- djm@cvs.openbsd.org 2001/03/13 22:42:54

[openssh.git] / packet.c

diff --git a/packet.c b/packet.c
index 5213e43e898ffee60c39e7abbca46904553faaa8..1a634cff45e35b7af5e2517f59860040df446455 100644 (file)
--- a/packet.c
+++ b/packet.c
@@ -37,7 +37,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: packet.c,v 1.51 2001/02/12 22:56:09 deraadt Exp $");
+RCSID("$OpenBSD: packet.c,v 1.56 2001/03/03 21:41:07 millert Exp $");
 
 #include "xmalloc.h"
 #include "buffer.h"
@@ -389,7 +389,7 @@ packet_start2(int type)
 void
 packet_start(int type)
 {
-       DBG(debug("packet_start[%d]",type));
+       DBG(debug("packet_start[%d]", type));
        if (use_ssh2_packet_format)
                packet_start2(type);
        else
@@ -586,7 +586,7 @@ packet_send2(void)
                        if (i % 4 == 0)
                                rand = arc4random();
                        cp[i] = rand & 0xff;
-                       rand <<= 8;
+                       rand >>= 8;
                }
        } else {
                /* clear padding */
@@ -660,10 +660,13 @@ int
 packet_read(int *payload_len_ptr)
 {
        int type, len;
-       fd_set set;
+       fd_set *setp;
        char buf[8192];
        DBG(debug("packet_read()"));
 
+       setp = (fd_set *)xmalloc(howmany(connection_in+1, NFDBITS) *
+           sizeof(fd_mask));
+
        /* Since we are blocking, ensure that all written packets have been sent. */
        packet_write_wait();
 
@@ -678,17 +681,20 @@ packet_read(int *payload_len_ptr)
                    || type == SSH_CMSG_EXIT_CONFIRMATION))
                        packet_integrity_check(*payload_len_ptr, 0, type);
                /* If we got a packet, return it. */
-               if (type != SSH_MSG_NONE)
+               if (type != SSH_MSG_NONE) {
+                       xfree(setp);
                        return type;
+               }
                /*
                 * Otherwise, wait for some data to arrive, add it to the
                 * buffer, and try again.
                 */
-               FD_ZERO(&set);
-               FD_SET(connection_in, &set);
+               memset(setp, 0, howmany(connection_in + 1, NFDBITS) *
+                   sizeof(fd_mask));
+               FD_SET(connection_in, setp);
 
                /* Wait for some data to arrive. */
-               while (select(connection_in + 1, &set, NULL, NULL, NULL) == -1 &&
+               while (select(connection_in + 1, setp, NULL, NULL, NULL) == -1 &&
                    (errno == EAGAIN || errno == EINTR))
                        ;
 
@@ -942,7 +948,7 @@ packet_read_poll2(int *payload_len_ptr)
        }
 
 #ifdef PACKET_DEBUG
-       fprintf(stderr, "read/plain[%d]:\r\n",type);
+       fprintf(stderr, "read/plain[%d]:\r\n", type);
        buffer_dump(&incoming_packet);
 #endif
        return (u_char)type;
@@ -1194,17 +1200,21 @@ packet_write_poll()
 void
 packet_write_wait()
 {
+       fd_set *setp;
+
+       setp = (fd_set *)xmalloc(howmany(connection_out + 1, NFDBITS) *
+           sizeof(fd_mask));
        packet_write_poll();
        while (packet_have_data_to_write()) {
-               fd_set set;
-
-               FD_ZERO(&set);
-               FD_SET(connection_out, &set);
-               while (select(connection_out + 1, NULL, &set, NULL, NULL) == -1 &&
+               memset(setp, 0, howmany(connection_out + 1, NFDBITS) *
+                   sizeof(fd_mask));
+               FD_SET(connection_out, setp);
+               while (select(connection_out + 1, NULL, setp, NULL, NULL) == -1 &&
                    (errno == EAGAIN || errno == EINTR))
                        ;
                packet_write_poll();
        }
+       xfree(setp);
 }
 
 /* Returns true if there is buffered data to write to the connection. */
@@ -1305,3 +1315,65 @@ packet_set_maxsize(int s)
        max_packet_size = s;
        return s;
 }
+
+/*
+ * 9.2.  Ignored Data Message
+ * 
+ *   byte      SSH_MSG_IGNORE
+ *   string    data
+ * 
+ * All implementations MUST understand (and ignore) this message at any
+ * time (after receiving the protocol version). No implementation is
+ * required to send them. This message can be used as an additional
+ * protection measure against advanced traffic analysis techniques.
+ */
+/* size of current + ignore message should be n*sumlen bytes (w/o mac) */
+void
+packet_inject_ignore(int sumlen)
+{
+       int blocksize, padlen, have, need, nb, mini, nbytes;
+       Enc *enc = NULL;
+
+       if (use_ssh2_packet_format == 0)
+               return;
+
+       have = buffer_len(&outgoing_packet);
+       debug2("packet_inject_ignore: current %d", have);
+       if (kex != NULL)
+       enc  = &kex->enc[MODE_OUT];
+       blocksize = enc ? enc->cipher->block_size : 8;
+       padlen = blocksize - (have % blocksize);
+       if (padlen < 4)
+               padlen += blocksize;
+       have += padlen;
+       have /= blocksize;      /* # of blocks for current message */
+
+       nb   = roundup(sumlen,  blocksize) / blocksize; /* blocks for both */
+       mini = roundup(5+1+4+4, blocksize) / blocksize; /* minsize ignore msg */
+       need = nb - (have % nb);                        /* blocks for ignore */
+       if (need <= mini)
+               need += nb;
+       nbytes = (need - mini) * blocksize;     /* size of ignore payload */
+       debug2("packet_inject_ignore: block %d have %d nb %d mini %d need %d",
+           blocksize, have, nb, mini, need);
+
+       /* enqueue current message and append a ignore message */
+       packet_send();
+       packet_send_ignore(nbytes);
+}
+
+void
+packet_send_ignore(int nbytes)
+{
+       u_int32_t rand = 0;
+       int i;
+
+       packet_start(compat20 ? SSH2_MSG_IGNORE : SSH_MSG_IGNORE);
+       packet_put_int(nbytes);
+       for(i = 0; i < nbytes; i++) {
+               if (i % 4 == 0)
+                       rand = arc4random();
+               packet_put_char(rand & 0xff);
+               rand >>= 8;
+       }
+}