Extract dhcp option from dhcp ack packet in udhcpc

Hi - I'm using udhcpc which comes with busybox 1.23.2 to support networking on my embedded board. I'm able to obtain dynamic IP address from a DHCP server.

The script /lib/netifd/dhcp.script is run and within it the setup_interface function. Can someone help me understand how to collect and access the TFTP server address value (by using a script variable) which comes in the DHCP ack packet as option 150?

There were some recent changes to udhcpc that is supposed to automatically create environment variables for known simple options. I have not examined to see if would work for option 150. Otherwise as far as I know you need to add the option to the options.c file and recompile.

https://git.busybox.net/busybox/

https://git.busybox.net/busybox/plai...c?h=1_9_stable
https://udhcp.busybox.net/README.udhcpc

Thanks for your response. I'm on version 1.23.2 as mentioned earlier, and there is no longer an options.c file. The documentation is outdated for a long time.

I finally figured out what is to be done. First, need to add a new macro in the list of option codes in common.h. I added it as '#define DHCP_OPTION_150 0x96'. Next, in dhcpc.c, a small code block needs to be added in udhcpc_main() and under the code block for DHCPACK, to extract the IP address:
temp = udhcp_get_option(&packet, DHCP_OPTION_150);
if (!temp) {
bb_error_msg("error: couldn't get opt 150");
} else {
uint32_t tftp_ip;
move_from_unaligned32(tftp_ip, temp);
tftp_ip = ntohl(tftp_ip);
}