options: Complete the transition to numeric toggles (`#if') For the sake of review, this commit alters only the code; the affiliated comments within the source files also need to be updated, but doing so now would obscure the operational changes that have been made here. * All on/off options have been switched to the numeric `#if' variant; that is the only way to make this `default_options.h.in' thing work in a reasonable manner. * There is now some very minor compile-time checking of the user's choice of options. * NO_FAST_EXPTMOD doesn't seem to be used, so it has been removed. * ENABLE_USER_ALGO_LIST was supposed to be renamed DROPBEAR_USER_ALGO_LIST, and this commit completes that work. * DROPBEAR_FUZZ seems to be a relatively new, as-yet undocumented option, which was added by the following commit: commit 6e0b539e9ca0b5628c6c5a3d118ad6a2e79e8039 Author: Matt Johnston <[email protected]> Date: Tue May 23 22:29:21 2017 +0800 split out checkpubkey_line() separately It has now been added to `sysoptions.h' and defined as `0' by default. * The configuration option `DROPBEAR_PASSWORD_ENV' is no longer listed in `default_options.h.in'; it is no longer meant to be set by the user, and is instead left to be defined in `sysoptions.h' (where it was already being defined) as merely the name of the environment variable in question: DROPBEAR_PASSWORD To enable or disable use of that environment variable, the user must now toggle `DROPBEAR_USE_DROPBEAR_PASSWORD'. * The sFTP support is now toggled by setting `DROPBEAR_SFTPSERVER', and the path of the sFTP server program is set independently through the usual SFTPSERVER_PATH.

--- a/svr-chansession.c	Wed Feb 14 23:09:40 2018 +0800
+++ b/svr-chansession.c	Thu Jul 20 19:38:26 2017 +0000
@@ -663,7 +663,7 @@
 			}
 		}
 		if (issubsys) {
-#ifdef SFTPSERVER_PATH
+#if DROPBEAR_SFTPSERVER
 			if ((cmdlen == 4) && strncmp(chansess->cmd, "sftp", 4) == 0) {
 				m_free(chansess->cmd);
 				chansess->cmd = m_strdup(SFTPSERVER_PATH);
@@ -687,7 +687,7 @@
 	}
 
 
-#ifdef LOG_COMMANDS
+#if LOG_COMMANDS
 	if (chansess->cmd) {
 		dropbear_log(LOG_INFO, "User %s executing '%s'", 
 						ses.authstate.pw_name, chansess->cmd);
@@ -774,7 +774,7 @@
 
 	pid_t pid;
 	struct logininfo *li = NULL;
-#ifdef DO_MOTD
+#if DO_MOTD
 	buffer * motdbuf = NULL;
 	int len;
 	struct stat sb;
@@ -826,7 +826,7 @@
 		login_login(li);
 		login_free_entry(li);
 
-#ifdef DO_MOTD
+#if DO_MOTD
 		if (svr_opts.domotd && !chansess->cmd) {
 			/* don't show the motd if ~/.hushlogin exists */