Merge pull request #97 from seionmoya/initial-etag

Initial ETag support
project-fika · Nov 15, 2024 · 5e1d1f8 · 5e1d1f8
2 parents 1b41d42 + db8dc04
commit 5e1d1f8
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Showing 5 changed files with 142 additions and 4 deletions.
diff --git a/Fuyu.Backend.BSG/Models/Responses/ResponseBody.cs b/Fuyu.Backend.BSG/Models/Responses/ResponseBody.cs
@@ -18,6 +18,6 @@ public class ResponseBody<T>
 
         // emits when '0'
         [DataMember(EmitDefaultValue = false)]
-        public int crc;
+        public uint crc;
     }
 }
diff --git a/Fuyu.Backend.BSG/Services/ETagService.cs b/Fuyu.Backend.BSG/Services/ETagService.cs
@@ -0,0 +1,60 @@
+using System;
+using System.Net;
+using System.Text;
+using System.Threading.Tasks;
+using Fuyu.Backend.BSG.Models.Responses;
+using Fuyu.Common.Hashing;
+using Fuyu.Common.Networking;
+using Fuyu.Common.Serialization;
+
+namespace Fuyu.Backend.BSG.Services
+{
+    public class ETagService
+    {
+        public static uint GetUIntETag(HttpContext context)
+        {
+            var value = context.GetETag();
+
+            if (string.IsNullOrWhiteSpace(value))
+            {
+                return 0u;
+            }
+
+            // NOTE: why BSG decided to put the crc is quotes is beyond me
+            // -- seionmoya, 2024-11-14
+            value = value.Replace("\"", string.Empty);
+
+            return Convert.ToUInt32(value);
+        }
+
+        public static uint GetCrc(object o)
+        {
+            var json = Json.Stringify(o);
+            var bytes = Encoding.UTF8.GetBytes(json);
+            return Crc32.Compute(bytes);
+        }
+
+        public static bool IsCacheInvalid(uint cached, uint crc)
+        {
+            return cached == 0u || cached != crc;
+        }
+
+        public static Task SendCachedAsync<TResponse>(HttpContext context, ResponseBody<TResponse> response)
+        {
+            var cached = GetUIntETag(context);
+            var crc = GetCrc(response.data);
+
+            if (IsCacheInvalid(cached, crc))
+            {
+                // outdated client cache
+                response.crc = crc;
+                return context.SendJsonAsync(Json.Stringify(response));
+            }
+            else
+            {
+                // up-to-date client cache
+                return context.SendStatus(HttpStatusCode.NotModified);
+            }   
+        }
+    }
+}
diff --git a/Fuyu.Backend.EFT/Controllers/Http/LocaleController.cs b/Fuyu.Backend.EFT/Controllers/Http/LocaleController.cs
@@ -2,8 +2,8 @@
 using System.Text.RegularExpressions;
 using System.Threading.Tasks;
 using Fuyu.Backend.BSG.Models.Responses;
+using Fuyu.Backend.BSG.Services;
 using Fuyu.Common.Networking;
-using Fuyu.Common.Serialization;
 
 namespace Fuyu.Backend.EFT.Controllers.Http
 {
@@ -16,7 +16,7 @@ public LocaleController() : base(PathExpression())
         {
         }
 
-        public override async Task RunAsync(HttpContext context)
+        public override Task RunAsync(HttpContext context)
         {
             var parameters = context.GetPathParameters(this);
 
@@ -27,7 +27,7 @@ public override async Task RunAsync(HttpContext context)
                 data = locale
             };
 
-            await context.SendJsonAsync(Json.Stringify(response));
+            return ETagService.SendCachedAsync(context, response);           
         }
     }
 }
diff --git a/Fuyu.Common/Hashing/Crc32.cs b/Fuyu.Common/Hashing/Crc32.cs
@@ -0,0 +1,73 @@
+namespace Fuyu.Common.Hashing
+{
+    public class Crc32
+    {
+        private static readonly uint[] _lookup = new uint[]
+        {
+            0x00000000, 0x77073096, 0xEE0E612C, 0x990951BA, 0x076DC419,
+            0x706AF48F, 0xE963A535, 0x9E6495A3, 0x0EDB8832, 0x79DCB8A4,
+            0xE0D5E91E, 0x97D2D988, 0x09B64C2B, 0x7EB17CBD, 0xE7B82D07,
+            0x90BF1D91, 0x1DB71064, 0x6AB020F2, 0xF3B97148, 0x84BE41DE,
+            0x1ADAD47D, 0x6DDDE4EB, 0xF4D4B551, 0x83D385C7, 0x136C9856,
+            0x646BA8C0, 0xFD62F97A, 0x8A65C9EC, 0x14015C4F, 0x63066CD9,
+            0xFA0F3D63, 0x8D080DF5, 0x3B6E20C8, 0x4C69105E, 0xD56041E4,
+            0xA2677172, 0x3C03E4D1, 0x4B04D447, 0xD20D85FD, 0xA50AB56B,
+            0x35B5A8FA, 0x42B2986C, 0xDBBBC9D6, 0xACBCF940, 0x32D86CE3,
+            0x45DF5C75, 0xDCD60DCF, 0xABD13D59, 0x26D930AC, 0x51DE003A,
+            0xC8D75180, 0xBFD06116, 0x21B4F4B5, 0x56B3C423, 0xCFBA9599,
+            0xB8BDA50F, 0x2802B89E, 0x5F058808, 0xC60CD9B2, 0xB10BE924,
+            0x2F6F7C87, 0x58684C11, 0xC1611DAB, 0xB6662D3D, 0x76DC4190,
+            0x01DB7106, 0x98D220BC, 0xEFD5102A, 0x71B18589, 0x06B6B51F,
+            0x9FBFE4A5, 0xE8B8D433, 0x7807C9A2, 0x0F00F934, 0x9609A88E,
+            0xE10E9818, 0x7F6A0DBB, 0x086D3D2D, 0x91646C97, 0xE6635C01,
+            0x6B6B51F4, 0x1C6C6162, 0x856530D8, 0xF262004E, 0x6C0695ED,
+            0x1B01A57B, 0x8208F4C1, 0xF50FC457, 0x65B0D9C6, 0x12B7E950,
+            0x8BBEB8EA, 0xFCB9887C, 0x62DD1DDF, 0x15DA2D49, 0x8CD37CF3,
+            0xFBD44C65, 0x4DB26158, 0x3AB551CE, 0xA3BC0074, 0xD4BB30E2,
+            0x4ADFA541, 0x3DD895D7, 0xA4D1C46D, 0xD3D6F4FB, 0x4369E96A,
+            0x346ED9FC, 0xAD678846, 0xDA60B8D0, 0x44042D73, 0x33031DE5,
+            0xAA0A4C5F, 0xDD0D7CC9, 0x5005713C, 0x270241AA, 0xBE0B1010,
+            0xC90C2086, 0x5768B525, 0x206F85B3, 0xB966D409, 0xCE61E49F,
+            0x5EDEF90E, 0x29D9C998, 0xB0D09822, 0xC7D7A8B4, 0x59B33D17,
+            0x2EB40D81, 0xB7BD5C3B, 0xC0BA6CAD, 0xEDB88320, 0x9ABFB3B6,
+            0x03B6E20C, 0x74B1D29A, 0xEAD54739, 0x9DD277AF, 0x04DB2615,
+            0x73DC1683, 0xE3630B12, 0x94643B84, 0x0D6D6A3E, 0x7A6A5AA8,
+            0xE40ECF0B, 0x9309FF9D, 0x0A00AE27, 0x7D079EB1, 0xF00F9344,
+            0x8708A3D2, 0x1E01F268, 0x6906C2FE, 0xF762575D, 0x806567CB,
+            0x196C3671, 0x6E6B06E7, 0xFED41B76, 0x89D32BE0, 0x10DA7A5A,
+            0x67DD4ACC, 0xF9B9DF6F, 0x8EBEEFF9, 0x17B7BE43, 0x60B08ED5,
+            0xD6D6A3E8, 0xA1D1937E, 0x38D8C2C4, 0x4FDFF252, 0xD1BB67F1,
+            0xA6BC5767, 0x3FB506DD, 0x48B2364B, 0xD80D2BDA, 0xAF0A1B4C,
+            0x36034AF6, 0x41047A60, 0xDF60EFC3, 0xA867DF55, 0x316E8EEF,
+            0x4669BE79, 0xCB61B38C, 0xBC66831A, 0x256FD2A0, 0x5268E236,
+            0xCC0C7795, 0xBB0B4703, 0x220216B9, 0x5505262F, 0xC5BA3BBE,
+            0xB2BD0B28, 0x2BB45A92, 0x5CB36A04, 0xC2D7FFA7, 0xB5D0CF31,
+            0x2CD99E8B, 0x5BDEAE1D, 0x9B64C2B0, 0xEC63F226, 0x756AA39C,
+            0x026D930A, 0x9C0906A9, 0xEB0E363F, 0x72076785, 0x05005713,
+            0x95BF4A82, 0xE2B87A14, 0x7BB12BAE, 0x0CB61B38, 0x92D28E9B,
+            0xE5D5BE0D, 0x7CDCEFB7, 0x0BDBDF21, 0x86D3D2D4, 0xF1D4E242,
+            0x68DDB3F8, 0x1FDA836E, 0x81BE16CD, 0xF6B9265B, 0x6FB077E1,
+            0x18B74777, 0x88085AE6, 0xFF0F6A70, 0x66063BCA, 0x11010B5C,
+            0x8F659EFF, 0xF862AE69, 0x616BFFD3, 0x166CCF45, 0xA00AE278,
+            0xD70DD2EE, 0x4E048354, 0x3903B3C2, 0xA7672661, 0xD06016F7,
+            0x4969474D, 0x3E6E77DB, 0xAED16A4A, 0xD9D65ADC, 0x40DF0B66,
+            0x37D83BF0, 0xA9BCAE53, 0xDEBB9EC5, 0x47B2CF7F, 0x30B5FFE9,
+            0xBDBDF21C, 0xCABAC28A, 0x53B39330, 0x24B4A3A6, 0xBAD03605,
+            0xCDD70693, 0x54DE5729, 0x23D967BF, 0xB3667A2E, 0xC4614AB8,
+            0x5D681B02, 0x2A6F2B94, 0xB40BBE37, 0xC30C8EA1, 0x5A05DF1B,
+            0x2D02EF8D
+        };
+
+        public static uint Compute(byte[] bytes)
+        {
+            var crc = uint.MaxValue;
+
+            foreach (var b in bytes)
+            {
+                crc = _lookup[(crc ^ b) & byte.MaxValue] ^ crc >> 8;
+            }
+
+            return ~crc;
+        }
+    }
+}
diff --git a/Fuyu.Common/Networking/HttpContext.cs b/Fuyu.Common/Networking/HttpContext.cs
@@ -47,6 +47,11 @@ public async Task<T> GetJsonAsync<T>()
             return Json.Parse<T>(json);
         }
 
+        public string GetETag()
+        {
+            return Request.Headers["If-None-Match"];
+        }
+
         public string GetSessionId()
         {
             return Request.Cookies["PHPSESSID"].Value;