Merge pull request #297 from adam-p/master

Make OpenSSL compilation conditional on all platforms.

MobileLibrary/iOS/build-psiphon-framework.sh

@@ -200,7 +200,7 @@ IOS_CGO_BUILD_FLAGS='// #cgo darwin CFLAGS: -I'"${OPENSSL_INCLUDE}"'\
 
 LC_ALL=C sed -i -- "s|// #cgo pkg-config: libssl|${IOS_CGO_BUILD_FLAGS}|" "${OPENSSL_SRC_DIR}/build.go"
 
-${GOPATH}/bin/gomobile bind -target ios -ldflags="${LDFLAGS}" -o "${INTERMEDIATE_OUPUT_DIR}/${INTERMEDIATE_OUPUT_FILE}" github.com/Psiphon-Labs/psiphon-tunnel-core/MobileLibrary/psi
+${GOPATH}/bin/gomobile bind -v -x -target ios -tags="OPENSSL IOS" -ldflags="${LDFLAGS}" -o "${INTERMEDIATE_OUPUT_DIR}/${INTERMEDIATE_OUPUT_FILE}" github.com/Psiphon-Labs/psiphon-tunnel-core/MobileLibrary/psi
 rc=$?; if [[ $rc != 0 ]]; then
   echo "FAILURE: ${GOPATH}/bin/gomobile bind -target ios -ldflags="${LDFLAGS}" -o "${INTERMEDIATE_OUPUT_DIR}/${INTERMEDIATE_OUPUT_FILE}" github.com/Psiphon-Labs/psiphon-tunnel-core/MobileLibrary/psi"
   exit $rc

README.md

@@ -46,6 +46,9 @@ Client Setup
 
 ##### macOS
 
+Building without OpenSSL support (that is, without indistinguishable TLS support) requires no extra steps. 
+To compile with OpenSSL support, follow these steps:
+
 1. You must have [Homebrew](http://brew.sh/) installed.
 
 2. `brew install openssl pkg-config`
@@ -58,10 +61,11 @@ Client Setup
    
    Make note of the "build variable" path for `PKG_CONFIG_PATH`.
    
-4. Set `PKG_CONFIG_PATH=<path discovered above>` when building. This can be easily done on the build command line like so:
+4. Set `PKG_CONFIG_PATH=<path discovered above>` when building, and provide the `-tags OPENSSL` flag. 
+   This can be easily done on the build command line like so:
 
    ```
-   $ PKG_CONFIG_PATH=<path discovered above> go build
+   $ PKG_CONFIG_PATH=<path discovered above> go build -tags OPENSSL
    ```
 
 ### Configure

psiphon/opensslConn.go

@@ -1,4 +1,4 @@
-// +build android windows darwin
+// +build OPENSSL
 
 /*
  * Copyright (c) 2015, Psiphon Inc.

psiphon/opensslConn_unsupported.go

@@ -1,4 +1,4 @@
-// +build !android,!windows,!darwin
+// +build !OPENSSL
 
 /*
  * Copyright (c) 2015, Psiphon Inc.