Implemented default URL for missing images (#2)

src/http.cpp

@@ -34,6 +34,7 @@ const Request http::parse_request(const string &request)
     }
 
     uint16_t size = 80;
+    string fallback;
     string digest = request.substr(8);
     std::transform(digest.begin(), digest.end(), digest.begin(), ::tolower);
     std::size_t pos_digest = digest.find('?');
@@ -43,30 +44,47 @@ const Request http::parse_request(const string &request)
         digest = digest.substr(0, pos_digest);
 
         string answer;
-        answer = get_parameter(request, "s");
-        if (!answer.empty())
         {
-            size = static_cast<uint16_t>(std::stoul(answer));
-        }
-        else
-        {
-            answer = get_parameter(request, "size");
+            answer = get_parameter(request, "s");
             if (!answer.empty())
             {
                 size = static_cast<uint16_t>(std::stoul(answer));
             }
+            else
+            {
+                answer = get_parameter(request, "size");
+                if (!answer.empty())
+                {
+                    size = static_cast<uint16_t>(std::stoul(answer));
+                }
+            }
+            if (size > 512)
+            {
+                size = 512;
+            }
+            if (size < 1)
+            {
+                size = 1;
+            }
         }
-        if (size > 512)
         {
-            size = 512;
-        }
-        if (size < 1)
-        {
-            size = 1;
+            answer = get_parameter(request, "d");
+            if (!answer.empty())
+            {
+                fallback = answer;
+            }
+            else
+            {
+                answer = get_parameter(request, "default");
+                if (!answer.empty())
+                {
+                    fallback = answer;
+                }
+            }
         }
     }
 
-    return { digest, size };
+    return { digest, size, fallback };
 }
 
 const string http::get_parameter(const string &request, const string &parameter)

src/libravatarserv.cpp

@@ -62,8 +62,19 @@ int main()
     }
     else
     {
-        cout << "Status: 404 Not Found\n\n";
         cerr << "Error " << std::to_string(answer.error) << ": Could not open file.\n";
+        if (avatar.fallback.empty())
+        {
+            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;
+            }
+        }
     }
 
     return 0;

src/libravatarserv.hpp

@@ -49,6 +49,7 @@ namespace http  // http.cpp
     {
         const string digest;
         uint16_t size;
+        const string fallback;
     };
 
     const Request parse_request(const string &request);