From d0eebc1f94cd2dd9f1543e46463ed416261b6fca Mon Sep 17 00:00:00 2001
From: Valerio Setti <valerio.setti@nordicsemi.no>
Date: Mon, 20 Nov 2023 15:17:53 +0100
Subject: [PATCH] ccm/gcm: improve code maintainability

Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>
---
 library/ccm.c | 23 ++++++++---------------
 library/gcm.c | 36 +++++++++++++-----------------------
 2 files changed, 21 insertions(+), 38 deletions(-)

diff --git a/library/ccm.c b/library/ccm.c
index 444351df0e..6700dc743d 100644
--- a/library/ccm.c
+++ b/library/ccm.c
@@ -130,20 +130,15 @@ static int mbedtls_ccm_crypt(mbedtls_ccm_context *ctx,
 
 #if defined(MBEDTLS_CIPHER_C)
     size_t olen = 0;
-
-    if ((ret = mbedtls_cipher_update(&ctx->cipher_ctx, ctx->ctr, 16, tmp_buf,
-                                     &olen)) != 0) {
-        ctx->state |= CCM_STATE__ERROR;
-        mbedtls_platform_zeroize(tmp_buf, sizeof(tmp_buf));
-        return ret;
-    }
+    ret = mbedtls_cipher_update(&ctx->cipher_ctx, ctx->ctr, 16, tmp_buf, &olen);
 #else
-    if ((ret = mbedtls_block_cipher_encrypt(&ctx->block_cipher_ctx, ctx->ctr, tmp_buf)) != 0) {
+    ret = mbedtls_block_cipher_encrypt(&ctx->block_cipher_ctx, ctx->ctr, tmp_buf);
+#endif
+    if (ret != 0) {
         ctx->state |= CCM_STATE__ERROR;
         mbedtls_platform_zeroize(tmp_buf, sizeof(tmp_buf));
         return ret;
     }
-#endif
 
     mbedtls_xor(output, input, tmp_buf + offset, use_len);
 
@@ -212,16 +207,14 @@ static int ccm_calculate_first_block_if_ready(mbedtls_ccm_context *ctx)
 
     /* Start CBC-MAC with first block*/
 #if defined(MBEDTLS_CIPHER_C)
-    if ((ret = mbedtls_cipher_update(&ctx->cipher_ctx, ctx->y, 16, ctx->y, &olen)) != 0) {
-        ctx->state |= CCM_STATE__ERROR;
-        return ret;
-    }
+    ret = mbedtls_cipher_update(&ctx->cipher_ctx, ctx->y, 16, ctx->y, &olen);
 #else
-    if ((ret = mbedtls_block_cipher_encrypt(&ctx->block_cipher_ctx, ctx->y, ctx->y)) != 0) {
+    ret = mbedtls_block_cipher_encrypt(&ctx->block_cipher_ctx, ctx->y, ctx->y);
+#endif
+    if (ret != 0) {
         ctx->state |= CCM_STATE__ERROR;
         return ret;
     }
-#endif
 
     return 0;
 }
diff --git a/library/gcm.c b/library/gcm.c
index 390bb3e156..8181ec88aa 100644
--- a/library/gcm.c
+++ b/library/gcm.c
@@ -68,15 +68,13 @@ static int gcm_gen_table(mbedtls_gcm_context *ctx)
 
 #if defined(MBEDTLS_CIPHER_C)
     size_t olen = 0;
-
-    if ((ret = mbedtls_cipher_update(&ctx->cipher_ctx, h, 16, h, &olen)) != 0) {
-        return ret;
-    }
+    ret = mbedtls_cipher_update(&ctx->cipher_ctx, h, 16, h, &olen);
 #else
-    if ((ret = mbedtls_block_cipher_encrypt(&ctx->block_cipher_ctx, h, h)) != 0) {
+    ret = mbedtls_block_cipher_encrypt(&ctx->block_cipher_ctx, h, h);
+#endif
+    if (ret != 0) {
         return ret;
     }
-#endif
 
     /* pack h as two 64-bits ints, big-endian */
     hi = MBEDTLS_GET_UINT32_BE(h,  0);
@@ -323,16 +321,13 @@ int mbedtls_gcm_starts(mbedtls_gcm_context *ctx,
 
 
 #if defined(MBEDTLS_CIPHER_C)
-    if ((ret = mbedtls_cipher_update(&ctx->cipher_ctx, ctx->y, 16,
-                                     ctx->base_ectr, &olen)) != 0) {
-        return ret;
-    }
+    ret = mbedtls_cipher_update(&ctx->cipher_ctx, ctx->y, 16, ctx->base_ectr, &olen);
 #else
-    if ((ret = mbedtls_block_cipher_encrypt(&ctx->block_cipher_ctx, ctx->y,
-                                            ctx->base_ectr)) != 0) {
+    ret = mbedtls_block_cipher_encrypt(&ctx->block_cipher_ctx, ctx->y, ctx->base_ectr);
+#endif
+    if (ret != 0) {
         return ret;
     }
-#endif
 
     return 0;
 }
@@ -423,22 +418,17 @@ static int gcm_mask(mbedtls_gcm_context *ctx,
                     unsigned char *output)
 {
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+
 #if defined(MBEDTLS_CIPHER_C)
     size_t olen = 0;
-
-    if ((ret = mbedtls_cipher_update(&ctx->cipher_ctx, ctx->y, 16, ectr,
-                                     &olen)) != 0) {
-        mbedtls_platform_zeroize(ectr, 16);
-        return ret;
-    }
-
+    ret = mbedtls_cipher_update(&ctx->cipher_ctx, ctx->y, 16, ectr, &olen);
 #else
-
-    if ((ret = mbedtls_block_cipher_encrypt(&ctx->block_cipher_ctx, ctx->y, ectr)) != 0) {
+    ret = mbedtls_block_cipher_encrypt(&ctx->block_cipher_ctx, ctx->y, ectr);
+#endif
+    if (ret != 0) {
         mbedtls_platform_zeroize(ectr, 16);
         return ret;
     }
-#endif
 
     if (ctx->mode == MBEDTLS_GCM_DECRYPT) {
         mbedtls_xor(ctx->buf + offset, ctx->buf + offset, input, use_len);