validate bridge network subnets (ipv4 and v6)

command/agent/agent.go

@@ -889,8 +889,28 @@ func convertClientConfig(agentConfig *Config) (*clientconfig.Config, error) {
 	conf.CNIPath = agentConfig.Client.CNIPath
 	conf.CNIConfigDir = agentConfig.Client.CNIConfigDir
 	conf.BridgeNetworkName = agentConfig.Client.BridgeNetworkName
-	conf.BridgeNetworkAllocSubnet = agentConfig.Client.BridgeNetworkSubnet
-	conf.BridgeNetworkAllocSubnetIPv6 = agentConfig.Client.BridgeNetworkSubnetIPv6
+	ipv4Subnet := agentConfig.Client.BridgeNetworkSubnet
+	if ipv4Subnet != "" {
+		ip, _, err := net.ParseCIDR(ipv4Subnet)
+		if err != nil {
+			return nil, fmt.Errorf("invalid bridge_network_subnet: %w", err)
+		}
+		if ip.To4() == nil {
+			return nil, fmt.Errorf("invalid bridge_network_subnet: %q is not an IPv4 address", ipv4Subnet)
+		}
+		conf.BridgeNetworkAllocSubnet = ipv4Subnet
+	}
+	ipv6Subnet := agentConfig.Client.BridgeNetworkSubnetIPv6
+	if ipv6Subnet != "" {
+		ip, _, err := net.ParseCIDR(ipv6Subnet)
+		if err != nil {
+			return nil, fmt.Errorf("invalid bridge_network_subnet_ipv6: %w", err)
+		}
+		if ip.To16() == nil {
+			return nil, fmt.Errorf("invalid bridge_network_subnet_ipv6: %q is not an IPv6 address", ipv6Subnet)
+		}
+		conf.BridgeNetworkAllocSubnetIPv6 = ipv6Subnet
+	}
 	conf.BridgeNetworkHairpinMode = agentConfig.Client.BridgeNetworkHairpinMode
 
 	for _, hn := range agentConfig.Client.HostNetworks {

command/agent/agent_test.go

@@ -13,6 +13,7 @@ import (
 	"time"
 
 	"github.com/hashicorp/nomad/ci"
+	clientconfig "github.com/hashicorp/nomad/client/config"
 	cstructs "github.com/hashicorp/nomad/client/structs"
 	"github.com/hashicorp/nomad/helper/pointer"
 	"github.com/hashicorp/nomad/helper/testlog"
@@ -677,6 +678,79 @@ func TestAgent_ServerConfig_RaftProtocol_3(t *testing.T) {
 	}
 }
 
+func TestConvertClientConfig(t *testing.T) {
+	ci.Parallel(t)
+	cases := []struct {
+		name string
+		// modConfig modifies the agent config before passing to convertClientConfig()
+		modConfig func(*Config)
+		// assert makes assertions about the resulting client config
+		assert    func(*testing.T, *clientconfig.Config)
+		expectErr string
+	}{
+		{
+			name: "default",
+			assert: func(t *testing.T, cc *clientconfig.Config) {
+				must.Eq(t, "global", cc.Region)
+			},
+		},
+		{
+			name: "ipv4 bridge subnet",
+			modConfig: func(c *Config) {
+				c.Client.BridgeNetworkSubnet = "10.0.0.0/24"
+			},
+			assert: func(t *testing.T, cc *clientconfig.Config) {
+				must.Eq(t, "10.0.0.0/24", cc.BridgeNetworkAllocSubnet)
+			},
+		},
+		{
+			name: "invalid ipv4 bridge subnet",
+			modConfig: func(c *Config) {
+				c.Client.BridgeNetworkSubnet = "invalid-ip4"
+			},
+			expectErr: "invalid bridge_network_subnet:",
+		},
+		{
+			name: "ipv6 bridge subnet",
+			modConfig: func(c *Config) {
+				c.Client.BridgeNetworkSubnetIPv6 = "fd00:a110:c8::/120"
+			},
+			assert: func(t *testing.T, cc *clientconfig.Config) {
+				must.Eq(t, "fd00:a110:c8::/120", cc.BridgeNetworkAllocSubnetIPv6)
+			},
+		},
+		{
+			name: "invalid ipv6 bridge subnet",
+			modConfig: func(c *Config) {
+				c.Client.BridgeNetworkSubnetIPv6 = "invalid-ip6"
+			},
+			expectErr: "invalid bridge_network_subnet_ipv6:",
+		},
+	}
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			c := DefaultConfig()
+
+			if tc.modConfig != nil {
+				tc.modConfig(c)
+			}
+
+			// method under test
+			cc, err := convertClientConfig(c)
+
+			if tc.expectErr != "" {
+				must.ErrorContains(t, err, tc.expectErr)
+			} else {
+				must.NoError(t, err)
+			}
+
+			if tc.assert != nil {
+				tc.assert(t, cc)
+			}
+		})
+	}
+}
+
 func TestAgent_ClientConfig_discovery(t *testing.T) {
 	ci.Parallel(t)
 	conf := DefaultConfig()