conntrack: fix coupled-options sanity checkings

This patch extends the generic_opt_check() function to add
extra information on the possible option combinations. Under
some specific situations, like the creation and getting of
a conntrack, you may specify the original or the reply tuple
but at least one MUST be present. This handling has been
always tricky, it still remains but we're more user friendly
at least.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 59 insertions, 18 deletions

diff --git a/src/conntrack.c b/src/conntrack.c
index 0305408..e1c57e5 100644
--- a/src/conntrack.c
+++ b/src/conntrack.c
@@ -115,6 +115,7 @@ static unsigned int global_option_offset = 0;
  *  0  illegal
  *  1  compulsory
  *  2  optional
+ *  3  undecided, see flag combination checkings in generic_opt_check()
  */
 
 static char commands_v_options[NUMBER_OF_CMD][NUMBER_OF_OPT] =
@@ -122,10 +123,10 @@ static char commands_v_options[NUMBER_OF_CMD][NUMBER_OF_OPT] =
 {
           /*   s d r q p t u z e [ ] { } a m i f n g o c b*/
 /*CT_LIST*/   {2,2,2,2,2,0,2,2,0,0,0,0,0,0,2,0,2,2,2,2,2,0},
-/*CT_CREATE*/ {2,2,2,2,1,1,2,0,0,0,0,0,0,2,2,0,0,2,2,0,0,0},
+/*CT_CREATE*/ {3,3,3,3,1,1,2,0,0,0,0,0,0,2,2,0,0,2,2,0,0,0},
 /*CT_UPDATE*/ {2,2,2,2,2,2,2,0,0,0,0,0,0,0,2,2,2,2,2,2,0,0},
 /*CT_DELETE*/ {2,2,2,2,2,2,2,0,0,0,0,0,0,0,2,2,2,2,2,2,0,0},
-/*CT_GET*/    {2,2,2,2,1,0,0,0,0,0,0,0,0,0,0,2,0,0,0,2,0,0},
+/*CT_GET*/    {3,3,3,3,1,0,0,0,0,0,0,0,0,0,0,2,0,0,0,2,0,0},
 /*CT_FLUSH*/  {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
 /*CT_EVENT*/  {2,2,2,2,2,0,0,0,2,0,0,0,0,0,2,0,0,2,2,2,2,2},
 /*VERSION*/   {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
@@ -141,6 +142,12 @@ static char commands_v_options[NUMBER_OF_CMD][NUMBER_OF_OPT] =
 /*X_STATS*/   {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
 };
 
+#define ADDR_VALID_FLAGS_MAX   2
+static unsigned int addr_valid_flags[ADDR_VALID_FLAGS_MAX] = {
+	CT_OPT_ORIG_SRC | CT_OPT_ORIG_DST,
+	CT_OPT_REPL_SRC | CT_OPT_REPL_DST,
+};
+
 static LIST_HEAD(proto_list);
 
 static unsigned int options;
@@ -260,12 +267,12 @@ static int bit2cmd(int command)
 	return i;
 }
 
-void generic_opt_check(int local_options, 
-		       int num_opts,
-		       char *optset, 
-		       const char *optflg[])
+int generic_opt_check(int local_options, int num_opts,
+		      char *optset, const char *optflg[],
+		      unsigned int *coupled_flags, int coupled_flags_size,
+		      int *partial)
 {
-	int i;
+	int i, matching = -1, special_case = 0;
 
 	for (i = 0; i < num_opts; i++) {
 		if (!(local_options & (1<<i))) {
@@ -280,7 +287,33 @@ void generic_opt_check(int local_options,
 					   "option `--%s' with this "
 					   "command", optflg[i]);
 		}
+		if (optset[i] == 3)
+			special_case = 1;
+	}
+
+	/* no weird flags combinations, leave */
+	if (!special_case || coupled_flags == NULL)
+		return 1;
+
+	*partial = -1;
+	for (i=0; i<coupled_flags_size; i++) {
+		/* we look for an exact matching to ensure this is correct */
+		if ((local_options & coupled_flags[i]) == coupled_flags[i]) {
+			matching = i;
+			break;
+		}
+		/* ... otherwise look for the first partial matching */
+		if ((local_options & coupled_flags[i]) && *partial < 0) {
+			*partial = i;
+		}
 	}
+
+	/* we found an exact matching, game over */
+	if (matching >= 0)
+		return 1;
+
+	/* report a partial matching to suggest something */
+	return 0;
 }
 
 static struct option *
@@ -995,7 +1028,7 @@ int main(int argc, char *argv[])
 {
 	int c, cmd;
 	unsigned int type = 0, event_mask = 0, l4flags = 0, status = 0;
-	int res = 0;
+	int res = 0, partial;
 	size_t socketbuffersize = 0;
 	int family = AF_UNSPEC;
 	char __obj[nfct_maxsize()];
@@ -1197,16 +1230,24 @@ int main(int argc, char *argv[])
 		family = AF_INET;
 
 	cmd = bit2cmd(command);
-	generic_opt_check(options,
-			  NUMBER_OF_OPT,
-			  commands_v_options[cmd],
-			  optflags);
-
-	if (command & (CT_CREATE|CT_GET) &&
-	    !((options & CT_OPT_ORIG_SRC && options & CT_OPT_ORIG_DST) ||
-	      (options & CT_OPT_REPL_SRC && options & CT_OPT_REPL_DST)))
-	      exit_error(PARAMETER_PROBLEM, "missing IP address");
-
+	res = generic_opt_check(options, NUMBER_OF_OPT,
+				commands_v_options[cmd], optflags,
+				addr_valid_flags, ADDR_VALID_FLAGS_MAX,
+				&partial);
+	if (!res) {
+		switch(partial) {
+		case -1:
+		case 0:
+			exit_error(PARAMETER_PROBLEM, "you have to specify "
+						      "`--src' and `--dst'");
+			break;
+		case 1:
+			exit_error(PARAMETER_PROBLEM, "you have to specify "
+						      "`--reply-src' and "
+						      "`--reply-dst'");
+			break;
+		}
+	}
 	if (!(command & CT_HELP) && h && h->final_check)
 		h->final_check(l4flags, cmd, obj);