php curl 给出与命令行不同的结果

Question

我正在从 URL 下载 ZIP，但我遇到了问题。我算法的第一步是检查给定 url 的 Content-Type 和 Content-Length 是什么：

$ch = curl_init();

curl_setopt($ch, CURLOPT_URL, "https://www.dropbox.com/s/0hvgw7nvbdnh13d/ColaClassic.zip");
curl_setopt($ch, CURLOPT_HEADER, 1); //I
curl_setopt($ch, CURLOPT_NOBODY, 1); //without body
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1); //L
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);

curl_exec($ch);
$content_type = curl_getinfo($ch, CURLINFO_CONTENT_TYPE);

但是，变量$content-type 的值是text/html; charset=utf-8

然后我像这样从命令行检查Content-Type：

curl -IL https://www.dropbox.com/s/0hvgw7nvbdnh13d/ColaClassic.zip

我得到了正确的结果 (application/zip)。

那么，这两个代码有什么区别，如何在我的 php 脚本中得到正确的Content-Type？

编辑：

curl_setopt($ch, CURLOPT_URL, 'https://www.dropbox.com/s/0hvgw7nvbdnh13d/ColaClassic.zip');
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, 'HEAD');
curl_setopt($ch, CURLOPT_NOBODY, true);
curl_setopt($ch, CURLOPT_HEADER, true);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
curl_setopt($ch, CURLOPT_VERBOSE, true);
curl_setopt($ch, CURLOPT_STDERR, $verbose);
curl_setopt($ch, CURLOPT_BINARYTRANSFER, true);

php curl 的详细输出：

* Hostname was found in DNS cache
* Hostname in DNS cache was stale, zapped
*   Trying 162.125.69.1...
* Connected to www.dropbox.com (162.125.69.1) port 443 (#14)
* successfully set certificate verify locations:
*   CAfile: none
  CApath: /etc/ssl/certs
* SSL connection using ECDHE-RSA-AES128-GCM-SHA256
* Server certificate:
*    subject: businessCategory=Private Organization; 1.3.6.1.4.1.311.60.2.1.3=US; 1.3.6.1.4.1.311.60.2.1.2=Delaware; serialNumber=4348296; C=US; ST=California; L=San Francisco; O=Dropbox, Inc; CN=www.dropbox.com
*    start date: 2017-11-14 00:00:00 GMT
*    expire date: 2020-02-11 12:00:00 GMT
*    subjectAltName: www.dropbox.com matched
*    issuer: C=US; O=DigiCert Inc; OU=www.digicert.com; CN=DigiCert SHA2 Extended Validation Server CA
*    SSL certificate verify ok.
> HEAD /s/0hvgw7nvbdnh13d/ColaClassic.zip HTTP/1.1
Host: www.dropbox.com
Accept: */*

命令行 curl 的详细输出：

*   Trying 162.125.69.1...
* TCP_NODELAY set
* Connected to www.dropbox.com (162.125.69.1) 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/ssl/cert.pem
  CApath: none
* TLSv1.2 (OUT), TLS handshake, Client hello (1):
* TLSv1.2 (IN), TLS handshake, Server hello (2):
* TLSv1.2 (IN), TLS handshake, Certificate (11):
* TLSv1.2 (IN), TLS handshake, Server key exchange (12):
* TLSv1.2 (IN), TLS handshake, Server finished (14):
* TLSv1.2 (OUT), TLS handshake, Client key exchange (16):
* TLSv1.2 (OUT), TLS change cipher, Client hello (1):
* TLSv1.2 (OUT), TLS handshake, Finished (20):
* TLSv1.2 (IN), TLS change cipher, Client hello (1):
* TLSv1.2 (IN), TLS handshake, Finished (20):
* SSL connection using TLSv1.2 / ECDHE-RSA-CHACHA20-POLY1305
* ALPN, server accepted to use h2
* Server certificate:
*  subject: businessCategory=Private Organization; jurisdictionCountryName=US; jurisdictionStateOrProvinceName=Delaware; serialNumber=4348296; C=US; ST=California; L=San Francisco; O=Dropbox, Inc; CN=www.dropbox.com
*  start date: Nov 14 00:00:00 2017 GMT
*  expire date: Feb 11 12:00:00 2020 GMT
*  subjectAltName: host "www.dropbox.com" matched cert's "www.dropbox.com"
*  issuer: C=US; O=DigiCert Inc; OU=www.digicert.com; CN=DigiCert SHA2 Extended Validation 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 0x7fd8c4007a00)
> HEAD /s/0hvgw7nvbdnh13d/ColaClassic.zip HTTP/2
> Host: www.dropbox.com
> User-Agent: curl/7.54.0
> Accept: */*

Answer 1

似乎 Dropbox 会根据用户代理发出不同的响应代码 - 或者更确切地说是缺少响应代码。您的命令行操作发送类似curl/7.47.0（或您的版本）的内容，而 php 脚本发送一个空的用户代理。将用户代理添加到您的 php 请求中将使 dropbox 以 HTTP/1.1 301 Moved Permanently 响应适当地响应，然后您的脚本将按预期跟随位置：

$ch = curl_init();
// emulates user agent from command line.
$user_agent = 'curl/' . curl_version()['version'];
curl_setopt($ch, CURLOPT_URL, "https://www.dropbox.com/s/0hvgw7nvbdnh13d/ColaClassic.zip");
curl_setopt($ch, CURLOPT_HEADER, 1); //I
curl_setopt($ch, CURLOPT_NOBODY, 1); //without body
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1); //L
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($ch, CURLOPT_USERAGENT, $user_agent);

curl_exec($ch);
$content_type = curl_getinfo($ch, CURLINFO_CONTENT_TYPE);
echo $content_type;

更新：奇怪的是，我只是尝试了一些其他的东西，比如模拟各种浏览器用户代理字符串，似乎 Dropbox 似乎只在使用 curl/X.X.X 用户代理时发出重定向。 ¯\_(ツ)_/¯