php curl常见错误：SSL错误、bool(false)

症状：php curl调用https出错
排查方法：在命令行中使用curl调用试试。
原因：服务器所在机房无法验证ssl证书。
解决办法：跳过ssl证书检查。
curl_setopt($ch, curlopt_ssl_verifypeer, false);

症状：php curl调用curl_exec返回bool(false)，命令行curl调用正常。
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($ch, curlopt_returntransfer, false);
返回：
http/1.1 100 continue
connection: close
原因：php curl接收到http 100就结束了，应该继续接收http 200
解决方案：
curl_setopt($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.