Bug #703 #844 PR #846: optionally fix packet header length --fixhdrlen

.github/workflows/github-actions-ci.yml

@@ -28,5 +28,5 @@ jobs:
       - name: List files in the repository
         run: ls ${{ github.workspace }}
       - name: tests
-        run: sudo make test
+        run: sudo make test || cat test/test.log
       - run: echo "This test's status is ${{ job.status }}."

configure.ac

@@ -1194,6 +1194,30 @@ if test $have_pcap_snapshot = yes ; then
               [Does libpcap have pcap_snapshot?])
 fi
 
+have_pcap_open_offline_with_tstamp_precision=no
+dnl Check to see if we've got pcap_open_offline_with_tstamp_precision()
+AC_MSG_CHECKING(for pcap_open_offline_with_tstamp_precision support)
+AC_LINK_IFELSE([AC_LANG_PROGRAM([[
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "$LPCAPINC"
+]],[[
+    pcap_t *pcap;
+    char ebuf[PCAP_ERRBUF_SIZE];
+    pcap = pcap_open_offline_with_tstamp_precision("fake.pcap", PCAP_TSTAMP_PRECISION_NANO, &ebuf[0]);
+]])],[
+    have_pcap_open_offline_with_tstamp_precision=yes
+    AC_MSG_RESULT(yes)
+], [
+    have_pcap_open_offline_with_tstamp_precision=no
+    AC_MSG_RESULT(no)
+])
+
+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?])
+fi
+
 
 # Tcpbridge requires libpcap and pcap_sendpacket()
 enable_tcpbridge=no

docs/CHANGELOG

@@ -1,4 +1,6 @@
 06/01/2024 Version 4.5.0-beta1
+    - --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)
     - add check for empty CIDR (#824 #843)
     - GitHub template for pull requests (#839)

docs/CREDIT

@@ -123,7 +123,8 @@ GithHub @plangarbalint
 
 Chuck Cottrill <GitHub @ChuckCottrill>
     - handle IPv6 fragment extensions
-
+    - --fixhdrlen option
+    - bug fixes
 
 Martin 'JaMa' Jansa <GitHub @shr-project>
     - configure.ac: unify search dirs for pcap and add lib32

lib/sll.h

@@ -77,7 +77,8 @@
 #ifndef _SLL_H_
 #define _SLL_H_
 
-#include <pcap/pcap-inttypes.h>
+//#include <pcap/pcap-inttypes.h>
+#include <inttypes.h>
 
 /*
  * A DLT_LINUX_SLL fake link-layer header.
@@ -86,11 +87,11 @@
 #define SLL_ADDRLEN    8            /* length of address field */
 
 struct sll_header {
     u_int16_t sll_pkttype;          /* packet type */
     u_int16_t sll_hatype;           /* link-layer address type */
     u_int16_t sll_halen;            /* link-layer address length */
     u_int8_t sll_addr[SLL_ADDRLEN]; /* link-layer address */
     u_int16_t sll_protocol;         /* protocol */
 };
 
 /*
@@ -99,11 +100,11 @@
 #define SLL2_HDR_LEN    20              /* total header length */
 
 struct sll2_header {
     u_int16_t sll2_protocol;            /* protocol */
     u_int16_t sll2_reserved_mbz;        /* reserved - must be zero */
     u_int32_t sll2_if_index;            /* 1-based interface index */
     u_int16_t sll2_hatype;              /* link-layer address type */
     u_int8_t  sll2_pkttype;             /* packet type */
     u_int8_t  sll2_halen;               /* link-layer address length */
     u_int8_t  sll2_addr[SLL_ADDRLEN];   /* link-layer address */
 };

src/defines.h.in

@@ -363,7 +363,7 @@ typedef u_int8_t uint8_t typedef u_int16_t uint16_t typedef u_int32_t uint32_t
 #define TIMEVAL_AS_TIMESPEC_SET(a, b)       \
     do {                                    \
         (a)->tv_sec = (b)->tv_sec;          \
-        (a)->tv_nsec = (b)->tv_usec;        \
+        (a)->tv_nsec = (b)->tv_usec * 1000; \
     } while(0)
 
 /* 

src/replay.c

@@ -98,13 +98,23 @@
     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)
  *
  * Internal to tcpreplay.  Does the heavy lifting.
  */
 static int
 replay_file(tcpreplay_t *ctx, int idx)
 {
     char *path;
     pcap_t *pcap = NULL;
@@ -117,7 +127,7 @@
 
     /* read from pcap file if we haven't cached things yet */
     if (!ctx->options->preload_pcap) {
-        if ((pcap = pcap_open_offline_with_tstamp_precision(path, PCAP_TSTAMP_PRECISION_NANO, ebuf)) == NULL) {
+        if ((pcap = tcpr_pcap_open(path, ebuf)) == NULL) {
             tcpreplay_seterr(ctx, "Error opening pcap file: %s", ebuf);
             return -1;
         }
@@ -133,7 +143,7 @@
 
     } else {
         if (!ctx->options->file_cache[idx].cached) {
-            if ((pcap = pcap_open_offline_with_tstamp_precision(path, PCAP_TSTAMP_PRECISION_NANO, ebuf)) == NULL) {
+            if ((pcap = tcpr_pcap_open(path, ebuf)) == NULL) {
                 tcpreplay_seterr(ctx, "Error opening pcap file: %s", ebuf);
                 return -1;
             }
@@ -145,7 +155,7 @@
     if (ctx->options->verbose) {
         /* in cache mode, we may not have opened the file */
         if (pcap == NULL)
-            if ((pcap = pcap_open_offline_with_tstamp_precision(path, PCAP_TSTAMP_PRECISION_NANO, ebuf)) == NULL) {
+            if ((pcap = tcpr_pcap_open(path, ebuf)) == NULL) {
                 tcpreplay_seterr(ctx, "Error opening pcap file: %s", ebuf);
                 return -1;
             }
@@ -192,7 +202,7 @@
  * Internal to tcpreplay, does the heavy lifting for --dualfile
  */
 static int
 replay_two_files(tcpreplay_t *ctx, int idx1, int idx2)
 {
     char *path1, *path2;
     pcap_t *pcap1 = NULL, *pcap2 = NULL;
@@ -214,26 +224,26 @@
 
     /* read from first pcap file if we haven't cached things yet */
     if (!ctx->options->preload_pcap) {
-        if ((pcap1 = pcap_open_offline(path1, ebuf)) == NULL) {
+        if ((pcap1 = tcpr_pcap_open(path1, ebuf)) == NULL) {
             tcpreplay_seterr(ctx, "Error opening pcap file: %s", ebuf);
             return -1;
         }
         ctx->options->file_cache[idx1].dlt = pcap_datalink(pcap1);
-        if ((pcap2 = pcap_open_offline(path2, ebuf)) == NULL) {
+        if ((pcap2 = tcpr_pcap_open(path2, ebuf)) == NULL) {
             tcpreplay_seterr(ctx, "Error opening pcap file: %s", ebuf);
             return -1;
         }
         ctx->options->file_cache[idx2].dlt = pcap_datalink(pcap2);
     } else {
         if (!ctx->options->file_cache[idx1].cached) {
-            if ((pcap1 = pcap_open_offline(path1, ebuf)) == NULL) {
+            if ((pcap1 = tcpr_pcap_open(path1, ebuf)) == NULL) {
                 tcpreplay_seterr(ctx, "Error opening pcap file: %s", ebuf);
                 return -1;
             }
             ctx->options->file_cache[idx1].dlt = pcap_datalink(pcap1);
         }
         if (!ctx->options->file_cache[idx2].cached) {
-            if ((pcap2 = pcap_open_offline(path2, ebuf)) == NULL) {
+            if ((pcap2 = tcpr_pcap_open(path2, ebuf)) == NULL) {
                 tcpreplay_seterr(ctx, "Error opening pcap file: %s", ebuf);
                 return -1;
             }
@@ -293,7 +303,7 @@
     if (ctx->options->verbose) {
         /* in cache mode, we may not have opened the file */
         if (pcap1 == NULL) {
-            if ((pcap1 = pcap_open_offline(path1, ebuf)) == NULL) {
+            if ((pcap1 = tcpr_pcap_open(path1, ebuf)) == NULL) {
                 tcpreplay_seterr(ctx, "Error opening pcap file: %s", ebuf);
                 return -1;
             }

src/tcpedit/edit_packet.c

@@ -78,12 +78,13 @@ fix_ipv4_checksums(tcpedit_t *tcpedit, struct pcap_pkthdr *pkthdr, ipv4_hdr_t *i
     /* calc the L4 checksum if we have the whole packet && not a frag or first frag */
     if (pkthdr->caplen == pkthdr->len && (htons(ip_hdr->ip_off) & (IP_MF | IP_OFFMASK)) == 0) {
         if (ip_len != (int)(pkthdr->caplen - l2len)) {
-            tcpedit_seterr(tcpedit,
-                           "caplen minus L2 length %u does IPv4 header length %u: pkt=" COUNTER_SPEC,
-                           pkthdr->caplen - l2len,
-                           ip_len,
-                           tcpedit->runtime.packetnum);
-            return TCPEDIT_ERROR;
+            tcpedit_setwarn(tcpedit,
+                            "skipping packet " COUNTER_SPEC " because caplen %u minus L2 length %u does not equal IPv4 header length %u. Consider option '--fixhdrlen'.",
+                            tcpedit->runtime.packetnum,
+                            pkthdr->caplen,
+                            l2len,
+                            ip_len);
+            return TCPEDIT_WARN;
         }
         ret1 = do_checksum(tcpedit,
                            (u_char *)ip_hdr,

src/tcpedit/parse_args.c

@@ -95,6 +95,10 @@ tcpedit_post_args(tcpedit_t *tcpedit)
     if (HAVE_OPT(FIXCSUM))
         tcpedit->fixcsum = true;
 
+    /* --fixhdrlen */
+    if (HAVE_OPT(FIXHDRLEN))
+        tcpedit->fixhdrlen = true;
+
     /* --efcs */
     if (HAVE_OPT(EFCS))
         tcpedit->efcs = true;

src/tcpedit/tcpedit.c

@@ -44,7 +44,7 @@
  *          1 on change
  */
 int
 tcpedit_packet(tcpedit_t *tcpedit, struct pcap_pkthdr **pkthdr, u_char **pktdata, tcpr_dir_t direction)
 {
     bool fuzz_once = tcpedit->fuzz_seed != 0;
     ipv4_hdr_t *ip_hdr;
@@ -315,12 +315,20 @@
         }
     }
 
-    /* ensure IP header length is correct */
-    if (ip_hdr != NULL) {
-        fix_ipv4_length(*pkthdr, ip_hdr, l2len);
-        needtorecalc = 1;
-    } else if (ip6_hdr != NULL) {
-        needtorecalc |= fix_ipv6_length(*pkthdr, ip6_hdr, l2len);
+    /* fixhdrlen option ensure IP header length is correct */
+    /* do we need to fix checksums? -- must always do this last! */
+    if (tcpedit->fixhdrlen) {
+        /* ensure IP header length is correct */
+        int changed = 0;
+        if (ip_hdr != NULL) {
+            changed = fix_ipv4_length(*pkthdr, ip_hdr, l2len);
+        } else if (ip6_hdr != NULL) {
+            changed = fix_ipv6_length(*pkthdr, ip6_hdr, l2len);
+        }
+        /* did the packet change? then needtorecalc checksum */
+        if (changed > 0) {
+            needtorecalc |= changed;
+        }
     }
 
     /* do we need to fix checksums? -- must always do this last! */

src/tcpedit/tcpedit_api.c

@@ -136,6 +136,17 @@ tcpedit_set_fixcsum(tcpedit_t *tcpedit, bool value)
     return TCPEDIT_OK;
 }
 
+/**
+ * \brief should we fix(?) header length?
+ */
+int
+tcpedit_set_fixhdrlen(tcpedit_t *tcpedit, bool value)
+{
+    assert(tcpedit);
+    tcpedit->fixhdrlen = value;
+    return TCPEDIT_OK;
+}
+
 /**
  * \brief should we remove the EFCS from the frame?
  */

src/tcpedit/tcpedit_api.h

@@ -40,6 +40,7 @@ int tcpedit_set_encoder_dltplugin_byname(tcpedit_t *, const char *);
 int tcpedit_set_skip_broadcast(tcpedit_t *, bool);
 int tcpedit_set_fixlen(tcpedit_t *, tcpedit_fixlen);
 int tcpedit_set_fixcsum(tcpedit_t *, bool);
+int tcpedit_set_fixhdrlen(tcpedit_t *, bool);
 int tcpedit_set_efcs(tcpedit_t *, bool);
 int tcpedit_set_ttl_mode(tcpedit_t *, tcpedit_ttl_mode);
 int tcpedit_set_ttl_value(tcpedit_t *, uint8_t);

src/tcpedit/tcpedit_opts.def

@@ -170,6 +170,18 @@ fixed.  Automatically enabled for packets modified with @samp{--seed},
 EOText;
 };
 
+flag = {
+    name        = fixhdrlen;
+    descrip     = "Alter IP/TCP header len to match packet length";
+    doc         = <<- EOText
+By default, tcpreplay will send packets with the original packet length,
+However, you may want the packet length revised to minimum packet size.
+Using this option, tcpreplay will rewrite (fix) the packet length,
+and recalculate checksums when packet length changes.
+Caution: undesired packet changes may occur when this option is specified.
+EOText;
+};
+
 flag = {
     name        = mtu;
     value       = m;

src/tcpedit/tcpedit_types.h

@@ -147,6 +147,9 @@ typedef struct {
 
     uint32_t fuzz_seed;
     uint32_t fuzz_factor;
+
+    /* fix header length */
+    bool fixhdrlen;
 } tcpedit_t;
 
 #ifdef __cplusplus

src/tcpreplay_api.h

@@ -187,6 +187,9 @@ typedef struct tcpreplay_s {
     uint32_t skip_packets;
     bool first_time;
 
+    /* fix header length */
+    bool fixhdrlen;
+
     /* counter stats */
     tcpreplay_stats_t stats;
     tcpreplay_stats_t static_stats; /* stats returned by tcpreplay_get_stats() */

test/Makefile.am

@@ -25,18 +25,22 @@ EXTRA_DIST = test.pcap test.auto_bridge test.auto_client test.auto_router \
 		test.rewrite_pnat test.rewrite_pad test.rewrite_trunc \
 		test.rewrite_mac test.rewrite_layer2 test.rewrite_config \
 		test.rewrite_skip test.rewrite_dltuser test.rewrite_dlthdlc \
-		test.rewrite_vlan802.1ad test.rewrite_vlandel test.rewrite_efcs test.rewrite_1ttl \
-		test.rewrite_2ttl test.rewrite_3ttl test.rewrite_enet_subsmac \
+		test.rewrite_vlan802.1ad test.rewrite_vlandel test.rewrite_efcs \
+		test.rewrite_1ttl test.rewrite_2ttl test.rewrite_3ttl \
+		test.rewrite_1ttl-hdrfix test.rewrite_2ttl-hdrfix test.rewrite_3ttl-hdrfix \
+		test.rewrite_enet_subsmac \
 		test.rewrite_mtutrunc test.rewrite_mac_seed test.rewrite_range_portmap \
 		test.rewrite_mac_seed_keep test.rewrite_l7fuzzing test.rewrite_sequence test.rewrite_fixcsum \
 		test.rewrite_fixlen_pad test.rewrite_fixlen_trunc test.rewrite_fixlen_del \
 		test2.rewrite_seed test2.rewrite_portmap test2.rewrite_endpoint \
 		test2.rewrite_pnat test2.rewrite_pad test2.rewrite_trunc \
 		test2.rewrite_mac test2.rewrite_layer2 test2.rewrite_config \
 		test2.rewrite_skip test2.rewrite_dltuser test2.rewrite_dlthdlc \
-		test2.rewrite_vlan802.1ad test2.rewrite_vlandel test2.rewrite_efcs test2.rewrite_1ttl \
+		test2.rewrite_vlan802.1ad test2.rewrite_vlandel test2.rewrite_efcs \
+		test2.rewrite_1ttl test2.rewrite_2ttl test2.rewrite_3ttl \
+		test2.rewrite_1ttl-hdrfix test2.rewrite_2ttl-hdrfix test2.rewrite_3ttl-hdrfix \
 		test2.rewrite_mtutrunc test2.rewrite_enet_subsmac \
-		test2.rewrite_2ttl test2.rewrite_3ttl test.rewrite_tos test2.rewrite_tos \
+		 test.rewrite_tos test2.rewrite_tos \
 		test2.rewrite_enet_subsmac test2.rewrite_mac_seed \
 		test2.rewrite_range_portmap test2.rewrite_mac_seed_keep \
 		test2.rewrite_l7fuzzing test2.rewrite_sequence test2.rewrite_fixcsum \
@@ -125,6 +129,9 @@ standard_bigendian:
 	$(TCPREWRITE) -i $(TEST_PCAP) -o test.rewrite_1ttl --ttl=58
 	$(TCPREWRITE) -i $(TEST_PCAP) -o test.rewrite_2ttl --ttl=+58
 	$(TCPREWRITE) -i $(TEST_PCAP) -o test.rewrite_3ttl --ttl=-58
+	$(TCPREWRITE) -i $(TEST_PCAP) -o test.rewrite_1ttl-hdrfix --ttl=59 --fixhdrlen
+	$(TCPREWRITE) -i $(TEST_PCAP) -o test.rewrite_2ttl-hdrfix --ttl=+59 --fixhdrlen
+	$(TCPREWRITE) -i $(TEST_PCAP) -o test.rewrite_3ttl-hdrfix --ttl=-59 --fixhdrlen
 	$(TCPREWRITE) -i $(TEST_PCAP) -o test.rewrite_mtutrunc --mtu-trunc --mtu=300
 	$(TCPREWRITE) -i $(TEST_PCAP) -o test.rewrite_l7fuzzing \
 		--fuzz-seed=42 --fuzz-factor=2
@@ -175,6 +182,9 @@ standard_littleendian:
 	$(TCPREWRITE) -i $(TEST_PCAP) -o test2.rewrite_1ttl --ttl=58
 	$(TCPREWRITE) -i $(TEST_PCAP) -o test2.rewrite_2ttl --ttl=+58
 	$(TCPREWRITE) -i $(TEST_PCAP) -o test2.rewrite_3ttl --ttl=-58
+	$(TCPREWRITE) -i $(TEST_PCAP) -o test2.rewrite_1ttl-hdrfix --ttl=59 --fixhdrlen
+	$(TCPREWRITE) -i $(TEST_PCAP) -o test2.rewrite_2ttl-hdrfix --ttl=+59 --fixhdrlen
+	$(TCPREWRITE) -i $(TEST_PCAP) -o test2.rewrite_3ttl-hdrfix --ttl=-59 --fixhdrlen
 	$(TCPREWRITE) -i $(TEST_PCAP) -o test2.rewrite_mtutrunc --mtu-trunc --mtu=300
 	$(TCPREWRITE) -i $(TEST_PCAP) -o test2.rewrite_l7fuzzing \
 		--fuzz-seed=42 --fuzz-factor=2
@@ -191,7 +201,8 @@ tcpprep: auto_router auto_bridge auto_client auto_server auto_first cidr regex \
 tcprewrite: rewrite_portmap rewrite_range_portmap rewrite_endpoint \
 	rewrite_pnat rewrite_trunc rewrite_pad rewrite_seed rewrite_mac \
 	rewrite_layer2 rewrite_config rewrite_skip rewrite_dltuser rewrite_dlthdlc \
-	rewrite_vlan802.1ad rewrite_vlandel rewrite_efcs rewrite_1ttl rewrite_2ttl rewrite_3ttl \
+	rewrite_vlan802.1ad rewrite_vlandel rewrite_efcs \
+	rewrite_1ttl rewrite_2ttl rewrite_3ttl rewrite_1ttl-hdrfix rewrite_2ttl-hdrfix rewrite_3ttl-hdrfix \
 	rewrite_tos rewrite_mtutrunc rewrite_enet_subsmac rewrite_mac_seed \
 	rewrite_mac_seed_keep rewrite_l7fuzzing rewrite_sequence rewrite_fixcsum \
 	rewrite_fixlen_pad rewrite_fixlen_trunc rewrite_fixlen_del
@@ -638,6 +649,39 @@ else
 endif
 	if [ $? ] ; then $(PRINTF) "\t\t\t%s\n" "FAILED"; else $(PRINTF) "\t\t\t%s\n" "OK"; fi
 
+rewrite_1ttl-hdrfix:
+	$(PRINTF) "%s" "[tcprewrite] Force TTL with header fix: "
+	$(PRINTF) "%s\n" "*** [tcprewrite] Force TTL header fix: " >> test.log
+	$(TCPREWRITE) $(ENABLE_DEBUG) -i $(TEST_PCAP) -o test.$@1 --ttl=59 --fixhdrlen >> test.log 2>&1
+if WORDS_BIGENDIAN
+	diff $(srcdir)/test.$@ test.$@1 >> test.log 2>&1
+else
+	diff $(srcdir)/test2.$@ test.$@1 >> test.log 2>&1
+endif
+	if [ $? ] ; then $(PRINTF) "\t%s\n" "FAILED"; else $(PRINTF) "\t%s\n" "OK"; fi
+
+rewrite_2ttl-hdrfix:
+	$(PRINTF) "%s" "[tcprewrite] Increase TTL with header fix:"
+	$(PRINTF) "%s\n" "*** [tcprewrite] Increase TTL with header fix: " >> test.log
+	$(TCPREWRITE) $(ENABLE_DEBUG) -i $(TEST_PCAP) -o test.$@1 --ttl=+59 --fixhdrlen  >> test.log 2>&1
+if WORDS_BIGENDIAN
+	diff $(srcdir)/test.$@ test.$@1 >> test.log 2>&1
+else
+	diff $(srcdir)/test2.$@ test.$@1 >> test.log 2>&1
+endif
+	if [ $? ] ; then $(PRINTF) "\t%s\n" "FAILED"; else $(PRINTF) "\t%s\n" "OK"; fi
+
+rewrite_3ttl-hdrfix:
+	$(PRINTF) "%s" "[tcprewrite] Reduce TTL with header fix: "
+	$(PRINTF) "%s\n" "*** [tcprewrite] Reduce TTL with header fix: " >> test.log
+	$(TCPREWRITE) $(ENABLE_DEBUG) -i $(TEST_PCAP) -o test.$@1 --ttl=-59 --fixhdrlen  >> test.log 2>&1
+if WORDS_BIGENDIAN
+	diff $(srcdir)/test.$@ test.$@1 >> test.log 2>&1
+else
+	diff $(srcdir)/test2.$@ test.$@1 >> test.log 2>&1
+endif
+	if [ $? ] ; then $(PRINTF) "\t%s\n" "FAILED"; else $(PRINTF) "\t%s\n" "OK"; fi
+
 rewrite_tos:
 	$(PRINTF) "%s" "[tcprewrite] TOS test: "
 	$(PRINTF) "%s\n" "*** [tcprewrite] TOS test: " >> test.log