Extract 403 and 405 errors to functions

Like what I did in edf6fceedd9b4169ceb63172c60733ef84d78951 for 500
errors, extract these errors to functions also.

Doesn't give us any gains in terms of reusability like it did before, as
we're only responding with each of these errors once, but it does clean
up the code in the `main()` function a bit.

2 files changed, 27 insertions, 13 deletions

diff --git a/license-generator/src/main.rs b/license-generator/src/main.rs
index f2beb26..296db0a 100644
--- a/license-generator/src/main.rs
+++ b/license-generator/src/main.rs
@@ -76,14 +76,7 @@ fn main() -> Result<()> {
         match req.param("REQUEST_METHOD") {
             Some(method) => {
                 if method != "POST" {
-                    response::set_405(&mut req.stdout(), "POST")
-                        .unwrap_or(());
-                    write!(&mut req.stdout(), "Content-Type: text/plain
-
-405 Method Not Allowed")
-                        .unwrap_or(());
-
-                    return;
+                    return response::error_405(&mut req.stdout(), "POST");
                 }
             },
             None => {
@@ -139,11 +132,10 @@ fn main() -> Result<()> {
             );
         }
 
-        response::set_403(&mut req.stdout()).unwrap_or(());
-        write!(&mut req.stdout(), "Content-Type: text/plain
-
-403 Forbidden: Invalid request signature")
-            .unwrap_or(());
+        response::error_403(
+            &mut req.stdout(),
+            Some("Invalid request signature")
+        );
     });
 
     Ok(())
diff --git a/license-generator/src/response.rs b/license-generator/src/response.rs
index aec2d22..a4e80bd 100644
--- a/license-generator/src/response.rs
+++ b/license-generator/src/response.rs
@@ -20,6 +20,28 @@ pub fn set_500<W: Write>(w: &mut W) -> Result<()> {
     Ok(writeln!(w, "Status: 500")?)
 }
 
+pub fn error_403<W: Write>(w: &mut W, message: Option<&str>) {
+    set_403(w).unwrap_or(());
+    write!(
+        w,
+        "Content-Type: text/plain
+
+403 Forbidden{}",
+        message.map_or_else(
+            || String::new(),
+            |m| format!(": {}", m)
+        )
+    ).unwrap_or(());
+}
+
+pub fn error_405<W: Write>(w: &mut W, allowed_methods: &str) {
+    set_405(w, allowed_methods).unwrap_or(());
+    write!(w, "Content-Type: text/plain
+
+405 Method Not Allowed")
+        .unwrap_or(());
+}
+
 pub fn error_500<W: Write>(w: &mut W, error: Option<Error>) {
     if let Some(error) = error {
         error!("{}", error);