hostalias() is not thread-safe. So, introduce _res_hostalias()

and use it.

Obtained from:	BIND9

3 files changed, 29 insertions, 14 deletions

diff --git a/lib/libc/net/getaddrinfo.c b/lib/libc/net/getaddrinfo.c
index b695e58..8e7f566 100644
--- a/lib/libc/net/getaddrinfo.c
+++ b/lib/libc/net/getaddrinfo.c
@@ -2283,7 +2283,7 @@ _yp_getaddrinfo(rv, cb_data, ap)
 
 /* resolver logic */
 
-extern const char *__hostalias(const char *);
+extern const char *_res_hostalias(const char *, char *, size_t);
 
 /*
  * Formulate a normal query, send, and await answer.
@@ -2418,6 +2418,7 @@ res_searchN(name, target)
 	u_int dots;
 	int trailing_dot, ret, saved_herrno;
 	int got_nodata = 0, got_servfail = 0, tried_as_is = 0;
+	char abuf[MAXDNAME];
 
 	if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
 		h_errno = NETDB_INTERNAL;
@@ -2436,7 +2437,7 @@ res_searchN(name, target)
 	/*
 	 * if there aren't any dots, it could be a user-level alias
 	 */
-	if (!dots && (cp = __hostalias(name)) != NULL)
+	if (!dots && (cp = _res_hostalias(name, abuf, sizeof(abuf))) != NULL)
 		return (res_queryN(cp, target));
 
 	/*
diff --git a/lib/libc/net/gethostbydns.c b/lib/libc/net/gethostbydns.c
index 7dc405d..24de7ff 100644
--- a/lib/libc/net/gethostbydns.c
+++ b/lib/libc/net/gethostbydns.c
@@ -96,6 +96,8 @@ static char *host_aliases[MAXALIASES];
 static char hostbuf[8*1024];
 static u_char host_addr[16];	/* IPv4 or IPv6 */
 
+extern const char *_res_hostalias(const char *, char *, size_t);
+
 #ifdef RESOLVSORT
 static void addrsort(char **, int);
 #endif
@@ -477,6 +479,7 @@ _dns_gethostbyname(void *rval, void *cb_data, va_list ap)
 	const char *cp;
 	char *bp, *ep;
 	int n, size, type, len;
+	char abuf[MAXDNAME];
 
 	name = va_arg(ap, const char *);
 	af = va_arg(ap, int);
@@ -510,7 +513,8 @@ _dns_gethostbyname(void *rval, void *cb_data, va_list ap)
 	 * this is also done in res_query() since we are not the only
 	 * function that looks up host names.
 	 */
-	if (!strchr(name, '.') && (cp = __hostalias(name)))
+	if (!strchr(name, '.') &&
+	    (cp = _res_hostalias(name, abuf, sizeof abuf)))
 		name = cp;
 
 	/*
diff --git a/lib/libc/net/res_query.c b/lib/libc/net/res_query.c
index 68ac05c..4158f98 100644
--- a/lib/libc/net/res_query.c
+++ b/lib/libc/net/res_query.c
@@ -97,6 +97,8 @@ __FBSDID("$FreeBSD$");
 #define MAXPACKET	1024
 #endif
 
+const char *_res_hostalias(const char *, char *, size_t);
+
 /*
  * Formulate a normal query, send, and await answer.
  * Returned answer is placed in supplied buffer "answer".
@@ -193,6 +195,7 @@ res_search(name, class, type, answer, anslen)
 	int anslen;		/* size of answer */
 {
 	const char *cp, * const *domain;
+	char tmp[MAXDNAME];
 	u_int dots;
 	int trailing_dot, ret, saved_herrno;
 	int got_nodata = 0, got_servfail = 0, tried_as_is = 0;
@@ -211,7 +214,7 @@ res_search(name, class, type, answer, anslen)
 		trailing_dot++;
 
 	/* If there aren't any dots, it could be a user-level alias */
-	if (!dots && (cp = hostalias(name)) != NULL)
+	if (!dots && (cp = _res_hostalias(name, tmp, sizeof tmp)) != NULL)
 		return (res_query(cp, class, type, answer, anslen));
 
 	/*
@@ -384,14 +387,11 @@ res_querydomain(name, domain, class, type, answer, anslen)
 }
 
 const char *
-hostalias(name)
-	const char *name;
+_res_hostalias(const char *name, char *dst, size_t siz)
 {
-	char *cp1, *cp2;
-	FILE *fp;
-	char *file;
+	char *file, *cp1, *cp2;
 	char buf[BUFSIZ];
-	static char abuf[MAXDNAME];
+	FILE *fp;
 
 	if (_res.options & RES_NOALIASES)
 		return (NULL);
@@ -413,18 +413,28 @@ hostalias(name)
 				;
 			if (!*cp1)
 				break;
-			for (cp2 = cp1 + 1; *cp2 && !isspace((unsigned char)*cp2); ++cp2)
+			for (cp2 = cp1 + 1; *cp2 &&
+			     !isspace((unsigned char)*cp2); ++cp2)
 				;
-			abuf[sizeof(abuf) - 1] = *cp2 = '\0';
-			strncpy(abuf, cp1, sizeof(abuf) - 1);
+			*cp2 = '\0';
+			strncpy(dst, cp1, siz - 1);
+			dst[siz - 1] = '\0';
 			fclose(fp);
-			return (abuf);
+			return (dst);
 		}
 	}
 	fclose(fp);
 	return (NULL);
 }
 
+const char *
+hostalias(const char *name)
+{
+	static char abuf[MAXDNAME];
+
+	return (_res_hostalias(name, abuf, sizeof abuf));
+}
+
 /*
  * Weak aliases for applications that use certain private entry points,
  * and fail to include <resolv.h>.