From 11a48b4de1e750eccbb8f96c4866d0810c0387f5 Mon Sep 17 00:00:00 2001
From: Eduard Vlad <eduardvlad11@online.de>
Date: Fri, 31 May 2024 17:23:33 +0200
Subject: [PATCH] add nonzero flag instead of random data for accessing it

---
 src/fping.c   | 10 +++++-----
 src/fping.h   |  2 +-
 src/socket4.c | 10 +++++++---
 src/socket6.c |  7 ++++---
 4 files changed, 17 insertions(+), 12 deletions(-)

diff --git a/src/fping.c b/src/fping.c
index c58e20c..acac062 100644
--- a/src/fping.c
+++ b/src/fping.c
@@ -357,7 +357,7 @@ int per_recv_flag, report_all_rtts_flag, name_flag, addr_flag, backoff_flag, rdn
 int multif_flag, timeout_flag, fast_reachable;
 int outage_flag = 0;
 int timestamp_flag = 0;
-int random_data_flag = 0;
+int nonzero_payload_flag = 0;
 int cumulative_stats_flag = 0;
 #if defined(DEBUG) || defined(_DEBUG)
 int randomly_lose_flag, trace_flag, print_per_system_flag;
@@ -543,7 +543,7 @@ int main(int argc, char **argv)
         { "quiet", 'q', OPTPARSE_NONE },
         { "squiet", 'Q', OPTPARSE_REQUIRED },
         { "retry", 'r', OPTPARSE_REQUIRED },
-        { "random", 'R', OPTPARSE_NONE },
+        { "nonzero", 'Z', OPTPARSE_NONE },
         { "stats", 's', OPTPARSE_NONE },
         { "src", 'S', OPTPARSE_REQUIRED },
         { "timeout", 't', OPTPARSE_REQUIRED },
@@ -734,8 +734,8 @@ int main(int argc, char **argv)
             timestamp_flag = 1;
             break;
 
-        case 'R':
-            random_data_flag = 1;
+        case 'Z':
+            nonzero_payload_flag = 1;
             break;
 
         case 'l':
@@ -2981,7 +2981,7 @@ void usage(int is_error)
     fprintf(out, "   -p, --period=MSEC  interval between ping packets to one target (in ms)\n");
     fprintf(out, "                      (in loop and count modes, default: %.0f ms)\n", perhost_interval / 1e6);
     fprintf(out, "   -r, --retry=N      number of retries (default: %d)\n", DEFAULT_RETRY);
-    fprintf(out, "   -R, --random       random packet data (to foil link data compression)\n");
+    fprintf(out, "   -Z, --nonzero      non-zero packet data (same payload as ping 0xA ...)\n");
     fprintf(out, "   -S, --src=IP       set source address\n");
     fprintf(out, "   -t, --timeout=MSEC individual target initial timeout (default: %.0f ms,\n", timeout / 1e6);
     fprintf(out, "                      except with -l/-c/-C, where it's the -p period up to 2000 ms)\n");
diff --git a/src/fping.h b/src/fping.h
index c0acdfb..d4fc1cc 100644
--- a/src/fping.h
+++ b/src/fping.h
@@ -22,7 +22,7 @@ extern int trace_flag;
 void crash_and_burn( char *message );
 void errno_crash_and_burn( char *message );
 int in_cksum( unsigned short *p, int n );
-extern int random_data_flag;
+extern int nonzero_payload_flag;
 
 /* socket.c */
 int  open_ping_socket_ipv4(int *socktype);
diff --git a/src/socket4.c b/src/socket4.c
index d7c4ae3..8feb12b 100644
--- a/src/socket4.c
+++ b/src/socket4.c
@@ -133,6 +133,7 @@ int socket_sendto_ping_ipv4(int s, struct sockaddr* saddr, socklen_t saddr_len,
 {
     struct icmp* icp;
     int n;
+    size_t i;
 
     icp = (struct icmp*)ping_buffer_ipv4;
 
@@ -142,9 +143,12 @@ int socket_sendto_ping_ipv4(int s, struct sockaddr* saddr, socklen_t saddr_len,
     icp->icmp_seq = htons(icmp_seq_nr);
     icp->icmp_id = icmp_id_nr;
 
-    if (random_data_flag) {
-        for (n = ((char*)&icp->icmp_data - (char*)icp); n < ping_pkt_size_ipv4; ++n) {
-            ping_buffer_ipv4[n] = random() & 0xFF;
+    if (nonzero_payload_flag) {
+        // for (n = ((char*)&icp->icmp_data - (char*)icp); n < ping_pkt_size_ipv4; ++n) {
+        //     ping_buffer_ipv4[n] = random() & 0xFF;
+        // }
+        for(n = (char*) &icp->icmp_data - (char*)icp, i = 0xA; n < ping_pkt_size_ipv4; ++n, i += 1) {
+            ping_buffer_ipv4[n] = i & 0xFF;
         }
     }
 
diff --git a/src/socket6.c b/src/socket6.c
index 84a84ea..40e5b60 100644
--- a/src/socket6.c
+++ b/src/socket6.c
@@ -115,6 +115,7 @@ int socket_sendto_ping_ipv6(int s, struct sockaddr* saddr, socklen_t saddr_len,
 {
     struct icmp6_hdr* icp;
     int n;
+    size_t i;
 
     icp = (struct icmp6_hdr*)ping_buffer_ipv6;
     icp->icmp6_type = ICMP6_ECHO_REQUEST;
@@ -122,9 +123,9 @@ int socket_sendto_ping_ipv6(int s, struct sockaddr* saddr, socklen_t saddr_len,
     icp->icmp6_seq = htons(icmp_seq_nr);
     icp->icmp6_id = icmp_id_nr;
 
-    if (random_data_flag) {
-        for (n = sizeof(struct icmp6_hdr); n < ping_pkt_size_ipv6; ++n) {
-            ping_buffer_ipv6[n] = random() & 0xFF;
+    if (nonzero_payload_flag) {
+        for (n = sizeof(struct icmp6_hdr), i = 0xA; n < ping_pkt_size_ipv6; ++n, i+=1) {
+            ping_buffer_ipv6[n] = i & 0xFF;
         }
     }