1 files changed, 71 insertions, 0 deletions
diff --git a/src/util/lang.c b/src/util/lang.c
new file mode 100644
index 000000000..3f6a4291f
--- /dev/null
+++ b/src/util/lang.c
@@ -0,0 +1,71 @@
+/*
+  This file is part of TALER
+  Copyright (C) 2020 Taler Systems SA
+
+  TALER is free software; you can redistribute it and/or modify it under the
+  terms of the GNU General Public License as published by the Free Software
+  Foundation; either version 3, or (at your option) any later version.
+
+  TALER is distributed in the hope that it will be useful, but WITHOUT ANY
+  WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+  A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License along with
+  TALER; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+*/
+/**
+ * @file lang.c
+ * @brief Utility functions for parsing and matching RFC 7231 language strings.
+ * @author Christian Grothoff
+ */
+#include "platform.h"
+#include "taler_util.h"
+
+
+/**
+ * Check if @a lang matches the @a language_pattern, and if so with
+ * which preference.
+ * See also: https://tools.ietf.org/html/rfc7231#section-5.3.1
+ *
+ * @param language_pattern a language preferences string
+ *        like "fr-CH, fr;q=0.9, en;q=0.8, *;q=0.1"
+ * @param lang the 2-digit language to match
+ * @return q-weight given for @a lang in @a language_pattern, 1.0 if no weights are given;
+ *         0 if @a lang is not in @a language_pattern
+ */
+double
+TALER_language_matches (const char *language_pattern,
+                        const char *lang)
+{
+  char *p = GNUNET_strdup (language_pattern);
+  char *sptr;
+  double r = 0.0;
+
+  for (char *tok = strtok_r (p, ",", &sptr);
+       NULL != tok;
+       tok = strtok_r (NULL, ",", &sptr))
+  {
+    char *sptr2;
+    char *lp = strtok_r (tok, ";", &sptr2);
+    char *qp = strtok_r (NULL, ";", &sptr2);
+    double q = 1.0;
+
+    while (isspace ((int) *lp))
+      lp++;
+    if (NULL != qp)
+      while (isspace ((int) *qp))
+        qp++;
+    GNUNET_break_op ( (NULL == qp) ||
+                      (1 == sscanf (qp,
+                                    "q=%lf",
+                                    &q)) );
+    if (0 == strcasecmp (lang,
+                         lp))
+      r = GNUNET_MAX (r, q);
+  }
+  GNUNET_free (p);
+  return r;
+}
+
+
+/* end of lang.c */