From 54be7c0e2cf00d01962e4186f8952f5e5e7dc138 Mon Sep 17 00:00:00 2001
From: Esteban Borai <estebanborai@gmail.com>
Date: Wed, 14 Oct 2020 23:07:05 -0300
Subject: [PATCH] add: entity tag support

Implements an Entity Tag hash by obtaining the date created, the
date of the last modification and the size of the file.
---
 CHANGELOG.md                         |  6 ++++++
 src/config.rs                        |  2 --
 src/handler/file_explorer/handler.rs | 11 +++++++++--
 src/server/etag.rs                   | 17 +++++++++++++++++
 src/server/mod.rs                    |  2 ++
 5 files changed, 34 insertions(+), 4 deletions(-)
 create mode 100644 src/server/etag.rs

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5056567c..7f36bcc9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,11 @@
 # Changes
 
+## v0.0.10
+
+### Added
+
+* [Etag Support](https://github.com/EstebanBorai/http-server/commit/32dc9a2e6b32bb18906ef06d45c155731d91519e)
+
 ## v0.0.9
 
 ### Added
diff --git a/src/config.rs b/src/config.rs
index 63811990..d2e26630 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -28,8 +28,6 @@ impl From<App<'static, 'static>> for Config {
         };
 
         let silent = matches.is_present(SILENT.1);
-
-        // at this point the values provided to the config are validated by the CLI
         Self {
             address,
             port,
diff --git a/src/handler/file_explorer/handler.rs b/src/handler/file_explorer/handler.rs
index bedb0fb5..30e7543c 100644
--- a/src/handler/file_explorer/handler.rs
+++ b/src/handler/file_explorer/handler.rs
@@ -1,5 +1,6 @@
 use crate::file_explorer::FileExplorer;
 use crate::handler::build_html;
+use crate::server::make_entity_tag;
 use ascii::AsciiString;
 use std::fs::{read_dir, File};
 use tiny_http::{Request, Response, ResponseBox};
@@ -16,10 +17,12 @@ pub fn file_explorer(request: Request, file_explorer: &FileExplorer) -> (Request
         Ok(entry) => {
             if entry.is_file {
                 let mime_type = mime_guess::from_path(&entry.path)
-                    .first_or_octet_stream()
-                    .to_string();
+                .first_or_octet_stream()
+                .to_string();
                 let mime_type = AsciiString::from_ascii(mime_type.as_bytes()).unwrap();
                 let file = File::open(entry.path).unwrap();
+                let entity_tag = make_entity_tag(&file.metadata().unwrap());
+                let entity_tag = AsciiString::from_ascii(entity_tag).unwrap();
 
                 (
                     request,
@@ -28,6 +31,10 @@ pub fn file_explorer(request: Request, file_explorer: &FileExplorer) -> (Request
                             field: "Content-Type".parse().unwrap(),
                             value: mime_type,
                         })
+                        .with_header(tiny_http::Header {
+                            field: "Etag".parse().unwrap(),
+                            value: entity_tag
+                        })
                         .boxed(),
                 )
             } else {
diff --git a/src/server/etag.rs b/src/server/etag.rs
new file mode 100644
index 00000000..88abc545
--- /dev/null
+++ b/src/server/etag.rs
@@ -0,0 +1,17 @@
+use std::fs::Metadata;
+use std::time::SystemTime;
+use std::hash::{Hash, Hasher};
+use std::collections::hash_map::DefaultHasher;
+
+/// Creates an Entity Tag from a `File` `Metadata`
+pub fn make_entity_tag(meta: &Metadata) -> String {
+  let mut created_hasher = DefaultHasher::new();
+  let mut modified_hasher = DefaultHasher::new();
+  let mut size_hasher = DefaultHasher::new();
+
+  meta.len().hash(&mut size_hasher);
+  meta.created().unwrap_or(SystemTime::now()).hash(&mut created_hasher);
+  meta.modified().unwrap_or(SystemTime::now()).hash(&mut modified_hasher);
+
+  format!("{0:x}{1:x}{2:x}", created_hasher.finish(), modified_hasher.finish(), size_hasher.finish())
+}
diff --git a/src/server/mod.rs b/src/server/mod.rs
index 8e815309..61a62336 100644
--- a/src/server/mod.rs
+++ b/src/server/mod.rs
@@ -1,3 +1,5 @@
+mod etag;
 mod http;
 
+pub use etag::*;
 pub use http::*;