static void
svr_sessionloop() {
if (svr_ses.connect_time != 0
&& monotonic_now() - svr_ses.connect_time >= AUTH_TIMEOUT) {
dropbear_close("Timeout before auth");
}
}
/* called when the remote side closes the connection */
void session_remoteclosed() {
close(ses.sock);
ses.sock = -1;
dropbear_close("Exited normally");
}
/* 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.authstate.authdone) {
if (secs - ses.connecttime >= AUTH_TIMEOUT) {
dropbear_close("Timeout before userauth");
}
}
/* 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();
}
}
/* called when the remote side closes the connection */
static void svr_remoteclosed() {
close(ses.sock);
ses.sock = -1;
dropbear_close("Exited normally");
}
/* called when the remote side closes the connection */
static void svr_remoteclosed() {
m_close(ses.sock_in);
m_close(ses.sock_out);
ses.sock_in = -1;
ses.sock_out = -1;
dropbear_close("Exited normally");
}
/* Non-blocking function reading available portion of a packet into the
* ses's buffer, decrypting the length if encrypted, decrypting the
* full portion if possible */
void read_packet() {
int len;
unsigned int maxlen;
unsigned char blocksize;
TRACE(("enter read_packet"));
blocksize = ses.keys->recv_algo_crypt->blocksize;
if (ses.readbuf == NULL || ses.readbuf->len < blocksize) {
/* In the first blocksize of a packet */
/* Read the first blocksize of the packet, so we can decrypt it and
* find the length of the whole packet */
read_packet_init();
/* If we don't have the length of decryptreadbuf, we didn't read
* a whole blocksize and should exit */
if (ses.decryptreadbuf->len == 0) {
TRACE(("leave read_packet: packetinit done"));
return;
}
}
/* Attempt to read the remainder of the packet, note that there
* mightn't be any available (EAGAIN) */
assert(ses.readbuf != NULL);
maxlen = ses.readbuf->len - ses.readbuf->pos;
len = read(ses.sock, buf_getptr(ses.readbuf, maxlen), maxlen);
buf_incrpos(ses.readbuf, len);
if (len == 0) {
dropbear_close("remote host closed connection");
}
if (len < 0) {
if (errno == EINTR || errno == EAGAIN) {
TRACE(("leave read_packet: EINTR or EAGAIN"));
return;
} else {
dropbear_exit("error reading");
}
}
if ((unsigned int)len == maxlen) {
/* The whole packet has been read */
decrypt_packet();
/* The main select() loop in session.h will process_packet() to
* handle the packet contents... */
}
TRACE(("leave read_packet"));
}
/* non-blocking function writing out a current encrypted packet */
void write_packet() {
int len, written;
buffer * writebuf;
TRACE(("enter write_packet"));
assert(!isempty(&ses.writequeue));
/* Get the next buffer in the queue of encrypted packets to write*/
writebuf = (buffer*)examine(&ses.writequeue);
len = writebuf->len - writebuf->pos;
assert(len > 0);
/* Try to write as much as possible */
written = write(ses.sock, buf_getptr(writebuf, len), len);
if (written < 0) {
if (errno == EINTR) {
TRACE(("leave writepacket: EINTR"));
return;
} else {
dropbear_exit("error writing");
}
}
if (written == 0) {
dropbear_close("remote host closed connection");
}
if (written == len) {
/* We've finished with the packet, free it */
dequeue(&ses.writequeue);
buf_free(writebuf);
} else {
/* More packet left to write, leave it in the queue for later */
buf_incrpos(writebuf, written);
}
TRACE(("leave write_packet"));
}
/* process a decrypted packet, call the appropriate handler */
void process_packet() {
unsigned char type;
TRACE(("enter process_packet"));
type = buf_getbyte(ses.payload);
TRACE(("process_packet: packet type = %d", type));
/* these packets we can receive at any time, regardless of expecting
* other packets: */
switch(type) {
case SSH_MSG_IGNORE:
case SSH_MSG_DEBUG:
TRACE(("received SSH_MSG_IGNORE or SSH_MSG_DEBUG"));
goto out;
case SSH_MSG_UNIMPLEMENTED:
/* debugging XXX */
TRACE(("SSH_MSG_UNIMPLEMENTED"));
dropbear_exit("received SSH_MSG_UNIMPLEMENTED");
case SSH_MSG_DISCONNECT:
/* TODO cleanup? */
dropbear_close("Disconnect received");
}
/* check that we aren't expecting a particular packet */
if (ses.expecting && ses.expecting != type) {
/* TODO send disconnect? */
dropbear_exit("unexpected packet type %d, expected %d", type,
ses.expecting);
}
/* handle the packet depending on type */
ses.expecting = 0;
switch (type) {
case SSH_MSG_SERVICE_REQUEST:
recv_msg_service_request();
break;
case SSH_MSG_USERAUTH_REQUEST:
recv_msg_userauth_request();
break;
case SSH_MSG_KEXINIT:
recv_msg_kexinit();
break;
case SSH_MSG_KEXDH_INIT:
recv_msg_kexdh_init();
break;
case SSH_MSG_NEWKEYS:
recv_msg_newkeys();
break;
/* this is ugly, need to make a cleaner way to do it */
case SSH_MSG_CHANNEL_DATA:
case SSH_MSG_CHANNEL_WINDOW_ADJUST:
case SSH_MSG_CHANNEL_REQUEST:
case SSH_MSG_CHANNEL_OPEN:
case SSH_MSG_CHANNEL_EOF:
case SSH_MSG_CHANNEL_CLOSE:
case SSH_MSG_CHANNEL_OPEN_CONFIRMATION:
case SSH_MSG_CHANNEL_OPEN_FAILURE:
/* these should be checked for authdone below */
process_postauth_packet(type);
break;
default:
/* TODO this possibly should be handled */
TRACE(("unknown packet"));
recv_unimplemented();
break;
}
out:
buf_free(ses.payload);
ses.payload = NULL;
TRACE(("leave process_packet"));
}
/* Function used to read the initial portion of a packet, and determine the
* length. Only called during the first BLOCKSIZE of a packet. */
static void read_packet_init() {
unsigned int maxlen;
int len;
unsigned char blocksize;
unsigned char macsize;
blocksize = ses.keys->recv_algo_crypt->blocksize;
macsize = ses.keys->recv_algo_mac->hashsize;
if (ses.readbuf == NULL) {
/* start of a new packet */
ses.readbuf = buf_new(INIT_READBUF);
assert(ses.decryptreadbuf == NULL);
ses.decryptreadbuf = buf_new(blocksize);
}
maxlen = blocksize - ses.readbuf->pos;
/* read the rest of the packet if possible */
len = read(ses.sock, buf_getwriteptr(ses.readbuf, maxlen),
maxlen);
if (len == 0) {
dropbear_close("remote host closed connection");
}
if (len < 0) {
if (errno == EINTR) {
TRACE(("leave read_packet_init: EINTR"));
return;
}
dropbear_exit("error reading");
}
buf_incrwritepos(ses.readbuf, len);
if ((unsigned int)len != maxlen) {
/* don't have enough bytes to determine length, get next time */
return;
}
/* now we have the first block, need to get packet length, so we decrypt
* the first block (only need first 4 bytes) */
buf_setpos(ses.readbuf, 0);
if (ses.keys->recv_algo_crypt->cipherdesc == NULL) {
/* copy it */
memcpy(buf_getwriteptr(ses.decryptreadbuf, blocksize),
buf_getptr(ses.readbuf, blocksize),
blocksize);
} else {
/* decrypt it */
if (cbc_decrypt(buf_getptr(ses.readbuf, blocksize),
buf_getwriteptr(ses.decryptreadbuf,blocksize),
&ses.keys->recv_symmetric_struct) != CRYPT_OK) {
dropbear_exit("error decrypting");
}
}
buf_setlen(ses.decryptreadbuf, blocksize);
len = buf_getint(ses.decryptreadbuf) + 4 + macsize;
buf_setpos(ses.readbuf, blocksize);
/* check packet length */
if ((len > MAX_PACKET_LEN) ||
(len < MIN_PACKET_LEN + macsize) ||
((len - macsize) % blocksize != 0)) {
dropbear_exit("bad packet size");
}
buf_resize(ses.readbuf, len);
buf_setlen(ses.readbuf, len);
}
/* process a decrypted packet, call the appropriate handler */
void process_packet() {
unsigned char type;
unsigned int i;
TRACE2(("enter process_packet"))
type = buf_getbyte(ses.payload);
TRACE(("process_packet: packet type = %d, len %d", type, ses.payload->len))
ses.lastpacket = type;
ses.last_packet_time = time(NULL);
/* These packets we can receive at any time */
switch(type) {
case SSH_MSG_IGNORE:
goto out;
case SSH_MSG_DEBUG:
goto out;
case SSH_MSG_UNIMPLEMENTED:
/* debugging XXX */
TRACE(("SSH_MSG_UNIMPLEMENTED"))
dropbear_exit("Received SSH_MSG_UNIMPLEMENTED");
case SSH_MSG_DISCONNECT:
/* TODO cleanup? */
dropbear_close("Disconnect received");
}
/* This applies for KEX, where the spec says the next packet MUST be
* NEWKEYS */
if (ses.requirenext != 0) {
if (ses.requirenext == type)
{
/* Got what we expected */
TRACE(("got expected packet %d during kexinit", type))
}
else
{
/* RFC4253 7.1 - various messages are allowed at this point.
The only ones we know about have already been handled though,
so just return "unimplemented" */
if (type >= 1 && type <= 49
&& type != SSH_MSG_SERVICE_REQUEST
&& type != SSH_MSG_SERVICE_ACCEPT
&& type != SSH_MSG_KEXINIT)
{
TRACE(("unknown allowed packet during kexinit"))
recv_unimplemented();
goto out;
}
else
{
TRACE(("disallowed packet during kexinit"))
dropbear_exit("Unexpected packet type %d, expected %d", type,
ses.requirenext);
}
}
}
/* Check if we should ignore this packet. Used currently only for
* KEX code, with first_kex_packet_follows */
if (ses.ignorenext) {
TRACE(("Ignoring packet, type = %d", type))
ses.ignorenext = 0;
goto out;
}
/* Only clear the flag after we have checked ignorenext */
if (ses.requirenext != 0 && ses.requirenext == type)
{
ses.requirenext = 0;
}
/* Kindly the protocol authors gave all the preauth packets type values
* less-than-or-equal-to 60 ( == MAX_UNAUTH_PACKET_TYPE ).
* NOTE: if the protocol changes and new types are added, revisit this
* assumption */
if ( !ses.authstate.authdone && type > MAX_UNAUTH_PACKET_TYPE ) {
dropbear_exit("Received message %d before userauth", type);
}
for (i = 0; ; i++) {
if (ses.packettypes[i].type == 0) {
/* end of list */
break;
}
if (ses.packettypes[i].type == type) {
ses.packettypes[i].handler();
goto out;
}
}
/* TODO do something more here? */
TRACE(("preauth unknown packet"))
recv_unimplemented();
out:
buf_free(ses.payload);
ses.payload = NULL;
TRACE2(("leave process_packet"))
}
/* process a decrypted packet, call the appropriate handler */
void process_packet() {
unsigned char type;
unsigned int i;
TRACE(("enter process_packet"))
type = buf_getbyte(ses.payload);
TRACE(("process_packet: packet type = %d", type))
ses.lastpacket = type;
/* These packets we can receive at any time */
switch(type) {
case SSH_MSG_IGNORE:
case SSH_MSG_DEBUG:
TRACE(("received SSH_MSG_IGNORE or SSH_MSG_DEBUG"))
goto out;
case SSH_MSG_UNIMPLEMENTED:
/* debugging XXX */
TRACE(("SSH_MSG_UNIMPLEMENTED"))
dropbear_exit("received SSH_MSG_UNIMPLEMENTED");
case SSH_MSG_DISCONNECT:
/* TODO cleanup? */
dropbear_close("Disconnect received");
}
/* This applies for KEX, where the spec says the next packet MUST be
* NEWKEYS */
if (ses.requirenext != 0) {
if (ses.requirenext != type) {
/* TODO send disconnect? */
dropbear_exit("unexpected packet type %d, expected %d", type,
ses.requirenext);
} else {
/* Got what we expected */
ses.requirenext = 0;
}
}
/* Check if we should ignore this packet. Used currently only for
* KEX code, with first_kex_packet_follows */
if (ses.ignorenext) {
TRACE(("Ignoring packet, type = %d", type))
ses.ignorenext = 0;
goto out;
}
/* Kindly the protocol authors gave all the preauth packets type values
* less-than-or-equal-to 60 ( == MAX_UNAUTH_PACKET_TYPE ).
* NOTE: if the protocol changes and new types are added, revisit this
* assumption */
if ( !ses.authstate.authdone && type > MAX_UNAUTH_PACKET_TYPE ) {
dropbear_exit("received message %d before userauth", type);
}
for (i = 0; ; i++) {
if (ses.packettypes[i].type == 0) {
/* end of list */
break;
}
if (ses.packettypes[i].type == type) {
ses.packettypes[i].handler();
goto out;
}
}
/* TODO do something more here? */
TRACE(("preauth unknown packet"))
recv_unimplemented();
out:
buf_free(ses.payload);
ses.payload = NULL;
TRACE(("leave process_packet"))
}
