Fix minor bugs

ChangeLog

@@ -1,6 +1,7 @@
 2018-04-20
 - Fix bug in sorting when guessing flow direction. Issue #92
 - Update nfdump.1 man page for xsrcport & xdstport aggregations. Request #109
+- Fix minor bugs
 
 2018-04-01
 - Add program exit in nfx.c after panic with correupt data file

bin/grammar.y

@@ -1607,7 +1607,7 @@ term:	ANY { /* this is an unconditionally true expression, as a filter applies i
 			uint64_t mask;
 			uint32_t offset, shift;
 			char *s = &$2[5];
-			if ( s == '\0' ) {
+			if ( *s == '\0' ) {
 				yyerror("Missing label number");
 				YYABORT;
 			}
@@ -1678,7 +1678,7 @@ term:	ANY { /* this is an unconditionally true expression, as a filter applies i
 			uint64_t mask;
 			uint32_t offset, shift;
 			char *s = &$2[3];
-			if ( s == '\0' ) {
+			if ( *s == '\0' ) {
 				yyerror("Missing label number");
 				YYABORT;
 			}

bin/nf_common.c

@@ -2389,7 +2389,7 @@ static void String_Flags(master_record_t *r, char *string) {
 
 	// if record contains unusuall flags, print the flags in hex as 0x.. number
 	if ( r->tcp_flags > 63 ) {
-		snprintf(string, 7, "  0x%2x\n", r->tcp_flags );
+		snprintf(string, 7, "  0x%2x", r->tcp_flags );
 	} else {
 		string[0] = r->tcp_flags & 32 ? 'U' : '.';
 		string[1] = r->tcp_flags & 16 ? 'A' : '.';

bin/nfdump.c

@@ -1053,6 +1053,11 @@ char 		Ident[IDENTLEN];
 			print_format = DefaultMode;
 	}
 
+	// limit input chars
+	if ( strlen(print_format) > 512 ) {
+		LogError("Length of ouput format string too big - > 512\n");
+		exit(255);
+	}
 	if ( strncasecmp(print_format, "fmt:", 4) == 0 ) {
 		// special user defined output format
 		char *format = &print_format[4];