Add output format advice

Author: sfan5

src/binary-read.c

@@ -29,8 +29,9 @@ int binary_read_header(struct reader *r, FILE *f)
 	skip_align(f, sizeof(h));
 
 	if(h.magic != FILE_MAGIC) {
+		log_error("File header not found or incorrect.");
 		if(h.magic == bswap(FILE_MAGIC))
-			log_error("This file was created on a system of differing endianness, reading it is not (yet) supported.");
+			log_raw("This file was created on a system of differing endianness, reading it is not (yet) supported.");
 		return -1;
 	}
 	if(h.version != 1) {

src/main.c

@@ -19,6 +19,7 @@
 static int read_targets_from_file(const char *filename, int stream_targets);
 static void usage(void);
 static inline bool is_all_ff(const uint8_t *buf, int len);
+static inline char *find_dot(char *str);
 
 enum operating_mode {
 	M_SCAN, M_PRINT_HOSTS,
@@ -75,7 +76,7 @@ int main(int argc, char *argv[])
 	ip_type = IP_TYPE_TCP;
 	interface = NULL; // automatically picked
 	outfile = stdout;
-	outdef = &output_list;
+	outdef = NULL;
 
 	srand(time(NULL) ^ getpid());
 	memset(source_mac, 0xff, 6);
@@ -208,6 +209,18 @@ int main(int argc, char *argv[])
 					perror("open output file");
 					return 1;
 				}
+				char *dot = find_dot(optarg);
+				if(!outdef && dot) {
+					const char *suggest = NULL;
+					if(!strcmp(dot+1, "bin"))
+						suggest = "binary";
+					else if(!strcmp(dot+1, "json"))
+						suggest = "json";
+					if(suggest) {
+						log_warning("It looks like you might want a different "
+							"output format, try --output-format %s.", suggest);
+					}
+				}
 				outfile = f;
 				break;
 			}
@@ -226,6 +239,9 @@ int main(int argc, char *argv[])
 		}
 	}
 
+	if(!outdef)
+		outdef = &output_list;
+
 	int max_args = 1;
 	if(mode == M_READSCAN) {
 		max_args = 0;
@@ -553,3 +569,15 @@ static inline bool is_all_ff(const uint8_t *buf, int len)
 	}
 	return true;
 }
+
+static inline char *find_dot(char *str)
+{
+	char *p = str + strlen(str);
+	do {
+		if(*p == '/')
+			break;
+		if(*p == '.')
+			return p;
+	} while((p--) > str);
+	return NULL;
+}