[#11] Add Network Snapshot

Signed-off-by: Pavel Gross <p.gross@yadro.com>

src/FrostFS.SDK.ClientV2/Services/SessionServiceProvider.cs

@@ -0,0 +1,57 @@
+using System.Threading.Tasks;
+
+using FrostFS.SDK.ClientV2.Mappers.GRPC;
+using FrostFS.Session;
+
+namespace FrostFS.SDK.ClientV2;
+
+internal class SessionServiceProvider : ContextAccessor
+{  
+    private readonly SessionService.SessionServiceClient? _sessionServiceClient;
+
+    internal SessionServiceProvider(SessionService.SessionServiceClient? sessionServiceClient, ClientEnvironment context)
+        : base (context)
+    {
+        _sessionServiceClient = sessionServiceClient;
+    }
+
+    internal async Task<SessionToken> CreateSessionAsync(ulong expiration, Context ctx)
+    {
+        var request = new CreateRequest
+        {
+            Body = new CreateRequest.Types.Body
+            {
+                OwnerId = Context.Owner.ToGrpcMessage(),
+                Expiration = expiration
+            }
+        };
+
+        request.AddMetaHeader();
+        request.Sign(Context.Key);
+
+        var token = await CreateSession(request, ctx);
+
+        return token;
+    }
+
+    internal async Task<SessionToken> CreateSession(CreateRequest request, Context ctx)
+    {
+        var resp = await _sessionServiceClient!.CreateAsync(request, null, ctx.Deadline, ctx.CancellationToken);
+        
+        return new SessionToken
+        {
+            Body = new SessionToken.Types.Body
+            {
+                Id = resp.Body.Id,
+                SessionKey = resp.Body.SessionKey,
+                OwnerId = request.Body.OwnerId,
+                Lifetime = new SessionToken.Types.Body.Types.TokenLifetime
+                {
+                    Exp = request.Body.Expiration,
+                    Iat = resp.MetaHeader.Epoch,
+                    Nbf = resp.MetaHeader.Epoch,
+                }
+            }
+        };
+    }
+}