Re: [PATCH 2/3] Add new function ip_get__assigned_addresses_from_net()

[Michael Tremer <michael.tremer@ipfire.org>]

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On Fri, 2018-02-23 at 11:05 +0000, Jonatan Schlag via network wrote:
> This function is neede by IPsec to set the routes correctly.
> We can now now find a source IP for a given net.
> This way is ugly because the source IP
> is unpredictable if we get multiple IPs.
> 
> Signed-off-by: Jonatan Schlag <jonatan.schlag(a)ipfire.org>
> ---
>  src/functions/functions.ip | 25 +++++++++++++++++++++++++
>  1 file changed, 25 insertions(+)
> 
> diff --git a/src/functions/functions.ip b/src/functions/functions.ip
> index 3b43da7..ef40bcc 100644
> --- a/src/functions/functions.ip
> +++ b/src/functions/functions.ip
> @@ -205,3 +205,28 @@ ip_address_del() {
>  
>  	return ${EXIT_OK}
>  }
> +
> +# Get all currently assigned addresse for a given network
> +ip_get_assigned_addresses_from_net() {
> +	local net=${1}
> +	shift
> +	local args="$@"
> +
> +	assert ip_net_is_valid ${net}

I think this assertion isn't needed because "ip" will check this and just throw
an error.

> +	local line
> +	local ips

It would be nicer if the "ips" variable would be called "addresses" because that
is the term that we actually use most of the time.

> +	# We read the output of $(ip addr show to ${net} ${args})
> +	while read -r line; do
> +		# We are only interested in lines which start with inet or
> inet6
> +		[[ "${line}" =~ ^(inet6 |inet ) ]] || continue
> +
> +		# We need the second word the line
> +		line=(${line})
> +		list_append "ips" "$(ip_split_prefix "${line[1]}")"

You could also achieve this by passing the line argument up to the first space
and use the "%" and "#" parameters in the brackets.

I am not sure if the conversion to the array has any implications.

> +	done <<< "$(ip addr show to "${net}" ${args})"
> +
> +	# We sort the list to get the lowest IP as first item
> +	print "$(list_sort ${ips})"

You don't need to call print here. This will create a subshell for the list_sort
call, but list_sort already prints the output, so you can just write:

  list_sort ${ips}

That will be a lot faster.

> +}

-Michael