Add conditional compilation of default firewall driver

The NETAVARK_DEFAULT_FW environment variable controls the default
firewall driver that will be used by the compiled Netavark.
Currently supported values are "iptables" (the default, if the
environment variable is unset), "nftables", and "none" (we'll add
"firewalld" as a supported value once that driver is done).

Unsupported values result in a panic/failure to build.

Signed-off-by: Matt Heon <mheon@redhat.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/build.rs b/build.rs
index e8091f2..4dd01e5 100644
--- a/build.rs
+++ b/build.rs
@@ -63,4 +63,18 @@ fn main() {
         Err(_) => "".to_string(),
     };
     println!("cargo:rustc-env=GIT_COMMIT={commit}");
+
+    // Handle default firewall driver.
+    // Allowed values "nftables" and "iptables".
+    let fwdriver = match env::var("NETAVARK_DEFAULT_FW")
+        .unwrap_or("iptables".to_string())
+        .as_str()
+    {
+        "nftables" => "nftables",
+        "iptables" => "iptables",
+        "none" => "none",
+        inv => panic!("Invalid default firewall driver {}", inv),
+    };
+    println!("cargo:rustc-cfg=default_fw=\"{}\"", fwdriver);
+    println!("cargo:rustc-env=DEFAULT_FW={fwdriver}");
 }