Build: implement cryptopp submodule. Fixes #210

* Also, adjust related cmake + make
* References #141

.gitmodules

@@ -2,3 +2,7 @@
 	path = deps/cpp-netlib
 	url = https://github.com/cpp-netlib/cpp-netlib.git
 	branch = 0.13-release
+[submodule "deps/cryptopp"]
+	path = deps/cryptopp
+	url = https://github.com/weidai11/cryptopp.git
+	branch = master

CMakeLists.txt

@@ -113,9 +113,9 @@ endif()
 if(WITH_CRYPTOPP)
   find_package(CryptoPP REQUIRED)
   if(NOT DEFINED CRYPTO++_INCLUDE_DIR)
-    message(SEND_ERROR "Could not find Crypto++. Please download and install it first!")
+    message(SEND_ERROR "Could not find Crypto++. See building instructions.")
   endif()
-  include_directories(${CRYPTO++_INCLUDE_DIR})
+  include_directories(${CRYPTO++_INCLUDE_DIR}/../)  # We back-track for <cryptopp/*>
 endif()
 
 if(APPLE)

Makefile

@@ -57,6 +57,7 @@ remove-build = rm -fR $(build)
 # Dependencies
 deps = deps
 cpp-netlib = $(deps)/cpp-netlib
+cryptopp = $(deps)/cryptopp
 
 # Current off-by-default build options
 cmake-upnp       = -D WITH_UPNP=ON
@@ -75,6 +76,7 @@ cmake-data-path = -D KOVRI_DATA_PATH=$(data-path)
 
 # Release types
 # TODO(unassigned): put these to good use. We'll require rewrite of root recipe.
+# TODO(unassigned): use release flag for dependencies when we release
 cmake-debug = -D CMAKE_BUILD_TYPE=Debug
 #cmake-release = -D CMAKE_BUILD_TYPE=Release
 
@@ -87,6 +89,8 @@ all: shared
 dependencies:
 	mkdir -p $(cpp-netlib)/$(build)
 	cd $(cpp-netlib)/$(build) && $(cmake) $(cmake-debug) ../ && $(MAKE)
+	mkdir -p $(cryptopp)/$(build)
+	cd $(cryptopp)/$(build) && $(cmake) $(cmake-debug) ../ && $(MAKE)
 
 shared:
 	mkdir -p $(build)

cmake/FindCryptoPP.cmake

@@ -34,22 +34,31 @@ if(CRYPTO++_INCLUDE_DIR AND CRYPTO++_LIBRARIES)
    set(CRYPTO++_FOUND TRUE)
 
 else(CRYPTO++_INCLUDE_DIR AND CRYPTO++_LIBRARIES)
-  find_path(CRYPTO++_INCLUDE_DIR cryptopp/cryptlib.h
-  /usr/include
-  /usr/local/include
-  $ENV{SystemDrive}/Crypto++/include
-  $ENV{CRYPTOPP}
-  $ENV{CRYPTOPP}/..
-  $ENV{CRYPTOPP}/include
-  ${PROJECT_SOURCE_DIR}/../..)
+  find_path(CRYPTO++_INCLUDE_DIR cryptlib.h
+  ${PROJECT_SOURCE_DIR}/deps/cryptopp)
 
-  find_library(CRYPTO++_LIBRARIES NAMES cryptopp
-  PATHS
-  /usr/lib
-  /usr/local/lib
-  /opt/local/lib
-  $ENV{SystemDrive}/Crypto++/lib
-  $ENV{CRYPTOPP}/lib)
+  # Commented to prevent confusion if submodule was not built correctly.
+  # Uncomment when we stop using a submodule.
+  #find_path(CRYPTO++_INCLUDE_DIR cryptopp/cryptlib.h
+  #/usr/include
+  #/usr/local/include
+  #$ENV{SystemDrive}/Crypto++/include
+  #$ENV{CRYPTOPP}
+  #$ENV{CRYPTOPP}/..
+  #$ENV{CRYPTOPP}/include
+  #${PROJECT_SOURCE_DIR}/../..)
+
+  find_library(CRYPTO++_LIBRARIES NAMES cryptopp PATHS
+  ${PROJECT_SOURCE_DIR}/deps/cryptopp)
+
+  # Commented to prevent confusion if submodule was not built correctly.
+  # Uncomment when we stop using a submodule.
+  #find_library(CRYPTO++_LIBRARIES NAMES cryptopp PATHS
+  #/usr/lib
+  #/usr/local/lib
+  #/opt/local/lib
+  #$ENV{SystemDrive}/Crypto++/lib
+  #$ENV{CRYPTOPP}/lib)
 
   if(MSVC AND NOT CRYPTO++_LIBRARIES) # Give a chance for MSVC multiconfig
   if(CMAKE_SIZEOF_VOID_P EQUAL 8)
@@ -78,7 +87,7 @@ else(CRYPTO++_INCLUDE_DIR AND CRYPTO++_LIBRARIES)
   message(STATUS "Found Crypto++: ${CRYPTO++_INCLUDE_DIR}, ${CRYPTO++_LIBRARIES}")
   else(CRYPTO++_INCLUDE_DIR AND CRYPTO++_LIBRARIES)
   set(CRYPTO++_FOUND FALSE)
-  message(STATUS "Crypto++ not found.")
+  message(SEND_ERROR "Crypto++ not found.")
   endif(CRYPTO++_INCLUDE_DIR AND CRYPTO++_LIBRARIES)
 
   mark_as_advanced(CRYPTO++_INCLUDE_DIR CRYPTO++_LIBRARIES)