add "resolveip", a small DNS lookup utility for use in scripts (#4876)

SVN-Revision: 27666

package/resolveip/Makefile

@@ -0,0 +1,44 @@
+#
+# Copyright (C) 2011 OpenWrt.org
+#
+# This is free software, licensed under the GNU General Public License v2.
+# See /LICENSE for more information.
+#
+
+include $(TOPDIR)/rules.mk
+
+PKG_NAME:=resolveip
+PKG_RELEASE:=1
+
+include $(INCLUDE_DIR)/package.mk
+
+define Package/resolveip
+  SECTION:=utils
+  CATEGORY:=Base system
+  TITLE:=Simple DNS resolver with configurable timeout
+endef
+
+define Package/resolveip/description
+ This package contains the small resolveip utility which
+ can be used by scripts to turn host names into numeric
+ IP addresses. It supports IPv4 and IPv6 resolving and
+ has a configurable timeout to guarantee a certain maximum
+ runtime in case of slow or defunct DNS servers.
+endef
+
+define Build/Prepare
+	$(INSTALL_DIR) $(PKG_BUILD_DIR)
+	$(INSTALL_DATA) ./src/resolveip.c $(PKG_BUILD_DIR)/
+endef
+
+define Build/Compile
+	$(TARGET_CC) $(TARGET_CFLAGS) -Wall \
+		-o $(PKG_BUILD_DIR)/resolveip $(PKG_BUILD_DIR)/resolveip.c
+endef
+
+define Package/resolveip/install
+	$(INSTALL_DIR) $(1)/usr/bin
+	$(INSTALL_BIN) $(PKG_BUILD_DIR)/resolveip $(1)/usr/bin/
+endef
+
+$(eval $(call BuildPackage,resolveip))

package/resolveip/src/resolveip.c

@@ -0,0 +1,98 @@
+/*
+ * Based on code found at https://dev.openwrt.org/ticket/4876 .
+ * Extended by Jo-Philipp Wich <jow@openwrt.org> for use in OpenWrt.
+ *
+ * You may use this program under the terms of the GPLv2 license.
+ */
+
+#include <string.h>
+#include <stdio.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netdb.h>
+#include <arpa/inet.h>
+#include <netinet/in.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <signal.h>
+
+
+static void abort_query(int sig)
+{
+	exit(1);
+}
+
+static void show_usage(void)
+{
+	printf("Usage:\n");
+	printf("	resolveip -h\n");
+	printf("	resolveip [-t timeout] hostname\n");
+	printf("	resolveip -4 [-t timeout] hostname\n");
+	printf("	resolveip -6 [-t timeout] hostname\n");
+	exit(255);
+}
+
+int main(int argc, char **argv)
+{
+	int timeout = 3;
+	char opt;
+    char ipaddr[INET6_ADDRSTRLEN];
+    void *addr;
+    struct addrinfo *res, *rp;
+	struct sigaction sa = {	.sa_handler = &abort_query };
+    struct addrinfo hints = {
+    	.ai_family   = AF_UNSPEC,
+    	.ai_socktype = SOCK_STREAM,
+    	.ai_protocol = IPPROTO_TCP,
+    	.ai_flags    = 0
+    };
+
+	while ((opt = getopt(argc, argv, "46t:h")) > -1)
+	{
+		switch (opt)
+		{
+			case '4':
+				hints.ai_family = AF_INET;
+				break;
+
+			case '6':
+				hints.ai_family = AF_INET6;
+				break;
+
+			case 't':
+				timeout = atoi(optarg);
+				if (timeout <= 0)
+					show_usage();
+				break;
+
+			case 'h':
+				show_usage();
+				break;
+		}
+	}
+
+	if (!argv[optind])
+		show_usage();
+
+	sigaction(SIGALRM, &sa, NULL);
+	alarm(timeout);
+
+	if (getaddrinfo(argv[optind], NULL, &hints, &res))
+		exit(2);
+
+    for (rp = res; rp != NULL; rp = rp->ai_next)
+    {
+		addr = (rp->ai_family == AF_INET)
+			? (void *)&((struct sockaddr_in *)rp->ai_addr)->sin_addr
+			: (void *)&((struct sockaddr_in6 *)rp->ai_addr)->sin6_addr
+		;
+
+		if (!inet_ntop(rp->ai_family, addr, ipaddr, INET6_ADDRSTRLEN - 1))
+			exit(3);
+
+		printf("%s\n", ipaddr);
+	}
+
+	freeaddrinfo(res);
+	exit(0);
+}