src/src/lookups/json.c

   1 /*************************************************
   2 *     Exim - an Internet mail transport agent    *
   3 *************************************************/
   4
   5 /* Copyright (c) Jeremy Harris 2019 */
   6 /* See the file NOTICE for conditions of use and distribution. */
   7
   8 #include "../exim.h"
   9 #include "lf_functions.h"
  10 #include <jansson.h>
  11
  12
  13
  14 /* All use of allocations will be done against the POOL_SEARCH memory,
  15 which is freed once by search_tidyup(). Make the free call a dummy.
  16 This burns some 300kB in handling a 37kB JSON file, for the benefit of
  17 a fast free.  The alternative of staying with malloc is nearly as bad,
  18 eyeballing the activity there are 20% the number of free vs. alloc
  19 calls (before the big bunch at the end).
  20
  21 Assume that the file is trusted, so no tainting */
  22
  23 static void *
  24 json_malloc(size_t nbytes)
  25 {
  26 void * p = store_get((int)nbytes, FALSE);
  27 /* debug_printf("%s %d: %p\n", __FUNCTION__, (int)nbytes, p); */
  28 return p;
  29 }
  30 static void
  31 json_free(void * p)
  32 {
  33 /* debug_printf("%s: %p\n", __FUNCTION__, p); */
  34 }
  35
  36 /*************************************************
  37 *              Open entry point                  *
  38 *************************************************/
  39
  40 /* See local README for interface description */
  41
  42 static void *
  43 json_open(const uschar * filename, uschar ** errmsg)
  44 {
  45 FILE * f;
  46
  47 json_set_alloc_funcs(json_malloc, json_free);
  48
  49 if (!(f = Ufopen(filename, "rb")))
  50   {
  51   int save_errno = errno;
  52   *errmsg = string_open_failed(errno, "%s for json search", filename);
  53   errno = save_errno;
  54   return NULL;
  55   }
  56 return f;
  57 }
  58
  59
  60
  61 /*************************************************
  62 *             Check entry point                  *
  63 *************************************************/
  64
  65 static BOOL
  66 json_check(void *handle, const uschar *filename, int modemask, uid_t *owners,
  67   gid_t *owngroups, uschar **errmsg)
  68 {
  69 return lf_check_file(fileno((FILE *)handle), filename, S_IFREG, modemask,
  70   owners, owngroups, "json", errmsg) == 0;
  71 }
  72
  73
  74
  75 /*************************************************
  76 *         Find entry point for lsearch           *
  77 *************************************************/
  78
  79 /* See local README for interface description */
  80
  81 static int
  82 json_find(void * handle, const uschar * filename, const uschar * keystring,
  83   int length, uschar ** result, uschar ** errmsg, uint * do_cache)
  84 {
  85 FILE * f = handle;
  86 json_t * j, * j0;
  87 json_error_t jerr;
  88 uschar * key;
  89 int sep = 0;
  90
  91 length = length;        /* Keep picky compilers happy */
  92 do_cache = do_cache;    /* Keep picky compilers happy */
  93
  94 rewind(f);
  95 if (!(j = json_loadf(f, 0, &jerr)))
  96   {
  97   *errmsg = string_sprintf("json error on open: %.*s\n",
  98        JSON_ERROR_TEXT_LENGTH, jerr.text);
  99   return FAIL;
 100   }
 101 j0 = j;
 102
 103 for (int k = 1;  (key = string_nextinlist(&keystring, &sep, NULL, 0)); k++)
 104   {
 105   BOOL numeric = TRUE;
 106   for (uschar * s = key; *s; s++) if (!isdigit(*s)) { numeric = FALSE; break; }
 107
 108   if (!(j = numeric
 109         ? json_array_get(j, (size_t) strtoul(CS key, NULL, 10))
 110         : json_object_get(j, CCS key)
 111      ) )
 112     {
 113     DEBUG(D_lookup) debug_printf_indent("%s, for key %d: '%s'\n",
 114       numeric
 115       ? US"bad index, or not json array"
 116       : US"no such key, or not json object",
 117       k, key);
 118     json_decref(j0);
 119     return FAIL;
 120     }
 121   }
 122
 123 switch (json_typeof(j))
 124   {
 125   case JSON_STRING:
 126     *result = string_copyn(CUS json_string_value(j), json_string_length(j));
 127     break;
 128   case JSON_INTEGER:
 129     *result = string_sprintf("%" JSON_INTEGER_FORMAT, json_integer_value(j));
 130     break;
 131   case JSON_REAL:
 132     *result = string_sprintf("%f", json_real_value(j));
 133     break;
 134   case JSON_TRUE:       *result = US"true";     break;
 135   case JSON_FALSE:      *result = US"false";    break;
 136   case JSON_NULL:       *result = NULL;         break;
 137   default:              *result = US json_dumps(j, 0); break;
 138   }
 139 json_decref(j0);
 140 return OK;
 141 }
 142
 143
 144
 145 /*************************************************
 146 *              Close entry point                 *
 147 *************************************************/
 148
 149 /* See local README for interface description */
 150
 151 static void
 152 json_close(void *handle)
 153 {
 154 (void)fclose((FILE *)handle);
 155 }
 156
 157
 158
 159 /*************************************************
 160 *         Version reporting entry point          *
 161 *************************************************/
 162
 163 /* See local README for interface description. */
 164
 165 #include "../version.h"
 166
 167 void
 168 json_version_report(FILE *f)
 169 {
 170 fprintf(f, "Library version: json: Jansonn version %s\n", JANSSON_VERSION);
 171 }
 172
 173
 174 static lookup_info json_lookup_info = {
 175   US"json",                      /* lookup name */
 176   lookup_absfile,                /* uses absolute file name */
 177   json_open,                  /* open function */
 178   json_check,                 /* check function */
 179   json_find,                  /* find function */
 180   json_close,                 /* close function */
 181   NULL,                          /* no tidy function */
 182   NULL,                          /* no quoting function */
 183   json_version_report         /* version reporting */
 184 };
 185
 186
 187 #ifdef DYNLOOKUP
 188 #define json_lookup_module_info _lookup_module_info
 189 #endif
 190
 191 static lookup_info *_lookup_list[] = { &json_lookup_info };
 192 lookup_module_info json_lookup_module_info = { LOOKUP_MODULE_INFO_MAGIC, _lookup_list, 1 };
 193
 194 /* End of lookups/json.c */