ndp: Use warn(3)

[Klemens Nanni]

All of these fprintf(3) to standard error (with exit(3) afterwards) can
be simplified.

OK?

Index: ndp.c
===================================================================
RCS file: /cvs/src/usr.sbin/ndp/ndp.c,v
retrieving revision 1.93
diff -u -p -r1.93 ndp.c
--- ndp.c       28 Jun 2019 13:32:49 -0000      1.93
+++ ndp.c       22 Aug 2019 18:33:38 -0000
@@ -257,8 +257,7 @@ file(char *name)
        char line[100], arg[5][50], *args[5];
 
        if ((fp = fopen(name, "r")) == NULL) {
-               fprintf(stderr, "ndp: cannot open %s\n", name);
-               exit(1);
+               err(1, "cannot open %s", name);
        }
        args[0] = &arg[0][0];
        args[1] = &arg[1][0];
@@ -270,7 +269,7 @@ file(char *name)
                i = sscanf(line, "%49s %49s %49s %49s %49s",
                    arg[0], arg[1], arg[2], arg[3], arg[4]);
                if (i < 2) {
-                       fprintf(stderr, "ndp: bad line: %s\n", line);
+                       warnx("bad line: %s", line);
                        retval = 1;
                        continue;
                }
@@ -333,8 +332,7 @@ set(int argc, char **argv)
        hints.ai_family = AF_INET6;
        gai_error = getaddrinfo(host, NULL, &hints, &res);
        if (gai_error) {
-               fprintf(stderr, "ndp: %s: %s\n", host,
-                       gai_strerror(gai_error));
+               warnx("%s: %s", host, gai_strerror(gai_error));
                return 1;
        }
        sin->sin6_addr = ((struct sockaddr_in6 *)res->ai_addr)->sin6_addr;
@@ -379,7 +377,7 @@ set(int argc, char **argv)
                /*
                 * IPv4 arp command retries with sin_other = SIN_PROXY here.
                 */
-               fprintf(stderr, "set: cannot configure a new entry\n");
+               warnx("set: cannot configure a new entry");
                return 1;
        }
 
@@ -408,8 +406,7 @@ get(char *host)
        hints.ai_family = AF_INET6;
        gai_error = getaddrinfo(host, NULL, &hints, &res);
        if (gai_error) {
-               fprintf(stderr, "ndp: %s: %s\n", host,
-                   gai_strerror(gai_error));
+               warnx("%s: %s", host, gai_strerror(gai_error));
                return;
        }
        sin->sin6_addr = ((struct sockaddr_in6 *)res->ai_addr)->sin6_addr;
@@ -451,8 +448,7 @@ delete(char *host)
                hints.ai_flags = AI_NUMERICHOST;
        gai_error = getaddrinfo(host, NULL, &hints, &res);
        if (gai_error) {
-               fprintf(stderr, "ndp: %s: %s\n", host,
-                   gai_strerror(gai_error));
+               warnx("%s: %s", host, gai_strerror(gai_error));
                return 1;
        }
        sin->sin6_addr = ((struct sockaddr_in6 *)res->ai_addr)->sin6_addr;
@@ -478,7 +474,7 @@ delete(char *host)
                /*
                 * IPv4 arp command retries with sin_other = SIN_PROXY here.
                 */
-               fprintf(stderr, "delete: cannot delete non-NDP entry\n");
+               warnx("delete: cannot delete non-NDP entry");
                return 1;
        }
 
@@ -741,7 +737,7 @@ ndp_ether_aton(char *a, u_char *n)
        i = sscanf(a, "%x:%x:%x:%x:%x:%x", &o[0], &o[1], &o[2],
            &o[3], &o[4], &o[5]);
        if (i != 6) {
-               fprintf(stderr, "ndp: invalid Ethernet address '%s'\n", a);
+               warnx("invalid Ethernet address '%s'", a);
                return (1);
        }
        for (i = 0; i < 6; i++)
@@ -778,8 +774,7 @@ rtmsg(int cmd)
 
        switch (cmd) {
        default:
-               fprintf(stderr, "ndp: internal wrong cmd\n");
-               exit(1);
+               errx(1, "internal wrong cmd");
        case RTM_ADD:
                rtm->rtm_addrs |= RTA_GATEWAY;
                if (expire_time) {
@@ -825,8 +820,7 @@ doit:
        } while (l > 0 && (rtm->rtm_version != RTM_VERSION ||
            rtm->rtm_seq != seq || rtm->rtm_pid != pid));
        if (l == -1)
-               (void) fprintf(stderr, "ndp: read from routing socket: %s\n",
-                   strerror(errno));
+               warn("read from routing socket");
        return (0);
 }