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examples: replace grep command in NM dispatcher script

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Some grep implementations detect binary data and return success without
matching whole line. This might be an issue for the DHCPv6 NTP FQDN
check. The GNU grep in the C locale seems to check only for the NUL
character, which cannot be passed in an environment variable, but other
implementations might behave differently and there doesn't seem to be a
portable way to force matching the whole line.

Instead of the grep command, check for invalid characters by comparing
the length of the input passed through "tr -d -c".
This commit is contained in:
Miroslav Lichvar 2022-03-23 15:17:03 +01:00
parent 25f80a1a9d
commit fca8966ada
1 changed files with 5 additions and 1 deletions
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6
examples/chrony.nm-dispatcher.dhcp
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@ -19,7 +19,11 @@ add_servers_from_dhcp() {
rm -f "$dhcp_server_file" rm -f "$dhcp_server_file"
for server in $dhcp_ntp_servers; do for server in $dhcp_ntp_servers; do
# Check for invalid characters (from the DHCPv6 NTP FQDN suboption) # Check for invalid characters (from the DHCPv6 NTP FQDN suboption)
printf '%s\n' "$server" | grep -E -q '^[-A-Za-z0-9:.]{1,255}$' || continue len1=$(printf '%s' "$server" | wc -c)
len2=$(printf '%s' "$server" | tr -d -c 'A-Za-z0-9:.-' | wc -c)
if [ "$len1" -ne "$len2" ] || [ "$len2" -lt 1 ] || [ "$len2" -gt 255 ]; then
continue
fi
printf 'server %s %s\n' "$server" "$server_options" >> "$dhcp_server_file" printf 'server %s %s\n' "$server" "$server_options" >> "$dhcp_server_file"
done done