git-credential-manager/src/shared/Core/Authentication/OAuth/OAuth2SystemWebBrowser.cs at cb4afc0d6e2087ef17aaba0f20d0a29257cb7eea · git-ecosystem/git-credential-manager · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
using System;
using System.Collections.Generic;
using System.Net;
using System.Net.Sockets;
using System.Threading;
using System.Threading.Tasks;

namespace GitCredentialManager.Authentication.OAuth
{
    public class OAuth2WebBrowserOptions
    {
        internal const string DefaultSuccessHtml = @"<!DOCTYPE html><html><head>
<style>body{font-family:sans-serif;}dt{font-weight:bold;}dd{margin-bottom:10px;}</style>
<title>Authentication successful</title></head>
<body><h1>Authentication successful</h1><p>You can now close this page.</p></body>
</html>";
        internal const string DefaultFailureHtmlFormat = @"<!DOCTYPE html><html><head>
<style>body{{font-family:sans-serif;}}dt{{font-weight:bold;}}dd{{margin-bottom:10px;}}</style>
<title>Authentication failed</title></head>
<body><h1>Authentication failed</h1><dl>
<dt>Error:</dt><dd>{0}</dd>
<dt>Description:</dt><dd>{1}</dd>
<dt>URL:</dt><dd>{2}</dd>
</dl></body></html>";

        public string SuccessResponseHtml { get; set; }
        public string FailureResponseHtmlFormat { get; set; }

        public Uri SuccessRedirect { get; set; }
        public Uri FailureRedirectFormat { get; set; }
    }

    public class OAuth2SystemWebBrowser : IOAuth2WebBrowser
    {
        private readonly ISessionManager _sessionManager;
        private readonly OAuth2WebBrowserOptions _options;

        public OAuth2SystemWebBrowser(ISessionManager sessionManager, OAuth2WebBrowserOptions options)
        {
            EnsureArgument.NotNull(sessionManager, nameof(sessionManager));
            EnsureArgument.NotNull(options, nameof(options));

            _sessionManager = sessionManager;
            _options = options;
        }

        public Uri UpdateRedirectUri(Uri uri)
        {
            if (!uri.IsLoopback)
            {
                throw new ArgumentException("Only localhost is supported as a redirect URI.", nameof(uri));
            }

            // If a port has been specified use it, otherwise find a free one
            if (uri.IsDefaultPort)
            {
                int port = GetFreeTcpPort();
                return new UriBuilder(uri) {Port = port}.Uri;
            }

            return uri;
        }

        public async Task<Uri> GetAuthenticationCodeAsync(Uri authorizationUri, Uri redirectUri, CancellationToken ct)
        {
            if (!redirectUri.IsLoopback)
            {
                throw new ArgumentException("Only localhost is supported as a redirect URI.", nameof(redirectUri));
            }

            Task<Uri> interceptTask = InterceptRequestsAsync(redirectUri, ct);

            _sessionManager.OpenBrowser(authorizationUri);

            return await interceptTask;
        }

        private async Task<Uri> InterceptRequestsAsync(Uri listenUri, CancellationToken ct)
        {
            // Create a TaskCompletionSource which completes when we're asked to cancel.
            // We can then await the this task together with other tasks that don't take a
            // CancellationToken and exit the method quickly when cancelled.
            var tcs = new TaskCompletionSource<Uri>();
            ct.Register(() => tcs.SetCanceled());

            // Prefixes must end with a '/'
            string prefix = listenUri.GetLeftPart(UriPartial.Path);
            if (!prefix.EndsWith("/"))
            {
                prefix += "/";
            }

            var listener = new HttpListener {Prefixes = {prefix}};
            listener.Start();

            try
            {
                Task<HttpListenerContext> contextTask = listener.GetContextAsync();
                Task<Uri> cancelTask = tcs.Task;

                Task completedTask = await Task.WhenAny(contextTask, tcs.Task);

                // Check if we 'completed' the context task or the cancellation task
                if (completedTask == cancelTask)
                {
                    // We were cancelled!
                    return await cancelTask;
                }

                // We intercepted a request!
                HttpListenerContext context = await contextTask;

                await HandleInterceptedRequestAsync(context.Request, context.Response);

                // Return the final intercepted URI
                return context.Request.Url;
            }
            finally
            {
                listener.Stop();
                listener.Close();
            }
        }

        private async Task HandleInterceptedRequestAsync(HttpListenerRequest request, HttpListenerResponse response)
        {
            IDictionary<string, string> queryParams = request.QueryString.ToDictionary(StringComparer.OrdinalIgnoreCase);

            // If we have an error value then the request failed and we should reply with a page containing the error information
            bool hasError = queryParams.TryGetValue(OAuth2Constants.AuthorizationGrantResponse.ErrorCodeParameter, out string errorCode);
            queryParams.TryGetValue(OAuth2Constants.AuthorizationGrantResponse.ErrorDescriptionParameter, out string errorDescription);
            queryParams.TryGetValue(OAuth2Constants.AuthorizationGrantResponse.ErrorUriParameter, out string errorUri);
            if (hasError)
            {
                string FormatError(string format)
                {
                    if (string.IsNullOrWhiteSpace(errorCode)) errorCode = "unknown";
                    if (string.IsNullOrWhiteSpace(errorDescription)) errorDescription = "Unknown error.";
                    if (string.IsNullOrWhiteSpace(errorUri)) errorUri = "none";
                    return string.Format(format, errorCode, errorDescription, errorUri);
                }

                // Prefer redirection options to raw HTML
                if (_options.FailureRedirectFormat != null)
                {
                    string failureUrl = FormatError(_options.FailureRedirectFormat.ToString());
                    response.Redirect(failureUrl);
                    response.Close();
                }
                else
                {
                    string failureHtml = FormatError(_options.FailureResponseHtmlFormat ?? OAuth2WebBrowserOptions.DefaultFailureHtmlFormat);
                    await response.WriteResponseAsync(failureHtml);
                    response.Close();
                }
            }
            else
            {
                // Prefer redirection options to raw HTML
                if (_options.SuccessRedirect != null)
                {
                    string successUrl = _options.SuccessRedirect.ToString();
                    response.Redirect(successUrl);
                    response.Close();
                }
                else
                {
                    string successHtml = _options.SuccessResponseHtml ?? OAuth2WebBrowserOptions.DefaultSuccessHtml;
                    await response.WriteResponseAsync(successHtml);
                    response.Close();
                }
            }
        }

        private static int GetFreeTcpPort()
        {
            var listener = new TcpListener(IPAddress.Loopback, 0);

            try
            {
                listener.Start();
                return ((IPEndPoint) listener.LocalEndpoint).Port;
            }
            finally
            {
                listener.Stop();
            }
        }

    }
}