Merge pull request #312 from adam-p/master

Add obfuscated server list functionality to iOS library

MobileLibrary/iOS/PsiphonTunnel/PsiphonTunnel/PsiphonTunnel.h

@@ -52,10 +52,13 @@ FOUNDATION_EXPORT const unsigned char PsiphonTunnelVersionString[];
  - Remote server list functionality is not strictly required, but absence greatly undermines circumvention ability.
    - `RemoteServerListUrl`
    - `RemoteServerListSignaturePublicKey`
+ - Obfuscated server list functionality is also not strictly required, but aids circumvention ability.
+   - `ObfuscatedServerListRootURL`
 
  Optional fields (if you don't need them, don't set them):
- - `DataStoreDirectory`: If not set, the library will use a sane location. Override if the client wants to restrict where operational data is kept.
- - `RemoteServerListDownloadFilename`: See comment for `DataStoreDirectory`.
+ - `DataStoreDirectory`: If not set, the library will use a sane location. Override if the client wants to restrict where operational data is kept. If overridden, the directory must already exist and be writable.
+ - `RemoteServerListDownloadFilename`: If not set, the library will use a sane location. Override if the client wants to restrict where operational data is kept.
+ - `ObfuscatedServerListDownloadDirectory`: If not set, the library will use a sane location. Override if the client wants to restrict where operational data is kept. If overridden, the directory must already exist and be writable.
  - `ClientPlatform`: Should not be set by most library consumers.
  - `UpstreamProxyUrl`
  - `EmitDiagnosticNotices`

MobileLibrary/iOS/PsiphonTunnel/PsiphonTunnel/PsiphonTunnel.m

@@ -183,6 +183,10 @@
         return nil;
     }
     
+    //
+    // DataStoreDirectory
+    //
+    
     // Some clients will have a data directory that they'd prefer the Psiphon
     // library use, but if not we'll default to the user Library directory.
     NSURL *defaultDataStoreDirectoryURL = [libraryURL URLByAppendingPathComponent:@"datastore" isDirectory:YES];
@@ -205,9 +209,11 @@
         [self logMessage:[NSString stringWithFormat: @"DataStoreDirectory overridden from '%@' to '%@'", [defaultDataStoreDirectoryURL path], config[@"DataStoreDirectory"]]];
     }
     
-    // See previous comment.
-    NSString *defaultRemoteServerListFilename = [[libraryURL URLByAppendingPathComponent:@"remote_server_list" isDirectory:NO] path];
+    //
+    // Remote Server List
+    //
     
+    NSString *defaultRemoteServerListFilename = [[libraryURL URLByAppendingPathComponent:@"remote_server_list" isDirectory:NO] path];
     if (defaultRemoteServerListFilename == nil) {
         [self logMessage:@"Unable to create defaultRemoteServerListFilename"];
         return nil;
@@ -226,6 +232,34 @@
         config[@"RemoteServerListSignaturePublicKey"] == nil) {
         [self logMessage:@"Remote server list functionality will be disabled"];
     }
+    
+    //
+    // Obfuscated Server List
+    //
+    
+    NSURL *defaultOSLDirectoryURL = [libraryURL URLByAppendingPathComponent:@"osl" isDirectory:YES];
+    if (defaultOSLDirectoryURL == nil) {
+        [self logMessage:@"Unable to create defaultOSLDirectory"];
+        return nil;
+    }
+    
+    if (config[@"ObfuscatedServerListDownloadDirectory"] == nil) {
+        [fileManager createDirectoryAtURL:defaultOSLDirectoryURL withIntermediateDirectories:YES attributes:nil error:&err];
+        if (err != nil) {
+            [self logMessage:[NSString stringWithFormat: @"Unable to create defaultOSLDirectoryURL: %@", err.localizedDescription]];
+            return nil;
+        }
+        
+        config[@"ObfuscatedServerListDownloadDirectory"] = [defaultOSLDirectoryURL path];
+    }
+    else {
+        [self logMessage:[NSString stringWithFormat: @"ObfuscatedServerListDownloadDirectory overridden from '%@' to '%@'", [defaultOSLDirectoryURL path], config[@"ObfuscatedServerListDownloadDirectory"]]];
+    }
+    
+    // If ObfuscatedServerListRootURL is absent, we'll leave it out, but log the absence.
+    if (config[@"ObfuscatedServerListRootURL"] == nil) {
+        [self logMessage:@"Obfuscated server list functionality will be disabled"];
+    }
 
     // Other optional fields not being altered. If not set, their defaults will be used:
     // * EstablishTunnelTimeoutSeconds