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/*
* Trivial binary packet protocol for the 'bare' ssh-connection
* protocol used in PuTTY's SSH-2 connection sharing system.
*/
#include <assert.h>
#include "putty.h"
#include "ssh.h"
#include "bpp.h"
#include "sshcr.h"
struct ssh2_bare_bpp_state {
int crState;
long packetlen, maxlen;
unsigned char *data;
unsigned long incoming_sequence, outgoing_sequence;
PktIn *pktin;
BinaryPacketProtocol bpp;
};
static void ssh2_bare_bpp_free(BinaryPacketProtocol *bpp);
static void ssh2_bare_bpp_handle_input(BinaryPacketProtocol *bpp);
static void ssh2_bare_bpp_handle_output(BinaryPacketProtocol *bpp);
static PktOut *ssh2_bare_bpp_new_pktout(int type);
static const BinaryPacketProtocolVtable ssh2_bare_bpp_vtable = {
.free = ssh2_bare_bpp_free,
.handle_input = ssh2_bare_bpp_handle_input,
.handle_output = ssh2_bare_bpp_handle_output,
.new_pktout = ssh2_bare_bpp_new_pktout,
.queue_disconnect = ssh2_bpp_queue_disconnect, /* in common.c */
/* packet size limit, per protocol spec in sharing.c comment */
.packet_size_limit = 0x4000,
};
BinaryPacketProtocol *ssh2_bare_bpp_new(LogContext *logctx)
{
struct ssh2_bare_bpp_state *s = snew(struct ssh2_bare_bpp_state);
memset(s, 0, sizeof(*s));
s->bpp.vt = &ssh2_bare_bpp_vtable;
s->bpp.logctx = logctx;
ssh_bpp_common_setup(&s->bpp);
return &s->bpp;
}
static void ssh2_bare_bpp_free(BinaryPacketProtocol *bpp)
{
struct ssh2_bare_bpp_state *s =
container_of(bpp, struct ssh2_bare_bpp_state, bpp);
sfree(s->pktin);
sfree(s);
}
#define BPP_READ(ptr, len) do \
{ \
bool success; \
crMaybeWaitUntilV((success = bufchain_try_fetch_consume( \
s->bpp.in_raw, ptr, len)) || \
s->bpp.input_eof); \
if (!success) \
goto eof; \
ssh_check_frozen(s->bpp.ssh); \
} while (0)
static void ssh2_bare_bpp_handle_input(BinaryPacketProtocol *bpp)
{
struct ssh2_bare_bpp_state *s =
container_of(bpp, struct ssh2_bare_bpp_state, bpp);
crBegin(s->crState);
while (1) {
/* Read the length field. */
{
unsigned char lenbuf[4];
BPP_READ(lenbuf, 4);
s->packetlen = toint(GET_32BIT_MSB_FIRST(lenbuf));
}
if (s->packetlen <= 0 || s->packetlen >= (long)OUR_V2_PACKETLIMIT) {
ssh_sw_abort(s->bpp.ssh, "Invalid packet length received");
crStopV;
}
/*
* Allocate the packet to return, now we know its length.
*/
s->pktin = snew_plus(PktIn, s->packetlen);
s->pktin->qnode.prev = s->pktin->qnode.next = NULL;
s->pktin->qnode.on_free_queue = false;
s->maxlen = 0;
s->data = snew_plus_get_aux(s->pktin);
s->pktin->sequence = s->incoming_sequence++;
/*
* Read the remainder of the packet.
*/
BPP_READ(s->data, s->packetlen);
/*
* The data we just read is precisely the initial type byte
* followed by the packet payload.
*/
s->pktin->type = s->data[0];
s->data++;
s->packetlen--;
BinarySource_INIT(s->pktin, s->data, s->packetlen);
if (s->pktin->type == SSH2_MSG_EXT_INFO) {
/*
* Mild layer violation: EXT_INFO is not permitted in the
* bare ssh-connection protocol. Faulting it here means
* that ssh2_common_filter_queue doesn't receive it in the
* first place unless it's legal to have sent it.
*/
ssh_proto_error(s->bpp.ssh, "Remote side sent SSH2_MSG_EXT_INFO "
"in bare connection protocol");
return;
}
/*
* Log incoming packet, possibly omitting sensitive fields.
*/
if (s->bpp.logctx) {
logblank_t blanks[MAX_BLANKS];
int nblanks = ssh2_censor_packet(
s->bpp.pls, s->pktin->type, false,
make_ptrlen(s->data, s->packetlen), blanks);
log_packet(s->bpp.logctx, PKT_INCOMING, s->pktin->type,
ssh2_pkt_type(s->bpp.pls->kctx, s->bpp.pls->actx,
s->pktin->type),
get_ptr(s->pktin), get_avail(s->pktin), nblanks, blanks,
&s->pktin->sequence, 0, NULL);
}
if (ssh2_bpp_check_unimplemented(&s->bpp, s->pktin)) {
sfree(s->pktin);
s->pktin = NULL;
continue;
}
s->pktin->qnode.formal_size = get_avail(s->pktin);
pq_push(&s->bpp.in_pq, s->pktin);
s->pktin = NULL;
}
eof:
if (!s->bpp.expect_close) {
ssh_remote_error(s->bpp.ssh,
"Remote side unexpectedly closed network connection");
} else {
ssh_remote_eof(s->bpp.ssh, "Remote side closed network connection");
}
return; /* avoid touching s now it's been freed */
crFinishV;
}
static PktOut *ssh2_bare_bpp_new_pktout(int pkt_type)
{
PktOut *pkt = ssh_new_packet();
pkt->length = 4; /* space for packet length */
pkt->type = pkt_type;
put_byte(pkt, pkt_type);
return pkt;
}
static void ssh2_bare_bpp_format_packet(struct ssh2_bare_bpp_state *s,
PktOut *pkt)
{
if (s->bpp.logctx) {
ptrlen pktdata = make_ptrlen(pkt->data + 5, pkt->length - 5);
logblank_t blanks[MAX_BLANKS];
int nblanks = ssh2_censor_packet(
s->bpp.pls, pkt->type, true, pktdata, blanks);
log_packet(s->bpp.logctx, PKT_OUTGOING, pkt->type,
ssh2_pkt_type(s->bpp.pls->kctx, s->bpp.pls->actx,
pkt->type),
pktdata.ptr, pktdata.len, nblanks, blanks,
&s->outgoing_sequence,
pkt->downstream_id, pkt->additional_log_text);
}
s->outgoing_sequence++; /* only for diagnostics, really */
PUT_32BIT_MSB_FIRST(pkt->data, pkt->length - 4);
bufchain_add(s->bpp.out_raw, pkt->data, pkt->length);
}
static void ssh2_bare_bpp_handle_output(BinaryPacketProtocol *bpp)
{
struct ssh2_bare_bpp_state *s =
container_of(bpp, struct ssh2_bare_bpp_state, bpp);
PktOut *pkt;
while ((pkt = pq_pop(&s->bpp.out_pq)) != NULL) {
ssh2_bare_bpp_format_packet(s, pkt);
ssh_free_pktout(pkt);
}
ssh_sendbuffer_changed(bpp->ssh);
}
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