How do I split a string in make?

# Retrieves a host part of the given string (without port).
# Param:
#   1. String to parse in form 'host[:port]'.
host = $(firstword $(subst :, ,$1))

# Returns a port (if any).
# If there is no port part in the string, returns the second argument
# (if specified).
# Param:
#   1. String to parse in form 'host[:port]'.
#   2. (optional) Fallback value.
port = $(or $(word 2,$(subst :, ,$1)),$(value 2))

Usage:

$(call host,foo.example.com) # foo.example.com
$(call port,foo.example.com,80) # 80

$(call host,ssl.example.com:443) # ssl.example.com
$(call port,ssl.example.com:443,80) # 443