acme-client: add a check in parser

[Sebastian Benoit]

add an extra check for existing "api ..." line in the config.
move the check of existing "account ..." line from main.c to the parser.

The first one actually triggers a null deref later on if you have a broken
config.

ok?

diff --git usr.sbin/acme-client/main.c usr.sbin/acme-client/main.c
index d96bf40e036..fd0f7339891 100644
--- usr.sbin/acme-client/main.c
+++ usr.sbin/acme-client/main.c
@@ -156,11 +156,6 @@ main(int argc, char *argv[])
 
        acctkey = authority->account;
 
-       if (acctkey == NULL) {
-               /* XXX replace with existance check in parse.y */
-               err(EXIT_FAILURE, "no account key in config?");
-       }
-
        if ((chngdir = domain->challengedir) == NULL)
                if ((chngdir = strdup(WWW_DIR)) == NULL)
                        err(EXIT_FAILURE, "strdup");
diff --git usr.sbin/acme-client/parse.y usr.sbin/acme-client/parse.y
index dc38e120bb6..abc7da6f8fa 100644
--- usr.sbin/acme-client/parse.y
+++ usr.sbin/acme-client/parse.y
@@ -186,7 +186,16 @@ authority  : AUTHORITY STRING {
                                YYERROR;
                        }
                } '{' optnl authorityopts_l '}' {
-                       /* XXX enforce minimum config here */
+                       if (auth->api == NULL) {
+                               yyerror("authority %s: no api URL specified",
+                                   auth->name);
+                               YYERROR;
+                       }
+                       if (auth->account == NULL) {
+                               yyerror("authority %s: no account key file "
+                                   "specified", auth->name);
+                               YYERROR;
+                       }
                        auth = NULL;
                }
                ;