[PATCH 5/7] ipaccess-proxy: more robust option parsing and checking

[pablo]

From: Pablo Neira Ayuso <pa...@gnumonks.org>

With this patch, ipaccess-proxy makes more robust option checking:

$ ./ipaccess-proxy -l 1.1.1.1 -b 2.2.2.2 -e
ERROR: missing mandatory argument for `-e' option

And we return to shell to enforce the user to try again with the
appropriate invocation.

Before this patch, the default getopt_long() error handling was
enabled which displayed this message:

./ipaccess-proxy: option requires an argument -- 'e'

and ipaccess-proxy continued working.

This is generic enough to cover other option that require mandatory
arguments like `--bsc' and `--listen'.
---
 openbsc/src/ipaccess/ipaccess-proxy.c |   15 +++++++++++++++
 1 files changed, 15 insertions(+), 0 deletions(-)

diff --git a/openbsc/src/ipaccess/ipaccess-proxy.c 
b/openbsc/src/ipaccess/ipaccess-proxy.c
index 55658cf..dd0a739 100644
--- a/openbsc/src/ipaccess/ipaccess-proxy.c
+++ b/openbsc/src/ipaccess/ipaccess-proxy.c
@@ -1133,6 +1133,9 @@ static void handle_options(int argc, char** argv)
 {
        int options_mask = 0;
 
+       /* disable explicit missing arguments error output from getopt_long */
+       opterr = 0;
+
        while (1) {
                int option_index = 0, c;
                static struct option long_options[] = {
@@ -1176,6 +1179,18 @@ static void handle_options(int argc, char** argv)
                case 'e':
                        log_set_log_level(stderr_target, atoi(optarg));
                        break;
+               case '?':
+                       if (optopt) {
+                               printf("ERROR: missing mandatory argument "
+                                      "for `%s' option\n", argv[optind-1]);
+                       } else {
+                               printf("ERROR: unknown option `%s'\n",
+                                       argv[optind-1]);
+                       }
+                       print_usage();
+                       print_help();
+                       exit(EXIT_FAILURE);
+                       break;
                default:
                        /* ignore */
                        break;
-- 
1.7.2.3