xmdp add scan time key (#636)

Thank you !

general/package/xmdp/src/Makefile

@@ -1,4 +1,4 @@
-CFLAGS=-Wall -Wpedantic
+CFLAGS=-Os -Wall -Wpedantic
 LDFLAGS=-lm
 
 all: xmdp

general/package/xmdp/src/xmdp.c

@@ -2,6 +2,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <time.h>
 
 #include <arpa/inet.h>
 #include <netdb.h>
@@ -21,6 +22,8 @@
 
 #define MIN(x, y) ((x) < (y) ? (x) : (y))
 
+static int scansec = 0;
+
 const char brpkt[] =
     "\xff\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xfa\x05"
     "\x00\x00\x00\x00";
@@ -91,7 +94,10 @@ void sigalarm(int sig) {
   }
 }
 
-int main() {
+int scan() {
+  time_t start, current;
+  start = time(NULL);
+
   bsock = socket(AF_INET, SOCK_DGRAM, 0);
   if (bsock == -1) {
     perror("socket");
@@ -128,6 +134,12 @@ int main() {
   uint32_t *seen_vec = malloc(seen_cap * sizeof(*seen_vec));
 
   while (1) {
+	current = time(NULL);
+
+	if ((scansec > 0) && (current-start > scansec)) {
+	  exit(EXIT_SUCCESS);
+	}
+
     char buf[1024];
     struct sockaddr_in their_addr;
     socklen_t addr_len = sizeof their_addr;
@@ -226,3 +238,18 @@ int main() {
 
   free(seen_vec);
 }
+
+int main(int argc, char *argv[]) {
+    int opt;
+    while ((opt = getopt(argc, argv, "t:")) != -1) {
+        switch (opt) {
+		case 't':
+			scansec = atoi(optarg);
+			break;
+		default:
+			printf("Usage: %s [-t seconds]\n", argv[0]);
+			exit(EXIT_FAILURE);
+		}
+	}
+  	return scan();
+}