gss krb5 mech enhanced error messages

Save detailed error messages (usually from the krb5 library) in
per-thread storage, mapping each error code to the most recently
produced message for it.  Return the message from display_status.

Currently not implemented for a few cases where the krb5 mechanism
returns a minor status code of 0, or another value different from the
libkrb5 error code.

Other functions are available to store a generic string or formatted
message, but aren't used much at present.

Tested with these errors in context establishment:
 * missing ccache (libkrb5 shows pathname if FILE: type)
 * missing keytab (libkrb5 shows pathname if FILE: type)
 * server principal unknown (libkrb5 shows server principal)

ticket: new

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@19672 dc483132-0cff-0310-8789-dd5450dbe970

1 files changed, 131 insertions, 2 deletions

diff --git a/src/lib/gssapi/krb5/disp_status.c b/src/lib/gssapi/krb5/disp_status.c
index 1988d50c67..9a0399d78b 100644
--- a/src/lib/gssapi/krb5/disp_status.c
+++ b/src/lib/gssapi/krb5/disp_status.c
@@ -26,6 +26,130 @@
 
 /* XXXX internationalization!! */
 
+static inline int
+compare_OM_uint32 (OM_uint32 a, OM_uint32 b)
+{
+    if (a < b)
+	return -1;
+    else if (a == b)
+	return 0;
+    else
+	return 1;
+}
+static inline void
+free_string (char *s)
+{
+    free(s);
+}
+#include "error_map.h"
+#include <stdio.h>
+char *get_error_message(OM_uint32 minor_code)
+{
+    gsserrmap *p = k5_getspecific(K5_KEY_GSS_KRB5_ERROR_MESSAGE);
+    char *msg = 0;
+#ifdef DEBUG
+    fprintf(stderr, "%s(%lu, p=%p)", __func__, (unsigned long) minor_code,
+	    (void *) p);
+#endif
+    if (p) {
+	char **v = gsserrmap_find(p, minor_code);
+	if (v) {
+	    msg = *v;
+#ifdef DEBUG
+	    fprintf(stderr, " FOUND!");
+#endif
+	}
+    }
+    if (msg == 0)
+	msg = error_message(minor_code);
+#ifdef DEBUG
+    fprintf(stderr, " -> %p/%s\n", (void *) msg, msg);
+#endif
+    return msg;
+}
+#define save_error_string_nocopy gss_krb5_save_error_string_nocopy
+static int save_error_string_nocopy(OM_uint32 minor_code, char *msg)
+{
+    gsserrmap *p;
+    int ret;
+
+#ifdef DEBUG
+    fprintf(stderr, "%s(%lu, %s)", __func__, (unsigned long) minor_code, msg);
+#endif
+    p = k5_getspecific(K5_KEY_GSS_KRB5_ERROR_MESSAGE);
+    if (!p) {
+	p = malloc(sizeof(*p));
+	if (p == NULL) {
+	    ret = 1;
+	    goto fail;
+	}
+	if (gsserrmap_init(p) != 0) {
+	    free(p);
+	    p = NULL;
+	    ret = 1;
+	    goto fail;
+	}
+	if (k5_setspecific(K5_KEY_GSS_KRB5_ERROR_MESSAGE, p) != 0) {
+	    gsserrmap_destroy(p);
+	    free(p);
+	    p = NULL;
+	    ret = 1;
+	    goto fail;
+	}
+    }
+    ret = gsserrmap_replace_or_insert(p, minor_code, msg);
+fail:
+#ifdef DEBUG
+    fprintf(stderr, " p=%p %s\n", (void *)p, ret ? "FAIL" : "SUCCESS");
+#endif
+    return ret;
+}
+void save_error_string(OM_uint32 minor_code, char *msg)
+{
+    char *s = strdup(msg);
+    if (s) {
+	if (save_error_string_nocopy(minor_code, s) != 0)
+	    free(s);
+    }
+}
+void save_error_message(OM_uint32 minor_code, const char *format, ...)
+{
+    char *s;
+    int n;
+    va_list ap;
+
+    va_start(ap, format);
+    n = vasprintf(&s, format, ap);
+    va_end(ap);
+    if (n >= 0) {
+	if (save_error_string_nocopy(minor_code, s) != 0)
+	    free(s);
+    }
+}
+void krb5_gss_save_error_info(OM_uint32 minor_code, krb5_context ctx)
+{
+    char *s;
+
+#ifdef DEBUG
+    fprintf(stderr, "%s(%lu, ctx=%p)\n", __func__,
+	    (unsigned long) minor_code, (void *)ctx);
+#endif
+    s = krb5_get_error_message(ctx, minor_code);
+#ifdef DEBUG
+    fprintf(stderr, "%s(%lu, ctx=%p) saving: %s\n", __func__,
+	    (unsigned long) minor_code, (void *)ctx, s);
+#endif
+    save_error_string(minor_code, s);
+    /* The get_error_message call above resets the error message in
+       ctx.  Put it back, in case we make this call again *sigh*.  */
+    krb5_set_error_message(ctx, minor_code, "%s", s);
+    krb5_free_error_message(ctx, s);
+}
+void krb5_gss_delete_error_info(void *p)
+{
+    gsserrmap_destroy(p);
+}
+
 /**/
 
 OM_uint32
@@ -59,8 +183,13 @@ krb5_gss_display_status(minor_status, status_value, status_type,
 	 return(GSS_S_FAILURE);
       }
 
-      return(g_display_com_err_status(minor_status, status_value,
-				      status_string));
+      /* If this fails, there's not much we can do...  */
+      if (g_make_string_buffer(krb5_gss_get_error_message(status_value),
+			       status_string) != 0)
+	  *minor_status = ENOMEM;
+      else
+	  *minor_status = 0;
+      return 0;
    } else {
       *minor_status = 0;
       return(GSS_S_BAD_STATUS);