MINOR: ssl: Add "del ssl ca-file" CLI command

This patch adds the "del ssl ca-file <cafile>" CLI command which can be
used to delete an unused CA file.
The CA file will be considered unused if its list of ckch instances is
empty. This command cannot be used to delete the uncommitted CA file of
a previous "set ssl ca-file" without commit. It only acts on
CA file entries already inserted in the CA file tree.

This fixes a subpart of GitHub issue #1057.

src/ssl_ckch.c

@@ -2837,6 +2837,50 @@ yield:
 	return 0; /* should come back */
 }
 
+/* parsing function of 'del ssl ca-file' */
+static int cli_parse_del_cafile(char **args, char *payload, struct appctx *appctx, void *private)
+{
+	struct cafile_entry *cafile_entry;
+	char *err = NULL;
+	char *filename;
+
+	if (!cli_has_level(appctx, ACCESS_LVL_ADMIN))
+		return 1;
+
+	if (!*args[3])
+		return cli_err(appctx, "'del ssl ca-file' expects a CA file name\n");
+
+	if (HA_SPIN_TRYLOCK(CKCH_LOCK, &ckch_lock))
+		return cli_err(appctx, "Can't delete the CA file!\nOperations on certificates are currently locked!\n");
+
+	filename = args[3];
+
+	cafile_entry = ssl_store_get_cafile_entry(filename, 0);
+	if (!cafile_entry) {
+		memprintf(&err, "CA file '%s' doesn't exist!\n", filename);
+		goto error;
+	}
+
+	if (!LIST_ISEMPTY(&cafile_entry->ckch_inst_link)) {
+		memprintf(&err, "CA file '%s' in use, can't be deleted!\n", filename);
+		goto error;
+	}
+
+	/* Remove the cafile_entry from the tree */
+	ebmb_delete(&cafile_entry->node);
+	ssl_store_delete_cafile_entry(cafile_entry);
+
+	memprintf(&err, "CA file '%s' deleted!\n", filename);
+
+	HA_SPIN_UNLOCK(CKCH_LOCK, &ckch_lock);
+	return cli_dynmsg(appctx, LOG_NOTICE, err);
+
+error:
+	memprintf(&err, "Can't remove the CA file: %s\n", err ? err : "");
+	HA_SPIN_UNLOCK(CKCH_LOCK, &ckch_lock);
+	return cli_dynerr(appctx, err);
+}
+
 
 void ckch_deinit()
 {
@@ -2865,6 +2909,7 @@ static struct cli_kw_list cli_kws = {{ },{
 	{ { "set", "ssl", "ca-file", NULL },    "set ssl ca-file <cafile> <payload>      : replace a CA file",                                                     cli_parse_set_cafile, NULL, NULL },
 	{ { "commit", "ssl", "ca-file", NULL }, "commit ssl ca-file <cafile>             : commit a CA file",                                                      cli_parse_commit_cafile, cli_io_handler_commit_cafile, cli_release_commit_cafile },
 	{ { "abort", "ssl", "ca-file", NULL },  "abort ssl ca-file <cafile>              : abort a transaction for a CA file",                                     cli_parse_abort_cafile, NULL, NULL },
+	{ { "del", "ssl", "ca-file", NULL },    "del ssl ca-file <cafile>                : delete an unused CA file",                                              cli_parse_del_cafile, NULL, NULL },
 	{ { "show", "ssl", "ca-file", NULL },   "show ssl ca-file [<cafile>[:<index>]]   : display the SSL CA files used in memory, or the details of a <cafile>, or a single certificate of index <index> of a CA file <cafile>", cli_parse_show_cafile, cli_io_handler_show_cafile, cli_release_show_cafile },
 	{ { NULL }, NULL, NULL, NULL }
 }};