nettrace: various fixes

1 files changed, 27 insertions, 6 deletions

diff --git a/src/fnettrace-dns/main.c b/src/fnettrace-dns/main.c
index eb2eb7238..32122754f 100644
--- a/src/fnettrace-dns/main.c
+++ b/src/fnettrace-dns/main.c
@@ -22,6 +22,8 @@
 #include <time.h>
 #include <linux/filter.h>
 #include <linux/if_ether.h>
+#include <sys/prctl.h>
+#include <signal.h>
 #define MAX_BUF_SIZE (64 * 1024)
 
 static char last[512] = {'\0'};
@@ -106,6 +108,18 @@ static void custom_bpf(int sock) {
         }
 }
 
+static void print_date(void) {
+        static int day = -1;
+        time_t now = time(NULL);
+        struct tm *t = localtime(&now);
+
+        if (day != t->tm_yday) {
+                printf("\nDNS trace for %s", ctime(&now));
+                day = t->tm_yday;
+        }
+        fflush(0);
+}
+
 static void run_trace(void) {
         // grab all Ethernet packets and use a custom BPF filter to get only UDP from source port 53
         int s = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
@@ -113,19 +127,24 @@ static void run_trace(void) {
                 errExit("socket");
         custom_bpf(s);
 
+        struct timeval tv;
+        tv.tv_sec = 10;
+        tv.tv_usec = 0;
         unsigned char buf[MAX_BUF_SIZE];
         while (1) {
                 fd_set rfds;
                 FD_ZERO(&rfds);
                 FD_SET(s, &rfds);
-                struct timeval tv;
-                tv.tv_sec = 1;
-                tv.tv_usec = 0;
                 int rv = select(s + 1, &rfds, NULL, NULL, &tv);
                 if (rv < 0)
                         errExit("select");
-                else if (rv == 0)
+                else if (rv == 0) {
+                        print_date();
+                        tv.tv_sec = 10;
+                        tv.tv_usec = 0;
                         continue;
+                }
+
                 unsigned bytes = recvfrom(s, buf, MAX_BUF_SIZE, 0, NULL, NULL);
 
                 if (bytes >= (14 + 20 + 8)) { // size of  MAC + IP + UDP headers
@@ -174,8 +193,10 @@ int main(int argc, char **argv) {
                 return 1;
         }
 
-        time_t now = time(NULL);
-        printf("DNS trace for %s\n", ctime(&now));
+        // kill the process if the parent died
+        prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0);
+
+        print_date();
         run_trace();
 
         return 0;