crypto: add functions missing in openssl 1.0.x

setup.py

@@ -52,6 +52,7 @@
 
 compress_source = 'src/borg/compress.pyx'
 crypto_ll_source = 'src/borg/crypto/low_level.pyx'
+crypto_helpers = 'src/borg/crypto/_crypto_helpers.c'
 chunker_source = 'src/borg/chunker.pyx'
 hashindex_source = 'src/borg/hashindex.pyx'
 item_source = 'src/borg/item.pyx'
@@ -730,7 +731,7 @@ def run(self):
 if not on_rtd:
     ext_modules += [
     Extension('borg.compress', [compress_source], libraries=['lz4'], include_dirs=include_dirs, library_dirs=library_dirs, define_macros=define_macros),
-    Extension('borg.crypto.low_level', [crypto_ll_source], libraries=crypto_libraries, include_dirs=include_dirs, library_dirs=library_dirs, define_macros=define_macros),
+    Extension('borg.crypto.low_level', [crypto_ll_source, crypto_helpers], libraries=crypto_libraries, include_dirs=include_dirs, library_dirs=library_dirs, define_macros=define_macros),
     Extension('borg.hashindex', [hashindex_source]),
     Extension('borg.item', [item_source]),
     Extension('borg.chunker', [chunker_source]),

src/borg/crypto/_crypto_helpers.c

@@ -0,0 +1,27 @@
+/* add missing HMAC functions, so OpenSSL 1.0.x can be used like 1.1 */
+
+#include <string.h>
+#include <openssl/opensslv.h>
+#include <openssl/hmac.h>
+
+#if OPENSSL_VERSION_NUMBER < 0x10100000L
+
+HMAC_CTX *HMAC_CTX_new(void)
+{
+   HMAC_CTX *ctx = OPENSSL_malloc(sizeof(*ctx));
+   if (ctx != NULL) {
+       memset(ctx, 0, sizeof *ctx);
+       HMAC_CTX_cleanup(ctx);
+   }
+   return ctx;
+}
+
+void HMAC_CTX_free(HMAC_CTX *ctx)
+{
+   if (ctx != NULL) {
+       HMAC_CTX_cleanup(ctx);
+       OPENSSL_free(ctx);
+   }
+}
+
+#endif

src/borg/crypto/_crypto_helpers.h

@@ -0,0 +1,11 @@
+/* add missing HMAC functions, so OpenSSL 1.0.x can be used like 1.1 */
+
+#include <openssl/opensslv.h>
+#include <openssl/hmac.h>
+
+#if OPENSSL_VERSION_NUMBER < 0x10100000L
+
+HMAC_CTX *HMAC_CTX_new(void);
+void HMAC_CTX_free(HMAC_CTX *ctx);
+
+#endif

src/borg/crypto/low_level.pyx

@@ -123,6 +123,14 @@ cdef extern from "openssl/hmac.h":
                     const unsigned char *data, int data_len,
                     unsigned char *md, unsigned int *md_len) nogil
 
+cdef extern from "_crypto_helpers.h":
+    ctypedef struct HMAC_CTX:
+        pass
+
+    HMAC_CTX *HMAC_CTX_new()
+    void HMAC_CTX_free(HMAC_CTX *a)
+
+
 import struct
 
 _int = struct.Struct('>I')