sasl: Post DIGEST-MD5 SSPI code tidy up

* Added comments to SSPI NTLM message generation
* Added comments to native DIGEST-MD5 code
* Removed redundant identity pointer

3 files changed, 43 insertions, 37 deletions

diff --git a/lib/curl_ntlm_msgs.c b/lib/curl_ntlm_msgs.c
index e222b73b7..969e6bf78 100644
--- a/lib/curl_ntlm_msgs.c
+++ b/lib/curl_ntlm_msgs.c
@@ -414,8 +414,8 @@ CURLcode Curl_ntlm_create_type1_message(const char *userp,
 
 #ifdef USE_WINDOWS_SSPI
 
-  SecBuffer buf;
-  SecBufferDesc desc;
+  SecBuffer type_1_buf;
+  SecBufferDesc type_1_desc;
   SECURITY_STATUS status;
   unsigned long attrs;
   TimeStamp tsDummy; /* For Windows 9x compatibility of SSPI calls */
@@ -434,8 +434,10 @@ CURLcode Curl_ntlm_create_type1_message(const char *userp,
     ntlm->p_identity = &ntlm->identity;
   }
   else
+    /* Use the current Windows user */
     ntlm->p_identity = NULL;
 
+  /* Acquire our credientials handle */
   status = s_pSecFn->AcquireCredentialsHandle(NULL,
                                               (TCHAR *) TEXT("NTLM"),
                                               SECPKG_CRED_OUTBOUND, NULL,
@@ -444,13 +446,15 @@ CURLcode Curl_ntlm_create_type1_message(const char *userp,
   if(status != SEC_E_OK)
     return CURLE_OUT_OF_MEMORY;
 
-  desc.ulVersion = SECBUFFER_VERSION;
-  desc.cBuffers  = 1;
-  desc.pBuffers  = &buf;
-  buf.cbBuffer   = NTLM_BUFSIZE;
-  buf.BufferType = SECBUFFER_TOKEN;
-  buf.pvBuffer   = ntlmbuf;
+  /* Setup the type-1 "output" security buffer */
+  type_1_desc.ulVersion = SECBUFFER_VERSION;
+  type_1_desc.cBuffers  = 1;
+  type_1_desc.pBuffers  = &type_1_buf;
+  type_1_buf.cbBuffer   = NTLM_BUFSIZE;
+  type_1_buf.BufferType = SECBUFFER_TOKEN;
+  type_1_buf.pvBuffer   = ntlmbuf;
 
+  /* Generate our type-1 message */
   status = s_pSecFn->InitializeSecurityContext(&ntlm->handle, NULL,
                                                (TCHAR *) TEXT(""),
                                                ISC_REQ_CONFIDENTIALITY |
@@ -458,19 +462,19 @@ CURLcode Curl_ntlm_create_type1_message(const char *userp,
                                                ISC_REQ_CONNECTION,
                                                0, SECURITY_NETWORK_DREP,
                                                NULL, 0,
-                                               &ntlm->c_handle, &desc,
+                                               &ntlm->c_handle, &type_1_desc,
                                                &attrs, &tsDummy);
 
   if(status == SEC_I_COMPLETE_AND_CONTINUE ||
      status == SEC_I_CONTINUE_NEEDED)
-    s_pSecFn->CompleteAuthToken(&ntlm->c_handle, &desc);
+    s_pSecFn->CompleteAuthToken(&ntlm->c_handle, &type_1_desc);
   else if(status != SEC_E_OK) {
     s_pSecFn->FreeCredentialsHandle(&ntlm->handle);
     return CURLE_RECV_ERROR;
   }
 
   ntlm->has_handles = 1;
-  size = buf.cbBuffer;
+  size = type_1_buf.cbBuffer;
 
 #else
 
@@ -602,8 +606,8 @@ CURLcode Curl_ntlm_create_type3_message(struct SessionHandle *data,
   size_t size;
 
 #ifdef USE_WINDOWS_SSPI
-  SecBuffer type_2;
-  SecBuffer type_3;
+  SecBuffer type_2_buf;
+  SecBuffer type_3_buf;
   SecBufferDesc type_2_desc;
   SecBufferDesc type_3_desc;
   SECURITY_STATUS status;
@@ -614,18 +618,23 @@ CURLcode Curl_ntlm_create_type3_message(struct SessionHandle *data,
   (void)userp;
   (void)data;
 
-  type_2_desc.ulVersion = type_3_desc.ulVersion  = SECBUFFER_VERSION;
-  type_2_desc.cBuffers  = type_3_desc.cBuffers   = 1;
-  type_2_desc.pBuffers  = &type_2;
-  type_3_desc.pBuffers  = &type_3;
-
-  type_2.BufferType = SECBUFFER_TOKEN;
-  type_2.pvBuffer   = ntlm->type_2;
-  type_2.cbBuffer   = ntlm->n_type_2;
-  type_3.BufferType = SECBUFFER_TOKEN;
-  type_3.pvBuffer   = ntlmbuf;
-  type_3.cbBuffer   = NTLM_BUFSIZE;
-
+  /* Setup the type-2 "input" security buffer */
+  type_2_desc.ulVersion = SECBUFFER_VERSION;
+  type_2_desc.cBuffers  = 1;
+  type_2_desc.pBuffers  = &type_2_buf;
+  type_2_buf.BufferType = SECBUFFER_TOKEN;
+  type_2_buf.pvBuffer   = ntlm->type_2;
+  type_2_buf.cbBuffer   = ntlm->n_type_2;
+
+  /* Setup the type-3 "output" security buffer */
+  type_3_desc.ulVersion = SECBUFFER_VERSION;
+  type_3_desc.cBuffers  = 1;
+  type_3_desc.pBuffers  = &type_3_buf;
+  type_3_buf.BufferType = SECBUFFER_TOKEN;
+  type_3_buf.pvBuffer   = ntlmbuf;
+  type_3_buf.cbBuffer   = NTLM_BUFSIZE;
+
+  /* Generate our type-3 message */
   status = s_pSecFn->InitializeSecurityContext(&ntlm->handle,
                                                &ntlm->c_handle,
                                                (TCHAR *) TEXT(""),
@@ -640,7 +649,7 @@ CURLcode Curl_ntlm_create_type3_message(struct SessionHandle *data,
   if(status != SEC_E_OK)
     return CURLE_RECV_ERROR;
 
-  size = type_3.cbBuffer;
+  size = type_3_buf.cbBuffer;
 
   Curl_ntlm_sspi_cleanup(ntlm);
 
diff --git a/lib/curl_sasl.c b/lib/curl_sasl.c
index 842bb727f..1968ccbc7 100644
--- a/lib/curl_sasl.c
+++ b/lib/curl_sasl.c
@@ -292,6 +292,7 @@ static CURLcode sasl_decode_digest_md5_message(const char *chlg64,
   size_t chlglen = 0;
   size_t chlg64len = strlen(chlg64);
 
+  /* Decode the base-64 encoded challenge message */
   if(chlg64len && *chlg64 != '=') {
     result = Curl_base64_decode(chlg64, &chlg, &chlglen);
     if(result)
diff --git a/lib/curl_sasl_sspi.c b/lib/curl_sasl_sspi.c
index 9b67498e9..d17e08c79 100644
--- a/lib/curl_sasl_sspi.c
+++ b/lib/curl_sasl_sspi.c
@@ -74,7 +74,6 @@ CURLcode Curl_sasl_create_digest_md5_message(struct SessionHandle *data,
   CtxtHandle ctx;
   PSecPkgInfo SecurityPackage;
   SEC_WINNT_AUTH_IDENTITY identity;
-  SEC_WINNT_AUTH_IDENTITY *identityp = NULL;
   SecBuffer chlg_buf;
   SecBuffer resp_buf;
   SecBufferDesc chlg_desc;
@@ -118,24 +117,21 @@ CURLcode Curl_sasl_create_digest_md5_message(struct SessionHandle *data,
     return result;
   }
 
-  /* Allow proper cleanup of the identity structure */
-  identityp = &identity;
-
   /* Acquire our credientials handle */
   status = s_pSecFn->AcquireCredentialsHandle(NULL,
                                               (TCHAR *) TEXT("WDigest"),
                                               SECPKG_CRED_OUTBOUND, NULL,
-                                              identityp, NULL, NULL,
+                                              &identity, NULL, NULL,
                                               &handle, &tsDummy);
 
   if(status != SEC_E_OK) {
-    Curl_sspi_free_identity(identityp);
+    Curl_sspi_free_identity(&identity);
     Curl_safefree(spn);
 
     return CURLE_OUT_OF_MEMORY;
   }
 
-  /* Setup the challenge security buffer */
+  /* Setup the challenge "input" security buffer */
   chlg_desc.ulVersion = SECBUFFER_VERSION;
   chlg_desc.cBuffers  = 1;
   chlg_desc.pBuffers  = &chlg_buf;
@@ -143,7 +139,7 @@ CURLcode Curl_sasl_create_digest_md5_message(struct SessionHandle *data,
   chlg_buf.pvBuffer   = chlg;
   chlg_buf.cbBuffer   = curlx_uztoul(chlglen);
 
-  /* Setup the response security buffer */
+  /* Setup the response "output" security buffer */
   resp_desc.ulVersion = SECBUFFER_VERSION;
   resp_desc.cBuffers  = 1;
   resp_desc.pBuffers  = &resp_buf;
@@ -151,7 +147,7 @@ CURLcode Curl_sasl_create_digest_md5_message(struct SessionHandle *data,
   resp_buf.pvBuffer   = resp;
   resp_buf.cbBuffer   = sizeof(resp);
 
-  /* Generate our challenge-response */
+  /* Generate our challenge-response message */
   status = s_pSecFn->InitializeSecurityContext(&handle,
                                                NULL,
                                                (TCHAR *) spn,
@@ -166,7 +162,7 @@ CURLcode Curl_sasl_create_digest_md5_message(struct SessionHandle *data,
     s_pSecFn->CompleteAuthToken(&handle, &resp_desc);
   else if(status != SEC_E_OK) {
     s_pSecFn->FreeCredentialsHandle(&handle);
-    Curl_sspi_free_identity(identityp);
+    Curl_sspi_free_identity(&identity);
     Curl_safefree(spn);
 
     return CURLE_RECV_ERROR;
@@ -181,7 +177,7 @@ CURLcode Curl_sasl_create_digest_md5_message(struct SessionHandle *data,
   s_pSecFn->FreeCredentialsHandle(&handle);
 
   /* Free the identity structure */
-  Curl_sspi_free_identity(identityp);
+  Curl_sspi_free_identity(&identity);
 
   /* Free the SPN */
   Curl_safefree(spn);