Fail to save static gateway for wan interface when choosing from existed interface items

[lifesboy]

Important notices

• [x] I have read the contributing guide lines at https://github.com/opnsense/core/blob/master/CONTRIBUTING.md
• [x] I am convinced that my issue is new after having checked both open and closed issues at https://github.com/opnsense/core/issues?q=is%3Aissue

Describe the bug

Choose an existed static gateway for wan interface then click on save. It's saving old gateway, not new gateway.

To Reproduce

Steps to reproduce the behavior:

1. Go to 'Interfaces > [WAN]'
2. Click on 'IPv4 Upstream Gateway'
3. Select another existed gateway item.(ex: current selected is: 'WAN_GWv46', select new gateway is 'WAN_GWv4')
4. Click on 'Save'
5. Check last saved backup file in: '/conf/backup/'
6. Verify key: ...<interfaces><wan><gateway>{saved_value}</gateway></wan>... saved_value is old: 'WAN_GWv46'

Expected behavior saved_value should be new gateway: 'WAN_GWv4'

Describe alternatives you considered in src/www/interfaces.php#L1341, it's updating $a_interfaces[$if] = $new_config but write_config() is saving global $config, which is not updated with $new_config. https://github.com/opnsense/core/blob/41a0a938f844f96450bc13dc35a9102016e650fd/src/www/interfaces.php#L1341

Screenshots

Relevant log files

<interfaces>
    <wan>
      <if>eno1</if>
      <descr>WAN</descr>
      <enable>1</enable>
      <spoofmac/>
      <blockpriv>1</blockpriv>
      <blockbogons>1</blockbogons>
      <ipaddr>192.168.1.18</ipaddr>
      <subnet>24</subnet>
      <gateway>WAN_GWv46</gateway>
    </wan>
...

[fichtner]

I cannot reproduce this. $a_interfaces is a reference to $config[interfaces]:

https://github.com/opnsense/core/blob/ea7709e2683f2754b7fb2150679020fef9964b80/src/www/interfaces.php#L310

Cheers, Franco

[lifesboy]

After use latest from master branch, this issue has been fixed. Thank you for your support!