From 4a25ae3064b4ba95ae0d4ddfcacd97b4431705f2 Mon Sep 17 00:00:00 2001
From: Mike Szczys <mike@golioth.io>
Date: Fri, 18 Oct 2024 17:25:42 -0500
Subject: [PATCH] port: linux: implement sha256 API

Signed-off-by: Mike Szczys <mike@golioth.io>
---
 port/linux/golioth_sdk/CMakeLists.txt |   2 +-
 port/linux/golioth_sys_linux.c        | 101 ++++++++++++++++++++++++++
 2 files changed, 102 insertions(+), 1 deletion(-)

diff --git a/port/linux/golioth_sdk/CMakeLists.txt b/port/linux/golioth_sdk/CMakeLists.txt
index 5e17c67a6..758e993e5 100644
--- a/port/linux/golioth_sdk/CMakeLists.txt
+++ b/port/linux/golioth_sdk/CMakeLists.txt
@@ -54,5 +54,5 @@ target_include_directories(golioth_sdk
         ${zcbor_dir}
 )
 target_link_libraries(golioth_sdk
-    PRIVATE coap-3 pthread rt)
+    PRIVATE coap-3 pthread rt crypto)
 target_compile_definitions(golioth_sdk PRIVATE -DHEATSHRINK_DYNAMIC_ALLOC=0)
diff --git a/port/linux/golioth_sys_linux.c b/port/linux/golioth_sys_linux.c
index 634316c37..2e6e4e888 100644
--- a/port/linux/golioth_sys_linux.c
+++ b/port/linux/golioth_sys_linux.c
@@ -5,8 +5,10 @@
  */
 
 #include <golioth/golioth_sys.h>
+#include <golioth/golioth_status.h>
 #include <assert.h>
 #include <errno.h>
+#include <openssl/evp.h>
 #include <poll.h>
 #include <pthread.h>
 #include <semaphore.h>
@@ -15,6 +17,8 @@
 #include <sys/eventfd.h>
 #include <time.h>
 #include <unistd.h>
+#include "../utils/hex.h"
+
 
 #define TAG "golioth_sys_linux"
 
@@ -375,6 +379,103 @@ void golioth_sys_thread_destroy(golioth_sys_thread_t thread)
     // process exits.
 }
 
+/*--------------------------------------------------
+ * Hash
+ *------------------------------------------------*/
+
+struct golioth_hash
+{
+    EVP_MD_CTX *mdctx;
+};
+
+golioth_sys_sha256_t golioth_sys_sha256_create(void)
+{
+    struct golioth_hash *hash;
+
+    hash = golioth_sys_malloc(sizeof(*hash));
+    if (!hash)
+    {
+        return NULL;
+    }
+
+    hash->mdctx = EVP_MD_CTX_new();
+    if (!hash->mdctx)
+    {
+        free(hash);
+        return NULL;
+    }
+
+    golioth_sys_sha256_init(hash);
+
+    return (golioth_sys_sha256_t) hash;
+}
+
+void golioth_sys_sha256_init(golioth_sys_sha256_t sha_ctx)
+{
+    if (!sha_ctx)
+    {
+        return;
+    }
+
+    struct golioth_hash *hash = sha_ctx;
+
+    EVP_MD *md = EVP_MD_fetch(NULL, "SHA2-256", NULL);
+    EVP_DigestInit_ex2(hash->mdctx, md, NULL);
+}
+
+void golioth_sys_sha256_free(golioth_sys_sha256_t sha_ctx)
+{
+    if (!sha_ctx)
+    {
+        return;
+    }
+
+    struct golioth_hash *hash = sha_ctx;
+    EVP_MD_CTX_free(hash->mdctx);
+    free(hash);
+}
+
+enum golioth_status golioth_sys_sha256_update(golioth_sys_sha256_t sha_ctx,
+                                              uint8_t *input,
+                                              size_t len)
+{
+    if (!sha_ctx || !input)
+    {
+        return GOLIOTH_ERR_NULL;
+    }
+
+    struct golioth_hash *hash = sha_ctx;
+    int err = EVP_DigestUpdate(hash->mdctx, input, len);
+    if (err)
+    {
+        return GOLIOTH_ERR_FAIL;
+    }
+
+    return GOLIOTH_OK;
+}
+
+enum golioth_status golioth_sys_sha256_finish(golioth_sys_sha256_t sha_ctx, uint8_t *output)
+{
+    if (!sha_ctx || !output)
+    {
+        return GOLIOTH_ERR_NULL;
+    }
+
+    struct golioth_hash *hash = sha_ctx;
+    int err = EVP_DigestFinal_ex(hash->mdctx, output, NULL);
+    if (err)
+    {
+        return GOLIOTH_ERR_FAIL;
+    }
+
+    return GOLIOTH_OK;
+}
+
+size_t golioth_sys_hex2bin(const char *hex, size_t hexlen, uint8_t *buf, size_t buflen)
+{
+    return hex2bin(hex, hexlen, buf, buflen);
+}
+
 /*--------------------------------------------------
  * Misc
  *------------------------------------------------*/