ftp: CURLOPT_FTP_SKIP_PASV_IP by default

The command line tool also independently sets --ftp-skip-pasv-ip by
default.

Ten test cases updated to adapt the modified --libcurl output.

Bug: https://curl.se/docs/CVE-2020-8284.html
CVE-2020-8284

Reported-by: Varnavas Papaioannou

docs/cmdline-opts/ftp-skip-pasv-ip.d

@@ -10,4 +10,6 @@ to curl's PASV command when curl connects the data connection. Instead curl
 will re-use the same IP address it already uses for the control
 connection.
 
+Since curl 7.74.0 this option is enabled by default.
+
 This option has no effect if PORT, EPRT or EPSV is used instead of PASV.

docs/libcurl/opts/CURLOPT_FTP_SKIP_PASV_IP.3

@@ -5,7 +5,7 @@
 .\" *                            | (__| |_| |  _ <| |___
 .\" *                             \___|\___/|_| \_\_____|
 .\" *
-.\" * Copyright (C) 1998 - 2017, Daniel Stenberg, <daniel@haxx.se>, et al.
+.\" * Copyright (C) 1998 - 2020, Daniel Stenberg, <daniel@haxx.se>, et al.
 .\" *
 .\" * This software is licensed as described in the file COPYING, which
 .\" * you should have received as part of this distribution. The terms
@@ -35,11 +35,13 @@ address it already uses for the control connection. But it will use the port
 number from the 227-response.
 
 This option thus allows libcurl to work around broken server installations
-that due to NATs, firewalls or incompetence report the wrong IP address back.
+that due to NATs, firewalls or incompetence report the wrong IP address
+back. Setting the option also reduces the risk for various sorts of client
+abuse by malicious servers.
 
 This option has no effect if PORT, EPRT or EPSV is used instead of PASV.
 .SH DEFAULT
-0
+1 since 7.74.0, was 0 before then.
 .SH PROTOCOLS
 FTP
 .SH EXAMPLE

lib/url.c

@@ -497,6 +497,7 @@ CURLcode Curl_init_userdefined(struct Curl_easy *data)
   set->ftp_use_eprt = TRUE;   /* FTP defaults to EPRT operations */
   set->ftp_use_pret = FALSE;  /* mainly useful for drftpd servers */
   set->ftp_filemethod = FTPFILE_MULTICWD;
+  set->ftp_skip_ip = TRUE;    /* skip PASV IP by default */
 #endif
   set->dns_cache_timeout = 60; /* Timeout every 60 seconds by default */
 

src/tool_cfgable.c

@@ -44,6 +44,7 @@ void config_init(struct OperationConfig *config)
   config->tcp_nodelay = TRUE; /* enabled by default */
   config->happy_eyeballs_timeout_ms = CURL_HET_DEFAULT;
   config->http09_allowed = FALSE;
+  config->ftp_skip_ip = TRUE;
 }
 
 static void free_config_fields(struct OperationConfig *config)

tests/data/test1400

@@ -73,6 +73,7 @@ int main(int argc, char *argv[])
   curl_easy_setopt(hnd, CURLOPT_USERAGENT, "stripped");
   curl_easy_setopt(hnd, CURLOPT_MAXREDIRS, 50L);
   curl_easy_setopt(hnd, CURLOPT_VERBOSE, 1L);
+  curl_easy_setopt(hnd, CURLOPT_FTP_SKIP_PASV_IP, 1L);
   curl_easy_setopt(hnd, CURLOPT_TCP_KEEPALIVE, 1L);
 
   /* Here is a list of options the curl code used that cannot get generated

tests/data/test1401

@@ -87,6 +87,7 @@ int main(int argc, char *argv[])
   curl_easy_setopt(hnd, CURLOPT_MAXREDIRS, 50L);
   curl_easy_setopt(hnd, CURLOPT_COOKIE, "chocolate=chip");
   curl_easy_setopt(hnd, CURLOPT_VERBOSE, 1L);
+  curl_easy_setopt(hnd, CURLOPT_FTP_SKIP_PASV_IP, 1L);
   curl_easy_setopt(hnd, CURLOPT_TCP_KEEPALIVE, 1L);
   curl_easy_setopt(hnd, CURLOPT_PROTOCOLS, (long)CURLPROTO_FILE |
                                            (long)CURLPROTO_FTP |

tests/data/test1402

@@ -78,6 +78,7 @@ int main(int argc, char *argv[])
   curl_easy_setopt(hnd, CURLOPT_USERAGENT, "stripped");
   curl_easy_setopt(hnd, CURLOPT_MAXREDIRS, 50L);
   curl_easy_setopt(hnd, CURLOPT_VERBOSE, 1L);
+  curl_easy_setopt(hnd, CURLOPT_FTP_SKIP_PASV_IP, 1L);
   curl_easy_setopt(hnd, CURLOPT_TCP_KEEPALIVE, 1L);
 
   /* Here is a list of options the curl code used that cannot get generated

tests/data/test1403

@@ -73,6 +73,7 @@ int main(int argc, char *argv[])
   curl_easy_setopt(hnd, CURLOPT_USERAGENT, "stripped");
   curl_easy_setopt(hnd, CURLOPT_MAXREDIRS, 50L);
   curl_easy_setopt(hnd, CURLOPT_VERBOSE, 1L);
+  curl_easy_setopt(hnd, CURLOPT_FTP_SKIP_PASV_IP, 1L);
   curl_easy_setopt(hnd, CURLOPT_TCP_KEEPALIVE, 1L);
 
   /* Here is a list of options the curl code used that cannot get generated

tests/data/test1404

@@ -147,6 +147,7 @@ int main(int argc, char *argv[])
   curl_easy_setopt(hnd, CURLOPT_USERAGENT, "stripped");
   curl_easy_setopt(hnd, CURLOPT_MAXREDIRS, 50L);
   curl_easy_setopt(hnd, CURLOPT_VERBOSE, 1L);
+  curl_easy_setopt(hnd, CURLOPT_FTP_SKIP_PASV_IP, 1L);
   curl_easy_setopt(hnd, CURLOPT_TCP_KEEPALIVE, 1L);
 
   /* Here is a list of options the curl code used that cannot get generated

tests/data/test1405

@@ -89,6 +89,7 @@ int main(int argc, char *argv[])
   curl_easy_setopt(hnd, CURLOPT_POSTQUOTE, slist2);
   curl_easy_setopt(hnd, CURLOPT_PREQUOTE, slist3);
   curl_easy_setopt(hnd, CURLOPT_VERBOSE, 1L);
+  curl_easy_setopt(hnd, CURLOPT_FTP_SKIP_PASV_IP, 1L);
   curl_easy_setopt(hnd, CURLOPT_TCP_KEEPALIVE, 1L);
 
   /* Here is a list of options the curl code used that cannot get generated

tests/data/test1406

@@ -79,6 +79,7 @@ int main(int argc, char *argv[])
   curl_easy_setopt(hnd, CURLOPT_URL, "smtp://%HOSTIP:%SMTPPORT/1406");
   curl_easy_setopt(hnd, CURLOPT_UPLOAD, 1L);
   curl_easy_setopt(hnd, CURLOPT_VERBOSE, 1L);
+  curl_easy_setopt(hnd, CURLOPT_FTP_SKIP_PASV_IP, 1L);
   curl_easy_setopt(hnd, CURLOPT_TCP_KEEPALIVE, 1L);
   curl_easy_setopt(hnd, CURLOPT_MAIL_FROM, "sender@example.com");
   curl_easy_setopt(hnd, CURLOPT_MAIL_RCPT, slist1);

tests/data/test1407

@@ -62,6 +62,7 @@ int main(int argc, char *argv[])
   curl_easy_setopt(hnd, CURLOPT_DIRLISTONLY, 1L);
   curl_easy_setopt(hnd, CURLOPT_USERPWD, "user:secret");
   curl_easy_setopt(hnd, CURLOPT_VERBOSE, 1L);
+  curl_easy_setopt(hnd, CURLOPT_FTP_SKIP_PASV_IP, 1L);
   curl_easy_setopt(hnd, CURLOPT_TCP_KEEPALIVE, 1L);
 
   /* Here is a list of options the curl code used that cannot get generated

tests/data/test1420

@@ -67,6 +67,7 @@ int main(int argc, char *argv[])
   curl_easy_setopt(hnd, CURLOPT_URL, "imap://%HOSTIP:%IMAPPORT/1420/;MAILINDEX=1");
   curl_easy_setopt(hnd, CURLOPT_USERPWD, "user:secret");
   curl_easy_setopt(hnd, CURLOPT_VERBOSE, 1L);
+  curl_easy_setopt(hnd, CURLOPT_FTP_SKIP_PASV_IP, 1L);
   curl_easy_setopt(hnd, CURLOPT_TCP_KEEPALIVE, 1L);
 
   /* Here is a list of options the curl code used that cannot get generated