Bug #863: implement tcpr_pcap_open() universally

Add macros that can properly convert between PCAP timestamps and timespec/timeval.

We still use pcap_open_offline() for tcprewrite.c, otherwise tests fail because timestamps get written inconsistently across libpcap versions.

Also fix multiplier calculation error.

configure.ac

@@ -1216,6 +1216,11 @@ AC_LINK_IFELSE([AC_LANG_PROGRAM([[
 
 if test $have_pcap_open_offline_with_tstamp_precision = yes ; then
     AC_DEFINE([HAVE_PCAP_OPEN_OFFLINE_WITH_TSTAMP_PRECISION], [1], [Does libpcap have pcap_open_offline_with_tstamp_precision?])
+    AC_DEFINE([PCAP_TSTAMP_US_TO_NS_MULTIPLIER], [1], [Multiplier for conversion from PCAP usec to nsec])
+    AC_DEFINE([PCAP_TSTAMP_US_TO_US_DIVISOR], [1000], [Divisor for conversion from PCAP usec to usec])
+else
+   AC_DEFINE([PCAP_TSTAMP_US_TO_NS_MULTIPLIER], [1000], [Multiplier for conversion from PCAP usec to nsec])
+   AC_DEFINE([PCAP_TSTAMP_US_TO_US_DIVISOR], [1], [Divisor for conversion from PCAP usec to usec])
 fi
 
 

docs/CHANGELOG

@@ -1,4 +1,5 @@
 06/01/2024 Version 4.5.0-beta1
+    - fix nansecond timestamp regression bug (#863)
     - --fixhdrlen option added to control action on packet length changes (#846)
     - incorrect checksum for certain IPv4 packets - fixed by #846 (#844)
     - add check for IPv6 extension header length (#827 #842)

src/common/fakepcapnav.c

@@ -26,6 +26,7 @@
 #include "defines.h"
 #include "config.h"
 #include "common.h"
+#include "utils.h"
 #include <stdlib.h>
 
 #ifndef HAVE_PCAPNAV
@@ -52,7 +53,7 @@ pcapnav_open_offline(const char *filename)
         err(-1, "malloc() error: unable to malloc pcapnav_t");
     }
 
-    pcapnav->pcap = pcap_open_offline(filename, errbuf);
+    pcapnav->pcap = tcpr_pcap_open(filename, errbuf);
     if (pcapnav->pcap == NULL) {
         errx(-1, "Error opening pcap file %s: %s", filename, errbuf);
     }

src/common/tcpdump.c

@@ -75,7 +75,7 @@ tcpdump_print(tcpdump_t *tcpdump, struct pcap_pkthdr *pkthdr, const u_char *data
 
     /* convert header to file-format packet header */
     actual_pkthdr.ts.ts_sec = (uint32_t)pkthdr->ts.tv_sec;
-    actual_pkthdr.ts.ts_usec = (uint32_t)pkthdr->ts.tv_sec;
+    actual_pkthdr.ts.ts_usec = (uint32_t)(pkthdr->ts.tv_usec / PCAP_TSTAMP_US_TO_US_DIVISOR);
     actual_pkthdr.caplen = pkthdr->caplen;
     actual_pkthdr.len = pkthdr->len;
 

src/common/utils.c

@@ -97,6 +97,17 @@ our_safe_strdup(const char *str, const char *funcname, int line, const char *fil
     return newstr;
 }
 
+pcap_t*
+tcpr_pcap_open(const char *path, char *ebuf)
+{
+#ifdef HAVE_PCAP_OPEN_OFFLINE_WITH_TSTAMP_PRECISION
+    return pcap_open_offline_with_tstamp_precision(path, PCAP_TSTAMP_PRECISION_NANO, ebuf);
+#else
+    return pcap_open_offline(path, ebuf);
+#endif
+}
+
+
 /**
  * calls free and sets to NULL.
  */

src/common/utils.h

@@ -47,6 +47,7 @@ void packet_stats(const tcpreplay_stats_t *stats);
 int format_date_time(struct timespec *when, char *buf, size_t len);
 uint32_t tcpr_random(uint32_t *seed);
 void restore_stdin(void);
+pcap_t* tcpr_pcap_open(const char *path, char *ebuf);
 
 /* our "safe" implimentations of functions which allocate memory */
 #define safe_malloc(x) our_safe_malloc(x, __FUNCTION__, __LINE__, __FILE__)

src/defines.h.in

@@ -359,14 +359,24 @@ typedef u_int8_t uint8_t typedef u_int16_t uint16_t typedef u_int32_t uint32_t
         (a)->tv_nsec = (b)->tv_nsec;                                                                                   \
     } while (0)
 
-/* libpcap puts nanosec values in tv_usec when pcap file is read with nanosec precision*/
-#define TIMEVAL_AS_TIMESPEC_SET(a, b)       \
-    do {                                    \
-        (a)->tv_sec = (b)->tv_sec;          \
-        (a)->tv_nsec = (b)->tv_usec * 1000; \
+/* libpcap that supports it, puts nanosecond values in tv_usec when pcap file is read with nanosec precision,
+ * and so tv_usec is directly copied to tv_nsec.
+ * But older versions do that do not support nanosecond precision need to multiply tv_usec by 1000 to convert
+ * to tv_nsec.
+ */
+#define PCAP_TIMEVAL_TO_TIMESPEC_SET(a, b)                              \
+    do {                                                                \
+        (b)->tv_sec = (a)->tv_sec;                                      \
+        (b)->tv_nsec = (a)->tv_usec * PCAP_TSTAMP_US_TO_NS_MULTIPLIER;  \
+    } while(0)
+
+#define PCAP_TIMEVAL_TO_TIMEVAL_SET(a, b)                               \
+    do {                                                                \
+        (b)->tv_sec = (a)->tv_sec;                                      \
+        (b)->tv_usec = (a)->tv_usec / PCAP_TSTAMP_US_TO_US_DIVISOR;     \
     } while(0)
 
-/* 
+/*
  * Help suppress some compiler warnings
  * No problem if variable is actually used 
 */

src/replay.c

@@ -98,16 +98,6 @@ tcpr_replay_index(tcpreplay_t *ctx)
     return rcode;
 }
 
-static pcap_t *
-tcpr_pcap_open(const char *path, char *ebuf)
-{
-#ifdef HAVE_PCAP_OPEN_OFFLINE_WITH_TSTAMP_PRECISION
-    return pcap_open_offline_with_tstamp_precision(path, PCAP_TSTAMP_PRECISION_NANO, ebuf);
-#else
-    return pcap_open_offline(path, ebuf);
-#endif
-}
-
 /**
  * \brief replay a pcap file out interface(s)
  *

src/send_packets.c

@@ -299,7 +299,7 @@ preload_pcap_file(tcpreplay_t *ctx, int idx)
         if (close(1) == -1)
             warnx("unable to close stdin: %s", strerror(errno));
 
-    if ((pcap = pcap_open_offline(path, ebuf)) == NULL)
+    if ((pcap = tcpr_pcap_open(path, ebuf)) == NULL)
         errx(-1, "Error opening pcap file: %s", ebuf);
 
     dlt = pcap_datalink(pcap);
@@ -388,7 +388,7 @@ send_packets(tcpreplay_t *ctx, pcap_t *pcap, int idx)
     while (!ctx->abort && read_next_packet &&
            (pktdata = get_next_packet(options, pcap, &pkthdr, idx, prev_packet)) != NULL) {
         struct timespec pkthdr_ts;
-        TIMEVAL_AS_TIMESPEC_SET(&pkthdr_ts, &pkthdr.ts); // libpcap puts nanosec values in tv_usec
+        PCAP_TIMEVAL_TO_TIMESPEC_SET(&pkthdr.ts, &pkthdr_ts);
         now_is_now = false;
         packetnum++;
 #if defined TCPREPLAY || defined TCPREPLAY_EDIT
@@ -739,9 +739,9 @@ send_dual_packets(tcpreplay_t *ctx, pcap_t *pcap1, int cache_file_idx1, pcap_t *
 
             if (options->speed.mode == speed_multiplier) {
                 struct timespec pkthdr_ts;
-                TIMEVAL_TO_TIMESPEC(&pkthdr_ptr->ts, &pkthdr_ts);
+                PCAP_TIMEVAL_TO_TIMESPEC_SET(&pkthdr_ptr->ts, &pkthdr_ts);
                 if (!timesisset(&last_pkt_ts)) {
-                    TIMEVAL_TO_TIMESPEC(&pkthdr_ptr->ts, &last_pkt_ts);
+                    PCAP_TIMEVAL_TO_TIMESPEC_SET(&pkthdr_ptr->ts, &last_pkt_ts);
                 } else if (timescmp(&pkthdr_ts, &last_pkt_ts, >)) {
                     struct timespec delta;
 

src/tcpprep.c

@@ -91,7 +91,7 @@ main(int argc, char *argv[])
 
 readpcap:
     /* open the pcap file */
-    if ((options->pcap = pcap_open_offline(OPT_ARG(PCAP), errbuf)) == NULL) {
+    if ((options->pcap = tcpr_pcap_open(OPT_ARG(PCAP), errbuf)) == NULL) {
         close(out_file);
         tcpprep_close(tcpprep);
         errx(-1, "Error opening libpcap: %s", errbuf);