ensure parsing numeric address before any host query.

Inspired by:	NetBSD

1 files changed, 126 insertions, 13 deletions

diff --git a/lib/libc/net/gethostnamadr.c b/lib/libc/net/gethostnamadr.c
index f5c3382..2409502 100644
--- a/lib/libc/net/gethostnamadr.c
+++ b/lib/libc/net/gethostnamadr.c
@@ -34,6 +34,7 @@ __FBSDID("$FreeBSD$");
 #include <netdb.h>
 #include <stdio.h>
 #include <ctype.h>
+#include <errno.h>
 #include <string.h>
 #include <stdarg.h>
 #include <nsswitch.h>
@@ -47,9 +48,12 @@ extern int _nis_gethostbyname(void *, void *, va_list);
 extern int _ht_gethostbyaddr(void *, void *, va_list);
 extern int _dns_gethostbyaddr(void *, void *, va_list);
 extern int _nis_gethostbyaddr(void *, void *, va_list);
+extern const char *_res_hostalias(const char *, char *, size_t);
+
+static struct hostent *gethostbyname_internal(const char *, int);
 
 /* Host lookup order if nsswitch.conf is broken or nonexistant */
-static const ns_src default_src[] = { 
+static const ns_src default_src[] = {
 	{ NSSRC_FILES, NS_SUCCESS },
 	{ NSSRC_DNS, NS_SUCCESS },
 	{ 0 }
@@ -62,31 +66,140 @@ gethostbyname(const char *name)
 
 	if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
 		h_errno = NETDB_INTERNAL;
-		return (NULL);
+		return NULL;
+	}
+	if (_res.options & RES_USE_INET6) {
+		hp = gethostbyname_internal(name, AF_INET6);
+		if (hp)
+			return hp;
 	}
-	if (_res.options & RES_USE_INET6) {		/* XXX */
-		hp = gethostbyname2(name, AF_INET6);	/* XXX */
-		if (hp)					/* XXX */
-			return (hp);			/* XXX */
-	}						/* XXX */
-	return (gethostbyname2(name, AF_INET));
+	return gethostbyname_internal(name, AF_INET);
 }
 
 struct hostent *
-gethostbyname2(const char *name, int type)
+gethostbyname2(const char *name, int af)
+{
+	if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
+		h_errno = NETDB_INTERNAL;
+		return NULL;
+	}
+	return gethostbyname_internal(name, af);
+}
+
+static struct hostent *
+gethostbyname_internal(const char *name, int af)
 {
+	const char *cp;
+	char *bp, *ep;
 	struct hostent *hp = 0;
-	int rval;
+	int size, rval;
+	char abuf[MAXDNAME];
 
+	static struct hostent host;
+	static char *h_addr_ptrs[2];
+	static char *host_aliases[1];
+	static char hostbuf[MAXDNAME + IN6ADDRSZ + sizeof(uint32_t)];
+	static uint32_t host_addr[4];	/* IPv4 or IPv6 */
 	static const ns_dtab dtab[] = {
 		NS_FILES_CB(_ht_gethostbyname, NULL)
 		{ NSSRC_DNS, _dns_gethostbyname, NULL },
 		NS_NIS_CB(_nis_gethostbyname, NULL) /* force -DHESIOD */
 		{ 0 }
-	};       
-	
+	};
+
+	switch (af) {
+	case AF_INET:
+		size = INADDRSZ;
+		break;
+	case AF_INET6:
+		size = IN6ADDRSZ;
+		break;
+	default:
+		h_errno = NETDB_INTERNAL;
+		errno = EAFNOSUPPORT;
+		return NULL;
+	}
+
+	host.h_addrtype = af;
+	host.h_length = size;
+
+	/*
+	 * if there aren't any dots, it could be a user-level alias.
+	 * this is also done in res_query() since we are not the only
+	 * function that looks up host names.
+	 */
+	if (!strchr(name, '.') &&
+	    (cp = _res_hostalias(name, abuf, sizeof abuf)))
+		name = cp;
+
+	/*
+	 * disallow names consisting only of digits/dots, unless
+	 * they end in a dot.
+	 */
+	if (isdigit((u_char)name[0]))
+		for (cp = name;; ++cp) {
+			if (!*cp) {
+				if (*--cp == '.')
+					break;
+				/*
+				 * All-numeric, no dot at the end.
+				 * Fake up a hostent as if we'd actually
+				 * done a lookup.
+				 */
+				if (inet_pton(af, name, host_addr) <= 0) {
+					h_errno = HOST_NOT_FOUND;
+					return NULL;
+				}
+				strncpy(hostbuf, name, MAXDNAME);
+				hostbuf[MAXDNAME] = '\0';
+				bp = hostbuf + MAXDNAME;
+				ep = hostbuf + sizeof hostbuf;
+				host.h_name = hostbuf;
+				host.h_aliases = host_aliases;
+				host_aliases[0] = NULL;
+				h_addr_ptrs[0] = (char *)host_addr;
+				h_addr_ptrs[1] = NULL;
+				host.h_addr_list = h_addr_ptrs;
+				if (_res.options & RES_USE_INET6)
+					_map_v4v6_hostent(&host, &bp, &ep);
+				h_errno = NETDB_SUCCESS;
+				return &host;
+			}
+			if (!isdigit((u_char)*cp) && *cp != '.')
+				break;
+		}
+	if ((isxdigit((u_char)name[0]) && strchr(name, ':') != NULL) ||
+	    name[0] == ':')
+		for (cp = name;; ++cp) {
+			if (!*cp) {
+				if (*--cp == '.')
+					break;
+				/*
+				 * All-IPv6-legal, no dot at the end.
+				 * Fake up a hostent as if we'd actually
+				 * done a lookup.
+				 */
+				if (inet_pton(af, name, host_addr) <= 0) {
+					h_errno = HOST_NOT_FOUND;
+					return NULL;
+				}
+				strncpy(hostbuf, name, MAXDNAME);
+				hostbuf[MAXDNAME] = '\0';
+				host.h_name = hostbuf;
+				host.h_aliases = host_aliases;
+				host_aliases[0] = NULL;
+				h_addr_ptrs[0] = (char *)host_addr;
+				h_addr_ptrs[1] = NULL;
+				host.h_addr_list = h_addr_ptrs;
+				h_errno = NETDB_SUCCESS;
+				return &host;
+			}
+			if (!isxdigit((u_char)*cp) && *cp != ':' && *cp != '.')
+				break;
+		}
+
 	rval = _nsdispatch((void *)&hp, dtab, NSDB_HOSTS, "gethostbyname",
-			  default_src, name, type);
+	    default_src, name, af);
 
 	if (rval != NS_SUCCESS)
 		return NULL;