[PATCH] config hook: prevent two hooks with the same settings

[Jonatan Schlag <jonatan.schlag@ipfire.org>]

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A ipv4-static config with the same IPv4 address twice is senseless.
A new function zone_config_check_same_setting is introduced.
The function provides an easy way to check if a config
of the given hook has the same value for a given key.
We can now check inside hook_new if an ipv4-static or ipv6-static config
with the same value exist and break with an error.

Fixes: #11418

Signed-off-by: Jonatan Schlag <jonatan.schlag(a)ipfire.org>
---
 src/functions/functions.zone  | 33 +++++++++++++++++++++++++++++++++
 src/hooks/configs/ipv4-static |  5 +++++
 src/hooks/configs/ipv6-static |  5 +++++
 3 files changed, 43 insertions(+)

diff --git a/src/functions/functions.zone b/src/functions/functions.zone
index d121225..768bb9f 100644
--- a/src/functions/functions.zone
+++ b/src/functions/functions.zone
@@ -1024,6 +1024,39 @@ zone_config_get_new_id() {
 	done
 }
 
+zone_config_check_same_setting() {
+	# This functions checks if a config hook
+	# with the same setting is already configured for this zone.
+	# Returns True when yes and False when no.
+
+	assert [ $# -eq 4 ]
+
+	local zone=${1}
+	local hook=${2}
+	local key=${3}
+	local value=${4}
+
+	# The key should be local for this function
+	local ${key}
+	local config
+
+	for config in $(zone_configs_list ${zone}); do
+		# Check if the config is from the given hook, when not continue
+		if  [[ $(zone_config_get_hook "${zone}" "${config}") != ${hook} ]]; then
+			continue
+		fi
+		# Get the value of the key for a given function
+		zone_config_settings_read "${zone}" "${config}" \
+                --ignore-superfluous-settings "${key}"
+		# Check if the value of the config and the passed value are eqal
+		if [[ "${value}" == "${!key}" ]]; then
+			return ${EXIT_TRUE}
+		fi
+	done
+
+	return ${EXIT_FALSE}
+}
+
 zone_config_get_hook() {
 	assert [ $# -eq 2 ]
 
diff --git a/src/hooks/configs/ipv4-static b/src/hooks/configs/ipv4-static
index c395200..9454282 100644
--- a/src/hooks/configs/ipv4-static
+++ b/src/hooks/configs/ipv4-static
@@ -102,6 +102,11 @@ hook_new() {
 		exit ${EXIT_CONF_ERROR}
 	fi
 
+	if zone_config_check_same_setting "${zone}" "ipv4-static" "ADDRESS" "${ADDRESS}"; then
+		error "An ipv4-static config with the same IPv4 address is already configured"
+		exit ${EXIT_CONF_ERROR}
+	fi
+
 	if ! isset GATEWAY && zone_is_nonlocal "${zone}"; then
 		warning "You did not configure a gateway for a non-local zone"
 	fi
diff --git a/src/hooks/configs/ipv6-static b/src/hooks/configs/ipv6-static
index f43ef7e..b0f6537 100644
--- a/src/hooks/configs/ipv6-static
+++ b/src/hooks/configs/ipv6-static
@@ -59,6 +59,11 @@ hook_new() {
 		GATEWAY=$(ipv6_format "${GATEWAY}")
 	fi
 
+	if zone_config_check_same_setting "${zone}" "ipv6-static" "ADDRESS" "${ADDRESS}"; then
+		error "An ipv6-static config with the same IPv6 address is already configured"
+		exit ${EXIT_CONF_ERROR}
+	fi
+
 	zone_config_settings_write "${zone}" "${HOOK}"
 
 	exit ${EXIT_OK}
-- 
2.6.3