From 9bb8d54607d536ad7aba6e6a5e554154542269d6 Mon Sep 17 00:00:00 2001
From: zersh <zersh@mail.ru>
Date: Sat, 25 Jan 2025 23:55:19 +0300
Subject: [PATCH] Update softnet.sh

In newer versions of bash (>5.1), you might encounter the error:

line 37: printf: 0x00000000 00000000 00000000: invalid hex number

I have added error handling. I also implemented a check to determine if the server is an LXC container. If it is, then only the allocated (cgroup) CPUs are displayed.
---
 how-to-receive-a-packet/softnet.sh | 111 ++++++++++++++++++++++++++---
 1 file changed, 100 insertions(+), 11 deletions(-)

diff --git a/how-to-receive-a-packet/softnet.sh b/how-to-receive-a-packet/softnet.sh
index be26381..09301f9 100755
--- a/how-to-receive-a-packet/softnet.sh
+++ b/how-to-receive-a-packet/softnet.sh
@@ -24,28 +24,117 @@ Output column definitions:
 collision  # of times that two cpus collided trying to get the device queue lock.
 
 EOI
-	exit 1
+    exit 1
 }
 
-
+if [ "$1" = "-h" ]; then
+    usage
+fi
 
 softnet_stats_header() {
-	printf "%3s %10s %10s %10s %10s %10s %10s\n" cpu total dropped squeezed collision rps flow_limit
+    printf "%3s %10s %10s %10s %10s %10s %10s\n" cpu total dropped squeezed collision rps flow_limit
 }
 
 softnet_stats_format() {
-	printf "%3u %10lu %10lu %10lu %10lu %10lu %10lu\n" "$1" "0x$2" "0x$3" "0x$4" "0x$5" "0x$6" "0x$7"
+    local cpu=$1
+    local total_hex=$2
+    local dropped_hex=$3
+    local squeezed_hex=$4
+    local collision_hex=$5
+    local rps_hex=$6
+    local flow_limit_hex=${7:-0}
+
+    local total_dec=$((16#$total_hex))
+    local dropped_dec=$((16#$dropped_hex))
+    local squeezed_dec=$((16#$squeezed_hex))
+    local collision_dec=$((16#$collision_hex))
+    local rps_dec=$((16#$rps_hex))
+    local flow_limit_dec=$((16#$flow_limit_hex))
+    
+    printf "%3u %10lu %10lu %10lu %10lu %10lu %10lu\n" "$cpu" "$total_dec" "$dropped_dec" "$squeezed_dec" "$collision_dec" "$rps_dec" "$flow_limit_dec"
+}
+
+is_lxc_container() {
+    if systemd-detect-virt -c | grep -qi "lxc"; then
+        return 0
+    fi
+    return 1
 }
 
+parse_cpu_ranges() {
+    local IFS=','
+    local range cpu_ranges=$1
+    local cpus=()
+
+    for range in $cpu_ranges; do
+        if [[ $range =~ - ]]; then
+            IFS='-' read start end <<< "$range"
+            for ((i=start; i<=end; i++)); do
+                cpus+=($i)
+            done
+        else
+            cpus+=($range)
+        fi
+    done
+  echo "${cpus[@]}"
+}
 
-getopts h flag && usage
+get_lxc_cpus() {
+    local cpus
+    if [ -f "/sys/fs/cgroup/cpuset/lxc/cpuset.cpus" ]; then
+        cpus=$(cat "/sys/fs/cgroup/cpuset/lxc/cpuset.cpus")
+    elif [ -f "/sys/fs/cgroup/cpuset/cpuset.cpus" ]; then
+        cpus=$(cat "/sys/fs/cgroup/cpuset/cpuset.cpus")
+    else
+        echo "Unable to determine allocated CPUs for LXC"
+        exit 1
+    fi
+    parse_cpu_ranges "$cpus"
+}
+
+process_softnet_line() {
+    local line=$1
+    local cpu_index=$2
+
+    set -- $line
+    local total=$1
+    local dropped=$2
+    local squeezed=$3
+    local j1=$4
+    local j2=$5
+    local j3=$6
+    local j4=$7
+    local j5=$8
+    local collision=$9
+    local rps=${10}
+    local flow_limit_count=${11:-0}
+
+    softnet_stats_format "$cpu_index" "$total" "$dropped" "$squeezed" "$collision" "$rps" "$flow_limit_count"
+}
 
 cpu=0
+# for normal header
+if is_lxc_container; then
+    echo "Running inside LXC container."
+    cpus=($(get_lxc_cpus))  # Получаем массив CPU
+    echo "CPUs allocated to this container: ${cpus[@]}"
+fi
 softnet_stats_header
-while read total dropped squeezed j1 j2 j3 j4 j5 collision rps flow_limit_count
-do
-	# the last field does not appear on older kernels
-	# https://github.com/torvalds/linux/commit/99bbc70741903c063b3ccad90a3e06fc55df9245#diff-5dd540e75b320a50866267e9c52b3289R165
-	softnet_stats_format $((cpu++)) "$total" "$dropped" "$squeezed" "$collision" "$rps" "${flow_limit_count:-0}"
-done < /proc/net/softnet_stat
 
+if is_lxc_container; then
+    cpus=($(get_lxc_cpus))  # Получаем массив CPU
+    while read line
+    do
+        if [[ " ${cpus[*]} " =~ " $cpu " ]]; then
+            process_softnet_line "$line" "$cpu"
+        fi
+        ((cpu++))
+    done < /proc/net/softnet_stat
+else
+#    echo "Not running inside LXC container."
+    while read line
+    do
+        process_softnet_line "$line" "$cpu"
+        ((cpu++))
+    done < /proc/net/softnet_stat
+fi