ktutil: Add import command and other improvements

- Add an import command that imports JSON as output by
   `ktutil list --json --keys`.

   This is enables one to filter/edit keytabs with jq!

 - Add a `merge` alias for the `copy` command, since that's effectively
   what it does.

 - Add a `--copy-duplicates` option to the `copy`/`merge` command.

 - Add a `--no-create` option to the `get` command.

 - Add a `--no-change-keys` option to the `get` command.

 - Make `add` complain if it can't finish writing to the keytab.

admin/add.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997-2005 Kungliga Tekniska Högskolan
+ * Copyright (c) 1997-2022 Kungliga Tekniska Högskolan
  * (Royal Institute of Technology, Stockholm, Sweden).
  * All rights reserved.
  *
@@ -32,6 +32,8 @@
  */
 
 #include "ktutil_locl.h"
+#include <heimbase.h>
+#include <base64.h>
 
 RCSID("$Id$");
 
@@ -153,6 +155,178 @@ kt_add(struct add_options *opt, int argc, char **argv)
 	krb5_warn(context, ret, "add");
  out:
     krb5_kt_free_entry(context, &entry);
-    krb5_kt_close(context, keytab);
+    if (ret == 0) {
+        ret = krb5_kt_close(context, keytab);
+        if (ret)
+            krb5_warn(context, ret, "Could not write the keytab");
+    } else {
+        krb5_kt_close(context, keytab);
+    }
+    return ret != 0;
+}
+
+/* We might be reading from a pipe, so we can't use rk_undumpdata() */
+static char *
+read_file(FILE *f)
+{
+    size_t alloced;
+    size_t len = 0;
+    size_t bytes;
+    char *res, *end, *p;
+
+    if ((res = malloc(1024)) == NULL)
+        err(1, "Out of memory");
+    alloced = 1024;
+
+    end = res + alloced;
+    p = res;
+    do {
+        if (p == end) {
+            char *tmp;
+
+            if ((tmp = realloc(res, alloced + (alloced > 1))) == NULL)
+                err(1, "Out of memory");
+            alloced += alloced > 1;
+            p = tmp + (p - res);
+            res = tmp;
+            end = res + alloced;
+        }
+        bytes = fread(p, 1, end - p, f);
+        len += bytes;
+        p += bytes;
+    } while (bytes && !feof(f) && !ferror(f));
+
+    if (ferror(f))
+        errx(1, "Could not read all input");
+    if (p == end) {
+        char *tmp;
+
+        if ((tmp = strndup(res, len)) == NULL)
+            err(1, "Out of memory");
+        free(res);
+        res = tmp;
+    }
+    if (strlen(res) != len)
+        err(1, "Embedded NULs in input!");
+    return res;
+}
+
+static void
+json2keytab_entry(heim_dict_t d, krb5_keytab kt, size_t idx)
+{
+    krb5_keytab_entry e;
+    krb5_error_code ret;
+    heim_object_t v;
+    uint64_t u;
+    int64_t i;
+    char *buf = NULL;
+
+    memset(&e, 0, sizeof(e));
+
+    v = heim_dict_get_value(d, HSTR("timestamp"));
+    if (heim_get_tid(v) != HEIM_TID_NUMBER)
+        goto bad;
+    u = heim_number_get_long(v);
+    e.timestamp = u;
+    if (u != (uint64_t)e.timestamp)
+        goto bad;
+
+    v = heim_dict_get_value(d, HSTR("kvno"));
+    if (heim_get_tid(v) != HEIM_TID_NUMBER)
+        goto bad;
+    i = heim_number_get_long(v);
+    e.vno = i;
+    if (i != (int64_t)e.vno)
+        goto bad;
+
+    v = heim_dict_get_value(d, HSTR("enctype_number"));
+    if (heim_get_tid(v) != HEIM_TID_NUMBER)
+        goto bad;
+    i = heim_number_get_long(v);
+    e.keyblock.keytype = i;
+    if (i != (int64_t)e.keyblock.keytype)
+        goto bad;
+
+    v = heim_dict_get_value(d, HSTR("key"));
+    if (heim_get_tid(v) != HEIM_TID_STRING)
+        goto bad;
+    {
+        const char *s = heim_string_get_utf8(v);
+        int declen;
+
+        if ((buf = malloc(strlen(s))) == NULL)
+            err(1, "Out of memory");
+        declen = rk_base64_decode(s, buf);
+        if (declen < 0)
+            goto bad;
+        e.keyblock.keyvalue.data = buf;
+        e.keyblock.keyvalue.length = declen;
+    }
+
+    v = heim_dict_get_value(d, HSTR("principal"));
+    if (heim_get_tid(v) != HEIM_TID_STRING)
+        goto bad;
+    ret = krb5_parse_name(context, heim_string_get_utf8(v), &e.principal);
+    if (ret == 0)
+        ret = krb5_kt_add_entry(context, kt, &e);
+
+    /* For now, ignore aliases; besides, they're never set anywhere in-tree */
+
+    if (ret)
+        krb5_warn(context, ret,
+                  "Could not parse or write keytab entry %lu",
+                  (unsigned long)idx);
+bad:
+    krb5_free_principal(context, e.principal);
+}
+
+int
+kt_import(void *opt, int argc, char **argv)
+{
+    krb5_error_code ret;
+    krb5_keytab kt;
+    heim_object_t o;
+    heim_error_t json_err = NULL;
+    heim_json_flags_t flags = HEIM_JSON_F_STRICT;
+    FILE *f = argc == 0 ? stdin : fopen(argv[0], "r");
+    size_t alen, i;
+    char *json;
+
+    if (f == NULL)
+        err(1, "Could not open file %s", argv[0]);
+
+    json = read_file(f);
+    o = heim_json_create(json, 10, flags, &json_err);
+    free(json);
+    if (o == NULL) {
+        if (json_err != NULL) {
+            o = heim_error_copy_string(json_err);
+            if (o)
+                errx(1, "Could not parse JSON: %s", heim_string_get_utf8(o));
+        }
+        errx(1, "Could not parse JSON");
+    }
+
+    if (heim_get_tid(o) != HEIM_TID_ARRAY)
+        errx(1, "JSON text must be an array");
+
+    alen = heim_array_get_length(o);
+    if (alen == 0)
+        errx(1, "Empty JSON array; not overwriting keytab");
+
+    if ((kt = ktutil_open_keytab()) == NULL)
+	err(1, "Could not open keytab");
+
+    for (i = 0; i < alen; i++) {
+        heim_object_t e = heim_array_get_value(o, i);
+
+        if (heim_get_tid(e) != HEIM_TID_DICT)
+            warnx("Element %ld of JSON text array is not an object", (long)i);
+        else
+            json2keytab_entry(heim_array_get_value(o, i), kt, i);
+    }
+    ret = krb5_kt_close(context, kt);
+    if (ret)
+        krb5_warn(context, ret, "Could not write the keytab");
     return ret != 0;
 }