This was suggested by deraadt@, sorry.
On Thu, Nov 08, 2018 at 08:05:13PM -0500, Bryan Steele wrote:
> These libc functions are used to map hardware MAC addresses to hostnames
> and vice versa. If it exists, /etc/ethers will typically contain a
> number of lines like so:
>
> 34:00:8a:56:10:20 superman
>
> In addition to that, there is support for using a YP (nee Yellow Pee)
> lookup service:
>
> "If a '+' appears alone on a line in the file, then ether_hostton() will
> consult the x ethers.byname YP map, and ether_ntohost() will consult the
> ethers.byaddr YP map."
>
> This support currently interferes with my work to reduce the pledge(2)
> in tcpdump(8), as the "inet" promise is required to perform these
> lookups..
>
> I've come up with small a diff to remove it, but it was suggested there
> may be some interactions with ldap, and I'm not sure how important this
> functionality may be to existing YP users (I am not one).
>
> Any objections to this approach? (Missing man page removal bits)
>
> -Bryan.
>
> Index: ethers.c
> ===================================================================
> RCS file: /cvs/src/lib/libc/net/ethers.c,v
> retrieving revision 1.25
> diff -u -p -u -r1.25 ethers.c
> --- lib/libc/net/ethers.c 21 Sep 2016 04:38:56 -0000 1.25
> +++ lib/libc/net/ethers.c 8 Nov 2018 23:54:19 -0000
> @@ -34,9 +34,6 @@
> #include <string.h>
> #include <ctype.h>
> #include <limits.h>
> -#ifdef YP
> -#include <rpcsvc/ypclnt.h>
> -#endif
>
> #ifndef _PATH_ETHERS
> #define _PATH_ETHERS "/etc/ethers"
> @@ -99,18 +96,6 @@ ether_ntohost(char *hostname, struct eth
> char buf[BUFSIZ+1], *p;
> size_t len;
> struct ether_addr try;
> -#ifdef YP
> - char trybuf[sizeof("xx:xx:xx:xx:xx:xx")];
> - int trylen;
> -#endif
> -
> -#ifdef YP
> - snprintf(trybuf, sizeof trybuf, "%x:%x:%x:%x:%x:%x",
> - e->ether_addr_octet[0], e->ether_addr_octet[1],
> - e->ether_addr_octet[2], e->ether_addr_octet[3],
> - e->ether_addr_octet[4], e->ether_addr_octet[5]);
> - trylen = strlen(trybuf);
> -#endif
>
> f = fopen(_PATH_ETHERS, "re");
> if (f == NULL)
> @@ -123,26 +108,9 @@ ether_ntohost(char *hostname, struct eth
> (void)memcpy(buf, p, len);
> buf[len] = '\n'; /* code assumes newlines later on */
> buf[len+1] = '\0';
> -#ifdef YP
> - /* A + in the file means try YP now. */
> - if (!strncmp(buf, "+\n", sizeof(buf))) {
> - char *ypbuf, *ypdom;
> - int ypbuflen;
> -
> - if (yp_get_default_domain(&ypdom))
> - continue;
> - if (yp_match(ypdom, "ethers.byaddr", trybuf,
> - trylen, &ypbuf, &ypbuflen))
> - continue;
> - if (ether_line(ypbuf, &try, hostname) == 0) {
> - free(ypbuf);
> - (void)fclose(f);
> - return (0);
> - }
> - free(ypbuf);
> + /* A + in the file meant try YP, ignore it. */
> + if (!strncmp(buf, "+\n", sizeof(buf)))
> continue;
> - }
> -#endif
> if (ether_line(buf, &try, hostname) == 0 &&
> memcmp(&try, e, sizeof(try)) == 0) {
> (void)fclose(f);
> @@ -161,9 +129,6 @@ ether_hostton(const char *hostname, stru
> char buf[BUFSIZ+1], *p;
> char try[HOST_NAME_MAX+1];
> size_t len;
> -#ifdef YP
> - int hostlen = strlen(hostname);
> -#endif
>
> f = fopen(_PATH_ETHERS, "re");
> if (f==NULL)
> @@ -177,26 +142,9 @@ ether_hostton(const char *hostname, stru
> memcpy(buf, p, len);
> buf[len] = '\n'; /* code assumes newlines later on */
> buf[len+1] = '\0';
> -#ifdef YP
> - /* A + in the file means try YP now. */
> - if (!strncmp(buf, "+\n", sizeof(buf))) {
> - char *ypbuf, *ypdom;
> - int ypbuflen;
> -
> - if (yp_get_default_domain(&ypdom))
> - continue;
> - if (yp_match(ypdom, "ethers.byname", hostname, hostlen,
> - &ypbuf, &ypbuflen))
> - continue;
> - if (ether_line(ypbuf, e, try) == 0) {
> - free(ypbuf);
> - (void)fclose(f);
> - return (0);
> - }
> - free(ypbuf);
> + /* A + in the file meant try YP, ignore it. */
> + if (!strncmp(buf, "+\n", sizeof(buf)))
> continue;
> - }
> -#endif
> if (ether_line(buf, e, try) == 0 && strcmp(hostname, try) == 0)
> {
> (void)fclose(f);
> return (0);
