[openwrt/openwrt] openvpn: fix interface with mbedtls_sha256

[LEDE Commits]

hauke pushed a commit to openwrt/openwrt.git, branch master:
https://git.lede-project.org/42b94a74e98a1f9517d2baf8c6e8a61051bd6124

commit 42b94a74e98a1f9517d2baf8c6e8a61051bd6124
Author: Russell Senior <russell at personaltelco.net>
AuthorDate: Fri Feb 16 04:39:00 2018 -0800

    openvpn: fix interface with mbedtls_sha256
    
    Between mbedtls 2.6.0 and 2.7.0, the void returning mbedtls_MODULE* functions
    were deprecated in favor of functions returning an int error code.  Use
    the new function mbedtls_sha256_ret().
    
    Signed-off-by: Russell Senior <russell at personaltelco.net>
    Tested-by: Koen Vandeputte <koen.vandeputte at ncentric.com>
---
 .../300-mbedtls_dont_use_deprecated_sha256_function.patch     | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/package/network/services/openvpn/patches/300-mbedtls_dont_use_deprecated_sha256_function.patch b/package/network/services/openvpn/patches/300-mbedtls_dont_use_deprecated_sha256_function.patch
new file mode 100644
index 0000000..b9201a5
--- /dev/null
+++ b/package/network/services/openvpn/patches/300-mbedtls_dont_use_deprecated_sha256_function.patch
@@ -0,0 +1,11 @@
+--- a/src/openvpn/ssl_mbedtls.c
++++ b/src/openvpn/ssl_mbedtls.c
+@@ -803,7 +803,7 @@ tls_ctx_personalise_random(struct tls_ro
+     {
+         mbedtls_x509_crt *cert = ctx->crt_chain;
+ 
+-        mbedtls_sha256(cert->tbs.p, cert->tbs.len, sha256_hash, false);
++        mbedtls_sha256_ret(cert->tbs.p, cert->tbs.len, sha256_hash, false);
+         if (0 != memcmp(old_sha256_hash, sha256_hash, sizeof(sha256_hash)))
+         {
+             mbedtls_ctr_drbg_update(cd_ctx, sha256_hash, 32);