micro_http: Set the response headers Server value

And implement the Default trait for ResponseHeaders, falling back to
Firecracker API.

Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

micro_http/src/common/headers.rs

@@ -16,6 +16,8 @@ pub enum Header {
     Expect,
     /// Header `Transfer-Encoding`.
     TransferEncoding,
+    /// Header `Server`.
+    Server,
 }
 
 impl Header {
@@ -25,6 +27,7 @@ impl Header {
             Header::ContentType => b"Content-Type",
             Header::Expect => b"Expect",
             Header::TransferEncoding => b"Transfer-Encoding",
+            Header::Server => b"Server",
         }
     }
 
@@ -35,6 +38,7 @@ impl Header {
                 "Content-Type" => Ok(Header::ContentType),
                 "Expect" => Ok(Header::Expect),
                 "Transfer-Encoding" => Ok(Header::TransferEncoding),
+                "Server" => Ok(Header::Server),
                 _ => Err(RequestError::InvalidHeader),
             }
         } else {
@@ -130,6 +134,7 @@ impl Headers {
                             }
                             _ => Err(RequestError::InvalidHeader),
                         },
+                        Header::Server => Ok(()),
                     }
                 } else {
                     Err(RequestError::UnsupportedHeader)

micro_http/src/response.rs

@@ -70,16 +70,29 @@ impl StatusLine {
 /// Wrapper over the list of headers associated with a HTTP Response.
 /// When creating a ResponseHeaders object, the content type is initialized to `text/plain`.
 /// The content type can be updated with a call to `set_content_type`.
-#[derive(Default)]
 pub struct ResponseHeaders {
     content_length: i32,
     content_type: MediaType,
+    server: String,
+}
+
+impl Default for ResponseHeaders {
+    fn default() -> Self {
+        ResponseHeaders {
+            content_length: Default::default(),
+            content_type: Default::default(),
+            server: "Firecracker API".to_string(),
+        }
+    }
 }
 
 impl ResponseHeaders {
     /// Writes the headers to `buf` using the HTTP specification.
     pub fn write_all<T: Write>(&self, buf: &mut T) -> Result<(), WriteError> {
-        buf.write_all(b"Server: Firecracker API")?;
+        buf.write_all(Header::Server.raw())?;
+        buf.write_all(&[COLON, SP])?;
+        buf.write_all(self.server.as_bytes())?;
+
         buf.write_all(&[CR, LF])?;
         buf.write_all(b"Connection: keep-alive")?;
         buf.write_all(&[CR, LF])?;
@@ -104,6 +117,11 @@ impl ResponseHeaders {
         self.content_length = content_length;
     }
 
+    /// Sets the HTTP response header server.
+    pub fn set_server(&mut self, server: &str) {
+        self.server = String::from(server);
+    }
+
     /// Sets the content type to be written in the HTTP response.
     #[allow(unused)]
     pub fn set_content_type(&mut self, content_type: MediaType) {
@@ -141,6 +159,11 @@ impl Response {
         self.body = Some(body);
     }
 
+    /// Sets the HTTP response server.
+    pub fn set_server(&mut self, server: &str) {
+        self.headers.set_server(server);
+    }
+
     fn write_body<T: Write>(&self, mut buf: T) -> Result<(), WriteError> {
         if let Some(ref body) = self.body {
             buf.write_all(body.raw())?;
@@ -219,6 +242,35 @@ mod tests {
         assert!(response.write_all(&mut response_buf.as_mut()).is_err());
     }
 
+    #[test]
+    fn test_set_server() {
+        let mut response = Response::new(Version::Http10, StatusCode::OK);
+        let body = "This is a test";
+        let server = "rust-vmm API";
+        response.set_body(Body::new(body));
+        response.set_server(server);
+
+        assert!(response.status() == StatusCode::OK);
+        assert_eq!(response.body().unwrap(), Body::new(body));
+        assert_eq!(response.http_version(), Version::Http10);
+        assert_eq!(response.content_length(), 14);
+        assert_eq!(response.content_type(), MediaType::PlainText);
+
+        let expected_response = format!(
+            "HTTP/1.0 200 \r\n\
+             Server: {}\r\n\
+             Connection: keep-alive\r\n\
+             Content-Type: text/plain\r\n\
+             Content-Length: 14\r\n\r\n\
+             This is a test",
+            server
+        );
+
+        let mut response_buf: [u8; 123] = [0; 123];
+        assert!(response.write_all(&mut response_buf.as_mut()).is_ok());
+        assert!(response_buf.as_ref() == expected_response.as_bytes());
+    }
+
     #[test]
     fn test_status_code() {
         assert_eq!(StatusCode::Continue.raw(), b"100");