FTP: perform active connections non-blocking

1- Two new error codes are introduced.

CURLE_FTP_ACCEPT_FAILED to be set whenever ACCEPTing fails because of
FTP server connected.

CURLE_FTP_ACCEPT_TIMEOUT to be set whenever ACCEPTing timeouts.

Neither of these errors are considered fatal and control connection
remains OK because it could just be a firewall blocking server to
connect to the client.

2- One new setopt option was introduced.

CURLOPT_ACCEPTTIMEOUT_MS

It sets the maximum amount of time FTP client is going to wait for a
server to connect. Internal default accept timeout is 60 seconds.

1 files changed, 3 insertions, 0 deletions

diff --git a/lib/ftp.h b/lib/ftp.h
index b5b3adadf..4c1296fef 100644
--- a/lib/ftp.h
+++ b/lib/ftp.h
@@ -146,6 +146,9 @@ struct ftp_conn {
   int count2; /* general purpose counter for the state machine */
   int count3; /* general purpose counter for the state machine */
   ftpstate state; /* always use ftp.c:state() to change state! */
+  ftpstate state_saved; /* transfer type saved to be reloaded after
+                           data connection is established */
+  curl_off_t retr_size_saved; /* Size of retrieved file saved */
   char * server_os;     /* The target server operating system. */
   curl_off_t known_filesize; /* file size is different from -1, if wildcard
                                 LIST parsing was done and wc_statemach set