ftp: Move config file handling to Rust

Issue: 4082

Move the configuration file handling to Rust.

These changes will no longer terminate Suricata when there's an invalid
value for ftp.memcap. Like earlier Suricata releases, an error message
is logged "Invalid value <value> for ftp.memcap" but Suricata will no
longer terminate execution. It will use a default value of "0" instead.

doc/userguide/upgrade.rst

@@ -95,6 +95,9 @@ Major changes
   will need to be set before external modules can be loaded. See the
   new default configuration file or :ref:`lua-output-yaml` for more
   details.
+- If the configuration value ``ftp.memcap`` is invalid, Suricata will set it to ``0`` which means
+  no limit will be placed. In previous Suricata  releases, Suricata would terminate execution. A
+  warning message will be displayed `Invalid value <value> for ftp.memcap` when this occurs.
 
 Removals
 ~~~~~~~~

rust/src/ftp/ftp.rs

@@ -19,6 +19,7 @@ use std;
 use std::ffi::CString;
 use std::os::raw::{c_char, c_int, c_void};
 
+use crate::conf::{conf_get, get_memval};
 use crate::ftp::constant::*;
 use lazy_static::lazy_static;
 
@@ -182,6 +183,49 @@ impl FtpTransferCmd {
     }
 }
 
+#[no_mangle]
+pub unsafe extern "C" fn SCFTPGetConfigValues(
+    memcap: *mut u64, max_tx: *mut u32, max_line_len: *mut u32,
+) {
+    if let Some(val) = conf_get("app-layer.protocols.ftp.memcap") {
+        if let Ok(v) = get_memval(val) {
+            *memcap = v;
+            SCLogConfig!("FTP memcap: {}", v);
+        } else {
+            SCLogWarning!(
+                "Invalid value {} for ftp.memcap; defaulting to {}",
+                val,
+                *memcap
+            );
+        }
+    }
+    if let Some(val) = conf_get("app-layer.protocols.ftp.max-tx") {
+        if let Ok(v) = val.parse::<u32>() {
+            *max_tx = v;
+            SCLogConfig!("FTP max tx: {}", v);
+        } else {
+            SCLogWarning!(
+                "Invalid value {} for ftp.max-tx; defaulting to {}",
+                val,
+                *max_tx
+            );
+        }
+    }
+    // This value is often expressed with a unit suffix, e.g., 5kb, hence get_memval
+    if let Some(val) = conf_get("app-layer.protocols.ftp.max-line-length") {
+        if let Ok(v) = get_memval(val) {
+            *max_line_len = v as u32;
+            SCLogConfig!("FTP max line length: {}", v);
+        } else {
+            SCLogWarning!(
+                "Invalid value {} for ftp.max-line-length; defaulting to {}",
+                val,
+                *max_line_len
+            );
+        }
+    }
+}
+
 /// Returns *mut FtpTransferCmd
 #[no_mangle]
 pub unsafe extern "C" fn SCFTPTransferCmdNew() -> *mut FtpTransferCmd {

src/app-layer-ftp.c

@@ -58,41 +58,10 @@ static FTPTransaction *FTPGetOldestTx(const FtpState *, FTPTransaction *);
 
 static void FTPParseMemcap(void)
 {
-    const char *conf_val;
-
-    /** set config values for memcap, prealloc and hash_size */
-    if ((ConfGet("app-layer.protocols.ftp.memcap", &conf_val)) == 1)
-    {
-        if (ParseSizeStringU64(conf_val, &ftp_config_memcap) < 0) {
-            SCLogError("Error parsing ftp.memcap "
-                       "from conf file - %s.  Killing engine",
-                    conf_val);
-            exit(EXIT_FAILURE);
-        }
-        SCLogInfo("FTP memcap: %"PRIu64, ftp_config_memcap);
-    } else {
-        /* default to unlimited */
-        ftp_config_memcap = 0;
-    }
+    SCFTPGetConfigValues(&ftp_config_memcap, &ftp_config_maxtx, &ftp_max_line_len);
 
     SC_ATOMIC_INIT(ftp_memuse);
     SC_ATOMIC_INIT(ftp_memcap);
-
-    if ((ConfGet("app-layer.protocols.ftp.max-tx", &conf_val)) == 1) {
-        if (ParseSizeStringU32(conf_val, &ftp_config_maxtx) < 0) {
-            SCLogError("Error parsing ftp.max-tx "
-                       "from conf file - %s.",
-                    conf_val);
-        }
-        SCLogInfo("FTP max tx: %" PRIu32, ftp_config_maxtx);
-    }
-
-    if ((ConfGet("app-layer.protocols.ftp.max-line-length", &conf_val)) == 1) {
-        if (ParseSizeStringU32(conf_val, &ftp_max_line_len) < 0) {
-            SCLogError("Error parsing ftp.max-line-length from conf file - %s.", conf_val);
-        }
-        SCLogConfig("FTP max line length: %" PRIu32, ftp_max_line_len);
-    }
 }
 
 static void FTPIncrMemuse(uint64_t size)