/*
* Dropbear SSH
*
* Copyright (c) 2002-2004 Matt Johnston
* Portions Copyright (c) 2004 by Mihnea Stoenescu
* 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 "dbutil.h"
#include "algo.h"
#include "buffer.h"
#include "session.h"
#include "kex.h"
#include "ssh.h"
#include "packet.h"
#include "bignum.h"
#include "random.h"
/* diffie-hellman-group1-sha1 value for p */
static const unsigned char dh_p_val[] = {
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xC9, 0x0F, 0xDA, 0xA2,
0x21, 0x68, 0xC2, 0x34, 0xC4, 0xC6, 0x62, 0x8B, 0x80, 0xDC, 0x1C, 0xD1,
0x29, 0x02, 0x4E, 0x08, 0x8A, 0x67, 0xCC, 0x74, 0x02, 0x0B, 0xBE, 0xA6,
0x3B, 0x13, 0x9B, 0x22, 0x51, 0x4A, 0x08, 0x79, 0x8E, 0x34, 0x04, 0xDD,
0xEF, 0x95, 0x19, 0xB3, 0xCD, 0x3A, 0x43, 0x1B, 0x30, 0x2B, 0x0A, 0x6D,
0xF2, 0x5F, 0x14, 0x37, 0x4F, 0xE1, 0x35, 0x6D, 0x6D, 0x51, 0xC2, 0x45,
0xE4, 0x85, 0xB5, 0x76, 0x62, 0x5E, 0x7E, 0xC6, 0xF4, 0x4C, 0x42, 0xE9,
0xA6, 0x37, 0xED, 0x6B, 0x0B, 0xFF, 0x5C, 0xB6, 0xF4, 0x06, 0xB7, 0xED,
0xEE, 0x38, 0x6B, 0xFB, 0x5A, 0x89, 0x9F, 0xA5, 0xAE, 0x9F, 0x24, 0x11,
0x7C, 0x4B, 0x1F, 0xE6, 0x49, 0x28, 0x66, 0x51, 0xEC, 0xE6, 0x53, 0x81,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};
#define DH_P_LEN sizeof(dh_p_val)
static const int DH_G_VAL = 2;
static void kexinitialise();
void gen_new_keys();
#ifndef DISABLE_ZLIB
static void gen_new_zstreams();
#endif
static void read_kex_algos();
/* helper function for gen_new_keys */
static void hashkeys(unsigned char *out, int outlen,
const hash_state * hs, unsigned const char X);
/* Send our list of algorithms we can use */
void send_msg_kexinit() {
CHECKCLEARTOWRITE();
buf_putbyte(ses.writepayload, SSH_MSG_KEXINIT);
/* cookie */
genrandom(buf_getwriteptr(ses.writepayload, 16), 16);
buf_incrwritepos(ses.writepayload, 16);
/* kex algos */
buf_put_algolist(ses.writepayload, sshkex);
/* server_host_key_algorithms */
buf_put_algolist(ses.writepayload, sshhostkey);
/* encryption_algorithms_client_to_server */
buf_put_algolist(ses.writepayload, sshciphers);
/* encryption_algorithms_server_to_client */
buf_put_algolist(ses.writepayload, sshciphers);
/* mac_algorithms_client_to_server */
buf_put_algolist(ses.writepayload, sshhashes);
/* mac_algorithms_server_to_client */
buf_put_algolist(ses.writepayload, sshhashes);
/* compression_algorithms_client_to_server */
buf_put_algolist(ses.writepayload, sshcompress);
/* compression_algorithms_server_to_client */
buf_put_algolist(ses.writepayload, sshcompress);
/* languages_client_to_server */
buf_putstring(ses.writepayload, "", 0);
/* languages_server_to_client */
buf_putstring(ses.writepayload, "", 0);
/* first_kex_packet_follows - unimplemented for now */
buf_putbyte(ses.writepayload, 0x00);
/* reserved unit32 */
buf_putint(ses.writepayload, 0);
/* set up transmitted kex packet buffer for hashing.
* This is freed after the end of the kex */
ses.transkexinit = buf_newcopy(ses.writepayload);
encrypt_packet();
ses.dataallowed = 0; /* don't send other packets during kex */
TRACE(("DATAALLOWED=0"))
TRACE(("-> KEXINIT"))
ses.kexstate.sentkexinit = 1;
}
/* *** NOTE regarding (send|recv)_msg_newkeys ***
* Changed by mihnea from the original kex.c to set dataallowed after a
* completed key exchange, no matter the order in which it was performed.
* This enables client mode without affecting server functionality.
*/
/* Bring new keys into use after a key exchange, and let the client know*/
void send_msg_newkeys() {
TRACE(("enter send_msg_newkeys"))
/* generate the kexinit request */
CHECKCLEARTOWRITE();
buf_putbyte(ses.writepayload, SSH_MSG_NEWKEYS);
encrypt_packet();
/* set up our state */
if (ses.kexstate.recvnewkeys) {
TRACE(("while RECVNEWKEYS=1"))
gen_new_keys();
kexinitialise(); /* we've finished with this kex */
TRACE((" -> DATAALLOWED=1"))
ses.dataallowed = 1; /* we can send other packets again now */
ses.kexstate.donefirstkex = 1;
} else {
ses.kexstate.sentnewkeys = 1;
TRACE(("SENTNEWKEYS=1"))
}
TRACE(("-> MSG_NEWKEYS"))
TRACE(("leave send_msg_newkeys"))
}
/* Bring the new keys into use after a key exchange */
void recv_msg_newkeys() {
TRACE(("<- MSG_NEWKEYS"))
TRACE(("enter recv_msg_newkeys"))
/* simply check if we've sent SSH_MSG_NEWKEYS, and if so,
* switch to the new keys */
if (ses.kexstate.sentnewkeys) {
TRACE(("while SENTNEWKEYS=1"))
gen_new_keys();
kexinitialise(); /* we've finished with this kex */
TRACE((" -> DATAALLOWED=1"))
ses.dataallowed = 1; /* we can send other packets again now */
ses.kexstate.donefirstkex = 1;
} else {
TRACE(("RECVNEWKEYS=1"))
ses.kexstate.recvnewkeys = 1;
}
TRACE(("leave recv_msg_newkeys"))
}
/* Set up the kex for the first time */
void kexfirstinitialise() {
ses.kexstate.donefirstkex = 0;
kexinitialise();
}
/* Reset the kex state, ready for a new negotiation */
static void kexinitialise() {
struct timeval tv;
TRACE(("kexinitialise()"))
/* sent/recv'd MSG_KEXINIT */
ses.kexstate.sentkexinit = 0;
ses.kexstate.recvkexinit = 0;
/* sent/recv'd MSG_NEWKEYS */
ses.kexstate.recvnewkeys = 0;
ses.kexstate.sentnewkeys = 0;
/* first_packet_follows */
ses.kexstate.firstfollows = 0;
ses.kexstate.datatrans = 0;
ses.kexstate.datarecv = 0;
if (gettimeofday(&tv, 0) < 0) {
dropbear_exit("Error getting time");
}
ses.kexstate.lastkextime = tv.tv_sec;
}
/* Helper function for gen_new_keys, creates a hash. It makes a copy of the
* already initialised hash_state hs, which should already have processed
* the dh_K and hash, since these are common. X is the letter 'A', 'B' etc.
* out must have at least min(SHA1_HASH_SIZE, outlen) bytes allocated.
* The output will only be expanded once, as we are assured that
* outlen <= 2*SHA1_HASH_SIZE for all known hashes.
*
* See Section 7.2 of rfc4253 (ssh transport) for details */
static void hashkeys(unsigned char *out, int outlen,
const hash_state * hs, const unsigned char X) {
hash_state hs2;
unsigned char k2[SHA1_HASH_SIZE]; /* used to extending */
memcpy(&hs2, hs, sizeof(hash_state));
sha1_process(&hs2, &X, 1);
sha1_process(&hs2, ses.session_id, SHA1_HASH_SIZE);
sha1_done(&hs2, out);
if (SHA1_HASH_SIZE < outlen) {
/* need to extend */
memcpy(&hs2, hs, sizeof(hash_state));
sha1_process(&hs2, out, SHA1_HASH_SIZE);
sha1_done(&hs2, k2);
memcpy(&out[SHA1_HASH_SIZE], k2, outlen - SHA1_HASH_SIZE);
}
}
/* Generate the actual encryption/integrity keys, using the results of the
* key exchange, as specified in section 5.2 of the IETF secsh-transport
* draft. This occurs after the DH key-exchange.
*
* ses.newkeys is the new set of keys which are generated, these are only
* taken into use after both sides have sent a newkeys message */
/* Originally from kex.c, generalized for cli/svr mode --mihnea */
void gen_new_keys() {
unsigned char C2S_IV[MAX_IV_LEN];
unsigned char C2S_key[MAX_KEY_LEN];
unsigned char S2C_IV[MAX_IV_LEN];
unsigned char S2C_key[MAX_KEY_LEN];
/* unsigned char key[MAX_KEY_LEN]; */
unsigned char *trans_IV, *trans_key, *recv_IV, *recv_key;
hash_state hs;
unsigned int C2S_keysize, S2C_keysize;
char mactransletter, macrecvletter; /* Client or server specific */
int recv_cipher = 0, trans_cipher = 0;
TRACE(("enter gen_new_keys"))
/* the dh_K and hash are the start of all hashes, we make use of that */
sha1_init(&hs);
sha1_process_mp(&hs, ses.dh_K);
mp_clear(ses.dh_K);
m_free(ses.dh_K);
sha1_process(&hs, ses.hash, SHA1_HASH_SIZE);
m_burn(ses.hash, SHA1_HASH_SIZE);
if (IS_DROPBEAR_CLIENT) {
trans_IV = C2S_IV;
recv_IV = S2C_IV;
trans_key = C2S_key;
recv_key = S2C_key;
C2S_keysize = ses.newkeys->trans_algo_crypt->keysize;
S2C_keysize = ses.newkeys->recv_algo_crypt->keysize;
mactransletter = 'E';
macrecvletter = 'F';
} else {
trans_IV = S2C_IV;
recv_IV = C2S_IV;
trans_key = S2C_key;
recv_key = C2S_key;
C2S_keysize = ses.newkeys->recv_algo_crypt->keysize;
S2C_keysize = ses.newkeys->trans_algo_crypt->keysize;
mactransletter = 'F';
macrecvletter = 'E';
}
hashkeys(C2S_IV, SHA1_HASH_SIZE, &hs, 'A');
hashkeys(S2C_IV, SHA1_HASH_SIZE, &hs, 'B');
hashkeys(C2S_key, C2S_keysize, &hs, 'C');
hashkeys(S2C_key, S2C_keysize, &hs, 'D');
recv_cipher = find_cipher(ses.newkeys->recv_algo_crypt->cipherdesc->name);
if (recv_cipher < 0)
dropbear_exit("crypto error");
if (cbc_start(recv_cipher, recv_IV, recv_key,
ses.newkeys->recv_algo_crypt->keysize, 0,
&ses.newkeys->recv_symmetric_struct) != CRYPT_OK) {
dropbear_exit("crypto error");
}
trans_cipher = find_cipher(ses.newkeys->trans_algo_crypt->cipherdesc->name);
if (trans_cipher < 0)
dropbear_exit("crypto error");
if (cbc_start(trans_cipher, trans_IV, trans_key,
ses.newkeys->trans_algo_crypt->keysize, 0,
&ses.newkeys->trans_symmetric_struct) != CRYPT_OK) {
dropbear_exit("crypto error");
}
/* MAC keys */
hashkeys(ses.newkeys->transmackey,
ses.newkeys->trans_algo_mac->keysize, &hs, mactransletter);
hashkeys(ses.newkeys->recvmackey,
ses.newkeys->recv_algo_mac->keysize, &hs, macrecvletter);
#ifndef DISABLE_ZLIB
gen_new_zstreams();
#endif
/* Switch over to the new keys */
m_burn(ses.keys, sizeof(struct key_context));
m_free(ses.keys);
ses.keys = ses.newkeys;
ses.newkeys = NULL;
TRACE(("leave gen_new_keys"))
}
#ifndef DISABLE_ZLIB
/* Set up new zlib compression streams, close the old ones. Only
* called from gen_new_keys() */
static void gen_new_zstreams() {
/* create new zstreams */
if (ses.newkeys->recv_algo_comp == DROPBEAR_COMP_ZLIB) {
ses.newkeys->recv_zstream = (z_streamp)m_malloc(sizeof(z_stream));
ses.newkeys->recv_zstream->zalloc = Z_NULL;
ses.newkeys->recv_zstream->zfree = Z_NULL;
if (inflateInit(ses.newkeys->recv_zstream) != Z_OK) {
dropbear_exit("zlib error");
}
} else {
ses.newkeys->recv_zstream = NULL;
}
if (ses.newkeys->trans_algo_comp == DROPBEAR_COMP_ZLIB) {
ses.newkeys->trans_zstream = (z_streamp)m_malloc(sizeof(z_stream));
ses.newkeys->trans_zstream->zalloc = Z_NULL;
ses.newkeys->trans_zstream->zfree = Z_NULL;
if (deflateInit(ses.newkeys->trans_zstream, Z_DEFAULT_COMPRESSION)
!= Z_OK) {
dropbear_exit("zlib error");
}
} else {
ses.newkeys->trans_zstream = NULL;
}
/* clean up old keys */
if (ses.keys->recv_zstream != NULL) {
if (inflateEnd(ses.keys->recv_zstream) == Z_STREAM_ERROR) {
/* Z_DATA_ERROR is ok, just means that stream isn't ended */
dropbear_exit("crypto error");
}
m_free(ses.keys->recv_zstream);
}
if (ses.keys->trans_zstream != NULL) {
if (deflateEnd(ses.keys->trans_zstream) == Z_STREAM_ERROR) {
/* Z_DATA_ERROR is ok, just means that stream isn't ended */
dropbear_exit("crypto error");
}
m_free(ses.keys->trans_zstream);
}
}
#endif
/* Executed upon receiving a kexinit message from the client to initiate
* key exchange. If we haven't already done so, we send the list of our
* preferred algorithms. The client's requested algorithms are processed,
* and we calculate the first portion of the key-exchange-hash for used
* later in the key exchange. No response is sent, as the client should
* initiate the diffie-hellman key exchange */
/* Originally from kex.c, generalized for cli/svr mode --mihnea */
/* Belongs in common_kex.c where it should be moved after review */
void recv_msg_kexinit() {
unsigned int kexhashbuf_len = 0;
unsigned int remote_ident_len = 0;
unsigned int local_ident_len = 0;
TRACE(("<- KEXINIT"))
TRACE(("enter recv_msg_kexinit"))
if (!ses.kexstate.sentkexinit) {
/* we need to send a kex packet */
send_msg_kexinit();
TRACE(("continue recv_msg_kexinit: sent kexinit"))
}
/* start the kex hash */
local_ident_len = strlen(LOCAL_IDENT);
remote_ident_len = strlen((char*)ses.remoteident);
kexhashbuf_len = local_ident_len + remote_ident_len
+ ses.transkexinit->len + ses.payload->len
+ KEXHASHBUF_MAX_INTS;
ses.kexhashbuf = buf_new(kexhashbuf_len);
if (IS_DROPBEAR_CLIENT) {
/* read the peer's choice of algos */
read_kex_algos();
/* V_C, the client's version string (CR and NL excluded) */
buf_putstring(ses.kexhashbuf,
(unsigned char*)LOCAL_IDENT, local_ident_len);
/* V_S, the server's version string (CR and NL excluded) */
buf_putstring(ses.kexhashbuf, ses.remoteident, remote_ident_len);
/* I_C, the payload of the client's SSH_MSG_KEXINIT */
buf_putstring(ses.kexhashbuf,
ses.transkexinit->data, ses.transkexinit->len);
/* I_S, the payload of the server's SSH_MSG_KEXINIT */
buf_setpos(ses.payload, 0);
buf_putstring(ses.kexhashbuf, ses.payload->data, ses.payload->len);
} else {
/* SERVER */
/* read the peer's choice of algos */
read_kex_algos();
/* V_C, the client's version string (CR and NL excluded) */
buf_putstring(ses.kexhashbuf, ses.remoteident, remote_ident_len);
/* V_S, the server's version string (CR and NL excluded) */
buf_putstring(ses.kexhashbuf,
(unsigned char*)LOCAL_IDENT, local_ident_len);
/* I_C, the payload of the client's SSH_MSG_KEXINIT */
buf_setpos(ses.payload, 0);
buf_putstring(ses.kexhashbuf, ses.payload->data, ses.payload->len);
/* I_S, the payload of the server's SSH_MSG_KEXINIT */
buf_putstring(ses.kexhashbuf,
ses.transkexinit->data, ses.transkexinit->len);
ses.requirenext = SSH_MSG_KEXDH_INIT;
}
buf_free(ses.transkexinit);
ses.transkexinit = NULL;
/* the rest of ses.kexhashbuf will be done after DH exchange */
ses.kexstate.recvkexinit = 1;
TRACE(("leave recv_msg_kexinit"))
}
/* Initialises and generate one side of the diffie-hellman key exchange values.
* See the ietf-secsh-transport draft, section 6, for details */
/* dh_pub and dh_priv MUST be already initialised */
void gen_kexdh_vals(mp_int *dh_pub, mp_int *dh_priv) {
DEF_MP_INT(dh_p);
DEF_MP_INT(dh_q);
DEF_MP_INT(dh_g);
TRACE(("enter send_msg_kexdh_reply"))
m_mp_init_multi(&dh_g, &dh_p, &dh_q, NULL);
/* read the prime and generator*/
bytes_to_mp(&dh_p, (unsigned char*)dh_p_val, DH_P_LEN);
if (mp_set_int(&dh_g, DH_G_VAL) != MP_OKAY) {
dropbear_exit("Diffie-Hellman error");
}
/* calculate q = (p-1)/2 */
/* dh_priv is just a temp var here */
if (mp_sub_d(&dh_p, 1, dh_priv) != MP_OKAY) {
dropbear_exit("Diffie-Hellman error");
}
if (mp_div_2(dh_priv, &dh_q) != MP_OKAY) {
dropbear_exit("Diffie-Hellman error");
}
/* Generate a private portion 0 < dh_priv < dh_q */
gen_random_mpint(&dh_q, dh_priv);
/* f = g^y mod p */
if (mp_exptmod(&dh_g, dh_priv, &dh_p, dh_pub) != MP_OKAY) {
dropbear_exit("Diffie-Hellman error");
}
mp_clear_multi(&dh_g, &dh_p, &dh_q, NULL);
}
/* This function is fairly common between client/server, with some substitution
* of dh_e/dh_f etc. Hence these arguments:
* dh_pub_us is 'e' for the client, 'f' for the server. dh_pub_them is
* vice-versa. dh_priv is the x/y value corresponding to dh_pub_us */
void kexdh_comb_key(mp_int *dh_pub_us, mp_int *dh_priv, mp_int *dh_pub_them,
sign_key *hostkey) {
mp_int dh_p;
mp_int *dh_e = NULL, *dh_f = NULL;
hash_state hs;
/* read the prime and generator*/
m_mp_init(&dh_p);
bytes_to_mp(&dh_p, dh_p_val, DH_P_LEN);
/* Check that dh_pub_them (dh_e or dh_f) is in the range [1, p-1] */
if (mp_cmp(dh_pub_them, &dh_p) != MP_LT
|| mp_cmp_d(dh_pub_them, 0) != MP_GT) {
dropbear_exit("Diffie-Hellman error");
}
/* K = e^y mod p = f^x mod p */
ses.dh_K = (mp_int*)m_malloc(sizeof(mp_int));
m_mp_init(ses.dh_K);
if (mp_exptmod(dh_pub_them, dh_priv, &dh_p, ses.dh_K) != MP_OKAY) {
dropbear_exit("Diffie-Hellman error");
}
/* clear no longer needed vars */
mp_clear_multi(&dh_p, NULL);
/* From here on, the code needs to work with the _same_ vars on each side,
* not vice-versaing for client/server */
if (IS_DROPBEAR_CLIENT) {
dh_e = dh_pub_us;
dh_f = dh_pub_them;
} else {
dh_e = dh_pub_them;
dh_f = dh_pub_us;
}
/* Create the remainder of the hash buffer, to generate the exchange hash */
/* K_S, the host key */
buf_put_pub_key(ses.kexhashbuf, hostkey, ses.newkeys->algo_hostkey);
/* e, exchange value sent by the client */
buf_putmpint(ses.kexhashbuf, dh_e);
/* f, exchange value sent by the server */
buf_putmpint(ses.kexhashbuf, dh_f);
/* K, the shared secret */
buf_putmpint(ses.kexhashbuf, ses.dh_K);
/* calculate the hash H to sign */
sha1_init(&hs);
buf_setpos(ses.kexhashbuf, 0);
sha1_process(&hs, buf_getptr(ses.kexhashbuf, ses.kexhashbuf->len),
ses.kexhashbuf->len);
sha1_done(&hs, ses.hash);
buf_burn(ses.kexhashbuf);
buf_free(ses.kexhashbuf);
ses.kexhashbuf = NULL;
/* first time around, we set the session_id to H */
if (ses.session_id == NULL) {
/* create the session_id, this never needs freeing */
ses.session_id = (unsigned char*)m_malloc(SHA1_HASH_SIZE);
memcpy(ses.session_id, ses.hash, SHA1_HASH_SIZE);
}
}
/* read the other side's algo list. buf_match_algo is a callback to match
* algos for the client or server. */
static void read_kex_algos() {
/* for asymmetry */
algo_type * c2s_hash_algo = NULL;
algo_type * s2c_hash_algo = NULL;
algo_type * c2s_cipher_algo = NULL;
algo_type * s2c_cipher_algo = NULL;
algo_type * c2s_comp_algo = NULL;
algo_type * s2c_comp_algo = NULL;
/* the generic one */
algo_type * algo = NULL;
/* which algo couldn't match */
char * erralgo = NULL;
int goodguess = 0;
int allgood = 1; /* we AND this with each goodguess and see if its still
true after */
buf_incrpos(ses.payload, 16); /* start after the cookie */
ses.newkeys = (struct key_context*)m_malloc(sizeof(struct key_context));
/* kex_algorithms */
algo = ses.buf_match_algo(ses.payload, sshkex, &goodguess);
allgood &= goodguess;
if (algo == NULL) {
erralgo = "kex";
goto error;
}
TRACE(("kex algo %s", algo->name))
ses.newkeys->algo_kex = algo->val;
/* server_host_key_algorithms */
algo = ses.buf_match_algo(ses.payload, sshhostkey, &goodguess);
allgood &= goodguess;
if (algo == NULL) {
erralgo = "hostkey";
goto error;
}
TRACE(("hostkey algo %s", algo->name))
ses.newkeys->algo_hostkey = algo->val;
/* encryption_algorithms_client_to_server */
c2s_cipher_algo = ses.buf_match_algo(ses.payload, sshciphers, &goodguess);
if (c2s_cipher_algo == NULL) {
erralgo = "enc c->s";
goto error;
}
TRACE(("enc c2s is %s", c2s_cipher_algo->name))
/* encryption_algorithms_server_to_client */
s2c_cipher_algo = ses.buf_match_algo(ses.payload, sshciphers, &goodguess);
if (s2c_cipher_algo == NULL) {
erralgo = "enc s->c";
goto error;
}
TRACE(("enc s2c is %s", s2c_cipher_algo->name))
/* mac_algorithms_client_to_server */
c2s_hash_algo = ses.buf_match_algo(ses.payload, sshhashes, &goodguess);
if (c2s_hash_algo == NULL) {
erralgo = "mac c->s";
goto error;
}
TRACE(("hash c2s is %s", c2s_hash_algo->name))
/* mac_algorithms_server_to_client */
s2c_hash_algo = ses.buf_match_algo(ses.payload, sshhashes, &goodguess);
if (s2c_hash_algo == NULL) {
erralgo = "mac s->c";
goto error;
}
TRACE(("hash s2c is %s", s2c_hash_algo->name))
/* compression_algorithms_client_to_server */
c2s_comp_algo = ses.buf_match_algo(ses.payload, sshcompress, &goodguess);
if (c2s_comp_algo == NULL) {
erralgo = "comp c->s";
goto error;
}
TRACE(("hash c2s is %s", c2s_comp_algo->name))
/* compression_algorithms_server_to_client */
s2c_comp_algo = ses.buf_match_algo(ses.payload, sshcompress, &goodguess);
if (s2c_comp_algo == NULL) {
erralgo = "comp s->c";
goto error;
}
TRACE(("hash s2c is %s", s2c_comp_algo->name))
/* languages_client_to_server */
buf_eatstring(ses.payload);
/* languages_server_to_client */
buf_eatstring(ses.payload);
/* first_kex_packet_follows */
if (buf_getbool(ses.payload)) {
ses.kexstate.firstfollows = 1;
/* if the guess wasn't good, we ignore the packet sent */
if (!allgood) {
ses.ignorenext = 1;
}
}
/* Handle the asymmetry */
if (IS_DROPBEAR_CLIENT) {
ses.newkeys->recv_algo_crypt =
(struct dropbear_cipher*)s2c_cipher_algo->data;
ses.newkeys->trans_algo_crypt =
(struct dropbear_cipher*)c2s_cipher_algo->data;
ses.newkeys->recv_algo_mac =
(struct dropbear_hash*)s2c_hash_algo->data;
ses.newkeys->trans_algo_mac =
(struct dropbear_hash*)c2s_hash_algo->data;
ses.newkeys->recv_algo_comp = s2c_comp_algo->val;
ses.newkeys->trans_algo_comp = c2s_comp_algo->val;
} else {
/* SERVER */
ses.newkeys->recv_algo_crypt =
(struct dropbear_cipher*)c2s_cipher_algo->data;
ses.newkeys->trans_algo_crypt =
(struct dropbear_cipher*)s2c_cipher_algo->data;
ses.newkeys->recv_algo_mac =
(struct dropbear_hash*)c2s_hash_algo->data;
ses.newkeys->trans_algo_mac =
(struct dropbear_hash*)s2c_hash_algo->data;
ses.newkeys->recv_algo_comp = c2s_comp_algo->val;
ses.newkeys->trans_algo_comp = s2c_comp_algo->val;
}
/* reserved for future extensions */
buf_getint(ses.payload);
return;
error:
dropbear_exit("no matching algo %s", erralgo);
}