1 files changed, 74 insertions, 0 deletions
diff --git a/libc/inet/hostid.c b/libc/inet/hostid.c
new file mode 100644
index 000000000..475eaf497
--- /dev/null
+++ b/libc/inet/hostid.c
@@ -0,0 +1,74 @@
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+#include <sys/param.h>
+#include <netinet/in.h>
+#include <netdb.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+
+#define HOSTID "/etc/hostid"
+
+int sethostid(long int new_id)
+{
+	int fd;
+	int ret;
+
+	if (geteuid() || getuid()) return errno=EPERM;
+	if ((fd=open(HOSTID,O_CREAT|O_WRONLY,0644))<0) return -1;
+	ret = write(fd,(void *)&new_id,sizeof(new_id)) == sizeof(new_id)
+		? 0 : -1;
+	close (fd);
+	return ret;
+}
+
+long int gethostid(void)
+{
+        char host[MAXHOSTNAMELEN + 1];
+	int fd, id;
+
+	/* If hostid was already set the we can return that value.
+	 * It is not an error if we cannot read this file. It is not even an
+	 * error if we cannot read all the bytes, we just carry on trying...
+	 */
+	if ((fd=open(HOSTID,O_RDONLY))>=0 && read(fd,(void *)&id,sizeof(id)))
+	{
+		close (fd);
+		return id;
+	}
+	if (fd >= 0) close (fd);
+
+	/* Try some methods of returning a unique 32 bit id. Clearly IP
+	 * numbers, if on the internet, will have a unique address. If they
+	 * are not on the internet then we can return 0 which means they should
+	 * really set this number via a sethostid() call. If their hostname
+	 * returns the loopback number (i.e. if they have put their hostname
+	 * in the /etc/hosts file with 127.0.0.1) then all such hosts will
+	 * have a non-unique hostid, but it doesn't matter anyway and
+	 * gethostid() will return a non zero number without the need for
+	 * setting one anyway.
+	 *						Mitch
+	 */
+	if (gethostname(host,MAXHOSTNAMELEN)>=0 && *host) {
+		struct hostent *hp;
+		struct in_addr in;
+
+		if ((hp = gethostbyname(host)) == (struct hostent *)NULL)
+
+		/* This is not a error if we get here, as all it means is that
+		 * this host is not on a network and/or they have not
+		 * configured their network properly. So we return the unset
+		 * hostid which should be 0, meaning that they should set it !!
+		 */
+			return 0;
+		else {
+			memcpy((char *) &in, (char *) hp->h_addr, hp->h_length);
+
+			/* Just so it doesn't look exactly like the IP addr */
+			return(in.s_addr<<16|in.s_addr>>16);
+		}
+	}
+	else return 0;
+
+}