Fix timestamp buffer segmentation fault in recv_packet

packet-exchange/src/common.h

@@ -18,6 +18,8 @@
 
 #define MAX_BUFFER_SIZE 1024
 
+#define TIMESTAMP_BUFFER_SIZE 64
+
 uint64_t ts_to_uint(struct timespec t);
 void add_ns(struct timespec *t, uint64_t ns);
 uint64_t calcdiff_ns(struct timespec t1, struct timespec t2);

packet-exchange/src/recv_packet.c

@@ -39,7 +39,7 @@ static ingress_stat_t *stats;
 static uint64_t *kernel_latency_hist;
 static int use_histogram;
 
-static uint64_t timestamps_buffer[64];
+static uint64_t timestamps_buffer[TIMESTAMP_BUFFER_SIZE];
 static int ts_buf_read_index = 0;
 static int ts_buf_write_index = 0;
 
@@ -132,7 +132,8 @@ void recv_udp_packet() {
 
   if (params->use_timestamps) {
     clock_gettime(CLOCK_REALTIME, &ts);
-    timestamps_buffer[ts_buf_write_index++] = ts_to_uint(ts);
+    timestamps_buffer[ts_buf_write_index] = ts_to_uint(ts);
+    ts_buf_write_index = (ts_buf_write_index + 1) % TIMESTAMP_BUFFER_SIZE;
   }
 
   iov.iov_base = &rx_buffer;
@@ -156,7 +157,8 @@ void recv_udp_packet() {
 
         struct timespec *stamp = (struct timespec *)CMSG_DATA(cmsg);
 
-        uint64_t kernel_latency = timestamps_buffer[ts_buf_read_index++] - ts_to_uint(*stamp);
+        uint64_t kernel_latency = timestamps_buffer[ts_buf_read_index] - ts_to_uint(*stamp);
+        ts_buf_read_index = (ts_buf_read_index + 1) % TIMESTAMP_BUFFER_SIZE;
         kernel_latency /= 1000u;
 
         stats->min_kernel_latency = min(kernel_latency, stats->min_kernel_latency);

packet-exchange/src/send_packet.c

@@ -37,8 +37,6 @@
 #include "common.h"
 #include "send_packet.h"
 
-#define TIMESTAMP_BUFFER_SIZE 64
-
 static void *poll_thread(void *p);
 static void process_error_queue();