Added settings to redirect to libravatar.org if the user was not found

or the fallback is unknown.

README.md

@@ -73,6 +73,35 @@ The avatar directory could look like this:
 └── [  16]  user+newsletter@example.com -> user@example.com
 ```
 
+### Configuration
+
+Configuration is done through environment variables.
+
+#### LIBRAVATARSERV_DIR
+
+The directory containing the avatars.
+
+Default: empty
+
+#### LIBRAVATARSERV_DEFAULT_FALLBACK
+
+Controls what happens if no fallback was requested.
+
+Default: 404
+
+#### LIBRAVATARSERV_REDIRECT_NOFALLBACK
+
+Set to 1 to redirect to libravatar.org if the requested fallback is not
+supported.
+
+Default: 0
+
+#### LIBRAVATARSERV_REDIRECT_NOUSER
+
+Set to 1 to redirect to libravatar.org if the user is not found.
+
+Default: 0
+
 ## Install
 
 ### Gentoo

doc/nginx-example.conf

@@ -13,7 +13,10 @@ server {
         include /etc/nginx/fastcgi_params;
         fastcgi_pass    unix:/var/run/cgi-fcgiwrap.socket-1;
         fastcgi_param SCRIPT_FILENAME /usr/bin/libravatarserv;
-        fastcgi_param LIBRAVATARSERV_DEFAULT_FALLBACK 404;
+
+        # fastcgi_param LIBRAVATARSERV_DEFAULT_FALLBACK 404;
+        # fastcgi_param LIBRAVATARSERV_REDIRECT_NOFALLBACK 0;
+        # fastcgi_param LIBRAVATARSERV_REDIRECT_NOUSER 0;
     }
 }
 
@@ -29,6 +32,5 @@ server {
         include /etc/nginx/fastcgi_params;
         fastcgi_pass    unix:/var/run/cgi-fcgiwrap.socket-1;
         fastcgi_param SCRIPT_FILENAME /usr/bin/libravatarserv;
-        fastcgi_param LIBRAVATARSERV_DEFAULT_FALLBACK 404;
     }
 }

src/http.cpp

@@ -21,6 +21,7 @@
 
 using std::cout;
 using std::cerr;
+using std::endl;
 using namespace http;
 
 const Request http::parse_request(const string &request)
@@ -109,3 +110,21 @@ const string http::get_parameter(const string &request, const string &parameter)
 
     return "";
 }
+
+void http::send_redirect(const Request &request)
+{
+    const char *env = std::getenv("HTTPS");
+    string baseurl;
+    if (env != nullptr && env[1] == 'n')
+    {
+        baseurl = "https://seccdn.libravatar.org";
+    }
+    else
+    {
+        baseurl = "http://cdn.libravatar.org";
+    }
+    cout << "Status: 307 Temporary Redirect\n";
+    cout << "Location: " << baseurl << "/avatar/"
+         << request.digest << "?s=" << request.size
+         << "&d=" << request.fallback << endl << endl;
+}

src/libravatarserv.cpp

@@ -65,11 +65,20 @@ int main()
     else
     {
         cerr << "Error " << std::to_string(image.error) << ": Could not open file.\n";
+        if (global::settings.redirect_nouser)
+        {
+            http::send_redirect(avatar);
+            return 0;
+        }
         if (avatar.fallback.empty())
         {
             avatar.fallback = settings.default_fallback;
         }
-        if (avatar.fallback.substr(0, 4) == "http")
+        if (avatar.fallback.substr(0, 3) == "404")
+        {
+            cout << "Status: 404 Not Found\n\n";
+        }
+        else if (avatar.fallback.substr(0, 4) == "http")
         {
             cout << "Status: 307 Temporary Redirect\n";
             cout << "Location: " << avatar.fallback << endl << endl;
@@ -106,8 +115,16 @@ int main()
         }
         else
         {
-            // If fallback is empty or unknown
-            cout << "Status: 404 Not Found\n\n";
+            if (global::settings.redirect_nofallback)
+            {
+                cout << "Status: 307 Temporary Redirect\n";
+                http::send_redirect(avatar);
+                return 0;
+            }
+            else
+            {
+                cout << "Status: 404 Not Found\n\n";
+            }
         }
     }
 
@@ -160,4 +177,16 @@ void read_settings()
     {
         global::settings.default_fallback = env;
     }
+
+    env = std::getenv("LIBRAVATARSERV_REDIRECT_NOFALLBACK");
+    if (env != nullptr && env[0] == '1')
+    {
+        global::settings.redirect_nofallback = true;
+    }
+
+    env = std::getenv("LIBRAVATARSERV_REDIRECT_NOUSER");
+    if (env != nullptr && env[0] == '1')
+    {
+        global::settings.redirect_nouser = true;
+    }
 }

src/libravatarserv.hpp

@@ -44,7 +44,9 @@ namespace global
     extern fs::path avatar_dir;
     extern struct Settings
     {
-        string default_fallback;
+        string default_fallback = "";
+        bool redirect_nofallback = false;
+        bool redirect_nouser = false;
     } settings;
 }
 
@@ -59,6 +61,7 @@ namespace http  // http.cpp
 
     const Request parse_request(const string &request);
     const string get_parameter(const string &request, const string &parameter);
+    void send_redirect(const Request &request);
 }
 
 namespace hash  // hash.cpp