Fix ping build on the FreeBSD

- Define iphdr structure to build busybox/ping
- Add missing includes

Signed-off-by: Alex Samorukov <samm@os2.kiev.ua>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

networking/ping.c

@@ -122,6 +122,10 @@
 //usage:       "round-trip min/avg/max = 20.1/20.1/20.1 ms\n"
 
 #include <net/if.h>
+#if defined(__FreeBSD__)
+# include <netinet/in.h> /* struct ip and friends */
+# include <netinet/ip.h>
+#endif
 #include <netinet/ip_icmp.h>
 #include "libbb.h"
 #include "common_bufsiz.h"
@@ -160,6 +164,40 @@
 # endif
 #endif
 
+#if defined(__FreeBSD__)
+/**
+ * On BSD the IPv4 struct is called struct ip and instead of iXX
+ * the members are called ip_XX. One could change this code to use
+ * struct ip but that would require to define _BSD_SOURCE and that
+ * might have other complications. Instead make sure struct iphdr
+ * is present on FreeBSD. The below is taken from GLIBC.
+ *
+ * The GNU C Library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ */
+struct iphdr {
+# if BYTE_ORDER == LITTLE_ENDIAN
+	unsigned int ihl:4;
+	unsigned int version:4;
+# elif BYTE_ORDER == BIG_ENDIAN
+	unsigned int version:4;
+	unsigned int ihl:4;
+# endif
+	uint8_t  tos;
+	uint16_t tot_len;
+	uint16_t id;
+	uint16_t frag_off;
+	uint8_t  ttl;
+	uint8_t  protocol;
+	uint16_t check;
+	uint32_t saddr;
+	uint32_t daddr;
+	/*The options start here. */
+};
+#endif
+
 enum {
 	DEFDATALEN = 56,
 	MAXIPLEN = 60,