+
+ if (s->ignorepkt) /* first_kex_packet_follows */
+ crWaitUntilV(pktin); /* Ignore packet */
+ }
+
+ if (ssh->kex->main_type == KEXTYPE_DH) {
+ /*
+ * Work out the number of bits of key we will need from the
+ * key exchange. We start with the maximum key length of
+ * either cipher...
+ */
+ {
+ int csbits, scbits;
+
+ csbits = s->cscipher_tobe->keylen;
+ scbits = s->sccipher_tobe->keylen;
+ s->nbits = (csbits > scbits ? csbits : scbits);
+ }
+ /* The keys only have hlen-bit entropy, since they're based on
+ * a hash. So cap the key size at hlen bits. */
+ if (s->nbits > ssh->kex->hash->hlen * 8)
+ s->nbits = ssh->kex->hash->hlen * 8;
+
+ /*
+ * If we're doing Diffie-Hellman group exchange, start by
+ * requesting a group.
+ */
+ if (!ssh->kex->pdata) {
+ logevent("Doing Diffie-Hellman group exchange");
+ ssh->pkt_kctx = SSH2_PKTCTX_DHGEX;
+ /*
+ * Work out how big a DH group we will need to allow that
+ * much data.
+ */
+ s->pbits = 512 << ((s->nbits - 1) / 64);
+ s->pktout = ssh2_pkt_init(SSH2_MSG_KEX_DH_GEX_REQUEST);
+ ssh2_pkt_adduint32(s->pktout, s->pbits);
+ ssh2_pkt_send_noqueue(ssh, s->pktout);
+
+ crWaitUntilV(pktin);
+ if (pktin->type != SSH2_MSG_KEX_DH_GEX_GROUP) {
+ bombout(("expected key exchange group packet from server"));
+ crStopV;
+ }
+ s->p = ssh2_pkt_getmp(pktin);
+ s->g = ssh2_pkt_getmp(pktin);
+ if (!s->p || !s->g) {
+ bombout(("unable to read mp-ints from incoming group packet"));
+ crStopV;
+ }
+ ssh->kex_ctx = dh_setup_gex(s->p, s->g);
+ s->kex_init_value = SSH2_MSG_KEX_DH_GEX_INIT;
+ s->kex_reply_value = SSH2_MSG_KEX_DH_GEX_REPLY;
+ } else {
+ ssh->pkt_kctx = SSH2_PKTCTX_DHGROUP;
+ ssh->kex_ctx = dh_setup_group(ssh->kex);
+ s->kex_init_value = SSH2_MSG_KEXDH_INIT;
+ s->kex_reply_value = SSH2_MSG_KEXDH_REPLY;
+ logeventf(ssh, "Using Diffie-Hellman with standard group \"%s\"",
+ ssh->kex->groupname);
+ }
+
+ logeventf(ssh, "Doing Diffie-Hellman key exchange with hash %s",
+ ssh->kex->hash->text_name);
+ /*
+ * Now generate and send e for Diffie-Hellman.
+ */
+ set_busy_status(ssh->frontend, BUSY_CPU); /* this can take a while */
+ s->e = dh_create_e(ssh->kex_ctx, s->nbits * 2);
+ s->pktout = ssh2_pkt_init(s->kex_init_value);
+ ssh2_pkt_addmp(s->pktout, s->e);
+ ssh2_pkt_send_noqueue(ssh, s->pktout);
+
+ set_busy_status(ssh->frontend, BUSY_WAITING); /* wait for server */
+ crWaitUntilV(pktin);
+ if (pktin->type != s->kex_reply_value) {
+ bombout(("expected key exchange reply packet from server"));
+ crStopV;
+ }
+ set_busy_status(ssh->frontend, BUSY_CPU); /* cogitate */
+ ssh_pkt_getstring(pktin, &s->hostkeydata, &s->hostkeylen);
+ s->hkey = ssh->hostkey->newkey(s->hostkeydata, s->hostkeylen);
+ s->f = ssh2_pkt_getmp(pktin);
+ if (!s->f) {
+ bombout(("unable to parse key exchange reply packet"));
+ crStopV;
+ }
+ ssh_pkt_getstring(pktin, &s->sigdata, &s->siglen);
+
+ s->K = dh_find_K(ssh->kex_ctx, s->f);
+
+ /* We assume everything from now on will be quick, and it might
+ * involve user interaction. */
+ set_busy_status(ssh->frontend, BUSY_NOT);
+
+ hash_string(ssh->kex->hash, ssh->exhash, s->hostkeydata, s->hostkeylen);
+ if (!ssh->kex->pdata) {
+ hash_uint32(ssh->kex->hash, ssh->exhash, s->pbits);
+ hash_mpint(ssh->kex->hash, ssh->exhash, s->p);
+ hash_mpint(ssh->kex->hash, ssh->exhash, s->g);
+ }
+ hash_mpint(ssh->kex->hash, ssh->exhash, s->e);
+ hash_mpint(ssh->kex->hash, ssh->exhash, s->f);
+
+ dh_cleanup(ssh->kex_ctx);
+ freebn(s->f);
+ if (!ssh->kex->pdata) {
+ freebn(s->g);
+ freebn(s->p);
+ }
+ } else {
+ logeventf(ssh, "Doing RSA key exchange with hash %s",
+ ssh->kex->hash->text_name);
+ ssh->pkt_kctx = SSH2_PKTCTX_RSAKEX;
+ /*
+ * RSA key exchange. First expect a KEXRSA_PUBKEY packet
+ * from the server.
+ */
+ crWaitUntilV(pktin);
+ if (pktin->type != SSH2_MSG_KEXRSA_PUBKEY) {
+ bombout(("expected RSA public key packet from server"));
+ crStopV;
+ }
+
+ ssh_pkt_getstring(pktin, &s->hostkeydata, &s->hostkeylen);
+ hash_string(ssh->kex->hash, ssh->exhash,
+ s->hostkeydata, s->hostkeylen);
+ s->hkey = ssh->hostkey->newkey(s->hostkeydata, s->hostkeylen);
+
+ {
+ char *keydata;
+ ssh_pkt_getstring(pktin, &keydata, &s->rsakeylen);
+ s->rsakeydata = snewn(s->rsakeylen, char);
+ memcpy(s->rsakeydata, keydata, s->rsakeylen);
+ }
+
+ s->rsakey = ssh_rsakex_newkey(s->rsakeydata, s->rsakeylen);
+ if (!s->rsakey) {
+ sfree(s->rsakeydata);
+ bombout(("unable to parse RSA public key from server"));
+ crStopV;
+ }
+
+ hash_string(ssh->kex->hash, ssh->exhash, s->rsakeydata, s->rsakeylen);
+
+ /*
+ * Next, set up a shared secret K, of precisely KLEN -
+ * 2*HLEN - 49 bits, where KLEN is the bit length of the
+ * RSA key modulus and HLEN is the bit length of the hash
+ * we're using.
+ */
+ {
+ int klen = ssh_rsakex_klen(s->rsakey);
+ int nbits = klen - (2*ssh->kex->hash->hlen*8 + 49);
+ int i, byte = 0;
+ unsigned char *kstr1, *kstr2, *outstr;
+ int kstr1len, kstr2len, outstrlen;
+
+ s->K = bn_power_2(nbits - 1);
+
+ for (i = 0; i < nbits; i++) {
+ if ((i & 7) == 0) {
+ byte = random_byte();
+ }
+ bignum_set_bit(s->K, i, (byte >> (i & 7)) & 1);
+ }
+
+ /*
+ * Encode this as an mpint.
+ */
+ kstr1 = ssh2_mpint_fmt(s->K, &kstr1len);
+ kstr2 = snewn(kstr2len = 4 + kstr1len, unsigned char);
+ PUT_32BIT(kstr2, kstr1len);
+ memcpy(kstr2 + 4, kstr1, kstr1len);
+
+ /*
+ * Encrypt it with the given RSA key.
+ */
+ outstrlen = (klen + 7) / 8;
+ outstr = snewn(outstrlen, unsigned char);
+ ssh_rsakex_encrypt(ssh->kex->hash, kstr2, kstr2len,
+ outstr, outstrlen, s->rsakey);
+
+ /*
+ * And send it off in a return packet.
+ */
+ s->pktout = ssh2_pkt_init(SSH2_MSG_KEXRSA_SECRET);
+ ssh2_pkt_addstring_start(s->pktout);
+ ssh2_pkt_addstring_data(s->pktout, (char *)outstr, outstrlen);
+ ssh2_pkt_send_noqueue(ssh, s->pktout);
+
+ hash_string(ssh->kex->hash, ssh->exhash, outstr, outstrlen);
+
+ sfree(kstr2);
+ sfree(kstr1);
+ sfree(outstr);
+ }
+
+ ssh_rsakex_freekey(s->rsakey);
+
+ crWaitUntilV(pktin);
+ if (pktin->type != SSH2_MSG_KEXRSA_DONE) {
+ sfree(s->rsakeydata);
+ bombout(("expected signature packet from server"));
+ crStopV;
+ }
+
+ ssh_pkt_getstring(pktin, &s->sigdata, &s->siglen);
+
+ sfree(s->rsakeydata);
+ }
+
+ hash_mpint(ssh->kex->hash, ssh->exhash, s->K);
+ assert(ssh->kex->hash->hlen <= sizeof(s->exchange_hash));
+ ssh->kex->hash->final(ssh->exhash, s->exchange_hash);
+
+ ssh->kex_ctx = NULL;
+
+#if 0
+ debug(("Exchange hash is:\n"));
+ dmemdump(s->exchange_hash, ssh->kex->hash->hlen);
+#endif
+
+ if (!s->hkey ||
+ !ssh->hostkey->verifysig(s->hkey, s->sigdata, s->siglen,
+ (char *)s->exchange_hash,
+ ssh->kex->hash->hlen)) {
+ bombout(("Server's host key did not match the signature supplied"));
+ crStopV;
+ }
+
+ /*
+ * Authenticate remote host: verify host key. (We've already
+ * checked the signature of the exchange hash.)
+ */
+ s->keystr = ssh->hostkey->fmtkey(s->hkey);
+ s->fingerprint = ssh->hostkey->fingerprint(s->hkey);
+ ssh_set_frozen(ssh, 1);
+ s->dlgret = verify_ssh_host_key(ssh->frontend,
+ ssh->savedhost, ssh->savedport,
+ ssh->hostkey->keytype, s->keystr,
+ s->fingerprint,
+ ssh_dialog_callback, ssh);
+ if (s->dlgret < 0) {
+ do {
+ crReturnV;
+ if (pktin) {
+ bombout(("Unexpected data from server while waiting"
+ " for user host key response"));
+ crStopV;
+ }
+ } while (pktin || inlen > 0);
+ s->dlgret = ssh->user_response;
+ }
+ ssh_set_frozen(ssh, 0);
+ if (s->dlgret == 0) {
+ ssh_disconnect(ssh, "User aborted at host key verification", NULL,
+ 0, TRUE);
+ crStopV;
+ }
+ if (!s->got_session_id) { /* don't bother logging this in rekeys */
+ logevent("Host key fingerprint is:");
+ logevent(s->fingerprint);
+ }
+ sfree(s->fingerprint);
+ sfree(s->keystr);
+ ssh->hostkey->freekey(s->hkey);
+
+ /*
+ * The exchange hash from the very first key exchange is also
+ * the session id, used in session key construction and
+ * authentication.
+ */
+ if (!s->got_session_id) {
+ assert(sizeof(s->exchange_hash) <= sizeof(ssh->v2_session_id));
+ memcpy(ssh->v2_session_id, s->exchange_hash,
+ sizeof(s->exchange_hash));
+ ssh->v2_session_id_len = ssh->kex->hash->hlen;
+ assert(ssh->v2_session_id_len <= sizeof(ssh->v2_session_id));
+ s->got_session_id = TRUE;
+ }
+
+ /*
+ * Send SSH2_MSG_NEWKEYS.
+ */
+ s->pktout = ssh2_pkt_init(SSH2_MSG_NEWKEYS);
+ ssh2_pkt_send_noqueue(ssh, s->pktout);
+ ssh->outgoing_data_size = 0; /* start counting from here */
+
+ /*
+ * We've sent client NEWKEYS, so create and initialise
+ * client-to-server session keys.
+ */
+ if (ssh->cs_cipher_ctx)
+ ssh->cscipher->free_context(ssh->cs_cipher_ctx);
+ ssh->cscipher = s->cscipher_tobe;
+ ssh->cs_cipher_ctx = ssh->cscipher->make_context();
+
+ if (ssh->cs_mac_ctx)
+ ssh->csmac->free_context(ssh->cs_mac_ctx);
+ ssh->csmac = s->csmac_tobe;
+ ssh->cs_mac_ctx = ssh->csmac->make_context();
+
+ if (ssh->cs_comp_ctx)
+ ssh->cscomp->compress_cleanup(ssh->cs_comp_ctx);
+ ssh->cscomp = s->cscomp_tobe;
+ ssh->cs_comp_ctx = ssh->cscomp->compress_init();
+
+ /*
+ * Set IVs on client-to-server keys. Here we use the exchange
+ * hash from the _first_ key exchange.
+ */
+ {
+ unsigned char keyspace[SSH2_KEX_MAX_HASH_LEN * SSH2_MKKEY_ITERS];
+ assert(sizeof(keyspace) >= ssh->kex->hash->hlen * SSH2_MKKEY_ITERS);
+ ssh2_mkkey(ssh,s->K,s->exchange_hash,'C',keyspace);
+ assert((ssh->cscipher->keylen+7) / 8 <=
+ ssh->kex->hash->hlen * SSH2_MKKEY_ITERS);
+ ssh->cscipher->setkey(ssh->cs_cipher_ctx, keyspace);
+ ssh2_mkkey(ssh,s->K,s->exchange_hash,'A',keyspace);
+ assert(ssh->cscipher->blksize <=
+ ssh->kex->hash->hlen * SSH2_MKKEY_ITERS);
+ ssh->cscipher->setiv(ssh->cs_cipher_ctx, keyspace);
+ ssh2_mkkey(ssh,s->K,s->exchange_hash,'E',keyspace);
+ assert(ssh->csmac->len <=
+ ssh->kex->hash->hlen * SSH2_MKKEY_ITERS);
+ ssh->csmac->setkey(ssh->cs_mac_ctx, keyspace);
+ smemclr(keyspace, sizeof(keyspace));
+ }
+
+ logeventf(ssh, "Initialised %.200s client->server encryption",
+ ssh->cscipher->text_name);
+ logeventf(ssh, "Initialised %.200s client->server MAC algorithm",
+ ssh->csmac->text_name);
+ if (ssh->cscomp->text_name)
+ logeventf(ssh, "Initialised %s compression",
+ ssh->cscomp->text_name);
+
+ /*
+ * Now our end of the key exchange is complete, we can send all
+ * our queued higher-layer packets.
+ */
+ ssh->queueing = FALSE;
+ ssh2_pkt_queuesend(ssh);
+
+ /*
+ * Expect SSH2_MSG_NEWKEYS from server.
+ */
+ crWaitUntilV(pktin);
+ if (pktin->type != SSH2_MSG_NEWKEYS) {
+ bombout(("expected new-keys packet from server"));
+ crStopV;
+ }
+ ssh->incoming_data_size = 0; /* start counting from here */
+
+ /*
+ * We've seen server NEWKEYS, so create and initialise
+ * server-to-client session keys.
+ */
+ if (ssh->sc_cipher_ctx)
+ ssh->sccipher->free_context(ssh->sc_cipher_ctx);
+ ssh->sccipher = s->sccipher_tobe;
+ ssh->sc_cipher_ctx = ssh->sccipher->make_context();
+
+ if (ssh->sc_mac_ctx)
+ ssh->scmac->free_context(ssh->sc_mac_ctx);
+ ssh->scmac = s->scmac_tobe;
+ ssh->sc_mac_ctx = ssh->scmac->make_context();
+
+ if (ssh->sc_comp_ctx)
+ ssh->sccomp->decompress_cleanup(ssh->sc_comp_ctx);
+ ssh->sccomp = s->sccomp_tobe;
+ ssh->sc_comp_ctx = ssh->sccomp->decompress_init();
+
+ /*
+ * Set IVs on server-to-client keys. Here we use the exchange
+ * hash from the _first_ key exchange.
+ */
+ {
+ unsigned char keyspace[SSH2_KEX_MAX_HASH_LEN * SSH2_MKKEY_ITERS];
+ assert(sizeof(keyspace) >= ssh->kex->hash->hlen * SSH2_MKKEY_ITERS);
+ ssh2_mkkey(ssh,s->K,s->exchange_hash,'D',keyspace);
+ assert((ssh->sccipher->keylen+7) / 8 <=
+ ssh->kex->hash->hlen * SSH2_MKKEY_ITERS);
+ ssh->sccipher->setkey(ssh->sc_cipher_ctx, keyspace);
+ ssh2_mkkey(ssh,s->K,s->exchange_hash,'B',keyspace);
+ assert(ssh->sccipher->blksize <=
+ ssh->kex->hash->hlen * SSH2_MKKEY_ITERS);
+ ssh->sccipher->setiv(ssh->sc_cipher_ctx, keyspace);
+ ssh2_mkkey(ssh,s->K,s->exchange_hash,'F',keyspace);
+ assert(ssh->scmac->len <=
+ ssh->kex->hash->hlen * SSH2_MKKEY_ITERS);
+ ssh->scmac->setkey(ssh->sc_mac_ctx, keyspace);
+ smemclr(keyspace, sizeof(keyspace));
+ }
+ logeventf(ssh, "Initialised %.200s server->client encryption",
+ ssh->sccipher->text_name);
+ logeventf(ssh, "Initialised %.200s server->client MAC algorithm",
+ ssh->scmac->text_name);
+ if (ssh->sccomp->text_name)
+ logeventf(ssh, "Initialised %s decompression",
+ ssh->sccomp->text_name);
+
+ /*
+ * Free shared secret.
+ */
+ freebn(s->K);
+
+ /*
+ * Key exchange is over. Loop straight back round if we have a
+ * deferred rekey reason.
+ */
+ if (ssh->deferred_rekey_reason) {
+ logevent(ssh->deferred_rekey_reason);
+ pktin = NULL;
+ ssh->deferred_rekey_reason = NULL;
+ goto begin_key_exchange;
+ }
+
+ /*
+ * Otherwise, schedule a timer for our next rekey.
+ */
+ ssh->kex_in_progress = FALSE;
+ ssh->last_rekey = GETTICKCOUNT();
+ if (conf_get_int(ssh->conf, CONF_ssh_rekey_time) != 0)
+ ssh->next_rekey = schedule_timer(conf_get_int(ssh->conf, CONF_ssh_rekey_time)*60*TICKSPERSEC,
+ ssh2_timer, ssh);
+
+ /*
+ * Now we're encrypting. Begin returning 1 to the protocol main
+ * function so that other things can run on top of the
+ * transport. If we ever see a KEXINIT, we must go back to the
+ * start.
+ *
+ * We _also_ go back to the start if we see pktin==NULL and
+ * inlen negative, because this is a special signal meaning
+ * `initiate client-driven rekey', and `in' contains a message
+ * giving the reason for the rekey.
+ *
+ * inlen==-1 means always initiate a rekey;
+ * inlen==-2 means that userauth has completed successfully and
+ * we should consider rekeying (for delayed compression).
+ */
+ while (!((pktin && pktin->type == SSH2_MSG_KEXINIT) ||
+ (!pktin && inlen < 0))) {
+ wait_for_rekey:
+ if (!ssh->protocol_initial_phase_done) {
+ ssh->protocol_initial_phase_done = TRUE;
+ /*
+ * Allow authconn to initialise itself.
+ */
+ do_ssh2_authconn(ssh, NULL, 0, NULL);
+ }
+ crReturnV;
+ }
+ if (pktin) {
+ logevent("Server initiated key re-exchange");
+ } else {
+ if (inlen == -2) {
+ /*
+ * authconn has seen a USERAUTH_SUCCEEDED. Time to enable
+ * delayed compression, if it's available.
+ *
+ * draft-miller-secsh-compression-delayed-00 says that you
+ * negotiate delayed compression in the first key exchange, and
+ * both sides start compressing when the server has sent
+ * USERAUTH_SUCCESS. This has a race condition -- the server
+ * can't know when the client has seen it, and thus which incoming
+ * packets it should treat as compressed.
+ *
+ * Instead, we do the initial key exchange without offering the
+ * delayed methods, but note if the server offers them; when we
+ * get here, if a delayed method was available that was higher
+ * on our list than what we got, we initiate a rekey in which we
+ * _do_ list the delayed methods (and hopefully get it as a
+ * result). Subsequent rekeys will do the same.
+ */
+ assert(!s->userauth_succeeded); /* should only happen once */
+ s->userauth_succeeded = TRUE;
+ if (!s->pending_compression)
+ /* Can't see any point rekeying. */
+ goto wait_for_rekey; /* this is utterly horrid */
+ /* else fall through to rekey... */
+ s->pending_compression = FALSE;
+ }
+ /*
+ * Now we've decided to rekey.
+ *
+ * Special case: if the server bug is set that doesn't
+ * allow rekeying, we give a different log message and
+ * continue waiting. (If such a server _initiates_ a rekey,
+ * we process it anyway!)
+ */
+ if ((ssh->remote_bugs & BUG_SSH2_REKEY)) {
+ logeventf(ssh, "Server bug prevents key re-exchange (%s)",
+ (char *)in);
+ /* Reset the counters, so that at least this message doesn't
+ * hit the event log _too_ often. */
+ ssh->outgoing_data_size = 0;
+ ssh->incoming_data_size = 0;
+ if (conf_get_int(ssh->conf, CONF_ssh_rekey_time) != 0) {
+ ssh->next_rekey =
+ schedule_timer(conf_get_int(ssh->conf, CONF_ssh_rekey_time)*60*TICKSPERSEC,
+ ssh2_timer, ssh);
+ }
+ goto wait_for_rekey; /* this is still utterly horrid */
+ } else {
+ logeventf(ssh, "Initiating key re-exchange (%s)", (char *)in);
+ }
+ }
+ goto begin_key_exchange;
+
+ crFinishV;
+}
+
+/*
+ * Add data to an SSH-2 channel output buffer.
+ */
+static void ssh2_add_channel_data(struct ssh_channel *c, char *buf,
+ int len)
+{
+ bufchain_add(&c->v.v2.outbuffer, buf, len);
+}
+
+/*
+ * Attempt to send data on an SSH-2 channel.
+ */
+static int ssh2_try_send(struct ssh_channel *c)
+{
+ Ssh ssh = c->ssh;
+ struct Packet *pktout;
+ int ret;
+
+ while (c->v.v2.remwindow > 0 && bufchain_size(&c->v.v2.outbuffer) > 0) {
+ int len;
+ void *data;
+ bufchain_prefix(&c->v.v2.outbuffer, &data, &len);
+ if ((unsigned)len > c->v.v2.remwindow)
+ len = c->v.v2.remwindow;
+ if ((unsigned)len > c->v.v2.remmaxpkt)
+ len = c->v.v2.remmaxpkt;
+ pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_DATA);
+ ssh2_pkt_adduint32(pktout, c->remoteid);
+ ssh2_pkt_addstring_start(pktout);
+ dont_log_data(ssh, pktout, PKTLOG_OMIT);
+ ssh2_pkt_addstring_data(pktout, data, len);
+ end_log_omission(ssh, pktout);
+ ssh2_pkt_send(ssh, pktout);
+ bufchain_consume(&c->v.v2.outbuffer, len);
+ c->v.v2.remwindow -= len;
+ }
+
+ /*
+ * After having sent as much data as we can, return the amount
+ * still buffered.
+ */
+ ret = bufchain_size(&c->v.v2.outbuffer);
+
+ /*
+ * And if there's no data pending but we need to send an EOF, send
+ * it.
+ */
+ if (!ret && c->pending_eof)
+ ssh_channel_try_eof(c);
+
+ return ret;
+}
+
+static void ssh2_try_send_and_unthrottle(Ssh ssh, struct ssh_channel *c)
+{
+ int bufsize;
+ if (c->closes & CLOSES_SENT_EOF)
+ return; /* don't send on channels we've EOFed */
+ bufsize = ssh2_try_send(c);
+ if (bufsize == 0) {
+ switch (c->type) {
+ case CHAN_MAINSESSION:
+ /* stdin need not receive an unthrottle
+ * notification since it will be polled */
+ break;
+ case CHAN_X11:
+ x11_unthrottle(c->u.x11.s);
+ break;
+ case CHAN_AGENT:
+ /* agent sockets are request/response and need no
+ * buffer management */
+ break;
+ case CHAN_SOCKDATA:
+ pfd_unthrottle(c->u.pfd.s);
+ break;
+ }
+ }
+}
+
+/*
+ * Set up most of a new ssh_channel for SSH-2.
+ */
+static void ssh2_channel_init(struct ssh_channel *c)
+{
+ Ssh ssh = c->ssh;
+ c->localid = alloc_channel_id(ssh);
+ c->closes = 0;
+ c->pending_eof = FALSE;
+ c->throttling_conn = FALSE;
+ c->v.v2.locwindow = c->v.v2.locmaxwin = c->v.v2.remlocwin =
+ conf_get_int(ssh->conf, CONF_ssh_simple) ? OUR_V2_BIGWIN : OUR_V2_WINSIZE;
+ c->v.v2.chanreq_head = NULL;
+ c->v.v2.throttle_state = UNTHROTTLED;
+ bufchain_init(&c->v.v2.outbuffer);
+}
+
+/*
+ * Construct the common parts of a CHANNEL_OPEN.
+ */
+static struct Packet *ssh2_chanopen_init(struct ssh_channel *c, char *type)
+{
+ struct Packet *pktout;
+
+ pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_OPEN);
+ ssh2_pkt_addstring(pktout, type);
+ ssh2_pkt_adduint32(pktout, c->localid);
+ ssh2_pkt_adduint32(pktout, c->v.v2.locwindow);/* our window size */
+ ssh2_pkt_adduint32(pktout, OUR_V2_MAXPKT); /* our max pkt size */
+ return pktout;
+}
+
+/*
+ * CHANNEL_FAILURE doesn't come with any indication of what message
+ * caused it, so we have to keep track of the outstanding
+ * CHANNEL_REQUESTs ourselves.
+ */
+static void ssh2_queue_chanreq_handler(struct ssh_channel *c,
+ cchandler_fn_t handler, void *ctx)
+{
+ struct outstanding_channel_request *ocr =
+ snew(struct outstanding_channel_request);
+
+ assert(!(c->closes & (CLOSES_SENT_CLOSE | CLOSES_RCVD_CLOSE)));
+ ocr->handler = handler;
+ ocr->ctx = ctx;
+ ocr->next = NULL;
+ if (!c->v.v2.chanreq_head)
+ c->v.v2.chanreq_head = ocr;
+ else
+ c->v.v2.chanreq_tail->next = ocr;
+ c->v.v2.chanreq_tail = ocr;
+}
+
+/*
+ * Construct the common parts of a CHANNEL_REQUEST. If handler is not
+ * NULL then a reply will be requested and the handler will be called
+ * when it arrives. The returned packet is ready to have any
+ * request-specific data added and be sent. Note that if a handler is
+ * provided, it's essential that the request actually be sent.
+ *
+ * The handler will usually be passed the response packet in pktin.
+ * If pktin is NULL, this means that no reply will ever be forthcoming
+ * (e.g. because the entire connection is being destroyed) and the
+ * handler should free any storage it's holding.
+ */
+static struct Packet *ssh2_chanreq_init(struct ssh_channel *c, char *type,
+ cchandler_fn_t handler, void *ctx)
+{
+ struct Packet *pktout;
+
+ assert(!(c->closes & (CLOSES_SENT_CLOSE | CLOSES_RCVD_CLOSE)));
+ pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
+ ssh2_pkt_adduint32(pktout, c->remoteid);
+ ssh2_pkt_addstring(pktout, type);
+ ssh2_pkt_addbool(pktout, handler != NULL);
+ if (handler != NULL)
+ ssh2_queue_chanreq_handler(c, handler, ctx);
+ return pktout;
+}
+
+/*
+ * Potentially enlarge the window on an SSH-2 channel.
+ */
+static void ssh2_handle_winadj_response(struct ssh_channel *, struct Packet *,
+ void *);
+static void ssh2_set_window(struct ssh_channel *c, int newwin)
+{
+ Ssh ssh = c->ssh;
+
+ /*
+ * Never send WINDOW_ADJUST for a channel that the remote side has
+ * already sent EOF on; there's no point, since it won't be
+ * sending any more data anyway. Ditto if _we've_ already sent
+ * CLOSE.
+ */
+ if (c->closes & (CLOSES_RCVD_EOF | CLOSES_SENT_CLOSE))
+ return;
+
+ /*
+ * If the remote end has a habit of ignoring maxpkt, limit the
+ * window so that it has no choice (assuming it doesn't ignore the
+ * window as well).
+ */
+ if ((ssh->remote_bugs & BUG_SSH2_MAXPKT) && newwin > OUR_V2_MAXPKT)
+ newwin = OUR_V2_MAXPKT;
+
+ /*
+ * Only send a WINDOW_ADJUST if there's significantly more window
+ * available than the other end thinks there is. This saves us
+ * sending a WINDOW_ADJUST for every character in a shell session.
+ *
+ * "Significant" is arbitrarily defined as half the window size.
+ */
+ if (newwin / 2 >= c->v.v2.locwindow) {
+ struct Packet *pktout;
+ unsigned *up;
+
+ /*
+ * In order to keep track of how much window the client
+ * actually has available, we'd like it to acknowledge each
+ * WINDOW_ADJUST. We can't do that directly, so we accompany
+ * it with a CHANNEL_REQUEST that has to be acknowledged.
+ *
+ * This is only necessary if we're opening the window wide.
+ * If we're not, then throughput is being constrained by
+ * something other than the maximum window size anyway.
+ */
+ if (newwin == c->v.v2.locmaxwin &&
+ !(ssh->remote_bugs & BUG_CHOKES_ON_WINADJ)) {
+ up = snew(unsigned);
+ *up = newwin - c->v.v2.locwindow;
+ pktout = ssh2_chanreq_init(c, "winadj@putty.projects.tartarus.org",
+ ssh2_handle_winadj_response, up);
+ ssh2_pkt_send(ssh, pktout);
+
+ if (c->v.v2.throttle_state != UNTHROTTLED)
+ c->v.v2.throttle_state = UNTHROTTLING;
+ } else {
+ /* Pretend the WINDOW_ADJUST was acked immediately. */
+ c->v.v2.remlocwin = newwin;
+ c->v.v2.throttle_state = THROTTLED;
+ }
+ pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
+ ssh2_pkt_adduint32(pktout, c->remoteid);
+ ssh2_pkt_adduint32(pktout, newwin - c->v.v2.locwindow);
+ ssh2_pkt_send(ssh, pktout);
+ c->v.v2.locwindow = newwin;
+ }
+}
+
+/*
+ * Find the channel associated with a message. If there's no channel,
+ * or it's not properly open, make a noise about it and return NULL.
+ */
+static struct ssh_channel *ssh2_channel_msg(Ssh ssh, struct Packet *pktin)
+{
+ unsigned localid = ssh_pkt_getuint32(pktin);
+ struct ssh_channel *c;
+
+ c = find234(ssh->channels, &localid, ssh_channelfind);
+ if (!c ||
+ (c->halfopen && pktin->type != SSH2_MSG_CHANNEL_OPEN_CONFIRMATION &&
+ pktin->type != SSH2_MSG_CHANNEL_OPEN_FAILURE)) {
+ char *buf = dupprintf("Received %s for %s channel %u",
+ ssh2_pkt_type(ssh->pkt_kctx, ssh->pkt_actx,
+ pktin->type),
+ c ? "half-open" : "nonexistent", localid);
+ ssh_disconnect(ssh, NULL, buf, SSH2_DISCONNECT_PROTOCOL_ERROR, FALSE);
+ sfree(buf);
+ return NULL;
+ }
+ return c;
+}
+
+static void ssh2_handle_winadj_response(struct ssh_channel *c,
+ struct Packet *pktin, void *ctx)
+{
+ unsigned *sizep = ctx;
+
+ /*
+ * Winadj responses should always be failures. However, at least
+ * one server ("boks_sshd") is known to return SUCCESS for channel
+ * requests it's never heard of, such as "winadj@putty". Raised
+ * with foxt.com as bug 090916-090424, but for the sake of a quiet
+ * life, we don't worry about what kind of response we got.
+ */
+
+ c->v.v2.remlocwin += *sizep;
+ sfree(sizep);
+ /*
+ * winadj messages are only sent when the window is fully open, so
+ * if we get an ack of one, we know any pending unthrottle is
+ * complete.
+ */
+ if (c->v.v2.throttle_state == UNTHROTTLING)
+ c->v.v2.throttle_state = UNTHROTTLED;
+}
+
+static void ssh2_msg_channel_response(Ssh ssh, struct Packet *pktin)
+{
+ struct ssh_channel *c = ssh2_channel_msg(ssh, pktin);
+ struct outstanding_channel_request *ocr;
+
+ if (!c) return;
+ ocr = c->v.v2.chanreq_head;
+ if (!ocr) {
+ ssh2_msg_unexpected(ssh, pktin);
+ return;
+ }
+ ocr->handler(c, pktin, ocr->ctx);
+ c->v.v2.chanreq_head = ocr->next;
+ sfree(ocr);
+ /*
+ * We may now initiate channel-closing procedures, if that
+ * CHANNEL_REQUEST was the last thing outstanding before we send
+ * CHANNEL_CLOSE.
+ */
+ ssh2_channel_check_close(c);
+}
+
+static void ssh2_msg_channel_window_adjust(Ssh ssh, struct Packet *pktin)
+{
+ struct ssh_channel *c;
+ c = ssh2_channel_msg(ssh, pktin);
+ if (!c)
+ return;
+ if (!(c->closes & CLOSES_SENT_EOF)) {
+ c->v.v2.remwindow += ssh_pkt_getuint32(pktin);
+ ssh2_try_send_and_unthrottle(ssh, c);
+ }
+}
+
+static void ssh2_msg_channel_data(Ssh ssh, struct Packet *pktin)
+{
+ char *data;
+ int length;
+ struct ssh_channel *c;
+ c = ssh2_channel_msg(ssh, pktin);
+ if (!c)
+ return;
+ if (pktin->type == SSH2_MSG_CHANNEL_EXTENDED_DATA &&
+ ssh_pkt_getuint32(pktin) != SSH2_EXTENDED_DATA_STDERR)
+ return; /* extended but not stderr */
+ ssh_pkt_getstring(pktin, &data, &length);
+ if (data) {
+ int bufsize = 0;
+ c->v.v2.locwindow -= length;
+ c->v.v2.remlocwin -= length;
+ switch (c->type) {
+ case CHAN_MAINSESSION:
+ bufsize =
+ from_backend(ssh->frontend, pktin->type ==
+ SSH2_MSG_CHANNEL_EXTENDED_DATA,
+ data, length);
+ break;
+ case CHAN_X11:
+ bufsize = x11_send(c->u.x11.s, data, length);
+ break;
+ case CHAN_SOCKDATA:
+ bufsize = pfd_send(c->u.pfd.s, data, length);
+ break;
+ case CHAN_AGENT:
+ while (length > 0) {
+ if (c->u.a.lensofar < 4) {
+ unsigned int l = min(4 - c->u.a.lensofar,
+ (unsigned)length);
+ memcpy(c->u.a.msglen + c->u.a.lensofar,
+ data, l);
+ data += l;
+ length -= l;
+ c->u.a.lensofar += l;
+ }
+ if (c->u.a.lensofar == 4) {
+ c->u.a.totallen =
+ 4 + GET_32BIT(c->u.a.msglen);
+ c->u.a.message = snewn(c->u.a.totallen,
+ unsigned char);
+ memcpy(c->u.a.message, c->u.a.msglen, 4);
+ }
+ if (c->u.a.lensofar >= 4 && length > 0) {
+ unsigned int l =
+ min(c->u.a.totallen - c->u.a.lensofar,
+ (unsigned)length);
+ memcpy(c->u.a.message + c->u.a.lensofar,
+ data, l);
+ data += l;
+ length -= l;
+ c->u.a.lensofar += l;
+ }
+ if (c->u.a.lensofar == c->u.a.totallen) {
+ void *reply;
+ int replylen;
+ c->u.a.outstanding_requests++;
+ if (agent_query(c->u.a.message,
+ c->u.a.totallen,
+ &reply, &replylen,
+ ssh_agentf_callback, c))
+ ssh_agentf_callback(c, reply, replylen);
+ sfree(c->u.a.message);
+ c->u.a.message = NULL;
+ c->u.a.lensofar = 0;
+ }
+ }
+ bufsize = 0;
+ break;
+ }
+ /*
+ * If it looks like the remote end hit the end of its window,
+ * and we didn't want it to do that, think about using a
+ * larger window.
+ */
+ if (c->v.v2.remlocwin <= 0 && c->v.v2.throttle_state == UNTHROTTLED &&
+ c->v.v2.locmaxwin < 0x40000000)
+ c->v.v2.locmaxwin += OUR_V2_WINSIZE;
+ /*
+ * If we are not buffering too much data,
+ * enlarge the window again at the remote side.
+ * If we are buffering too much, we may still
+ * need to adjust the window if the server's
+ * sent excess data.
+ */
+ ssh2_set_window(c, bufsize < c->v.v2.locmaxwin ?
+ c->v.v2.locmaxwin - bufsize : 0);
+ /*
+ * If we're either buffering way too much data, or if we're
+ * buffering anything at all and we're in "simple" mode,
+ * throttle the whole channel.
+ */
+ if ((bufsize > c->v.v2.locmaxwin ||
+ (conf_get_int(ssh->conf, CONF_ssh_simple) && bufsize > 0)) &&
+ !c->throttling_conn) {
+ c->throttling_conn = 1;
+ ssh_throttle_conn(ssh, +1);
+ }
+ }
+}
+
+static void ssh_channel_destroy(struct ssh_channel *c)
+{
+ Ssh ssh = c->ssh;
+
+ switch (c->type) {
+ case CHAN_MAINSESSION:
+ ssh->mainchan = NULL;
+ update_specials_menu(ssh->frontend);
+ break;
+ case CHAN_X11:
+ if (c->u.x11.s != NULL)
+ x11_close(c->u.x11.s);
+ logevent("Forwarded X11 connection terminated");
+ break;
+ case CHAN_AGENT:
+ sfree(c->u.a.message);
+ break;
+ case CHAN_SOCKDATA:
+ if (c->u.pfd.s != NULL)
+ pfd_close(c->u.pfd.s);
+ logevent("Forwarded port closed");
+ break;
+ }
+
+ del234(ssh->channels, c);
+ if (ssh->version == 2) {
+ bufchain_clear(&c->v.v2.outbuffer);
+ assert(c->v.v2.chanreq_head == NULL);
+ }
+ sfree(c);
+
+ /*
+ * See if that was the last channel left open.
+ * (This is only our termination condition if we're
+ * not running in -N mode.)
+ */
+ if (ssh->version == 2 &&
+ !conf_get_int(ssh->conf, CONF_ssh_no_shell) &&
+ count234(ssh->channels) == 0) {
+ /*
+ * We used to send SSH_MSG_DISCONNECT here,
+ * because I'd believed that _every_ conforming
+ * SSH-2 connection had to end with a disconnect
+ * being sent by at least one side; apparently
+ * I was wrong and it's perfectly OK to
+ * unceremoniously slam the connection shut
+ * when you're done, and indeed OpenSSH feels
+ * this is more polite than sending a
+ * DISCONNECT. So now we don't.
+ */
+ ssh_disconnect(ssh, "All channels closed", NULL, 0, TRUE);
+ }
+}
+
+static void ssh2_channel_check_close(struct ssh_channel *c)
+{
+ Ssh ssh = c->ssh;
+ struct Packet *pktout;
+
+ if ((!((CLOSES_SENT_EOF | CLOSES_RCVD_EOF) & ~c->closes) ||
+ c->type == CHAN_ZOMBIE) &&
+ !c->v.v2.chanreq_head &&
+ !(c->closes & CLOSES_SENT_CLOSE)) {
+ /*
+ * We have both sent and received EOF (or the channel is a
+ * zombie), and we have no outstanding channel requests, which
+ * means the channel is in final wind-up. But we haven't sent
+ * CLOSE, so let's do so now.
+ */
+ pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_CLOSE);
+ ssh2_pkt_adduint32(pktout, c->remoteid);
+ ssh2_pkt_send(ssh, pktout);
+ c->closes |= CLOSES_SENT_EOF | CLOSES_SENT_CLOSE;
+ }
+
+ if (!((CLOSES_SENT_CLOSE | CLOSES_RCVD_CLOSE) & ~c->closes)) {
+ assert(c->v.v2.chanreq_head == NULL);
+ /*
+ * We have both sent and received CLOSE, which means we're
+ * completely done with the channel.
+ */
+ ssh_channel_destroy(c);
+ }
+}
+
+static void ssh2_channel_got_eof(struct ssh_channel *c)
+{
+ if (c->closes & CLOSES_RCVD_EOF)
+ return; /* already seen EOF */
+ c->closes |= CLOSES_RCVD_EOF;
+
+ if (c->type == CHAN_X11) {
+ x11_send_eof(c->u.x11.s);
+ } else if (c->type == CHAN_AGENT) {
+ if (c->u.a.outstanding_requests == 0) {
+ /* Manufacture an outgoing EOF in response to the incoming one. */
+ sshfwd_write_eof(c);
+ }
+ } else if (c->type == CHAN_SOCKDATA) {
+ pfd_send_eof(c->u.pfd.s);
+ } else if (c->type == CHAN_MAINSESSION) {
+ Ssh ssh = c->ssh;
+
+ if (!ssh->sent_console_eof &&
+ (from_backend_eof(ssh->frontend) || ssh->got_pty)) {
+ /*
+ * Either from_backend_eof told us that the front end
+ * wants us to close the outgoing side of the connection
+ * as soon as we see EOF from the far end, or else we've
+ * unilaterally decided to do that because we've allocated
+ * a remote pty and hence EOF isn't a particularly
+ * meaningful concept.
+ */
+ sshfwd_write_eof(c);
+ }
+ ssh->sent_console_eof = TRUE;