Add test case: inject IPv4 based TCP payload packet after recv C2S first payload

src/stellar/inject.cpp

@@ -1,3 +1,4 @@
+#include <time.h>
 #include <errno.h>
 #include <assert.h>
 
@@ -209,7 +210,10 @@ static inline void calc_tcp_fingerprint(struct tcp_fingerprint *finger)
 {
 #define RANGE(rand, start, end) (start + rand % (end - start + 1)) // [start, end]
 
-    uint64_t random = 0x013579ABCDEF ^ stellar_get_monotonic_time_msec();
+    struct timespec time;
+    clock_gettime(CLOCK_MONOTONIC, &time);
+
+    uint64_t random = 0x013579ABCDEF ^ time.tv_nsec;
     finger->ipid = (uint16_t)(RANGE(random, 32767, 65535));
     finger->ttl = (uint8_t)(RANGE(random, 48, 120));
     finger->win = (uint16_t)(RANGE(random, 1000, 1460));