libbb: new option FEATURE_ETC_SERVICES: if off, /etc/services reads often avoided

In practice, "wget http://host.com/" always uses port 80.
People explicitly set non-standard ports via options or parameters
("telnet 1.2.3.4 567" or "telnet 1.2.3.4 ftp") instead of modifying
/etc/services.

function                                             old     new   delta
telnet_main                                         1466    1464      -2
rdate_main                                           215     198     -17
fakeidentd_main                                      269     252     -17
parse_url                                            459     392     -67
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 0/4 up/down: 0/-103)           Total: -103 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

3 files changed, 7 insertions, 6 deletions

diff --git a/networking/isrv_identd.c b/networking/isrv_identd.c
index 133d62a65..0c33dde4f 100644
--- a/networking/isrv_identd.c
+++ b/networking/isrv_identd.c
@@ -159,7 +159,7 @@ int fakeidentd_main(int argc UNUSED_PARAM, char **argv)
 	fd = 0;
 	if (!(opt & OPT_inetdwait)) {
 		fd = create_and_bind_stream_or_die(bind_address,
-				bb_lookup_port("identd", "tcp", 113));
+				bb_lookup_std_port("identd", "tcp", 113));
 		xlisten(fd, 5);
 	}
 
diff --git a/networking/telnet.c b/networking/telnet.c
index 15d6a08d8..1e6be85bd 100644
--- a/networking/telnet.c
+++ b/networking/telnet.c
@@ -643,7 +643,8 @@ int telnet_main(int argc UNUSED_PARAM, char **argv)
 	if (!*argv)
 		bb_show_usage();
 	host = *argv++;
-	port = bb_lookup_port(*argv ? *argv++ : "telnet", "tcp", 23);
+	port = *argv ? bb_lookup_port(*argv++, "tcp", 23)
+		: bb_lookup_std_port("telnet", "tcp", 23);
 	if (*argv) /* extra params?? */
 		bb_show_usage();
 
diff --git a/networking/wget.c b/networking/wget.c
index 2650b5384..b6c76e9dc 100644
--- a/networking/wget.c
+++ b/networking/wget.c
@@ -505,23 +505,23 @@ static void parse_url(const char *src_url, struct host_info *h)
 		*p = '\0';
 		h->host = p + 3;
 		if (strcmp(url, P_FTP) == 0) {
-			h->port = bb_lookup_port(P_FTP, "tcp", 21);
+			h->port = bb_lookup_std_port(P_FTP, "tcp", 21);
 		} else
 #if SSL_SUPPORTED
 # if ENABLE_FEATURE_WGET_HTTPS
 		if (strcmp(url, P_FTPS) == 0) {
-			h->port = bb_lookup_port(P_FTPS, "tcp", 990);
+			h->port = bb_lookup_std_port(P_FTPS, "tcp", 990);
 			h->protocol = P_FTPS;
 		} else
 # endif
 		if (strcmp(url, P_HTTPS) == 0) {
-			h->port = bb_lookup_port(P_HTTPS, "tcp", 443);
+			h->port = bb_lookup_std_port(P_HTTPS, "tcp", 443);
 			h->protocol = P_HTTPS;
 		} else
 #endif
 		if (strcmp(url, P_HTTP) == 0) {
  http:
-			h->port = bb_lookup_port(P_HTTP, "tcp", 80);
+			h->port = bb_lookup_std_port(P_HTTP, "tcp", 80);
 			h->protocol = P_HTTP;
 		} else {
 			*p = ':';