php curl常見錯誤：SSL錯誤、bool(false)

症狀：php curl調用https出錯 
排查方法：在命令行中使用curl調用試試。 
緣由：服務器所在機房沒法驗證SSL證書。 
解決辦法：跳過SSL證書檢查。 
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false); 

症狀：php curl調用curl_exec返回bool(false)，命令行curl調用正常。 
排查方法： 
var_dump(curl_error($ch)); 
返回： 
string(23) "Empty reply from server" 
再排查： 
curl_setopt($ch, CURLOPT_HEADER, true); 
curl_setopt($ch, CURLOPT_RETURNTRANSFER, false); 
返回： 
HTTP/1.1 100 Continue 
Connection: close 
緣由：php curl接收到HTTP 100就結束了，應該繼續接收HTTP 200 
解決方案： 
curl_setopt($ch, CURLOPT_HTTPHEADER, array('Expect:')); 

PHP and cURL: Disabling 100-continue header 
Published June 15th, 2006 
I've been using cURL (through PHP) to build a sort of proxy for a project I'm working on. I need to parse the returned headers (to recover the HTTP status), so had included a very simple script to do so. It had worked fine in the past, but for some reason barfed in this case. A closer look at what was being returned revealed that for some reason, Apache was prepending the ‘normal' headers with an extra response header: 

HTTP/1.1 100 Continue 

HTTP/1.1 200 OK Date: Fri, 09 Jun 2006 15:23:42 GMT 
Server: Apache 
...A bit of Googling revealed that this was to do with a header that cURL sends by default: 

Expect: 100-continue 

…which in turns tells Apache to send the extra header. I poked around a fair bit but couldn't quite find a workable solution short of manually removing the header in PHP, which seemed a bit clumsy. Finally, on a hunch I tried this: 

curl_setopt( $curl_handle, CURLOPT_HTTPHEADER, array( 'Expect:' ) ); 

…which basically overrides the original ‘Expect:' header with an empty one. 

Hope this helps someone.