Get rid of inet_aton(3).

inet_aton(3) is not a good interface to figure out if something looks
like an IP address and a reverse DNS lookup should be performed.

The modern way to do this is to chain getaddrinfo(3) with
getnameinfo(3). As a bonus this gives us reverse lookup for IPv6, too.

OK kn

diff --git a/usr.bin/w/w.c b/usr.bin/w/w.c
index c21c0b6..d5d5083 100644 (file)
--- a/usr.bin/w/w.c
+++ b/usr.bin/w/w.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: w.c,v 1.68 2022/12/04 23:50:50 cheloha Exp $  */
+/*     $OpenBSD: w.c,v 1.69 2024/08/19 07:28:22 florian Exp $  */
 
 /*-
  * Copyright (c) 1980, 1991, 1993, 1994
@@ -98,13 +98,13 @@ static void  pr_header(time_t *, int);
 static struct stat
                *ttystat(char *);
 static void     usage(int);
+static char    *hostlookup(char *, char *);
 
 int
 main(int argc, char *argv[])
 {
        extern char *__progname;
        struct kinfo_proc *kp;
-       struct hostent *hp;
        struct stat *stp;
        FILE *ut;
        struct in_addr addr;
@@ -295,29 +295,27 @@ main(int argc, char *argv[])
 
        for (ep = ehead; ep != NULL; ep = ep->next) {
                p = *ep->utmp.ut_host ? ep->utmp.ut_host : "-";
-               for (x = NULL, i = 0; p[i] != '\0' && i < UT_HOSTSIZE; i++)
+               for (x = NULL, i = 0; p[i] != '\0' && i < UT_HOSTSIZE; i++) {
                        if (p[i] == ':') {
                                x = &p[i];
                                *x++ = '\0';
                                break;
                        }
-               if (!nflag && inet_aton(p, &addr) &&
-                   (hp = gethostbyaddr((char *)&addr, sizeof(addr), AF_INET))) {
-                       if (domain[0] != '\0') {
-                               p = hp->h_name;
-                               p += strlen(hp->h_name);
-                               p -= strlen(domain);
-                               if (p > hp->h_name &&
-                                   strcasecmp(p, domain) == 0)
-                                       *p = '\0';
-                       }
-                       p = hp->h_name;
                }
+
                if (x) {
                        (void)snprintf(buf, sizeof(buf), "%s:%.*s", p,
                            (int)(ep->utmp.ut_host + UT_HOSTSIZE - x), x);
                        p = buf;
                }
+
+               if (!nflag) {
+                       char *tmp;
+
+                       if ((tmp = hostlookup(p, domain)) != NULL)
+                               p = tmp;
+               }
+
                (void)printf("%-*.*s %-2.2s %-*.*s ",
                    NAME_WIDTH, UT_NAMESIZE, ep->utmp.ut_name,
                    strncmp(ep->utmp.ut_line, "tty", 3) ?
@@ -509,3 +507,32 @@ usage(int wcmd)
                    "usage: uptime\n");
        exit (1);
 }
+
+static char*
+hostlookup(char *host, char *domain)
+{
+       static char buf[NI_MAXHOST];
+       struct addrinfo hints, *res;
+       int error;
+       char *p;
+
+       memset(&hints, 0, sizeof(hints));
+       if (getaddrinfo(host, NULL, &hints, &res) != 0)
+               return NULL;
+
+       error = getnameinfo(res->ai_addr, res->ai_addr->sa_len, buf,
+           sizeof(buf), NULL, 0, 0);
+       freeaddrinfo(res);
+
+       if (error)
+               return NULL;
+
+       if (domain[0] != '\0') {
+               p = buf;
+               p += strlen(buf);
+               p -= strlen(domain);
+               if (p > buf && strcasecmp(p, domain) == 0)
+                       *p = '\0';
+       }
+       return buf;
+}