DEV: udp: switch parser to getopt() instead of positional arguments

In order to ease addition of new types of perturbations to udp-perturb,
let's first switch to getopt() and get rid of the positional arguments.
The random seed was already a conditional option of the rate which was
a conditional option as well. We add -r and -s for the rate and the
seed, and new options will follow.

diff --git a/dev/udp/udp-perturb.c b/dev/udp/udp-perturb.c
index 824628d367a17fd661a314083b5f6f94dfc5a4ff..3df0f797f4bfc13caae350d23b5a59bf53371f8b 100644 (file)
--- a/dev/udp/udp-perturb.c
+++ b/dev/udp/udp-perturb.c
@@ -36,6 +36,7 @@
 #include <netdb.h>
 #include <fcntl.h>
 #include <errno.h>
+#include <getopt.h>
 #include <signal.h>
 #include <stdarg.h>
 #include <sys/stat.h>
@@ -409,31 +410,53 @@ int handle_bck(int fd, struct pollfd *pfd, struct conn *conns, int nbconn)
        return ret;
 }
 
+/* print the usage message for program named <name> and exit with status <status> */
+void usage(int status, const char *name)
+{
+       if (strchr(name, '/'))
+               name = strrchr(name, '/') + 1;
+       die(status,
+           "Usage: %s [-h] [options] [<laddr>:]<lport> [<saddr>:]<sport>\n"
+           "Options:\n"
+           "  -h           display this help\n"
+           "  -r rate      reorder/duplicate/lose around <rate>%% of packets\n"
+           "  -s seed      force initial random seed (currently %#x)\n"
+           "", name, prng_state);
+}
+
 int main(int argc, char **argv)
 {
        struct errmsg err;
        struct pollfd *pfd;
+       int opt;
        int i;
 
        err.len = 0;
        err.size = 100;
        err.msg = malloc(err.size);
 
-       if (argc < 3)
-               die(1, "Usage: %s [<laddr>:]<lport> [<saddr>:]<sport> [rand_rate%% [seed]]\n", argv[0]);
+       while ((opt = getopt(argc, argv, "hr:s:")) != -1) {
+               switch (opt) {
+               case 'r': // rand_rate%
+                       rand_rate = atoi(optarg);
+                       break;
+               case 's': // seed
+                       prng_state = atol(optarg);
+                       break;
+               default: // help, anything else
+                       usage(0, argv[0]);
+               }
+       }
+
+       if (argc - optind < 2)
+               usage(1, argv[0]);
 
-       if (addr_to_ss(argv[1], &frt_addr, &err) < 0)
+       if (addr_to_ss(argv[optind], &frt_addr, &err) < 0)
                die(1, "parsing listen address: %s\n", err.msg);
 
-       if (addr_to_ss(argv[2], &srv_addr, &err) < 0)
+       if (addr_to_ss(argv[optind+1], &srv_addr, &err) < 0)
                die(1, "parsing server address: %s\n", err.msg);
 
-       if (argc > 3)
-               rand_rate = atoi(argv[3]);
-
-       if (argc > 4)
-               prng_state = atol(argv[4]);
-
        pfd = calloc(sizeof(struct pollfd), MAXCONN + 1);
        if (!pfd)
                die(1, "out of memory\n");