krb5: Only generate a SPN when its not known

Prior to this change, we were generating the SPN in the SSPI code when
the credentials were NULL and in the GSS-API code when the context was
empty. It is better to decouple the SPN generation from these checks
and only generate it when the SPN itself is NULL.

This also brings this part of the Kerberos 5 code in line with the
Negotiate code.

2 files changed, 10 insertions, 7 deletions

diff --git a/lib/vauth/krb5_gssapi.c b/lib/vauth/krb5_gssapi.c
index e68053503..18c6dbb46 100644
--- a/lib/vauth/krb5_gssapi.c
+++ b/lib/vauth/krb5_gssapi.c
@@ -88,7 +88,7 @@ CURLcode Curl_auth_create_gssapi_user_message(struct SessionHandle *data,
   (void) userp;
   (void) passwdp;
 
-  if(krb5->context == GSS_C_NO_CONTEXT) {
+  if(!krb5->spn) {
     /* Generate our SPN */
     char *spn = Curl_auth_build_gssapi_spn(service, host);
     if(!spn)
@@ -112,7 +112,8 @@ CURLcode Curl_auth_create_gssapi_user_message(struct SessionHandle *data,
 
     free(spn);
   }
-  else {
+
+  if(krb5->context != GSS_C_NO_CONTEXT) {
     /* Decode the base-64 encoded challenge message */
     if(strlen(chlg64) && *chlg64 != '=') {
       result = Curl_base64_decode(chlg64, &chlg, &chlglen);
diff --git a/lib/vauth/krb5_sspi.c b/lib/vauth/krb5_sspi.c
index 6afd83dde..da08f8f03 100644
--- a/lib/vauth/krb5_sspi.c
+++ b/lib/vauth/krb5_sspi.c
@@ -85,6 +85,13 @@ CURLcode Curl_auth_create_gssapi_user_message(struct SessionHandle *data,
   unsigned long attrs;
   TimeStamp expiry; /* For Windows 9x compatibility of SSPI calls */
 
+  if(!krb5->spn) {
+    /* Generate our SPN */
+    krb5->spn = Curl_auth_build_spn(service, host);
+    if(!krb5->spn)
+      return CURLE_OUT_OF_MEMORY;
+  }
+
   if(!krb5->credentials) {
     /* Query the security package for Kerberos */
     status = s_pSecFn->QuerySecurityPackageInfo((TCHAR *)
@@ -104,11 +111,6 @@ CURLcode Curl_auth_create_gssapi_user_message(struct SessionHandle *data,
     if(!krb5->output_token)
       return CURLE_OUT_OF_MEMORY;
 
-    /* Generate our SPN */
-    krb5->spn = Curl_auth_build_spn(service, host);
-    if(!krb5->spn)
-      return CURLE_OUT_OF_MEMORY;
-
     if(userp && *userp) {
       /* Populate our identity structure */
       result = Curl_create_sspi_identity(userp, passwdp, &krb5->identity);