+/*
+ * $Source: /mit/kerberos/src/lib/krb/RCS/mk_safe.c,v $
+ * $Author: jtkohl $
+ *
+ * Copyright 1986, 1987, 1988 by the Massachusetts Institute
+ * of Technology.
+ *
+ * For copying and distribution information, please see the file
+ * <mit-copyright.h>.
+ *
+ * This routine constructs a Kerberos 'safe msg', i.e. authenticated
+ * using a private session key to seed a checksum. Msg is NOT
+ * encrypted.
+ *
+ * Note-- bcopy is used to avoid alignment problems on IBM RT
+ *
+ * Returns either <0 ===> error, or resulting size of message
+ *
+ * Steve Miller Project Athena MIT/DEC
+ */
+
+#ifndef lint
+static char *rcsid_mk_safe_c=
+"$Header: mk_safe.c,v 4.12 89/03/22 14:50:49 jtkohl Exp $";
+#endif /* lint */
+
+#include <mit-copyright.h>
+
+/* system include files */
+#include <stdio.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <netinet/in.h>
+#include <sys/time.h>
+
+/* application include files */
+#include <des.h>
+#include <krb.h>
+#include <prot.h>
+#include "lsb_addr_comp.h"
+
+extern char *errmsg();
+extern int errno;
+extern int krb_debug;
+
+/* static storage */
+
+static u_long cksum;
+static C_Block big_cksum[2];
+static struct timeval msg_time;
+static u_char msg_time_5ms;
+static long msg_time_sec;
+
+/*
+ * krb_mk_safe() constructs an AUTH_MSG_SAFE message. It takes some
+ * user data "in" of "length" bytes and creates a packet in "out"
+ * consisting of the user data, a timestamp, and the sender's network
+ * address, followed by a checksum computed on the above, using the
+ * given "key". The length of the resulting packet is returned.
+ *
+ * The "out" packet consists of:
+ *
+ * Size Variable Field
+ * ---- -------- -----
+ *
+ * 1 byte KRB_PROT_VERSION protocol version number
+ * 1 byte AUTH_MSG_SAFE | message type plus local
+ * HOST_BYTE_ORDER byte order in low bit
+ *
+ * ===================== begin checksum ================================
+ *
+ * 4 bytes length length of user data
+ * length in user data
+ * 1 byte msg_time_5ms timestamp milliseconds
+ * 4 bytes sender->sin.addr.s_addr sender's IP address
+ *
+ * 4 bytes msg_time_sec or timestamp seconds with
+ * -msg_time_sec direction in sign bit
+ *
+ * ======================= end checksum ================================
+ *
+ * 16 bytes big_cksum quadratic checksum of
+ * above using "key"
+ */
+
+long krb_mk_safe(in,out,length,key,sender,receiver)
+ u_char *in; /* application data */
+ u_char *out; /*
+ * put msg here, leave room for header!
+ * breaks if in and out (header stuff)
+ * overlap
+ */
+ u_long length; /* of in data */
+ C_Block *key; /* encryption key for seed and ivec */
+ struct sockaddr_in *sender; /* sender address */
+ struct sockaddr_in *receiver; /* receiver address */
+{
+ register u_char *p,*q;
+
+ /*
+ * get the current time to use instead of a sequence #, since
+ * process lifetime may be shorter than the lifetime of a session
+ * key.
+ */
+ if (gettimeofday(&msg_time,(struct timezone *)0)) {
+ return -1;
+ }
+ msg_time_sec = (long) msg_time.tv_sec;
+ msg_time_5ms = msg_time.tv_usec/5000; /* 5ms quanta */
+
+ p = out;
+
+ *p++ = KRB_PROT_VERSION;
+ *p++ = AUTH_MSG_SAFE | HOST_BYTE_ORDER;
+
+ q = p; /* start for checksum stuff */
+ /* stuff input length */
+ bcopy((char *)&length,(char *)p,sizeof(length));
+ p += sizeof(length);
+
+ /* make all the stuff contiguous for checksum */
+ bcopy((char *)in,(char *)p,(int) length);
+ p += length;
+
+ /* stuff time 5ms */
+ bcopy((char *)&msg_time_5ms,(char *)p,sizeof(msg_time_5ms));
+ p += sizeof(msg_time_5ms);
+
+ /* stuff source address */
+ bcopy((char *) &sender->sin_addr.s_addr,(char *)p,
+ sizeof(sender->sin_addr.s_addr));
+ p += sizeof(sender->sin_addr.s_addr);
+
+ /*
+ * direction bit is the sign bit of the timestamp. Ok until
+ * 2038??
+ */
+ /* For compatibility with broken old code, compares are done in VAX
+ byte order (LSBFIRST) */
+ if (lsb_net_ulong_less(sender->sin_addr.s_addr, /* src < recv */
+ receiver->sin_addr.s_addr)==-1)
+ msg_time_sec = -msg_time_sec;
+ else if (lsb_net_ulong_less(sender->sin_addr.s_addr,
+ receiver->sin_addr.s_addr)==0)
+ if (lsb_net_ushort_less(sender->sin_port,receiver->sin_port) == -1)
+ msg_time_sec = -msg_time_sec;
+ /*
+ * all that for one tiny bit! Heaven help those that talk to
+ * themselves.
+ */
+
+ /* stuff time sec */
+ bcopy((char *)&msg_time_sec,(char *)p,sizeof(msg_time_sec));
+ p += sizeof(msg_time_sec);
+
+#ifdef NOENCRYPTION
+ cksum = 0;
+ bzero(big_cksum, sizeof(big_cksum));
+#else /* Do encryption */
+ /* calculate the checksum of length, timestamps, and input data */
+ cksum = quad_cksum(q,big_cksum,p-q,2,key);
+#endif /* NOENCRYPTION */
+ if (krb_debug)
+ printf("\ncksum = %u",cksum);
+
+ /* stuff checksum */
+ bcopy((char *)big_cksum,(char *)p,sizeof(big_cksum));
+ p += sizeof(big_cksum);
+
+ return ((long)(p - out)); /* resulting size */
+
+}
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