disabling echo + parsing cmdline args

Signed-off-by: Mattias Andrée <maandree@operamail.com>

1 files changed, 106 insertions, 0 deletions

diff --git a/src/cerberus.c b/src/cerberus.c
new file mode 100644
index 0000000..5f4afdc
--- /dev/null
+++ b/src/cerberus.c
@@ -0,0 +1,106 @@
+/**
+ * cerberus – Minimal login program
+ * 
+ * Copyright © 2013  Mattias Andrée (maandree@member.fsf.org)
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#include <stdio.h>
+#include <termios.h>
+#include <unistd.h>
+
+
+/**
+ * Mane method
+ * 
+ * @param   argc  The number of command line arguments
+ * @param   argv  The command line arguments
+ * @return        Return code
+ */
+int main(int argc, char** argv)
+{
+  char* username = NULL;
+  char* hostname = NULL;
+  char preserve_env = 0;
+  struct termios saved_stty;
+  struct termios stty;
+  int i;
+  
+  /* Disable echoing */
+  tcgetattr(STDIN_FILENO, &saved_stty);
+  stty = saved_stty;
+  stty.c_lflag &= ~ECHO;
+  tcsetattr(STDIN_FILENO, TCSAFLUSH, &stty);
+  /* This should be done as early and quickly as possible so as little
+     as possible of the passphrase gets leaked to the output if the user
+     begins entering the passphrase directly after the username. */
+  
+  /* Parse command line arguments */
+  {
+    char double_dashed = 0;
+    char hostname_on_next = 0;
+    for (i = 1; i < argc; i++)
+      {
+	char *arg = *(argv + i);
+	char c;
+	
+	if (*arg == 0)
+	  ;
+	else if ((*arg == '-') && (double_dashed == 0))
+	  while ((c = *(++arg)))
+	    if ((c == 'V') || (c == 'H'))
+	      ;
+	    else if (c == 'p')
+	      preserve_env = 1;
+	    else if (c == 'h')
+	      {
+		if (*(arg + 1))
+		  hostname = arg + 1;
+		else
+		  hostname_on_next = 1;
+		break;
+	      }
+	    else if (c == 'f')
+	      {
+		if (*(arg + 1))
+		  username = arg + 1;
+		break;
+	      }
+	    else if (c == '-')
+	      {
+		double_dashed = 1;
+		break;
+	      }
+	    else
+	      fprintf(stderr, "%s: unrecognised options: -%c\n", *argv, c);
+	else if (hostname_on_next)
+	  {
+	    hostname = arg;
+	    hostname_on_next = 0;
+	  }
+	else
+	  username = arg;
+      }
+  }
+  
+  printf("Passphrase: ");
+  fflush(stdout);
+  
+  
+  /* Reset terminal settings */
+  tcsetattr(STDIN_FILENO, TCSAFLUSH, &saved_stty);
+  
+  return 0;
+}
+