From a31ccb658816bcd7a2b03b697b613da72c28f3d8 Mon Sep 17 00:00:00 2001
From: Veloman Yunkan <veloman.yunkan@gmail.com>
Date: Sun, 9 Oct 2022 21:29:38 +0400
Subject: [PATCH] Decoupling ETags from the server id

---
 src/server/etag.cpp   | 16 ++++++++--------
 src/server/etag.h     | 15 ++++++++-------
 src/server/response.h |  2 +-
 3 files changed, 17 insertions(+), 16 deletions(-)

diff --git a/src/server/etag.cpp b/src/server/etag.cpp
index e031ce46c..0492bdde1 100644
--- a/src/server/etag.cpp
+++ b/src/server/etag.cpp
@@ -41,7 +41,7 @@ const char all_options[] = "Zz";
 
 static_assert(ETag::OPTION_COUNT == sizeof(all_options) - 1, "");
 
-bool isValidServerId(const std::string& s)
+bool isValidETagBody(const std::string& s)
 {
   return !s.empty() && s.find_first_of("\"/") == std::string::npos;
 }
@@ -83,17 +83,17 @@ bool ETag::get_option(Option opt) const
 
 std::string ETag::get_etag() const
 {
-  if ( m_serverId.empty() )
+  if ( m_body.empty() )
     return std::string();
 
-  return "\"" + m_serverId + "/" + m_options + "\"";
+  return "\"" + m_body + "/" + m_options + "\"";
 }
 
-ETag::ETag(const std::string& serverId, const std::string& options)
+ETag::ETag(const std::string& body, const std::string& options)
 {
-  if ( isValidServerId(serverId) && isValidOptionsString(options) )
+  if ( isValidETagBody(body) && isValidOptionsString(options) )
   {
-    m_serverId = serverId;
+    m_body = body;
     m_options = options;
   }
 }
@@ -115,7 +115,7 @@ ETag ETag::parse(std::string s)
   return ETag(s.substr(0, i), s.substr(i+1));
 }
 
-ETag ETag::match(const std::string& etags, const std::string& server_id)
+ETag ETag::match(const std::string& etags, const std::string& body)
 {
   std::istringstream ss(etags);
   std::string etag_str;
@@ -125,7 +125,7 @@ ETag ETag::match(const std::string& etags, const std::string& server_id)
       etag_str.pop_back();
 
     const ETag etag = parse(etag_str);
-    if ( etag && etag.m_serverId == server_id )
+    if ( etag && etag.m_body == body )
       return etag;
   }
 
diff --git a/src/server/etag.h b/src/server/etag.h
index f8da02360..b6346e7e6 100644
--- a/src/server/etag.h
+++ b/src/server/etag.h
@@ -28,10 +28,11 @@ namespace kiwix {
 // The ETag string used by Kiwix server (more precisely, its value inside the
 // double quotes) consists of two parts:
 //
-// 1. ServerId - The string obtained on server start up
+// 1. Body    -  A string uniquely identifying the object or state from which
+//               the resource has been obtained.
 //
-// 2. Options -  Zero or more characters encoding the values of some of the
-//               headers of the response
+// 2. Options -  Zero or more characters encoding the type of the ETag and/or
+//               the values of some of the headers of the response
 //
 // The two parts are separated with a slash (/) symbol (which is always present,
 // even when the the options part is empty). Neither portion of a Kiwix ETag
@@ -40,7 +41,7 @@ namespace kiwix {
 //
 //   "abcdefghijklmn/"
 //   "1234567890/z"
-//   "1234567890/cz"
+//   "6f1d19d0-633f-087b-fb55-7ac324ff9baf/Zz"
 //
 // The options part of the Kiwix ETag allows to correctly set the required
 // headers when responding to a conditional If-None-Match request with a 304
@@ -59,10 +60,10 @@ class ETag
   public: // functions
     ETag() {}
 
-    void set_server_id(const std::string& id) { m_serverId = id; }
+    void set_body(const std::string& s) { m_body = s; }
     void set_option(Option opt);
 
-    explicit operator bool() const { return !m_serverId.empty(); }
+    explicit operator bool() const { return !m_body.empty(); }
 
     bool get_option(Option opt) const;
     std::string get_etag() const;
@@ -76,7 +77,7 @@ class ETag
     static ETag parse(std::string s);
 
   private: // data
-    std::string m_serverId;
+    std::string m_body;
     std::string m_options;
 };
 
diff --git a/src/server/response.h b/src/server/response.h
index d1aa90ffc..31bcfc0da 100644
--- a/src/server/response.h
+++ b/src/server/response.h
@@ -66,7 +66,7 @@ class Response {
 
     void set_code(int code) { m_returnCode = code; }
     void set_kind(Kind k);
-    void set_server_id(const std::string& id) { m_etag.set_server_id(id); }
+    void set_server_id(const std::string& id) { m_etag.set_body(id); }
     void add_header(const std::string& name, const std::string& value) { m_customHeaders[name] = value; }
 
     int getReturnCode() const { return m_returnCode; }