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encapsulate gzip logic for reuse (#654)

This commit is contained in:
Jesse Plamondon-Willard 2019-08-04 16:37:10 -04:00
parent 8e0ddd1d00
commit c86db64880
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4 changed files with 118 additions and 74 deletions
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82
src/SMAPI.Web/Controllers/LogParserController.cs
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@ -1,13 +1,11 @@
using System;
using System.IO;
using System.IO.Compression;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Options;
using StardewModdingAPI.Web.Framework;
using StardewModdingAPI.Web.Framework.Clients.Pastebin;
using StardewModdingAPI.Web.Framework.Compression;
using StardewModdingAPI.Web.Framework.ConfigModels;
using StardewModdingAPI.Web.Framework.LogParsing;
using StardewModdingAPI.Web.Framework.LogParsing.Models;
@ -27,9 +25,8 @@ namespace StardewModdingAPI.Web.Controllers
/// <summary>The underlying Pastebin client.</summary>
private readonly IPastebinClient Pastebin;
/// <summary>The first bytes in a valid zip file.</summary>
/// <remarks>See <a href="https://en.wikipedia.org/wiki/Zip_(file_format)#File_headers"/>.</remarks>
private const uint GzipLeadBytes = 0x8b1f;
/// <summary>The underlying text compression helper.</summary>
private readonly IGzipHelper GzipHelper;
/*********
@ -41,10 +38,12 @@ namespace StardewModdingAPI.Web.Controllers
/// <summary>Construct an instance.</summary>
/// <param name="siteConfig">The context config settings.</param>
/// <param name="pastebin">The Pastebin API client.</param>
public LogParserController(IOptions<SiteConfig> siteConfig, IPastebinClient pastebin)
/// <param name="gzipHelper">The underlying text compression helper.</param>
public LogParserController(IOptions<SiteConfig> siteConfig, IPastebinClient pastebin, IGzipHelper gzipHelper)
{
this.Config = siteConfig.Value;
this.Pastebin = pastebin;
this.GzipHelper = gzipHelper;
}
/***
@ -84,7 +83,7 @@ namespace StardewModdingAPI.Web.Controllers
return this.View("Index", new LogParserModel(this.Config.LogParserUrl, null) { UploadError = "The log file seems to be empty." });
// upload log
input = this.CompressString(input);
input = this.GzipHelper.CompressString(input);
SavePasteResult result = await this.Pastebin.PostAsync(input);
// handle errors
@ -106,75 +105,10 @@ namespace StardewModdingAPI.Web.Controllers
private async Task<PasteInfo> GetAsync(string id)
{
PasteInfo response = await this.Pastebin.GetAsync(id);
response.Content = this.DecompressString(response.Content);
response.Content = this.GzipHelper.DecompressString(response.Content);
return response;
}
/// <summary>Compress a string.</summary>
/// <param name="text">The text to compress.</param>
/// <remarks>Derived from <a href="https://stackoverflow.com/a/17993002/262123"/>.</remarks>
private string CompressString(string text)
{
// get raw bytes
byte[] buffer = Encoding.UTF8.GetBytes(text);
// compressed
byte[] compressedData;
using (MemoryStream stream = new MemoryStream())
{
using (GZipStream zipStream = new GZipStream(stream, CompressionLevel.Optimal, leaveOpen: true))
zipStream.Write(buffer, 0, buffer.Length);
stream.Position = 0;
compressedData = new byte[stream.Length];
stream.Read(compressedData, 0, compressedData.Length);
}
// prefix length
byte[] zipBuffer = new byte[compressedData.Length + 4];
Buffer.BlockCopy(compressedData, 0, zipBuffer, 4, compressedData.Length);
Buffer.BlockCopy(BitConverter.GetBytes(buffer.Length), 0, zipBuffer, 0, 4);
// return string representation
return Convert.ToBase64String(zipBuffer);
}
/// <summary>Decompress a string.</summary>
/// <param name="rawText">The compressed text.</param>
/// <remarks>Derived from <a href="https://stackoverflow.com/a/17993002/262123"/>.</remarks>
private string DecompressString(string rawText)
{
// get raw bytes
byte[] zipBuffer;
try
{
zipBuffer = Convert.FromBase64String(rawText);
}
catch
{
return rawText; // not valid base64, wasn't compressed by the log parser
}
// skip if not gzip
if (BitConverter.ToUInt16(zipBuffer, 4) != LogParserController.GzipLeadBytes)
return rawText;
// decompress
using (MemoryStream memoryStream = new MemoryStream())
{
// read length prefix
int dataLength = BitConverter.ToInt32(zipBuffer, 0);
memoryStream.Write(zipBuffer, 4, zipBuffer.Length - 4);
// read data
byte[] buffer = new byte[dataLength];
memoryStream.Position = 0;
using (GZipStream gZipStream = new GZipStream(memoryStream, CompressionMode.Decompress))
gZipStream.Read(buffer, 0, buffer.Length);
// return original string
return Encoding.UTF8.GetString(buffer);
}
}
}
}

89
src/SMAPI.Web/Framework/Compression/GzipHelper.cs Normal file
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@ -0,0 +1,89 @@
using System;
using System.IO;
using System.IO.Compression;
using System.Text;
namespace StardewModdingAPI.Web.Framework.Compression
{
/// <summary>Handles GZip compression logic.</summary>
internal class GzipHelper : IGzipHelper
{
/*********
** Fields
*********/
/// <summary>The first bytes in a valid zip file.</summary>
/// <remarks>See <a href="https://en.wikipedia.org/wiki/Zip_(file_format)#File_headers"/>.</remarks>
private const uint GzipLeadBytes = 0x8b1f;
/*********
** Public methods
*********/
/// <summary>Compress a string.</summary>
/// <param name="text">The text to compress.</param>
/// <remarks>Derived from <a href="https://stackoverflow.com/a/17993002/262123"/>.</remarks>
public string CompressString(string text)
{
// get raw bytes
byte[] buffer = Encoding.UTF8.GetBytes(text);
// compressed
byte[] compressedData;
using (MemoryStream stream = new MemoryStream())
{
using (GZipStream zipStream = new GZipStream(stream, CompressionLevel.Optimal, leaveOpen: true))
zipStream.Write(buffer, 0, buffer.Length);
stream.Position = 0;
compressedData = new byte[stream.Length];
stream.Read(compressedData, 0, compressedData.Length);
}
// prefix length
byte[] zipBuffer = new byte[compressedData.Length + 4];
Buffer.BlockCopy(compressedData, 0, zipBuffer, 4, compressedData.Length);
Buffer.BlockCopy(BitConverter.GetBytes(buffer.Length), 0, zipBuffer, 0, 4);
// return string representation
return Convert.ToBase64String(zipBuffer);
}
/// <summary>Decompress a string.</summary>
/// <param name="rawText">The compressed text.</param>
/// <remarks>Derived from <a href="https://stackoverflow.com/a/17993002/262123"/>.</remarks>
public string DecompressString(string rawText)
{
// get raw bytes
byte[] zipBuffer;
try
{
zipBuffer = Convert.FromBase64String(rawText);
}
catch
{
return rawText; // not valid base64, wasn't compressed by the log parser
}
// skip if not gzip
if (BitConverter.ToUInt16(zipBuffer, 4) != GzipHelper.GzipLeadBytes)
return rawText;
// decompress
using (MemoryStream memoryStream = new MemoryStream())
{
// read length prefix
int dataLength = BitConverter.ToInt32(zipBuffer, 0);
memoryStream.Write(zipBuffer, 4, zipBuffer.Length - 4);
// read data
byte[] buffer = new byte[dataLength];
memoryStream.Position = 0;
using (GZipStream gZipStream = new GZipStream(memoryStream, CompressionMode.Decompress))
gZipStream.Read(buffer, 0, buffer.Length);
// return original string
return Encoding.UTF8.GetString(buffer);
}
}
}
}

17
src/SMAPI.Web/Framework/Compression/IGzipHelper.cs Normal file
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@ -0,0 +1,17 @@
namespace StardewModdingAPI.Web.Framework.Compression
{
/// <summary>Handles GZip compression logic.</summary>
internal interface IGzipHelper
{
/*********
** Methods
*********/
/// <summary>Compress a string.</summary>
/// <param name="text">The text to compress.</param>
string CompressString(string text);
/// <summary>Decompress a string.</summary>
/// <param name="rawText">The compressed text.</param>
string DecompressString(string rawText);
}
}

4
src/SMAPI.Web/Startup.cs
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@ -20,6 +20,7 @@ using StardewModdingAPI.Web.Framework.Clients.GitHub;
using StardewModdingAPI.Web.Framework.Clients.ModDrop;
using StardewModdingAPI.Web.Framework.Clients.Nexus;
using StardewModdingAPI.Web.Framework.Clients.Pastebin;
using StardewModdingAPI.Web.Framework.Compression;
using StardewModdingAPI.Web.Framework.ConfigModels;
using StardewModdingAPI.Web.Framework.RewriteRules;
@ -149,6 +150,9 @@ namespace StardewModdingAPI.Web
devKey: api.PastebinDevKey
));
}
// init helpers
services.AddSingleton<IGzipHelper>(new GzipHelper());
}
/// <summary>The method called by the runtime to configure the HTTP request pipeline.</summary>