ssl版本为GnuTls导致的代码报错，PHP扩展curl sslversion GnuTLS更改为openssl

升级线上环境php版本，PHP5.5升级到5.6.30关于PHP扩展Curl SSLversion版本的坑。

经过了各个扩展模块的安装后升级成功，一周后PHP代码curl访问https相关的网站报错，查看openssl安装包如下

dpkg --list | grep openssl
  libevent-openssl-2.0-5            2.0.16-stable-1ubuntu0.2                          
  libgnutls-openssl27               2.12.14-5ubuntu3.12                                 
  openssl                              1.0.1-4ubuntu5.2                                   
  python-openssl                    0.12-1ubuntu2                                      

和测试环境（测试环境一切正常）对比缺少libcurl4-openssl-dev

apt-get install libcurl4-openssl-dev

安装成功查看ssl version还是GnuTls

尝试重新编译PHP，编译后查看

php -i 
curl

cURL support => enabled
cURL Information => 7.22.0
Age => 3
Features
AsynchDNS => No
Debug => No
GSS-Negotiate => Yes
IDN => Yes
IPv6 => Yes
Largefile => Yes
NTLM => Yes
SPNEGO => No
SSL => Yes
SSPI => No
krb4 => No
libz => Yes
CharConv => No
Protocols => dict, file, ftp, ftps, gopher, http, https, imap, imaps, ldap, pop3, pop3s, rtmp, rtsp, smtp, smtps, telnet, tftp
Host => x86_64-pc-linux-gnu
SSL Version => OpenSSL/1.0.1
ZLib Version => 1.2.3.4

已更改为openssl经上述判断因缺少libcurl4-openssl-dev包，ssl version默认使用了GnuTls