chachapoly: Use a function instead of an extern variable

Signed-off-by: Andreas Schneider <asn@cryptomilk.org>

include/libssh/crypto.h

@@ -161,4 +161,6 @@ struct ssh_cipher_struct {
     void (*cleanup)(struct ssh_cipher_struct *cipher);
 };
 
+const struct ssh_cipher_struct *ssh_get_chacha20poly1305_cipher(void);
+
 #endif /* _CRYPTO_H_ */

src/chachapoly.c

@@ -205,3 +205,8 @@ const struct ssh_cipher_struct chacha20poly1305_cipher = {
     .aead_decrypt = chacha20_poly1305_aead_decrypt,
     .cleanup = chacha20_cleanup
 };
+
+const struct ssh_cipher_struct *ssh_get_chacha20poly1305_cipher(void)
+{
+    return &chacha20poly1305_cipher;
+}

src/libcrypto.c

@@ -60,7 +60,6 @@
 
 #include "libssh/crypto.h"
 
-extern const struct ssh_cipher_struct chacha20poly1305_cipher;
 struct ssh_mac_ctx_struct {
   enum ssh_mac_e mac_type;
   union {
@@ -764,7 +763,7 @@ void libcrypto_init(void)
         cmp = strcmp(ssh_ciphertab[i].name, "chacha20-poly1305@openssh.com");
         if (cmp == 0) {
             memcpy(&ssh_ciphertab[i],
-                   &chacha20poly1305_cipher,
+                   ssh_get_chacha20poly1305_cipher(),
                    sizeof(struct ssh_cipher_struct));
             break;
         }

src/libgcrypt.c

@@ -35,8 +35,6 @@
 #ifdef HAVE_LIBGCRYPT
 #include <gcrypt.h>
 
-extern const struct ssh_cipher_struct chacha20poly1305_cipher;
-
 struct ssh_mac_ctx_struct {
   enum ssh_mac_e mac_type;
   gcry_md_hd_t ctx;
@@ -544,7 +542,7 @@ void libgcrypt_init(void)
         cmp = strcmp(ssh_ciphertab[i].name, "chacha20-poly1305@openssh.com");
         if (cmp == 0) {
             memcpy(&ssh_ciphertab[i],
-                   &chacha20poly1305_cipher,
+                   ssh_get_chacha20poly1305_cipher(),
                    sizeof(struct ssh_cipher_struct));
             break;
         }

src/libmbedcrypto.c

@@ -30,8 +30,6 @@
 #ifdef HAVE_LIBMBEDCRYPTO
 #include <mbedtls/md.h>
 
-extern const struct ssh_cipher_struct chacha20poly1305_cipher;
-
 struct ssh_mac_ctx_struct {
     enum ssh_mac_e mac_type;
     mbedtls_md_context_t ctx;
@@ -964,7 +962,7 @@ void ssh_mbedtls_init(void)
         cmp = strcmp(ssh_ciphertab[i].name, "chacha20-poly1305@openssh.com");
         if (cmp == 0) {
             memcpy(&ssh_ciphertab[i],
-                   &chacha20poly1305_cipher,
+                   ssh_get_chacha20poly1305_cipher(),
                    sizeof(struct ssh_cipher_struct));
             break;
         }