net: dhcp6: Fix OPT_BOOTFILE_PARAM parsing

RFC 5970 states that OPT_BOOTFILE_PARAM (option 60) can be
multiple parameters that start with a 16-bit length field followed
by the parameter. For example:
[ param-len 1 (16-bits) ] [ parameter 1 (variable length) ]

This fix ensure we're considering "param-len 1" in the parsing.

Signed-off-by: Sean Edmond <seanedmond@microsoft.com>

net: ipv6: Fix CID 453851 and CID 436278

CID 453851 : sprintf() shouldn't copy from/to tmp
CID 436278 : DHCP6 option_len should be checked before use

Signed-off-by: Sean Edmond <seanedmond@microsoft.com>
Reviewed-by: Ramon Fried <rfried.dev@gmail.com>

net: dhcp6: Add DHCPv6 (DHCP for IPv6)

Adds DHCPv6 protocol to u-boot.

Allows for address assignement with DHCPv6 4-message exchange
(SOLICIT->ADVERTISE->REQUEST->REPLY). Includes DHCPv6 options
required by RFC 8415. Also adds DHCPv6 options required
for PXE boot.

Possible enhancements:
- Duplicate address detection on DHCPv6 assigned address
- IPv6 address assignement through SLAAC
- Sending/parsing other DHCPv6 options (NTP, DNS, etc...)

Signed-off-by: Sean Edmond <seanedmond@microsoft.com>
Reviewed-by: Ramon Fried <rfried.dev@gmail.com>

net: ipv6: Fix CID 453851 and CID 436278

CID 453851 : sprintf() shouldn't copy from/to tmp
CID 436278 : DHCP6 option_len should be checked before use

Signed-off-by: Sean Edmond <seanedmond@microsoft.com>
Reviewed-by: Ramon Fried <rfried.dev@gmail.com>

net: dhcp6: Add DHCPv6 (DHCP for IPv6)

Adds DHCPv6 protocol to u-boot.

Allows for address assignement with DHCPv6 4-message exchange
(SOLICIT->ADVERTISE->REQUEST->REPLY). Includes DHCPv6 options
required by RFC 8415. Also adds DHCPv6 options required
for PXE boot.

Possible enhancements:
- Duplicate address detection on DHCPv6 assigned address
- IPv6 address assignement through SLAAC
- Sending/parsing other DHCPv6 options (NTP, DNS, etc...)

Signed-off-by: Sean Edmond <seanedmond@microsoft.com>
Reviewed-by: Ramon Fried <rfried.dev@gmail.com>