--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/common-session.c	Wed Mar 08 13:23:58 2006 +0000
@@ -0,0 +1,373 @@
+/*
+ * Dropbear - a SSH2 server
+ * 
+ * Copyright (c) 2002,2003 Matt Johnston
+ * All rights reserved.
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE. */
+
+#include "includes.h"
+#include "session.h"
+#include "dbutil.h"
+#include "packet.h"
+#include "algo.h"
+#include "buffer.h"
+#include "dss.h"
+#include "ssh.h"
+#include "random.h"
+#include "kex.h"
+#include "channel.h"
+#include "atomicio.h"
+
+static void checktimeouts();
+static int ident_readln(int fd, char* buf, int count);
+
+struct sshsession ses; /* GLOBAL */
+
+/* need to know if the session struct has been initialised, this way isn't the
+ * cleanest, but works OK */
+int sessinitdone = 0; /* GLOBAL */
+
+/* this is set when we get SIGINT or SIGTERM, the handler is in main.c */
+int exitflag = 0; /* GLOBAL */
+
+
+
+/* called only at the start of a session, set up initial state */
+void common_session_init(int sock, char* remotehost) {
+
+	TRACE(("enter session_init"))
+
+	ses.remotehost = remotehost;
+
+	ses.sock = sock;
+	ses.maxfd = sock;
+
+	ses.connecttimeout = 0;
+	
+	kexfirstinitialise(); /* initialise the kex state */
+
+	ses.writepayload = buf_new(MAX_TRANS_PAYLOAD_LEN);
+	ses.transseq = 0;
+
+	ses.readbuf = NULL;
+	ses.decryptreadbuf = NULL;
+	ses.payload = NULL;
+	ses.recvseq = 0;
+
+	initqueue(&ses.writequeue);
+
+	ses.requirenext = SSH_MSG_KEXINIT;
+	ses.dataallowed = 0; /* don't send data yet, we'll wait until after kex */
+	ses.ignorenext = 0;
+	ses.lastpacket = 0;
+
+	/* set all the algos to none */
+	ses.keys = (struct key_context*)m_malloc(sizeof(struct key_context));
+	ses.newkeys = NULL;
+	ses.keys->recv_algo_crypt = &dropbear_nocipher;
+	ses.keys->trans_algo_crypt = &dropbear_nocipher;
+	
+	ses.keys->recv_algo_mac = &dropbear_nohash;
+	ses.keys->trans_algo_mac = &dropbear_nohash;
+
+	ses.keys->algo_kex = -1;
+	ses.keys->algo_hostkey = -1;
+	ses.keys->recv_algo_comp = DROPBEAR_COMP_NONE;
+	ses.keys->trans_algo_comp = DROPBEAR_COMP_NONE;
+
+#ifndef DISABLE_ZLIB
+	ses.keys->recv_zstream = NULL;
+	ses.keys->trans_zstream = NULL;
+#endif
+
+	/* key exchange buffers */
+	ses.session_id = NULL;
+	ses.kexhashbuf = NULL;
+	ses.transkexinit = NULL;
+	ses.dh_K = NULL;
+	ses.remoteident = NULL;
+
+	ses.chantypes = NULL;
+
+	ses.allowprivport = 0;
+
+
+	TRACE(("leave session_init"))
+}
+
+void session_loop(void(*loophandler)()) {
+
+	fd_set readfd, writefd;
+	struct timeval timeout;
+	int val;
+
+	/* main loop, select()s for all sockets in use */
+	for(;;) {
+
+		timeout.tv_sec = SELECT_TIMEOUT;
+		timeout.tv_usec = 0;
+		FD_ZERO(&writefd);
+		FD_ZERO(&readfd);
+		dropbear_assert(ses.payload == NULL);
+		if (ses.sock != -1) {
+			FD_SET(ses.sock, &readfd);
+			if (!isempty(&ses.writequeue)) {
+				FD_SET(ses.sock, &writefd);
+			}
+		}
+
+		/* set up for channels which require reading/writing */
+		if (ses.dataallowed) {
+			setchannelfds(&readfd, &writefd);
+		}
+		val = select(ses.maxfd+1, &readfd, &writefd, NULL, &timeout);
+
+		if (exitflag) {
+			dropbear_exit("Terminated by signal");
+		}
+		
+		if (val < 0) {
+			if (errno == EINTR) {
+				/* This must happen even if we've been interrupted, so that
+				 * changed signal-handler vars can take effect etc */
+				if (loophandler) {
+					loophandler();
+				}
+				continue;
+			} else {
+				dropbear_exit("Error in select");
+			}
+		}
+
+		/* check for auth timeout, rekeying required etc */
+		checktimeouts();
+		
+		if (val == 0) {
+			/* timeout */
+			TRACE(("select timeout"))
+			continue;
+		}
+
+		/* process session socket's incoming/outgoing data */
+		if (ses.sock != -1) {
+			if (FD_ISSET(ses.sock, &writefd) && !isempty(&ses.writequeue)) {
+				write_packet();
+			}
+
+			if (FD_ISSET(ses.sock, &readfd)) {
+				read_packet();
+			}
+			
+			/* Process the decrypted packet. After this, the read buffer
+			 * will be ready for a new packet */
+			if (ses.payload != NULL) {
+				process_packet();
+			}
+		}
+
+		/* process pipes etc for the channels, ses.dataallowed == 0
+		 * during rekeying ) */
+		if (ses.dataallowed) {
+			channelio(&readfd, &writefd);
+		}
+
+		if (loophandler) {
+			loophandler();
+		}
+
+	} /* for(;;) */
+	
+	/* Not reached */
+}
+
+/* clean up a session on exit */
+void common_session_cleanup() {
+	
+	TRACE(("enter session_cleanup"))
+	
+	/* we can't cleanup if we don't know the session state */
+	if (!sessinitdone) {
+		TRACE(("leave session_cleanup: !sessinitdone"))
+		return;
+	}
+	
+	m_free(ses.session_id);
+	m_burn(ses.keys, sizeof(struct key_context));
+	m_free(ses.keys);
+
+	chancleanup();
+
+	TRACE(("leave session_cleanup"))
+}
+
+
+void session_identification() {
+
+	/* max length of 255 chars */
+	char linebuf[256];
+	int len = 0;
+	char done = 0;
+	int i;
+
+	/* write our version string, this blocks */
+	if (atomicio(write, ses.sock, LOCAL_IDENT "\r\n",
+				strlen(LOCAL_IDENT "\r\n")) == DROPBEAR_FAILURE) {
+		dropbear_exit("Error writing ident string");
+	}
+
+    /* If they send more than 50 lines, something is wrong */
+	for (i = 0; i < 50; i++) {
+		len = ident_readln(ses.sock, linebuf, sizeof(linebuf));
+
+		if (len < 0 && errno != EINTR) {
+			/* It failed */
+			break;
+		}
+
+		if (len >= 4 && memcmp(linebuf, "SSH-", 4) == 0) {
+			/* start of line matches */
+			done = 1;
+			break;
+		}
+	}
+
+	if (!done) {
+		TRACE(("err: %s for '%s'\n", strerror(errno), linebuf))
+		dropbear_exit("Failed to get remote version");
+	} else {
+		/* linebuf is already null terminated */
+		ses.remoteident = m_malloc(len);
+		memcpy(ses.remoteident, linebuf, len);
+	}
+
+    /* Shall assume that 2.x will be backwards compatible. */
+    if (strncmp(ses.remoteident, "SSH-2.", 6) != 0
+            && strncmp(ses.remoteident, "SSH-1.99-", 9) != 0) {
+        dropbear_exit("Incompatible remote version '%s'", ses.remoteident);
+    }
+
+	TRACE(("remoteident: %s", ses.remoteident))
+
+}
+
+/* returns the length including null-terminating zero on success,
+ * or -1 on failure */
+static int ident_readln(int fd, char* buf, int count) {
+	
+	char in;
+	int pos = 0;
+	int num = 0;
+	fd_set fds;
+	struct timeval timeout;
+
+	TRACE(("enter ident_readln"))
+
+	if (count < 1) {
+		return -1;
+	}
+
+	FD_ZERO(&fds);
+
+	/* select since it's a non-blocking fd */
+	
+	/* leave space to null-terminate */
+	while (pos < count-1) {
+
+		FD_SET(fd, &fds);
+
+		timeout.tv_sec = 1;
+		timeout.tv_usec = 0;
+		if (select(fd+1, &fds, NULL, NULL, &timeout) < 0) {
+			if (errno == EINTR) {
+				continue;
+			}
+			TRACE(("leave ident_readln: select error"))
+			return -1;
+		}
+
+		checktimeouts();
+		
+		/* Have to go one byte at a time, since we don't want to read past
+		 * the end, and have to somehow shove bytes back into the normal
+		 * packet reader */
+		if (FD_ISSET(fd, &fds)) {
+			num = read(fd, &in, 1);
+			/* a "\n" is a newline, "\r" we want to read in and keep going
+			 * so that it won't be read as part of the next line */
+			if (num < 0) {
+				/* error */
+				if (errno == EINTR) {
+					continue; /* not a real error */
+				}
+				TRACE(("leave ident_readln: read error"))
+				return -1;
+			}
+			if (num == 0) {
+				/* EOF */
+				TRACE(("leave ident_readln: EOF"))
+				return -1;
+			}
+			if (in == '\n') {
+				/* end of ident string */
+				break;
+			}
+			/* we don't want to include '\r's */
+			if (in != '\r') {
+				buf[pos] = in;
+				pos++;
+			}
+		}
+	}
+
+	buf[pos] = '\0';
+	TRACE(("leave ident_readln: return %d", pos+1))
+	return pos+1;
+}
+
+/* Check all timeouts which are required. Currently these are the time for
+ * user authentication, and the automatic rekeying. */
+static void checktimeouts() {
+
+	struct timeval tv;
+	long secs;
+
+	if (gettimeofday(&tv, 0) < 0) {
+		dropbear_exit("Error getting time");
+	}
+
+	secs = tv.tv_sec;
+	
+	if (ses.connecttimeout != 0 && secs > ses.connecttimeout) {
+			dropbear_close("Timeout before auth");
+	}
+
+	/* we can't rekey if we haven't done remote ident exchange yet */
+	if (ses.remoteident == NULL) {
+		return;
+	}
+
+	if (!ses.kexstate.sentkexinit
+			&& (secs - ses.kexstate.lastkextime >= KEX_REKEY_TIMEOUT
+			|| ses.kexstate.datarecv+ses.kexstate.datatrans >= KEX_REKEY_DATA)){
+		TRACE(("rekeying after timeout or max data reached"))
+		send_msg_kexinit();
+	}
+}
+