Improve NIS performace of getservbyname() and getservbyport(). Both these

functions are implimented as wrappers around getservent(), which means it's
up to getservent() to do all the work. The NIS support in getservent()
only allows it to scan through the services.byname map one entry at a
time until it finds the requested service name/port. This can be painfully
slow due to the overhead involved (lots and lots of successive RPCs).

To fix this, we allow getservbyname() and getservbyport() to signal
getservent() that if NIS is turned on (there's a '+' in /etc/services),
the usual yp_first()/yp_next() linear search should be abandoned and
yp_match() used instead. This causes getservent() to immediately
locate the requested entry instead of wasting time groping through the
whole map.

The downside is that this trick is accomplished by exporting a couple of
pointers from getservent.c which getservbyname.c and getservbyport.c can
preset in order to tell getservent() what to do. If all three functions
were in the same source module, then the extra cruft could be delcared
static to avoid poluting the global symbol space. Maybe they should be
combined anyway. For now I've settled on prepending lots of underscores.

1 files changed, 95 insertions, 7 deletions

diff --git a/lib/libc/net/getservent.c b/lib/libc/net/getservent.c
index 35e535a..6797b5a 100644
--- a/lib/libc/net/getservent.c
+++ b/lib/libc/net/getservent.c
@@ -57,13 +57,94 @@ static char *serv_aliases[MAXALIASES];
 int _serv_stayopen;
 
 #ifdef YP
+char *___getservbyname_yp = NULL;
+char *___getservbyproto_yp = NULL;
+int ___getservbyport_yp = 0;
+static char *yp_domain = NULL;
+
 static int
-_getypservent(line)
+_getservbyport_yp(line)
+	char *line;
+{
+	char *result;
+	int resultlen;
+	char buf[YPMAXRECORD];
+	int rv;
+
+	snprintf(buf, sizeof(buf), "%d/%s", ntohs(___getservbyport_yp),
+						___getservbyproto_yp);
+
+	___getservbyport_yp = 0;
+	___getservbyproto_yp = NULL;
+
+	if(!yp_domain) {
+		if(yp_get_default_domain(&yp_domain))
+			return (0);
+	}
+
+	/*
+	 * We have to be a little flexible here. Ideally you're supposed
+	 * to have both a services.byname and a services.byport map, but
+	 * some systems have only services.byname. FreeBSD cheats a little
+	 * by putting the services.byport information in the same map as
+	 * services.byname so that either case will work. We allow for both
+	 * possibilities here: if there is no services.byport map, we try
+	 * services.byname instead.
+	 */
+	if ((rv = yp_match(yp_domain, "services.byport", buf, strlen(buf),
+						&result, &resultlen))) {
+		if (rv == YPERR_MAP) {
+			if (yp_match(yp_domain, "services.byname", buf,
+					strlen(buf), &result, &resultlen))
+			return(0);
+		} else
+			return(0);
+	}
+		
+	/* getservent() expects lines terminated with \n -- make it happy */
+	snprintf(line, BUFSIZ, "%.*s\n", resultlen, result);
+
+	free(result);
+	return(1);
+}
+
+static int
+_getservbyname_yp(line)
+	char *line;
+{
+	char *result;
+	int resultlen;
+	char buf[YPMAXRECORD];
+
+	if(!yp_domain) {
+		if(yp_get_default_domain(&yp_domain))
+			return (0);
+	}
+
+	snprintf(buf, sizeof(buf), "%s/%s", ___getservbyname_yp,
+						___getservbyproto_yp);
+
+	___getservbyname_yp = 0;
+	___getservbyproto_yp = NULL;
+
+	if (yp_match(yp_domain, "services.byname", buf, strlen(buf),
+						&result, &resultlen)) {
+		return(0);
+	}
+		
+	/* getservent() expects lines terminated with \n -- make it happy */
+	snprintf(line, BUFSIZ, "%.*s\n", resultlen, result);
+
+	free(result);
+	return(1);
+}
+
+static int
+_getservent_yp(line)
 	char *line;
 {
 	static char *key = NULL;
 	static int keylen;
-	static char *yp_domain = NULL;
 	char *lastkey, *result;
 	int resultlen;
 	int rv;
@@ -93,9 +174,8 @@ _getypservent(line)
 		}
 	}
 
-	strncpy(line, result, BUFSIZ - 1);
 	/* getservent() expects lines terminated with \n -- make it happy */
-	strcat(line, "\n");
+	snprintf(line, BUFSIZ, "%.*s\n", resultlen, result);
 
 	free(result);
 
@@ -131,7 +211,7 @@ getservent()
 	register char *cp, **q;
 
 #ifdef YP
-	if (serv_stepping_yp && _getypservent(line)) {
+	if (serv_stepping_yp && _getservent_yp(line)) {
 		p = (char *)&line;
 		goto unpack;
 	}
@@ -143,8 +223,16 @@ again:
 	if ((p = fgets(line, BUFSIZ, servf)) == NULL)
 		return (NULL);
 #ifdef YP
-	if (*p == '+') {
-		if (!_getypservent(&line))
+	if (*p == '+' && _yp_check(NULL)) {
+		if (___getservbyname_yp != NULL) {
+			if (!_getservbyname_yp(&line))
+				goto tryagain;
+		} 
+		else if (___getservbyport_yp != 0) {
+			if (!_getservbyport_yp(&line))
+				goto tryagain;
+		}
+		else if (!_getservent_yp(&line))
 			goto tryagain;
 	}
 unpack: