Refactor code structure for improved readability and maintainability

libsrtp/crypto/hash/hmac_nss.c

@@ -0,0 +1,291 @@
+/*
+ *
+ * Copyright(c) 2013-2017, Cisco Systems, Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ *   Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ *
+ *   Redistributions in binary form must reproduce the above
+ *   copyright notice, this list of conditions and the following
+ *   disclaimer in the documentation and/or other materials provided
+ *   with the distribution.
+ *
+ *   Neither the name of the Cisco Systems, Inc. nor the names of its
+ *   contributors may be used to endorse or promote products derived
+ *   from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include "auth.h"
+#include "alloc.h"
+#include "err.h" /* for srtp_debug */
+#include "auth_test_cases.h"
+
+#define NSS_PKCS11_2_0_COMPAT 1
+
+#include <nss.h>
+#include <pk11pub.h>
+
+#define SHA1_DIGEST_SIZE 20
+
+/* the debug module for authentiation */
+
+srtp_debug_module_t srtp_mod_hmac = {
+    false,           /* debugging is off by default */
+    "hmac sha-1 nss" /* printable name for module   */
+};
+
+typedef struct {
+    NSSInitContext *nss;
+    PK11SymKey *key;
+    PK11Context *ctx;
+} srtp_hmac_nss_ctx_t;
+
+static srtp_err_status_t srtp_hmac_alloc(srtp_auth_t **a,
+                                         size_t key_len,
+                                         size_t out_len)
+{
+    extern const srtp_auth_type_t srtp_hmac;
+    srtp_hmac_nss_ctx_t *hmac;
+    NSSInitContext *nss;
+
+    debug_print(srtp_mod_hmac, "allocating auth func with key length %zu",
+                key_len);
+    debug_print(srtp_mod_hmac, "                          tag length %zu",
+                out_len);
+
+    /* check output length - should be less than 20 bytes */
+    if (out_len > SHA1_DIGEST_SIZE) {
+        return srtp_err_status_bad_param;
+    }
+
+    /* Initialize NSS equiv of NSS_NoDB_Init(NULL) */
+    nss = NSS_InitContext("", "", "", "", NULL,
+                          NSS_INIT_READONLY | NSS_INIT_NOCERTDB |
+                              NSS_INIT_NOMODDB | NSS_INIT_FORCEOPEN |
+                              NSS_INIT_OPTIMIZESPACE);
+    if (!nss) {
+        return srtp_err_status_auth_fail;
+    }
+
+    *a = (srtp_auth_t *)srtp_crypto_alloc(sizeof(srtp_auth_t));
+    if (*a == NULL) {
+        NSS_ShutdownContext(nss);
+        return srtp_err_status_alloc_fail;
+    }
+
+    hmac =
+        (srtp_hmac_nss_ctx_t *)srtp_crypto_alloc(sizeof(srtp_hmac_nss_ctx_t));
+    if (hmac == NULL) {
+        NSS_ShutdownContext(nss);
+        srtp_crypto_free(*a);
+        *a = NULL;
+        return srtp_err_status_alloc_fail;
+    }
+
+    hmac->nss = nss;
+    hmac->key = NULL;
+    hmac->ctx = NULL;
+
+    /* set pointers */
+    (*a)->state = hmac;
+    (*a)->type = &srtp_hmac;
+    (*a)->out_len = out_len;
+    (*a)->key_len = key_len;
+    (*a)->prefix_len = 0;
+
+    return srtp_err_status_ok;
+}
+
+static srtp_err_status_t srtp_hmac_dealloc(srtp_auth_t *a)
+{
+    srtp_hmac_nss_ctx_t *hmac;
+
+    hmac = (srtp_hmac_nss_ctx_t *)a->state;
+    if (hmac) {
+        /* free any PK11 values that have been created */
+        if (hmac->key) {
+            PK11_FreeSymKey(hmac->key);
+            hmac->key = NULL;
+        }
+
+        if (hmac->ctx) {
+            PK11_DestroyContext(hmac->ctx, PR_TRUE);
+            hmac->ctx = NULL;
+        }
+
+        if (hmac->nss) {
+            NSS_ShutdownContext(hmac->nss);
+            hmac->nss = NULL;
+        }
+
+        /* zeroize everything */
+        octet_string_set_to_zero(hmac, sizeof(srtp_hmac_nss_ctx_t));
+        srtp_crypto_free(hmac);
+    }
+
+    /* free memory */
+    srtp_crypto_free(a);
+
+    return srtp_err_status_ok;
+}
+
+static srtp_err_status_t srtp_hmac_start(void *statev)
+{
+    srtp_hmac_nss_ctx_t *hmac;
+    hmac = (srtp_hmac_nss_ctx_t *)statev;
+
+    if (PK11_DigestBegin(hmac->ctx) != SECSuccess) {
+        return srtp_err_status_auth_fail;
+    }
+    return srtp_err_status_ok;
+}
+
+static srtp_err_status_t srtp_hmac_init(void *statev,
+                                        const uint8_t *key,
+                                        size_t key_len)
+{
+    srtp_hmac_nss_ctx_t *hmac;
+    hmac = (srtp_hmac_nss_ctx_t *)statev;
+    PK11SymKey *sym_key;
+    PK11Context *ctx;
+
+    if (hmac->ctx) {
+        PK11_DestroyContext(hmac->ctx, PR_TRUE);
+        hmac->ctx = NULL;
+    }
+
+    if (hmac->key) {
+        PK11_FreeSymKey(hmac->key);
+        hmac->key = NULL;
+    }
+
+    PK11SlotInfo *slot = PK11_GetBestSlot(CKM_SHA_1_HMAC, NULL);
+    if (!slot) {
+        return srtp_err_status_bad_param;
+    }
+
+    /* explicitly cast away const of key */
+    SECItem key_item = { siBuffer, (unsigned char *)(uintptr_t)key, key_len };
+    sym_key = PK11_ImportSymKey(slot, CKM_SHA_1_HMAC, PK11_OriginUnwrap,
+                                CKA_SIGN, &key_item, NULL);
+    PK11_FreeSlot(slot);
+
+    if (!sym_key) {
+        return srtp_err_status_auth_fail;
+    }
+
+    SECItem param_item = { siBuffer, NULL, 0 };
+    ctx = PK11_CreateContextBySymKey(CKM_SHA_1_HMAC, CKA_SIGN, sym_key,
+                                     &param_item);
+    if (!ctx) {
+        PK11_FreeSymKey(sym_key);
+        return srtp_err_status_auth_fail;
+    }
+
+    hmac->key = sym_key;
+    hmac->ctx = ctx;
+
+    return srtp_err_status_ok;
+}
+
+static srtp_err_status_t srtp_hmac_update(void *statev,
+                                          const uint8_t *message,
+                                          size_t msg_octets)
+{
+    srtp_hmac_nss_ctx_t *hmac;
+    hmac = (srtp_hmac_nss_ctx_t *)statev;
+
+    debug_print(srtp_mod_hmac, "input: %s",
+                srtp_octet_string_hex_string(message, msg_octets));
+
+    if (PK11_DigestOp(hmac->ctx, message, msg_octets) != SECSuccess) {
+        return srtp_err_status_auth_fail;
+    }
+
+    return srtp_err_status_ok;
+}
+
+static srtp_err_status_t srtp_hmac_compute(void *statev,
+                                           const uint8_t *message,
+                                           size_t msg_octets,
+                                           size_t tag_len,
+                                           uint8_t *result)
+{
+    srtp_hmac_nss_ctx_t *hmac;
+    hmac = (srtp_hmac_nss_ctx_t *)statev;
+    uint8_t hash_value[SHA1_DIGEST_SIZE];
+    unsigned int len;
+
+    debug_print(srtp_mod_hmac, "input: %s",
+                srtp_octet_string_hex_string(message, msg_octets));
+
+    /* check tag length, return error if we can't provide the value expected */
+    if (tag_len > SHA1_DIGEST_SIZE) {
+        return srtp_err_status_bad_param;
+    }
+
+    if (PK11_DigestOp(hmac->ctx, message, msg_octets) != SECSuccess) {
+        return srtp_err_status_auth_fail;
+    }
+
+    if (PK11_DigestFinal(hmac->ctx, hash_value, &len, SHA1_DIGEST_SIZE) !=
+        SECSuccess) {
+        return srtp_err_status_auth_fail;
+    }
+
+    if (len < tag_len) {
+        return srtp_err_status_auth_fail;
+    }
+
+    /* copy hash_value to *result */
+    for (size_t i = 0; i < tag_len; i++) {
+        result[i] = hash_value[i];
+    }
+
+    debug_print(srtp_mod_hmac, "output: %s",
+                srtp_octet_string_hex_string(hash_value, tag_len));
+
+    return srtp_err_status_ok;
+}
+
+static const char srtp_hmac_description[] =
+    "hmac sha-1 authentication function";
+
+/*
+ * srtp_auth_type_t hmac is the hmac metaobject
+ */
+
+const srtp_auth_type_t srtp_hmac = {
+    srtp_hmac_alloc,        /* */
+    srtp_hmac_dealloc,      /* */
+    srtp_hmac_init,         /* */
+    srtp_hmac_compute,      /* */
+    srtp_hmac_update,       /* */
+    srtp_hmac_start,        /* */
+    srtp_hmac_description,  /* */
+    &srtp_hmac_test_case_0, /* */
+    SRTP_HMAC_SHA1          /* */
+};