discover/pxe-parser: Retrieve configs asynchronously
[petitboot] / discover / pxe-parser.c
index 4812c374d1991b74ba938e9fd935154982a6b3d3..4481e5da9f7c9709d31cea7e00e29709cf203d38 100644 (file)
@@ -8,6 +8,8 @@
 #include <talloc/talloc.h>
 #include <url/url.h>
 #include <log/log.h>
+#include <file/file.h>
+#include <i18n/i18n.h>
 
 #include "parser.h"
 #include "parser-conf.h"
@@ -197,87 +199,168 @@ static void pxe_process_pair(struct conf_context *ctx,
 
 }
 
-static int pxe_parse(struct discover_context *dc)
+/*
+ * Callback for asynchronous loads from pxe_parse()
+ * @param result Result of load_url_async()
+ * @param data   Pointer to associated conf_context
+ */
+static void pxe_conf_parse_cb(struct load_url_result *result, void *data)
 {
-       struct pb_url *pxe_base_url, *url;
-       struct pxe_parser_info *parser_info;
-       char **pxe_conf_files, **filename;
-       struct conf_context *conf;
-       bool complete_url;
+       struct conf_context *conf = data;
+       struct device_handler *handler;
+       struct boot_status status = {0};
+       char *buf = NULL;
        int len, rc;
-       char *buf;
 
-       /* Expects dhcp event parameters to support network boot */
-       if (!dc->event)
-               return -1;
+       if (!data)
+               return;
 
-       conf = talloc_zero(dc, struct conf_context);
+       if (!result || result->status != LOAD_OK) {
+               talloc_free(conf);
+               return;
+       }
+
+       rc = read_file(conf, result->local, &buf, &len);
+       if (rc) {
+               pb_log("Read failed during pxe callback for %s\n", result->local);
+               goto out_clean;
+       }
+
+       conf_parse_buf(conf, buf, len);
+
+       /* We may be called well after the original caller of iterate_parsers(),
+        * commit any new boot options ourselves */
+       handler = talloc_parent(conf);
+       device_handler_discover_context_commit(handler, conf->dc);
+
+       status.type = BOOT_STATUS_INFO;
+       /*
+        * TRANSLATORS: the format specifier in this string in an IP address,
+        * eg. 192.168.1.1
+        */
+       status.message = talloc_asprintf(conf, _("pxe: parsed config for %s"),
+                                       conf->dc->conf_url->host);
+       device_handler_boot_status(handler, &status);
+
+       talloc_free(buf);
+out_clean:
+       if (result->cleanup_local)
+               unlink(result->local);
+       talloc_free(conf);
+}
+
+/**
+ * Return a new conf_context and increment the talloc reference count on
+ * the discover_context struct.
+ * @param  ctx  Parent talloc context
+ * @param  orig Original discover_context
+ * @return      Pointer to new conf_context
+ */
+static struct conf_context *copy_context(void *ctx, struct discover_context *dc)
+{
+       struct pxe_parser_info *info;
+       struct conf_context *conf;
+
+       conf = talloc_zero(ctx, struct conf_context);
 
        if (!conf)
-               goto out;
+               return NULL;
 
-       conf->dc = dc;
        conf->get_pair = conf_get_pair_space;
        conf->process_pair = pxe_process_pair;
        conf->finish = pxe_finish;
+       info = talloc_zero(conf, struct pxe_parser_info);
+       if (!info) {
+               talloc_free(conf);
+               return NULL;
+       }
+       conf->parser_info = info;
+
+       /*
+        * The discover_context may be freed once pxe_parse() returns, but the
+        * callback will still need it. Take a reference so that that it will
+        * persist until the last callback completes.
+        */
+       conf->dc = talloc_reference(conf, dc);
 
-       parser_info = talloc_zero(conf, struct pxe_parser_info);
-       conf->parser_info = parser_info;
+       return conf;
+}
+
+static int pxe_parse(struct discover_context *dc)
+{
+       struct pb_url *pxe_base_url, *url;
+       char **pxe_conf_files, **filename;
+       struct conf_context *conf = NULL;
+       struct load_url_result *result;
+       void *ctx = talloc_parent(dc);
+       bool complete_url;
+
+       /* Expects dhcp event parameters to support network boot */
+       if (!dc->event)
+               return -1;
 
        dc->conf_url = user_event_parse_conf_url(dc, dc->event, &complete_url);
        if (!dc->conf_url)
-               goto out_conf;
+               return -1;
+
+       /*
+        * Retrieving PXE configs over the network can take some time depending
+        * on factors such as slow network, malformed paths, bad DNS, and
+        * overzealous firewalls. Instead of blocking the discover server while
+        * we wait for these, spawn an asynchronous job for each URL we can
+        * parse and process the resulting files in a callback. A separate
+        * conf_context is created for each job.
+        */
+       conf = copy_context(ctx, dc);
+       if (!conf)
+               return -1;
 
        if (complete_url) {
                /* we have a complete URL; use this and we're done. */
-               rc = parser_request_url(dc, dc->conf_url, &buf, &len);
-               if (rc)
+               result = load_url_async(conf->dc, conf->dc->conf_url,
+                                       pxe_conf_parse_cb, conf);
+               if (!result) {
+                       pb_log("load_url_async fails for %s\n",
+                                       dc->conf_url->path);
                        goto out_conf;
+               }
        } else {
                pxe_conf_files = user_event_parse_conf_filenames(dc, dc->event);
                if (!pxe_conf_files)
                        goto out_conf;
 
-               rc = -1;
-
                pxe_base_url = pb_url_join(dc, dc->conf_url, pxelinux_prefix);
                if (!pxe_base_url)
                        goto out_pxe_conf;
 
                for (filename = pxe_conf_files; *filename; filename++) {
-                       url = pb_url_join(dc, pxe_base_url, *filename);
+                       if (!conf) {
+                               conf = copy_context(ctx, dc);
+                       }
+                       url = pb_url_join(conf->dc, pxe_base_url, *filename);
                        if (!url)
                                continue;
-
-                       rc = parser_request_url(dc, url, &buf, &len);
-                       if (!rc) /* found one, just break */
-                               break;
-
-                       talloc_free(url);
+                       result = load_url_async(conf, url, pxe_conf_parse_cb,
+                                               conf);
+                       if (!result) {
+                               pb_log("load_url_async fails for %s\n",
+                                      conf->dc->conf_url->path);
+                               talloc_free(conf);
+                       }
+                       /* conf now needed by callback, don't reuse */
+                       conf = NULL;
                }
 
                talloc_free(pxe_base_url);
-
-               /* No configuration file found on the boot server */
-               if (rc)
-                       goto out_pxe_conf;
-
                talloc_free(pxe_conf_files);
        }
 
-       /* Call the config file parser with the data read from the file */
-       conf_parse_buf(conf, buf, len);
-
-       talloc_free(buf);
-       talloc_free(conf);
-
        return 0;
 
 out_pxe_conf:
        talloc_free(pxe_conf_files);
 out_conf:
        talloc_free(conf);
-out:
        return -1;
 }