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/*
20140120
Jan Mojzis
Public domain.
*/
#include "buf.h"
#include "ssh.h"
#include "e.h"
#include "bug.h"
#include "packetparser.h"
#include "str.h"
#include "packet.h"
int packet_channel_open(struct buf *b1, struct buf *b2) {
crypto_uint32 id, remotewindow, localwindow, maxpacket, chanlen;
long long pos = 0;
crypto_uint8 ch;
char *chan = (char *) b1->buf + pos;
/* parse packet */
pos = packetparser_uint8(b1->buf, b1->len, pos,
&ch); /* byte SSH_MSG_CHANNEL_OPEN */
if (ch != SSH_MSG_CHANNEL_OPEN) bug_proto();
pos = packetparser_uint32(
b1->buf, b1->len, pos,
&chanlen); /* string channel type in US-ASCII only */
chan = (char *) b1->buf + pos;
pos = packetparser_skip(b1->buf, b1->len, pos, chanlen);
pos = packetparser_uint32(b1->buf, b1->len, pos,
&id); /* uint32 sender channel */
pos =
packetparser_uint32(b1->buf, b1->len, pos,
&remotewindow); /* uint32 initial window size */
pos = packetparser_uint32(b1->buf, b1->len, pos,
&maxpacket); /* uint32 maximum packet size */
if (maxpacket > PACKET_LIMIT) maxpacket = PACKET_LIMIT;
if (str_equaln(chan, chanlen, "session")) {
/* byte SSH_MSG_CHANNEL_OPEN
string "session"
uint32 sender channel
uint32 initial window size
uint32 maximum packet size
*/
pos = packetparser_end(b1->buf, b1->len, pos);
/* send confirmation */
buf_purge(b1);
if (channel_open(packet.name, id, remotewindow, maxpacket,
&localwindow)) {
buf_purge(b2);
buf_putnum8(
b2,
SSH_MSG_CHANNEL_OPEN_CONFIRMATION); /* byte
SSH_MSG_CHANNEL_OPEN_CONFIRMATION
*/
buf_putnum32(b2, id); /* uint32 recipient channel */
buf_putnum32(b2, id); /* uint32 sender channel */
buf_putnum32(b2, localwindow); /* uint32 initial window size */
/*
XXX
use PACKET_LIMIT/2 as maximum packet size,
workaround for miscalculated packet_length
*/
buf_putnum32(b2,
PACKET_LIMIT / 2); /* uint32 maximum packet size */
packet_put(b2);
buf_purge(b2);
return 1;
}
}
/* reject channel */
buf_purge(b2);
buf_putnum8(
b2, SSH_MSG_CHANNEL_OPEN_FAILURE); /* byte SSH_MSG_CHANNEL_OPEN_FAILURE
*/
buf_putnum32(b2, id); /* uint32 recipient channel */
buf_putnum32(
b2, SSH_OPEN_ADMINISTRATIVELY_PROHIBITED); /* uint32 reason code */
buf_putstring(
b2, "only one 'session' channel allowed"); /* string description in
ISO-10646 UTF-8 encoding
[RFC3629] */
buf_putstring(b2, ""); /* string language tag [RFC3066] */
packet_put(b2);
buf_purge(b1);
buf_purge(b2);
return 1;
}
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