified: Fri, 09 Aug 2013 23:54:35 GMT
< server: ECS (dfw/27B2)
< vary: Accept-Encoding
< x-cache: HIT
< content-length: 1270
<
* Connection #0 to host www.example.com left intact
===============================================================
<h1>Requet 2</h1>
errmsg2: 'Could not resolve host: www.example.com'
verbose2:
* Expire in 0 ms for 6 (transfer 0x2b7a9a0)
* Found bundle for host www.example.com: 0x2b86800 [serially]
* Server doesn't support multi-use (yet)
* Expire in 1 ms for 1 (transfer 0x2b7a9a0)
* Expire in 0 ms for 1 (transfer 0x2b7a9a0)
* Hostname 'www.example.com' was found in DNS cache
* Expire in 0 ms for 1 (transfer 0x2b7a9a0)
* Trying 93.184.216.34...
* TCP_NODELAY set
* Expire in 149999 ms for 3 (transfer 0x2b7a9a0)
* Expire in 200 ms for 4 (transfer 0x2b7a9a0)
* Connected to www.example.com (93.184.216.34) port 443 (#1)
* ALPN, offering h2
* ALPN, offering http/1.1
* Cipher selection: ALL:!EXPORT:!EXPORT40:!EXPORT56:!aNULL:!LOW:!RC4:@STRENGTH
* successfully set certificate verify locations:
* CAfile: /etc/pki/tls/certs/ca-bundle.crt
CApath: none
* SSL connection using TLSv1.2 / ECDHE-RSA-AES128-GCM-SHA256
* ALPN, server accepted to use h2
* Server certificate:
* subject: C=US; ST=California; L=Los Angeles; O=Internet Corporation for Assigned Names and Numbers; OU=Technology; CN=www.example.org
* start date: Nov 28 00:00:00 2018 GMT
* expire date: Dec 2 12:00:00 2020 GMT
* subjectAltName: host "www.example.com" matched cert's "www.example.com"
* issuer: C=US; O=DigiCert Inc; CN=DigiCert SHA2 Secure Server CA
* SSL certificate verify ok.
* Using HTTP2, server supports multi-use
* Connection state changed (HTTP/2 confirmed)
* Copying HTTP/2 data in stream buffer to connection buffer after upgrade: len=0
* Using Stream ID: 1 (easy handle 0x2b7a9a0)
> GET / HTTP/2
Host: www.example.com
Accept: */*
* Connection state changed (MAX_CONCURRENT_STREAMS == 100)!
< HTTP/2 200
< cache-control: max-age=604800
< content-type: text/html; charset=UTF-8
< date: Tue, 19 Feb 2019 17:01:16 GMT
< etag: "1541025663+ident"
< expires: Tue, 26 Feb 2019 17:01:16 GMT
< last-modified: Fri, 09 Aug 2013 23:54:35 GMT
< server: ECS (dfw/562D)
< vary: Accept-Encoding
< x-cache: HIT
< content-length: 1270
<
* Could not resolve host: www.example.com
* Closing connection 1
===============================================================
<h1>Requet 3</h1>
errmsg3: 'Could not resolve host: www.example.com'
verbose3:
* Expire in 0 ms for 6 (transfer 0x2b80250)
* Found bundle for host www.example.com: 0x2b86800 [serially]
* Server doesn't support multi-use (yet)
* Expire in 1 ms for 1 (transfer 0x2b80250)
* Expire in 0 ms for 1 (transfer 0x2b80250)
* Hostname 'www.example.com' was found in DNS cache
* Expire in 0 ms for 1 (transfer 0x2b80250)
* Trying 93.184.216.34...
* TCP_NODELAY set
* Expire in 150000 ms for 3 (transfer 0x2b80250)
* Expire in 200 ms for 4 (transfer 0x2b80250)
* Connected to www.example.com (93.184.216.34) port 443 (#2)
* ALPN, offering h2
* ALPN, offering http/1.1
* Cipher selection: ALL:!EXPORT:!EXPORT40:!EXPORT56:!aNULL:!LOW:!RC4:@STRENGTH
* successfully set certificate verify locations:
* CAfile: /etc/pki/tls/certs/ca-bundle.crt
CApath: none
* SSL connection using TLSv1.2 / ECDHE-RSA-AES128-GCM-SHA256
* ALPN, server accepted to use h2
* Server certificate:
* subject: C=US; ST=California; L=Los Angeles; O=Internet Corporation for Assigned Names and Numbers; OU=Technology; CN=www.example.org
* start date: Nov 28 00:00:00 2018 GMT
* expire date: Dec 2 12:00:00 2020 GMT
* subjectAltName: host "www.example.com" matched cert's "www.example.com"
* issuer: C=US; O=DigiCert Inc; CN=DigiCert SHA2 Secure Server CA
* SSL certificate verify ok.
* Using HTTP2, server supports multi-use
* Connection state changed (HTTP/2 confirmed)
* Copying HTTP/2 data in stream buffer to connection buffer after upgrade: len=0
* Using Stream ID: 1 (easy handle 0x2b80250)
> GET / HTTP/2
Host: www.example.com
Accept: */*
* Connection state changed (MAX_CONCURRENT_STREAMS == 100)!
< HTTP/2 200
< accept-ranges: bytes
< cache-control: max-age=604800
< content-type: text/html; charset=UTF-8
< date: Tue, 19 Feb 2019 17:01:16 GMT
< etag: "1541025663"
< expires: Tue, 26 Feb 2019 17:01:16 GMT
< last-modified: Fri, 09 Aug 2013 23:54:35 GMT
< server: ECS (dfw/F4AA)
< vary: Accept-Encoding
< x-cache: HIT
< content-length: 1270
<
* Could not resolve host: www.example.com
* Closing connection 2
如您所见，只有第一个请求没有错误，请求 2 和 3 有错误“无法解析主机：www.example.com”，并且与第一个请求的详细程度不同。
附加信息
-
这个问题发生在 CentOS + PHP 7.0.33 + cURL 7.64.0 (released : 6th of February 2019)
fedora28 + PHP 7.2.14 + cURL 7.59.0 上不会出现此问题
如果 curl_multi 仅附加 1 个请求，则不会发生此问题
我想了解这种行为。如何使所有请求都像第一个请求一样而不产生此错误？
更新
将此行添加到$options 数组可修复问题中的特定示例，但这不是一个实际的解决方案，也不能解释为什么cURL 无法自行解析名称。
CURLOPT_RESOLVE => ["www.example.com:443:93.184.216.34"]
【问题讨论】：
这已被确认为 curl 中的一个错误，修复为 here @DanielStenberg 我知道您没有太多时间再次调试issue 3602，因为它的重现性不可靠，并且可能是由于 curl 以外的许多原因，但我希望有一天如果你能得到一些时间，再深入了解一下，因为我知道你是唯一一个可以深入这个领域的人:) 【参考方案1】：我也有同样的问题：https://github.com/amazeeio/lagoon/issues/923
这是一个 curl 回归：https://github.com/curl/curl/issues/3629 - 自从打开 bug 后已经解决。
感谢出色的测试脚本 :)
【讨论】：
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