Automatically look for non-standard library paths on macOS

Also fixes #19 `abort` error on macOS 10.15 when trying to load default
openssl library

README.md

@@ -17,22 +17,16 @@ To achieve compatibility with Apple AirDrop, OpenDrop requires the target platfo
 In addition, it requires Python >=3.6 as well as several libraries.
 
 **Apple Wireless Direct Link.**
-As AirDrop exclusively runs over Apple Wireless Direct Link (AWDL), OpenDrop is only supported on macOS or on Linux systems running
-an open re-implementation of AWDL such as [OWL](https://github.com/seemoo-lab/owl).
+As AirDrop exclusively runs over Apple Wireless Direct Link (AWDL), OpenDrop is only supported on macOS or on Linux systems running an open re-implementation of AWDL such as [OWL](https://github.com/seemoo-lab/owl).
 
 **Libraries.**
 OpenDrop relies on current versions of [OpenSSL](https://www.openssl.org) and [libarchive](https://www.libarchive.org).
-macOS ships with rather old versions of the two, so you will need to install newer version, for example, via [Homebrew](https://brew.sh).
-In any case, you will need to set the two environmental variables `LIBARCHIVE` and `LIBCRYPTO` accordingly.
-For example, use `brew` to install the libraries:
+macOS ships with rather old versions of the two, so you will need to install newer version, for example, via [Homebrew](https://brew.sh):
 ```bash
-brew install libarchive openssl@1.1
-```
-Then set environmental variables:
-```bash
-export LIBARCHIVE=/usr/local/opt/libarchive/lib/libarchive.dylib
-export LIBCRYPTO=/usr/local/opt/openssl@1.1/lib/libcrypto.dylib
+brew install libarchive openssl
 ```
+OpenDrop automatically sets `DYLD_LIBRARY_PATH` to look for the Homebrew versions. You may need to update the variable yourself if you install the libraries differently.
+
 Linux distributions should ship with more up-to-date versions, so this won't be necessary.
 
 

opendrop/__init__.py

@@ -18,7 +18,15 @@ along with this program.  If not, see <https://www.gnu.org/licenses/>.
 """
 
 import logging
+import platform
+import os
 
 __version__ = '0.10.2'
 
+if platform.system() == 'Darwin':
+	dyld_path = os.environ.get('DYLD_LIBRARY_PATH', '')  # save old path
+	openssl_path = '/usr/local/opt/openssl/lib'
+	archive_path = '/usr/local/opt/libarchive/lib'
+	os.environ['DYLD_LIBRARY_PATH'] = '{}:{}:{}'.format(dyld_path, openssl_path, archive_path)
+
 logger = logging.getLogger(__name__)

opendrop/util.py

@@ -22,7 +22,6 @@ import datetime
 import io
 import ipaddress
 import os
-import platform
 import plistlib
 import hashlib
 import ifaddr
@@ -40,18 +39,6 @@ from libarchive.ffi import (
     write_finish_entry,
 )
 from libarchive.write import ArchiveWrite, new_archive_read_disk
-if platform.system() == 'Darwin' and os.getenv('LIBCRYPTO') is not None:
-    import ctypescrypto
-    from ctypes import CDLL, c_uint64, c_void_p
-    ctypescrypto.__libname__ = os.environ['LIBCRYPTO']
-    ctypescrypto.libcrypto = CDLL(ctypescrypto.__libname__)
-    if hasattr(ctypescrypto.libcrypto,'OPENSSL_init_crypto'):
-        ctypescrypto.libcrypto.OPENSSL_init_crypto.argtypes = (c_uint64,c_void_p)
-        ctypescrypto.libcrypto.OPENSSL_init_crypto(2+4+8+0x40,None)
-        strings_loaded = True
-    else:
-        ctypescrypto.libcrypto.OPENSSL_add_all_algorithms_conf()
-        strings_loaded = False
 from ctypescrypto import cms, x509, pkey, oid