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ssh.c
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/*
* SSH backend.
*/
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <assert.h>
#include <limits.h>
#include <signal.h>
#include "putty.h"
#include "tree234.h"
#include "ssh.h"
#ifndef FALSE
#define FALSE 0
#endif
#ifndef TRUE
#define TRUE 1
#endif
#define SSH1_MSG_DISCONNECT 1 /* 0x1 */
#define SSH1_SMSG_PUBLIC_KEY 2 /* 0x2 */
#define SSH1_CMSG_SESSION_KEY 3 /* 0x3 */
#define SSH1_CMSG_USER 4 /* 0x4 */
#define SSH1_CMSG_AUTH_RSA 6 /* 0x6 */
#define SSH1_SMSG_AUTH_RSA_CHALLENGE 7 /* 0x7 */
#define SSH1_CMSG_AUTH_RSA_RESPONSE 8 /* 0x8 */
#define SSH1_CMSG_AUTH_PASSWORD 9 /* 0x9 */
#define SSH1_CMSG_REQUEST_PTY 10 /* 0xa */
#define SSH1_CMSG_WINDOW_SIZE 11 /* 0xb */
#define SSH1_CMSG_EXEC_SHELL 12 /* 0xc */
#define SSH1_CMSG_EXEC_CMD 13 /* 0xd */
#define SSH1_SMSG_SUCCESS 14 /* 0xe */
#define SSH1_SMSG_FAILURE 15 /* 0xf */
#define SSH1_CMSG_STDIN_DATA 16 /* 0x10 */
#define SSH1_SMSG_STDOUT_DATA 17 /* 0x11 */
#define SSH1_SMSG_STDERR_DATA 18 /* 0x12 */
#define SSH1_CMSG_EOF 19 /* 0x13 */
#define SSH1_SMSG_EXIT_STATUS 20 /* 0x14 */
#define SSH1_MSG_CHANNEL_OPEN_CONFIRMATION 21 /* 0x15 */
#define SSH1_MSG_CHANNEL_OPEN_FAILURE 22 /* 0x16 */
#define SSH1_MSG_CHANNEL_DATA 23 /* 0x17 */
#define SSH1_MSG_CHANNEL_CLOSE 24 /* 0x18 */
#define SSH1_MSG_CHANNEL_CLOSE_CONFIRMATION 25 /* 0x19 */
#define SSH1_SMSG_X11_OPEN 27 /* 0x1b */
#define SSH1_CMSG_PORT_FORWARD_REQUEST 28 /* 0x1c */
#define SSH1_MSG_PORT_OPEN 29 /* 0x1d */
#define SSH1_CMSG_AGENT_REQUEST_FORWARDING 30 /* 0x1e */
#define SSH1_SMSG_AGENT_OPEN 31 /* 0x1f */
#define SSH1_MSG_IGNORE 32 /* 0x20 */
#define SSH1_CMSG_EXIT_CONFIRMATION 33 /* 0x21 */
#define SSH1_CMSG_X11_REQUEST_FORWARDING 34 /* 0x22 */
#define SSH1_CMSG_AUTH_RHOSTS_RSA 35 /* 0x23 */
#define SSH1_MSG_DEBUG 36 /* 0x24 */
#define SSH1_CMSG_REQUEST_COMPRESSION 37 /* 0x25 */
#define SSH1_CMSG_AUTH_TIS 39 /* 0x27 */
#define SSH1_SMSG_AUTH_TIS_CHALLENGE 40 /* 0x28 */
#define SSH1_CMSG_AUTH_TIS_RESPONSE 41 /* 0x29 */
#define SSH1_CMSG_AUTH_CCARD 70 /* 0x46 */
#define SSH1_SMSG_AUTH_CCARD_CHALLENGE 71 /* 0x47 */
#define SSH1_CMSG_AUTH_CCARD_RESPONSE 72 /* 0x48 */
#define SSH1_AUTH_TIS 5 /* 0x5 */
#define SSH1_AUTH_CCARD 16 /* 0x10 */
#define SSH1_PROTOFLAG_SCREEN_NUMBER 1 /* 0x1 */
/* Mask for protoflags we will echo back to server if seen */
#define SSH1_PROTOFLAGS_SUPPORTED 0 /* 0x1 */
#define SSH2_MSG_DISCONNECT 1 /* 0x1 */
#define SSH2_MSG_IGNORE 2 /* 0x2 */
#define SSH2_MSG_UNIMPLEMENTED 3 /* 0x3 */
#define SSH2_MSG_DEBUG 4 /* 0x4 */
#define SSH2_MSG_SERVICE_REQUEST 5 /* 0x5 */
#define SSH2_MSG_SERVICE_ACCEPT 6 /* 0x6 */
#define SSH2_MSG_KEXINIT 20 /* 0x14 */
#define SSH2_MSG_NEWKEYS 21 /* 0x15 */
#define SSH2_MSG_KEXDH_INIT 30 /* 0x1e */
#define SSH2_MSG_KEXDH_REPLY 31 /* 0x1f */
#define SSH2_MSG_KEX_DH_GEX_REQUEST 30 /* 0x1e */
#define SSH2_MSG_KEX_DH_GEX_GROUP 31 /* 0x1f */
#define SSH2_MSG_KEX_DH_GEX_INIT 32 /* 0x20 */
#define SSH2_MSG_KEX_DH_GEX_REPLY 33 /* 0x21 */
#define SSH2_MSG_USERAUTH_REQUEST 50 /* 0x32 */
#define SSH2_MSG_USERAUTH_FAILURE 51 /* 0x33 */
#define SSH2_MSG_USERAUTH_SUCCESS 52 /* 0x34 */
#define SSH2_MSG_USERAUTH_BANNER 53 /* 0x35 */
#define SSH2_MSG_USERAUTH_PK_OK 60 /* 0x3c */
#define SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ 60 /* 0x3c */
#define SSH2_MSG_USERAUTH_INFO_REQUEST 60 /* 0x3c */
#define SSH2_MSG_USERAUTH_INFO_RESPONSE 61 /* 0x3d */
#define SSH2_MSG_GLOBAL_REQUEST 80 /* 0x50 */
#define SSH2_MSG_REQUEST_SUCCESS 81 /* 0x51 */
#define SSH2_MSG_REQUEST_FAILURE 82 /* 0x52 */
#define SSH2_MSG_CHANNEL_OPEN 90 /* 0x5a */
#define SSH2_MSG_CHANNEL_OPEN_CONFIRMATION 91 /* 0x5b */
#define SSH2_MSG_CHANNEL_OPEN_FAILURE 92 /* 0x5c */
#define SSH2_MSG_CHANNEL_WINDOW_ADJUST 93 /* 0x5d */
#define SSH2_MSG_CHANNEL_DATA 94 /* 0x5e */
#define SSH2_MSG_CHANNEL_EXTENDED_DATA 95 /* 0x5f */
#define SSH2_MSG_CHANNEL_EOF 96 /* 0x60 */
#define SSH2_MSG_CHANNEL_CLOSE 97 /* 0x61 */
#define SSH2_MSG_CHANNEL_REQUEST 98 /* 0x62 */
#define SSH2_MSG_CHANNEL_SUCCESS 99 /* 0x63 */
#define SSH2_MSG_CHANNEL_FAILURE 100 /* 0x64 */
/*
* Packet type contexts, so that ssh2_pkt_type can correctly decode
* the ambiguous type numbers back into the correct type strings.
*/
#define SSH2_PKTCTX_DHGROUP 0x0001
#define SSH2_PKTCTX_DHGEX 0x0002
#define SSH2_PKTCTX_KEX_MASK 0x000F
#define SSH2_PKTCTX_PUBLICKEY 0x0010
#define SSH2_PKTCTX_PASSWORD 0x0020
#define SSH2_PKTCTX_KBDINTER 0x0040
#define SSH2_PKTCTX_AUTH_MASK 0x00F0
#define SSH2_DISCONNECT_HOST_NOT_ALLOWED_TO_CONNECT 1 /* 0x1 */
#define SSH2_DISCONNECT_PROTOCOL_ERROR 2 /* 0x2 */
#define SSH2_DISCONNECT_KEY_EXCHANGE_FAILED 3 /* 0x3 */
#define SSH2_DISCONNECT_HOST_AUTHENTICATION_FAILED 4 /* 0x4 */
#define SSH2_DISCONNECT_MAC_ERROR 5 /* 0x5 */
#define SSH2_DISCONNECT_COMPRESSION_ERROR 6 /* 0x6 */
#define SSH2_DISCONNECT_SERVICE_NOT_AVAILABLE 7 /* 0x7 */
#define SSH2_DISCONNECT_PROTOCOL_VERSION_NOT_SUPPORTED 8 /* 0x8 */
#define SSH2_DISCONNECT_HOST_KEY_NOT_VERIFIABLE 9 /* 0x9 */
#define SSH2_DISCONNECT_CONNECTION_LOST 10 /* 0xa */
#define SSH2_DISCONNECT_BY_APPLICATION 11 /* 0xb */
#define SSH2_DISCONNECT_TOO_MANY_CONNECTIONS 12 /* 0xc */
#define SSH2_DISCONNECT_AUTH_CANCELLED_BY_USER 13 /* 0xd */
#define SSH2_DISCONNECT_NO_MORE_AUTH_METHODS_AVAILABLE 14 /* 0xe */
#define SSH2_DISCONNECT_ILLEGAL_USER_NAME 15 /* 0xf */
static const char *const ssh2_disconnect_reasons[] = {
NULL,
"host not allowed to connect",
"protocol error",
"key exchange failed",
"host authentication failed",
"MAC error",
"compression error",
"service not available",
"protocol version not supported",
"host key not verifiable",
"connection lost",
"by application",
"too many connections",
"auth cancelled by user",
"no more auth methods available",
"illegal user name",
};
#define SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED 1 /* 0x1 */
#define SSH2_OPEN_CONNECT_FAILED 2 /* 0x2 */
#define SSH2_OPEN_UNKNOWN_CHANNEL_TYPE 3 /* 0x3 */
#define SSH2_OPEN_RESOURCE_SHORTAGE 4 /* 0x4 */
#define SSH2_EXTENDED_DATA_STDERR 1 /* 0x1 */
/*
* Various remote-bug flags.
*/
#define BUG_CHOKES_ON_SSH1_IGNORE 1
#define BUG_SSH2_HMAC 2
#define BUG_NEEDS_SSH1_PLAIN_PASSWORD 4
#define BUG_CHOKES_ON_RSA 8
#define BUG_SSH2_RSA_PADDING 16
#define BUG_SSH2_DERIVEKEY 32
#define BUG_SSH2_REKEY 64
#define BUG_SSH2_PK_SESSIONID 128
/*
* Codes for terminal modes.
* Most of these are the same in SSH-1 and SSH-2.
* This list is derived from draft-ietf-secsh-connect-25 and
* SSH-1 RFC-1.2.31.
*/
static const struct {
const char* const mode;
int opcode;
enum { TTY_OP_CHAR, TTY_OP_BOOL } type;
} ssh_ttymodes[] = {
/* "V" prefix discarded for special characters relative to SSH specs */
{ "INTR", 1, TTY_OP_CHAR },
{ "QUIT", 2, TTY_OP_CHAR },
{ "ERASE", 3, TTY_OP_CHAR },
{ "KILL", 4, TTY_OP_CHAR },
{ "EOF", 5, TTY_OP_CHAR },
{ "EOL", 6, TTY_OP_CHAR },
{ "EOL2", 7, TTY_OP_CHAR },
{ "START", 8, TTY_OP_CHAR },
{ "STOP", 9, TTY_OP_CHAR },
{ "SUSP", 10, TTY_OP_CHAR },
{ "DSUSP", 11, TTY_OP_CHAR },
{ "REPRINT", 12, TTY_OP_CHAR },
{ "WERASE", 13, TTY_OP_CHAR },
{ "LNEXT", 14, TTY_OP_CHAR },
{ "FLUSH", 15, TTY_OP_CHAR },
{ "SWTCH", 16, TTY_OP_CHAR },
{ "STATUS", 17, TTY_OP_CHAR },
{ "DISCARD", 18, TTY_OP_CHAR },
{ "IGNPAR", 30, TTY_OP_BOOL },
{ "PARMRK", 31, TTY_OP_BOOL },
{ "INPCK", 32, TTY_OP_BOOL },
{ "ISTRIP", 33, TTY_OP_BOOL },
{ "INLCR", 34, TTY_OP_BOOL },
{ "IGNCR", 35, TTY_OP_BOOL },
{ "ICRNL", 36, TTY_OP_BOOL },
{ "IUCLC", 37, TTY_OP_BOOL },
{ "IXON", 38, TTY_OP_BOOL },
{ "IXANY", 39, TTY_OP_BOOL },
{ "IXOFF", 40, TTY_OP_BOOL },
{ "IMAXBEL", 41, TTY_OP_BOOL },
{ "ISIG", 50, TTY_OP_BOOL },
{ "ICANON", 51, TTY_OP_BOOL },
{ "XCASE", 52, TTY_OP_BOOL },
{ "ECHO", 53, TTY_OP_BOOL },
{ "ECHOE", 54, TTY_OP_BOOL },
{ "ECHOK", 55, TTY_OP_BOOL },
{ "ECHONL", 56, TTY_OP_BOOL },
{ "NOFLSH", 57, TTY_OP_BOOL },
{ "TOSTOP", 58, TTY_OP_BOOL },
{ "IEXTEN", 59, TTY_OP_BOOL },
{ "ECHOCTL", 60, TTY_OP_BOOL },
{ "ECHOKE", 61, TTY_OP_BOOL },
{ "PENDIN", 62, TTY_OP_BOOL }, /* XXX is this a real mode? */
{ "OPOST", 70, TTY_OP_BOOL },
{ "OLCUC", 71, TTY_OP_BOOL },
{ "ONLCR", 72, TTY_OP_BOOL },
{ "OCRNL", 73, TTY_OP_BOOL },
{ "ONOCR", 74, TTY_OP_BOOL },
{ "ONLRET", 75, TTY_OP_BOOL },
{ "CS7", 90, TTY_OP_BOOL },
{ "CS8", 91, TTY_OP_BOOL },
{ "PARENB", 92, TTY_OP_BOOL },
{ "PARODD", 93, TTY_OP_BOOL }
};
/* Miscellaneous other tty-related constants. */
#define SSH_TTY_OP_END 0
/* The opcodes for ISPEED/OSPEED differ between SSH-1 and SSH-2. */
#define SSH1_TTY_OP_ISPEED 192
#define SSH1_TTY_OP_OSPEED 193
#define SSH2_TTY_OP_ISPEED 128
#define SSH2_TTY_OP_OSPEED 129
/* Helper functions for parsing tty-related config. */
static unsigned int ssh_tty_parse_specchar(char *s)
{
unsigned int ret;
if (*s) {
char *next = NULL;
ret = ctrlparse(s, &next);
if (!next) ret = s[0];
} else {
ret = 255; /* special value meaning "don't set" */
}
return ret;
}
static unsigned int ssh_tty_parse_boolean(char *s)
{
if (stricmp(s, "yes") == 0 ||
stricmp(s, "on") == 0 ||
stricmp(s, "true") == 0 ||
stricmp(s, "+") == 0)
return 1; /* true */
else if (stricmp(s, "no") == 0 ||
stricmp(s, "off") == 0 ||
stricmp(s, "false") == 0 ||
stricmp(s, "-") == 0)
return 0; /* false */
else
return (atoi(s) != 0);
}
#define translate(x) if (type == x) return #x
#define translatec(x,ctx) if (type == x && (pkt_ctx & ctx)) return #x
static char *ssh1_pkt_type(int type)
{
translate(SSH1_MSG_DISCONNECT);
translate(SSH1_SMSG_PUBLIC_KEY);
translate(SSH1_CMSG_SESSION_KEY);
translate(SSH1_CMSG_USER);
translate(SSH1_CMSG_AUTH_RSA);
translate(SSH1_SMSG_AUTH_RSA_CHALLENGE);
translate(SSH1_CMSG_AUTH_RSA_RESPONSE);
translate(SSH1_CMSG_AUTH_PASSWORD);
translate(SSH1_CMSG_REQUEST_PTY);
translate(SSH1_CMSG_WINDOW_SIZE);
translate(SSH1_CMSG_EXEC_SHELL);
translate(SSH1_CMSG_EXEC_CMD);
translate(SSH1_SMSG_SUCCESS);
translate(SSH1_SMSG_FAILURE);
translate(SSH1_CMSG_STDIN_DATA);
translate(SSH1_SMSG_STDOUT_DATA);
translate(SSH1_SMSG_STDERR_DATA);
translate(SSH1_CMSG_EOF);
translate(SSH1_SMSG_EXIT_STATUS);
translate(SSH1_MSG_CHANNEL_OPEN_CONFIRMATION);
translate(SSH1_MSG_CHANNEL_OPEN_FAILURE);
translate(SSH1_MSG_CHANNEL_DATA);
translate(SSH1_MSG_CHANNEL_CLOSE);
translate(SSH1_MSG_CHANNEL_CLOSE_CONFIRMATION);
translate(SSH1_SMSG_X11_OPEN);
translate(SSH1_CMSG_PORT_FORWARD_REQUEST);
translate(SSH1_MSG_PORT_OPEN);
translate(SSH1_CMSG_AGENT_REQUEST_FORWARDING);
translate(SSH1_SMSG_AGENT_OPEN);
translate(SSH1_MSG_IGNORE);
translate(SSH1_CMSG_EXIT_CONFIRMATION);
translate(SSH1_CMSG_X11_REQUEST_FORWARDING);
translate(SSH1_CMSG_AUTH_RHOSTS_RSA);
translate(SSH1_MSG_DEBUG);
translate(SSH1_CMSG_REQUEST_COMPRESSION);
translate(SSH1_CMSG_AUTH_TIS);
translate(SSH1_SMSG_AUTH_TIS_CHALLENGE);
translate(SSH1_CMSG_AUTH_TIS_RESPONSE);
translate(SSH1_CMSG_AUTH_CCARD);
translate(SSH1_SMSG_AUTH_CCARD_CHALLENGE);
translate(SSH1_CMSG_AUTH_CCARD_RESPONSE);
return "unknown";
}
static char *ssh2_pkt_type(int pkt_ctx, int type)
{
translate(SSH2_MSG_DISCONNECT);
translate(SSH2_MSG_IGNORE);
translate(SSH2_MSG_UNIMPLEMENTED);
translate(SSH2_MSG_DEBUG);
translate(SSH2_MSG_SERVICE_REQUEST);
translate(SSH2_MSG_SERVICE_ACCEPT);
translate(SSH2_MSG_KEXINIT);
translate(SSH2_MSG_NEWKEYS);
translatec(SSH2_MSG_KEXDH_INIT, SSH2_PKTCTX_DHGROUP);
translatec(SSH2_MSG_KEXDH_REPLY, SSH2_PKTCTX_DHGROUP);
translatec(SSH2_MSG_KEX_DH_GEX_REQUEST, SSH2_PKTCTX_DHGEX);
translatec(SSH2_MSG_KEX_DH_GEX_GROUP, SSH2_PKTCTX_DHGEX);
translatec(SSH2_MSG_KEX_DH_GEX_INIT, SSH2_PKTCTX_DHGEX);
translatec(SSH2_MSG_KEX_DH_GEX_REPLY, SSH2_PKTCTX_DHGEX);
translate(SSH2_MSG_USERAUTH_REQUEST);
translate(SSH2_MSG_USERAUTH_FAILURE);
translate(SSH2_MSG_USERAUTH_SUCCESS);
translate(SSH2_MSG_USERAUTH_BANNER);
translatec(SSH2_MSG_USERAUTH_PK_OK, SSH2_PKTCTX_PUBLICKEY);
translatec(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, SSH2_PKTCTX_PASSWORD);
translatec(SSH2_MSG_USERAUTH_INFO_REQUEST, SSH2_PKTCTX_KBDINTER);
translatec(SSH2_MSG_USERAUTH_INFO_RESPONSE, SSH2_PKTCTX_KBDINTER);
translate(SSH2_MSG_GLOBAL_REQUEST);
translate(SSH2_MSG_REQUEST_SUCCESS);
translate(SSH2_MSG_REQUEST_FAILURE);
translate(SSH2_MSG_CHANNEL_OPEN);
translate(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
translate(SSH2_MSG_CHANNEL_OPEN_FAILURE);
translate(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
translate(SSH2_MSG_CHANNEL_DATA);
translate(SSH2_MSG_CHANNEL_EXTENDED_DATA);
translate(SSH2_MSG_CHANNEL_EOF);
translate(SSH2_MSG_CHANNEL_CLOSE);
translate(SSH2_MSG_CHANNEL_REQUEST);
translate(SSH2_MSG_CHANNEL_SUCCESS);
translate(SSH2_MSG_CHANNEL_FAILURE);
return "unknown";
}
#undef translate
#undef translatec
/* Enumeration values for fields in SSH-1 packets */
enum {
PKT_END, PKT_INT, PKT_CHAR, PKT_DATA, PKT_STR, PKT_BIGNUM,
/* These values are for communicating relevant semantics of
* fields to the packet logging code. */
PKTT_OTHER, PKTT_PASSWORD, PKTT_DATA
};
/*
* Coroutine mechanics for the sillier bits of the code. If these
* macros look impenetrable to you, you might find it helpful to
* read
*
* http://www.chiark.greenend.org.uk/~sgtatham/coroutines.html
*
* which explains the theory behind these macros.
*
* In particular, if you are getting `case expression not constant'
* errors when building with MS Visual Studio, this is because MS's
* Edit and Continue debugging feature causes their compiler to
* violate ANSI C. To disable Edit and Continue debugging:
*
* - right-click ssh.c in the FileView
* - click Settings
* - select the C/C++ tab and the General category
* - under `Debug info:', select anything _other_ than `Program
* Database for Edit and Continue'.
*/
#define crBegin(v) { int *crLine = &v; switch(v) { case 0:;
#define crState(t) \
struct t *s; \
if (!ssh->t) ssh->t = snew(struct t); \
s = ssh->t;
#define crFinish(z) } *crLine = 0; return (z); }
#define crFinishV } *crLine = 0; return; }
#define crReturn(z) \
do {\
*crLine =__LINE__; return (z); case __LINE__:;\
} while (0)
#define crReturnV \
do {\
*crLine=__LINE__; return; case __LINE__:;\
} while (0)
#define crStop(z) do{ *crLine = 0; return (z); }while(0)
#define crStopV do{ *crLine = 0; return; }while(0)
#define crWaitUntil(c) do { crReturn(0); } while (!(c))
#define crWaitUntilV(c) do { crReturnV; } while (!(c))
typedef struct ssh_tag *Ssh;
struct Packet;
static struct Packet *ssh1_pkt_init(int pkt_type);
static struct Packet *ssh2_pkt_init(int pkt_type);
static void ssh_pkt_ensure(struct Packet *, int length);
static void ssh_pkt_adddata(struct Packet *, void *data, int len);
static void ssh_pkt_addbyte(struct Packet *, unsigned char value);
static void ssh2_pkt_addbool(struct Packet *, unsigned char value);
static void ssh_pkt_adduint32(struct Packet *, unsigned long value);
static void ssh_pkt_addstring_start(struct Packet *);
static void ssh_pkt_addstring_str(struct Packet *, char *data);
static void ssh_pkt_addstring_data(struct Packet *, char *data, int len);
static void ssh_pkt_addstring(struct Packet *, char *data);
static unsigned char *ssh2_mpint_fmt(Bignum b, int *len);
static void ssh1_pkt_addmp(struct Packet *, Bignum b);
static void ssh2_pkt_addmp(struct Packet *, Bignum b);
static int ssh2_pkt_construct(Ssh, struct Packet *);
static void ssh2_pkt_send(Ssh, struct Packet *);
static void ssh2_pkt_send_noqueue(Ssh, struct Packet *);
static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
struct Packet *pktin);
static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
struct Packet *pktin);
/*
* Buffer management constants. There are several of these for
* various different purposes:
*
* - SSH1_BUFFER_LIMIT is the amount of backlog that must build up
* on a local data stream before we throttle the whole SSH
* connection (in SSH-1 only). Throttling the whole connection is
* pretty drastic so we set this high in the hope it won't
* happen very often.
*
* - SSH_MAX_BACKLOG is the amount of backlog that must build up
* on the SSH connection itself before we defensively throttle
* _all_ local data streams. This is pretty drastic too (though
* thankfully unlikely in SSH-2 since the window mechanism should
* ensure that the server never has any need to throttle its end
* of the connection), so we set this high as well.
*
* - OUR_V2_WINSIZE is the maximum window size we present on SSH-2
* channels.
*/
#define SSH1_BUFFER_LIMIT 32768
#define SSH_MAX_BACKLOG 32768
#define OUR_V2_WINSIZE 16384
#define OUR_V2_MAXPKT 0x4000UL
/* Maximum length of passwords/passphrases (arbitrary) */
#define SSH_MAX_PASSWORD_LEN 100
const static struct ssh_signkey *hostkey_algs[] = { &ssh_rsa, &ssh_dss };
const static struct ssh_mac *macs[] = {
&ssh_hmac_sha1, &ssh_hmac_sha1_96, &ssh_hmac_md5
};
const static struct ssh_mac *buggymacs[] = {
&ssh_hmac_sha1_buggy, &ssh_hmac_sha1_96_buggy, &ssh_hmac_md5
};
static void *ssh_comp_none_init(void)
{
return NULL;
}
static void ssh_comp_none_cleanup(void *handle)
{
}
static int ssh_comp_none_block(void *handle, unsigned char *block, int len,
unsigned char **outblock, int *outlen)
{
return 0;
}
static int ssh_comp_none_disable(void *handle)
{
return 0;
}
const static struct ssh_compress ssh_comp_none = {
"none",
ssh_comp_none_init, ssh_comp_none_cleanup, ssh_comp_none_block,
ssh_comp_none_init, ssh_comp_none_cleanup, ssh_comp_none_block,
ssh_comp_none_disable, NULL
};
extern const struct ssh_compress ssh_zlib;
const static struct ssh_compress *compressions[] = {
&ssh_zlib, &ssh_comp_none
};
enum { /* channel types */
CHAN_MAINSESSION,
CHAN_X11,
CHAN_AGENT,
CHAN_SOCKDATA,
CHAN_SOCKDATA_DORMANT /* one the remote hasn't confirmed */
};
/*
* 2-3-4 tree storing channels.
*/
struct ssh_channel {
Ssh ssh; /* pointer back to main context */
unsigned remoteid, localid;
int type;
/* True if we opened this channel but server hasn't confirmed. */
int halfopen;
/*
* In SSH-1, this value contains four bits:
*
* 1 We have sent SSH1_MSG_CHANNEL_CLOSE.
* 2 We have sent SSH1_MSG_CHANNEL_CLOSE_CONFIRMATION.
* 4 We have received SSH1_MSG_CHANNEL_CLOSE.
* 8 We have received SSH1_MSG_CHANNEL_CLOSE_CONFIRMATION.
*
* A channel is completely finished with when all four bits are set.
*/
int closes;
union {
struct ssh1_data_channel {
int throttling;
} v1;
struct ssh2_data_channel {
bufchain outbuffer;
unsigned remwindow, remmaxpkt;
unsigned locwindow;
} v2;
} v;
union {
struct ssh_agent_channel {
unsigned char *message;
unsigned char msglen[4];
unsigned lensofar, totallen;
} a;
struct ssh_x11_channel {
Socket s;
} x11;
struct ssh_pfd_channel {
Socket s;
} pfd;
} u;
};
/*
* 2-3-4 tree storing remote->local port forwardings. SSH-1 and SSH-2
* use this structure in different ways, reflecting SSH-2's
* altogether saner approach to port forwarding.
*
* In SSH-1, you arrange a remote forwarding by sending the server
* the remote port number, and the local destination host:port.
* When a connection comes in, the server sends you back that
* host:port pair, and you connect to it. This is a ready-made
* security hole if you're not on the ball: a malicious server
* could send you back _any_ host:port pair, so if you trustingly
* connect to the address it gives you then you've just opened the
* entire inside of your corporate network just by connecting
* through it to a dodgy SSH server. Hence, we must store a list of
* host:port pairs we _are_ trying to forward to, and reject a
* connection request from the server if it's not in the list.
*
* In SSH-2, each side of the connection minds its own business and
* doesn't send unnecessary information to the other. You arrange a
* remote forwarding by sending the server just the remote port
* number. When a connection comes in, the server tells you which
* of its ports was connected to; and _you_ have to remember what
* local host:port pair went with that port number.
*
* Hence, in SSH-1 this structure is indexed by destination
* host:port pair, whereas in SSH-2 it is indexed by source port.
*/
struct ssh_portfwd; /* forward declaration */
struct ssh_rportfwd {
unsigned sport, dport;
char dhost[256];
char *sportdesc;
struct ssh_portfwd *pfrec;
};
#define free_rportfwd(pf) ( \
((pf) ? (sfree((pf)->sportdesc)) : (void)0 ), sfree(pf) )
/*
* Separately to the rportfwd tree (which is for looking up port
* open requests from the server), a tree of _these_ structures is
* used to keep track of all the currently open port forwardings,
* so that we can reconfigure in mid-session if the user requests
* it.
*/
struct ssh_portfwd {
enum { DESTROY, KEEP, CREATE } status;
int type;
unsigned sport, dport;
char *saddr, *daddr;
char *sserv, *dserv;
struct ssh_rportfwd *remote;
int addressfamily;
void *local;
};
#define free_portfwd(pf) ( \
((pf) ? (sfree((pf)->saddr), sfree((pf)->daddr), \
sfree((pf)->sserv), sfree((pf)->dserv)) : (void)0 ), sfree(pf) )
struct Packet {
long length; /* length of `data' actually used */
long forcepad; /* SSH-2: force padding to at least this length */
int type; /* only used for incoming packets */
unsigned long sequence; /* SSH-2 incoming sequence number */
unsigned char *data; /* allocated storage */
unsigned char *body; /* offset of payload within `data' */
long savedpos; /* temporary index into `data' (for strings) */
long maxlen; /* amount of storage allocated for `data' */
long encrypted_len; /* for SSH-2 total-size counting */
/*
* State associated with packet logging
*/
int logmode;
int nblanks;
struct logblank_t *blanks;
};
static void ssh1_protocol(Ssh ssh, void *vin, int inlen,
struct Packet *pktin);
static void ssh2_protocol(Ssh ssh, void *vin, int inlen,
struct Packet *pktin);
static void ssh1_protocol_setup(Ssh ssh);
static void ssh2_protocol_setup(Ssh ssh);
static void ssh_size(void *handle, int width, int height);
static void ssh_special(void *handle, Telnet_Special);
static int ssh2_try_send(struct ssh_channel *c);
static void ssh2_add_channel_data(struct ssh_channel *c, char *buf, int len);
static void ssh_throttle_all(Ssh ssh, int enable, int bufsize);
static void ssh2_set_window(struct ssh_channel *c, unsigned newwin);
static int ssh_sendbuffer(void *handle);
static int ssh_do_close(Ssh ssh, int notify_exit);
static unsigned long ssh_pkt_getuint32(struct Packet *pkt);
static int ssh2_pkt_getbool(struct Packet *pkt);
static void ssh_pkt_getstring(struct Packet *pkt, char **p, int *length);
static void ssh2_timer(void *ctx, long now);
static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
struct Packet *pktin);
struct rdpkt1_state_tag {
long len, pad, biglen, to_read;
unsigned long realcrc, gotcrc;
unsigned char *p;
int i;
int chunk;
struct Packet *pktin;
};
struct rdpkt2_state_tag {
long len, pad, payload, packetlen, maclen;
int i;
int cipherblk;
unsigned long incoming_sequence;
struct Packet *pktin;
};
typedef void (*handler_fn_t)(Ssh ssh, struct Packet *pktin);
typedef void (*chandler_fn_t)(Ssh ssh, struct Packet *pktin, void *ctx);
struct queued_handler;
struct queued_handler {
int msg1, msg2;
chandler_fn_t handler;
void *ctx;
struct queued_handler *next;
};
struct ssh_tag {
const struct plug_function_table *fn;
/* the above field _must_ be first in the structure */
char *v_c, *v_s;
void *exhash;
Socket s;
void *ldisc;
void *logctx;
unsigned char session_key[32];
int v1_compressing;
int v1_remote_protoflags;
int v1_local_protoflags;
int agentfwd_enabled;
int X11_fwd_enabled;
int remote_bugs;
const struct ssh_cipher *cipher;
void *v1_cipher_ctx;
void *crcda_ctx;
const struct ssh2_cipher *cscipher, *sccipher;
void *cs_cipher_ctx, *sc_cipher_ctx;
const struct ssh_mac *csmac, *scmac;
void *cs_mac_ctx, *sc_mac_ctx;
const struct ssh_compress *cscomp, *sccomp;
void *cs_comp_ctx, *sc_comp_ctx;
const struct ssh_kex *kex;
const struct ssh_signkey *hostkey;
unsigned char v2_session_id[SSH2_KEX_MAX_HASH_LEN];
int v2_session_id_len;
void *kex_ctx;
char *savedhost;
int savedport;
int send_ok;
int echoing, editing;
void *frontend;
int ospeed, ispeed; /* temporaries */
int term_width, term_height;
tree234 *channels; /* indexed by local id */
struct ssh_channel *mainchan; /* primary session channel */
int ncmode; /* is primary channel direct-tcpip? */
int exitcode;
int close_expected;
int clean_exit;
tree234 *rportfwds, *portfwds;
enum {
SSH_STATE_PREPACKET,
SSH_STATE_BEFORE_SIZE,
SSH_STATE_INTERMED,
SSH_STATE_SESSION,
SSH_STATE_CLOSED
} state;
int size_needed, eof_needed;
struct Packet **queue;
int queuelen, queuesize;
int queueing;
unsigned char *deferred_send_data;
int deferred_len, deferred_size;
/*
* Gross hack: pscp will try to start SFTP but fall back to
* scp1 if that fails. This variable is the means by which
* scp.c can reach into the SSH code and find out which one it
* got.
*/
int fallback_cmd;
bufchain banner; /* accumulates banners during do_ssh2_authconn */
int pkt_ctx;
void *x11auth;
int version;
int v1_throttle_count;
int overall_bufsize;
int throttled_all;
int v1_stdout_throttling;
unsigned long v2_outgoing_sequence;
int ssh1_rdpkt_crstate;
int ssh2_rdpkt_crstate;
int do_ssh_init_crstate;
int ssh_gotdata_crstate;
int do_ssh1_login_crstate;
int do_ssh1_connection_crstate;
int do_ssh2_transport_crstate;
int do_ssh2_authconn_crstate;
void *do_ssh_init_state;
void *do_ssh1_login_state;
void *do_ssh2_transport_state;
void *do_ssh2_authconn_state;
struct rdpkt1_state_tag rdpkt1_state;
struct rdpkt2_state_tag rdpkt2_state;
/* SSH-1 and SSH-2 use this for different things, but both use it */
int protocol_initial_phase_done;
void (*protocol) (Ssh ssh, void *vin, int inlen,
struct Packet *pkt);
struct Packet *(*s_rdpkt) (Ssh ssh, unsigned char **data, int *datalen);
/*
* We maintain a full _copy_ of a Config structure here, not
* merely a pointer to it. That way, when we're passed a new
* one for reconfiguration, we can check the differences and
* potentially reconfigure port forwardings etc in mid-session.
*/
Config cfg;
/*
* Used to transfer data back from async callbacks.
*/
void *agent_response;
int agent_response_len;
int user_response;
/*
* The SSH connection can be set as `frozen', meaning we are
* not currently accepting incoming data from the network. This
* is slightly more serious than setting the _socket_ as
* frozen, because we may already have had data passed to us
* from the network which we need to delay processing until
* after the freeze is lifted, so we also need a bufchain to
* store that data.
*/
int frozen;
bufchain queued_incoming_data;
/*
* Dispatch table for packet types that we may have to deal
* with at any time.
*/
handler_fn_t packet_dispatch[256];
/*
* Queues of one-off handler functions for success/failure
* indications from a request.
*/
struct queued_handler *qhead, *qtail;
/*
* This module deals with sending keepalives.
*/
Pinger pinger;
/*
* Track incoming and outgoing data sizes and time, for
* size-based rekeys.
*/
unsigned long incoming_data_size, outgoing_data_size, deferred_data_size;
unsigned long max_data_size;
int kex_in_progress;
long next_rekey, last_rekey;
char *deferred_rekey_reason; /* points to STATIC string; don't free */
};
#define logevent(s) logevent(ssh->frontend, s)
/* logevent, only printf-formatted. */
static void logeventf(Ssh ssh, const char *fmt, ...)
{
va_list ap;
char *buf;
va_start(ap, fmt);
buf = dupvprintf(fmt, ap);
va_end(ap);
logevent(buf);
sfree(buf);
}
#define bombout(msg) \
do { \
char *text = dupprintf msg; \
ssh_do_close(ssh, FALSE); \
logevent(text); \
connection_fatal(ssh->frontend, "%s", text); \
sfree(text); \
} while (0)
/* Functions to leave bits out of the SSH packet log file. */
static void dont_log_password(Ssh ssh, struct Packet *pkt, int blanktype)
{
if (ssh->cfg.logomitpass)
pkt->logmode = blanktype;
}
static void dont_log_data(Ssh ssh, struct Packet *pkt, int blanktype)
{
if (ssh->cfg.logomitdata)
pkt->logmode = blanktype;
}
static void end_log_omission(Ssh ssh, struct Packet *pkt)
{
pkt->logmode = PKTLOG_EMIT;
}
/* Helper function for common bits of parsing cfg.ttymodes. */
static void parse_ttymodes(Ssh ssh, char *modes,
void (*do_mode)(void *data, char *mode, char *val),
void *data)
{
while (*modes) {
char *t = strchr(modes, '\t');
char *m = snewn(t-modes+1, char);
char *val;
strncpy(m, modes, t-modes);
m[t-modes] = '\0';
if (*(t+1) == 'A')
val = get_ttymode(ssh->frontend, m);
else
val = dupstr(t+2);
if (val)
do_mode(data, m, val);
sfree(m);
sfree(val);
modes += strlen(modes) + 1;
}
}
static int ssh_channelcmp(void *av, void *bv)
{
struct ssh_channel *a = (struct ssh_channel *) av;
struct ssh_channel *b = (struct ssh_channel *) bv;
if (a->localid < b->localid)
return -1;
if (a->localid > b->localid)
return +1;
return 0;
}
static int ssh_channelfind(void *av, void *bv)
{
unsigned *a = (unsigned *) av;
struct ssh_channel *b = (struct ssh_channel *) bv;
if (*a < b->localid)
return -1;
if (*a > b->localid)
return +1;
return 0;
}
static int ssh_rportcmp_ssh1(void *av, void *bv)
{
struct ssh_rportfwd *a = (struct ssh_rportfwd *) av;
struct ssh_rportfwd *b = (struct ssh_rportfwd *) bv;
int i;
if ( (i = strcmp(a->dhost, b->dhost)) != 0)
return i < 0 ? -1 : +1;
if (a->dport > b->dport)
return +1;
if (a->dport < b->dport)
return -1;
return 0;
}
static int ssh_rportcmp_ssh2(void *av, void *bv)
{
struct ssh_rportfwd *a = (struct ssh_rportfwd *) av;
struct ssh_rportfwd *b = (struct ssh_rportfwd *) bv;
if (a->sport > b->sport)
return +1;
if (a->sport < b->sport)
return -1;
return 0;
}
/*
* Special form of strcmp which can cope with NULL inputs. NULL is
* defined to sort before even the empty string.
*/
static int nullstrcmp(const char *a, const char *b)
{
if (a == NULL && b == NULL)
return 0;
if (a == NULL)
return -1;
if (b == NULL)
return +1;
return strcmp(a, b);
}
static int ssh_portcmp(void *av, void *bv)
{
struct ssh_portfwd *a = (struct ssh_portfwd *) av;
struct ssh_portfwd *b = (struct ssh_portfwd *) bv;
int i;
if (a->type > b->type)
return +1;
if (a->type < b->type)
return -1;
if (a->addressfamily > b->addressfamily)
return +1;
if (a->addressfamily < b->addressfamily)
return -1;
if ( (i = nullstrcmp(a->saddr, b->saddr)) != 0)
return i < 0 ? -1 : +1;
if (a->sport > b->sport)
return +1;