idn: use idn_free() to free allocated libidn memory

xfree() might crash on libidn memory on Windows.

From 'man idn_free':
"Under Windows, different parts of the same application may use different
 heap memory, and then it is important to deallocate memory allocated within
 the same  module  that  allocated it. This function makes that possible."

src/connect.c

@@ -54,6 +54,11 @@ as that of the covered work.  */
 #include <errno.h>
 #include <string.h>
 #include <sys/time.h>
+
+#ifdef ENABLE_IRI
+#include <idn-free.h>
+#endif
+
 #include "utils.h"
 #include "host.h"
 #include "connect.h"
@@ -278,7 +283,7 @@ connect_to_ip (const ip_address *ip, int port, const char *print)
               str = xmalloc (len);
               snprintf (str, len, "%s (%s)", name, print);
               str[len-1] = '\0';
-              xfree (name);
+              idn_free (name);
             }
 
           logprintf (LOG_VERBOSE, _("Connecting to %s|%s|:%d... "),

src/host.c

@@ -57,6 +57,10 @@ as that of the covered work.  */
 
 #include <errno.h>
 
+#ifdef ENABLE_IRI
+#include <idn-free.h>
+#endif
+
 #include "utils.h"
 #include "host.h"
 #include "url.h"
@@ -741,7 +745,7 @@ lookup_host (const char *host, int flags)
           str = xmalloc (len);
           snprintf (str, len, "%s (%s)", name, host);
           str[len-1] = '\0';
-          xfree (name);
+          idn_free (name);
         }
 
       logprintf (LOG_VERBOSE, _("Resolving %s... "),

src/iri.c

@@ -35,6 +35,7 @@ as that of the covered work.  */
 #include <iconv.h>
 #include <stringprep.h>
 #include <idna.h>
+#include <idn-free.h>
 #include <errno.h>
 
 #include "utils.h"

src/iri.h

@@ -39,6 +39,9 @@ struct iri {
 
 #ifdef ENABLE_IRI
 
+# include <idna.h>
+# include <idn-free.h>
+
 char *parse_charset (char *str);
 char *find_locale (void);
 bool check_encoding_name (char *encoding);
@@ -62,6 +65,7 @@ extern struct iri dummy_iri;
 #define locale_to_utf8(str)         (str)
 #define idn_encode(a,b)             NULL
 #define idn_decode(str)             NULL
+#define idn_free(str)               ((void)0)
 #define remote_to_utf8(a,b,c)       false
 #define iri_new()                   (&dummy_iri)
 #define iri_dup(a)                  (&dummy_iri)

src/url.c

@@ -897,6 +897,7 @@ url_parse (const char *url, int *error, struct iri *iri, bool percent_encode)
             {
               xfree (u->host);
               u->host = new;
+              u->idn_allocated = true;
               host_modified = true;
             }
         }
@@ -1175,7 +1176,13 @@ url_free (struct url *url)
 {
   if (url)
     {
-      xfree (url->host);
+      if (url->idn_allocated) {
+        idn_free (url->host);      /* A dummy if !defined(ENABLE_IRI) */
+        url->host = NULL;
+      }
+      else
+        xfree (url->host);
+
       xfree (url->path);
       xfree (url->url);
 

src/url.h

@@ -95,6 +95,10 @@ struct url
   /* Username and password (unquoted). */
   char *user;
   char *passwd;
+
+  /* 'host' is allocated by idna_to_ascii_8z() via idn_encode().
+   * Call 'idn_free()' to free this memory. */
+  bool idn_allocated;
 };
 
 /* Function declarations */