Add new option --retry-on-host-error

* doc/wget.texi: Add docs for --retry-on-host-error
* src/http.c (http_loop): Add code for HOSTERR
* src/init.c: Add option --retry-on-host-error
* src/main.c: Likewise
* src/options.h: Add options.retry_on_host_error

Copyright-paperwork-exempt: Yes

doc/wget.texi

@@ -1750,6 +1750,10 @@ some few obscure servers, which never send HTTP authentication
 challenges, but accept unsolicited auth info, say, in addition to
 form-based authentication.
 
+@item --retry-on-host-error
+Consider host errors, such as ``Temporary failure in name resolution'',
+as non-fatal, transient errors.
+
 @item --retry-on-http-error=@var{code[,code,...]}
 Consider given HTTP response codes as non-fatal, transient errors.
 Supply a comma-separated list of 3-digit HTTP response codes as

src/http.c

@@ -4386,7 +4386,18 @@ http_loop (const struct url *u, struct url *original_url, char **newloc,
           logputs (LOG_VERBOSE, "\n");
           logprintf (LOG_NOTQUIET, _("Cannot write to %s (%s).\n"),
                      quote (hstat.local_file), strerror (errno));
-        case HOSTERR: case CONIMPOSSIBLE: case PROXERR: case SSLINITFAILED:
+        case HOSTERR:
+          /* Fatal unless option set otherwise. */
+          if ( opt.retry_on_host_error )
+            {
+              printwhat (count, opt.ntry);
+              xfree (hstat.message);
+              xfree (hstat.error);
+              continue;
+            }
+          ret = err;
+          goto exit;
+        case CONIMPOSSIBLE: case PROXERR: case SSLINITFAILED:
         case CONTNOTSUPPORTED: case VERIFCERTERR: case FILEBADFILE:
         case UNKNOWNATTR:
           /* Fatal errors just return from the function.  */

src/init.c

@@ -313,6 +313,7 @@ static const struct {
   { "restrictfilenames", NULL,                  cmd_spec_restrict_file_names },
   { "retrsymlinks",     &opt.retr_symlinks,     cmd_boolean },
   { "retryconnrefused", &opt.retry_connrefused, cmd_boolean },
+  { "retryonhosterror", &opt.retry_on_host_error, cmd_boolean },
   { "retryonhttperror", &opt.retry_on_http_error, cmd_string },
   { "robots",           &opt.use_robots,        cmd_boolean },
   { "savecookies",      &opt.cookies_output,    cmd_file },

src/main.c

@@ -420,6 +420,7 @@ static struct cmdline_option option_data[] =
     { "restrict-file-names", 0, OPT_BOOLEAN, "restrictfilenames", -1 },
     { "retr-symlinks", 0, OPT_BOOLEAN, "retrsymlinks", -1 },
     { "retry-connrefused", 0, OPT_BOOLEAN, "retryconnrefused", -1 },
+    { "retry-on-host-error", 0, OPT_BOOLEAN, "retryonhosterror", -1 },
     { "retry-on-http-error", 0, OPT_VALUE, "retryonhttperror", -1 },
     { "save-cookies", 0, OPT_VALUE, "savecookies", -1 },
     { "save-headers", 0, OPT_BOOLEAN, "saveheaders", -1 },

src/options.h

@@ -41,6 +41,7 @@ struct options
   bool quiet;                   /* Are we quiet? */
   int ntry;                     /* Number of tries per URL */
   bool retry_connrefused;       /* Treat CONNREFUSED as non-fatal. */
+  bool retry_on_host_error;     /* Treat host errors as non-fatal. */
   char *retry_on_http_error;    /* Treat given HTTP errors as non-fatal. */
   bool background;              /* Whether we should work in background. */
   bool ignore_length;           /* Do we heed content-length at all?  */