+static int in_commasep_string(char *needle, char *haystack, int haylen) {
+ int needlen = strlen(needle);
+ while (1) {
+ /*
+ * Is it at the start of the string?
+ */
+ if (haylen >= needlen && /* haystack is long enough */
+ !memcmp(needle, haystack, needlen) && /* initial match */
+ (haylen == needlen || haystack[needlen] == ',')
+ /* either , or EOS follows */
+ )
+ return 1;
+ /*
+ * If not, search for the next comma and resume after that.
+ * If no comma found, terminate.
+ */
+ while (haylen > 0 && *haystack != ',')
+ haylen--, haystack++;
+ if (haylen == 0)
+ return 0;
+ haylen--, haystack++; /* skip over comma itself */
+ }
+}
+
+/*
+ * SSH2 key creation method.
+ */
+static void ssh2_mkkey(Bignum K, char *H, char *sessid, char chr, char *keyspace) {
+ SHA_State s;
+ /* First 20 bytes. */
+ SHA_Init(&s);
+ sha_mpint(&s, K);
+ SHA_Bytes(&s, H, 20);
+ SHA_Bytes(&s, &chr, 1);
+ SHA_Bytes(&s, sessid, 20);
+ SHA_Final(&s, keyspace);
+ /* Next 20 bytes. */
+ SHA_Init(&s);
+ sha_mpint(&s, K);
+ SHA_Bytes(&s, H, 20);
+ SHA_Bytes(&s, keyspace, 20);
+ SHA_Final(&s, keyspace+20);
+}
+
+/*
+ * Handle the SSH2 transport layer.
+ */
+static int do_ssh2_transport(unsigned char *in, int inlen, int ispkt)
+{
+ static int i, len;
+ static char *str;
+ static Bignum e, f, K;
+ static const struct ssh_mac **maclist;
+ static int nmacs;
+ static const struct ssh_cipher *cscipher_tobe = NULL;
+ static const struct ssh_cipher *sccipher_tobe = NULL;
+ static const struct ssh_mac *csmac_tobe = NULL;
+ static const struct ssh_mac *scmac_tobe = NULL;
+ static const struct ssh_compress *cscomp_tobe = NULL;
+ static const struct ssh_compress *sccomp_tobe = NULL;
+ static char *hostkeydata, *sigdata, *keystr, *fingerprint;
+ static int hostkeylen, siglen;
+ static void *hkey; /* actual host key */
+ static unsigned char exchange_hash[20];
+ static unsigned char first_exchange_hash[20];
+ static unsigned char keyspace[40];
+ static const struct ssh_cipher *preferred_cipher;
+ static const struct ssh_compress *preferred_comp;
+ static int first_kex;
+
+ crBegin;
+ random_init();
+ first_kex = 1;
+
+ /*
+ * Set up the preferred cipher and compression.
+ */
+ if (cfg.cipher == CIPHER_BLOWFISH) {
+ preferred_cipher = &ssh_blowfish_ssh2;
+ } else if (cfg.cipher == CIPHER_DES) {
+ logevent("Single DES not supported in SSH2; using 3DES");
+ preferred_cipher = &ssh_3des_ssh2;
+ } else if (cfg.cipher == CIPHER_3DES) {
+ preferred_cipher = &ssh_3des_ssh2;
+ } else {
+ /* Shouldn't happen, but we do want to initialise to _something_. */
+ preferred_cipher = &ssh_3des_ssh2;
+ }
+ if (cfg.compression)
+ preferred_comp = &ssh_zlib;
+ else
+ preferred_comp = &ssh_comp_none;
+
+ /*
+ * Be prepared to work around the buggy MAC problem.
+ */
+ if (cfg.buggymac)
+ maclist = buggymacs, nmacs = lenof(buggymacs);
+ else
+ maclist = macs, nmacs = lenof(macs);
+
+ begin_key_exchange:
+ /*
+ * Construct and send our key exchange packet.
+ */
+ ssh2_pkt_init(SSH2_MSG_KEXINIT);
+ for (i = 0; i < 16; i++)
+ ssh2_pkt_addbyte((unsigned char)random_byte());
+ /* List key exchange algorithms. */
+ ssh2_pkt_addstring_start();
+ for (i = 0; i < lenof(kex_algs); i++) {
+ ssh2_pkt_addstring_str(kex_algs[i]->name);
+ if (i < lenof(kex_algs)-1)
+ ssh2_pkt_addstring_str(",");
+ }
+ /* List server host key algorithms. */
+ ssh2_pkt_addstring_start();
+ for (i = 0; i < lenof(hostkey_algs); i++) {
+ ssh2_pkt_addstring_str(hostkey_algs[i]->name);
+ if (i < lenof(hostkey_algs)-1)
+ ssh2_pkt_addstring_str(",");
+ }
+ /* List client->server encryption algorithms. */
+ ssh2_pkt_addstring_start();
+ for (i = 0; i < lenof(ciphers)+1; i++) {
+ const struct ssh_cipher *c = i==0 ? preferred_cipher : ciphers[i-1];
+ ssh2_pkt_addstring_str(c->name);
+ if (i < lenof(ciphers))
+ ssh2_pkt_addstring_str(",");
+ }
+ /* List server->client encryption algorithms. */
+ ssh2_pkt_addstring_start();
+ for (i = 0; i < lenof(ciphers)+1; i++) {
+ const struct ssh_cipher *c = i==0 ? preferred_cipher : ciphers[i-1];
+ ssh2_pkt_addstring_str(c->name);
+ if (i < lenof(ciphers))
+ ssh2_pkt_addstring_str(",");
+ }
+ /* List client->server MAC algorithms. */
+ ssh2_pkt_addstring_start();
+ for (i = 0; i < nmacs; i++) {
+ ssh2_pkt_addstring_str(maclist[i]->name);
+ if (i < nmacs-1)
+ ssh2_pkt_addstring_str(",");
+ }
+ /* List server->client MAC algorithms. */
+ ssh2_pkt_addstring_start();
+ for (i = 0; i < nmacs; i++) {
+ ssh2_pkt_addstring_str(maclist[i]->name);
+ if (i < nmacs-1)
+ ssh2_pkt_addstring_str(",");
+ }
+ /* List client->server compression algorithms. */
+ ssh2_pkt_addstring_start();
+ for (i = 0; i < lenof(compressions)+1; i++) {
+ const struct ssh_compress *c = i==0 ? preferred_comp : compressions[i-1];
+ ssh2_pkt_addstring_str(c->name);
+ if (i < lenof(compressions))
+ ssh2_pkt_addstring_str(",");
+ }
+ /* List server->client compression algorithms. */
+ ssh2_pkt_addstring_start();
+ for (i = 0; i < lenof(compressions)+1; i++) {
+ const struct ssh_compress *c = i==0 ? preferred_comp : compressions[i-1];
+ ssh2_pkt_addstring_str(c->name);
+ if (i < lenof(compressions))
+ ssh2_pkt_addstring_str(",");
+ }
+ /* List client->server languages. Empty list. */
+ ssh2_pkt_addstring_start();
+ /* List server->client languages. Empty list. */
+ ssh2_pkt_addstring_start();
+ /* First KEX packet does _not_ follow, because we're not that brave. */
+ ssh2_pkt_addbool(FALSE);
+ /* Reserved. */
+ ssh2_pkt_adduint32(0);
+
+ exhash = exhashbase;
+ sha_string(&exhash, pktout.data+5, pktout.length-5);
+
+ ssh2_pkt_send();
+
+ if (!ispkt) crWaitUntil(ispkt);
+ sha_string(&exhash, pktin.data+5, pktin.length-5);
+
+ /*
+ * Now examine the other side's KEXINIT to see what we're up
+ * to.
+ */
+ if (pktin.type != SSH2_MSG_KEXINIT) {
+ bombout(("expected key exchange packet from server"));
+ crReturn(0);
+ }
+ kex = NULL; hostkey = NULL; cscipher_tobe = NULL; sccipher_tobe = NULL;
+ csmac_tobe = NULL; scmac_tobe = NULL; cscomp_tobe = NULL; sccomp_tobe = NULL;
+ pktin.savedpos += 16; /* skip garbage cookie */
+ ssh2_pkt_getstring(&str, &len); /* key exchange algorithms */
+ for (i = 0; i < lenof(kex_algs); i++) {
+ if (in_commasep_string(kex_algs[i]->name, str, len)) {
+ kex = kex_algs[i];
+ break;
+ }
+ }
+ ssh2_pkt_getstring(&str, &len); /* host key algorithms */
+ for (i = 0; i < lenof(hostkey_algs); i++) {
+ if (in_commasep_string(hostkey_algs[i]->name, str, len)) {
+ hostkey = hostkey_algs[i];
+ break;
+ }
+ }
+ ssh2_pkt_getstring(&str, &len); /* client->server cipher */
+ for (i = 0; i < lenof(ciphers)+1; i++) {
+ const struct ssh_cipher *c = i==0 ? preferred_cipher : ciphers[i-1];
+ if (in_commasep_string(c->name, str, len)) {
+ cscipher_tobe = c;
+ break;
+ }
+ }
+ ssh2_pkt_getstring(&str, &len); /* server->client cipher */
+ for (i = 0; i < lenof(ciphers)+1; i++) {
+ const struct ssh_cipher *c = i==0 ? preferred_cipher : ciphers[i-1];
+ if (in_commasep_string(c->name, str, len)) {
+ sccipher_tobe = c;
+ break;
+ }
+ }
+ ssh2_pkt_getstring(&str, &len); /* client->server mac */
+ for (i = 0; i < nmacs; i++) {
+ if (in_commasep_string(maclist[i]->name, str, len)) {
+ csmac_tobe = maclist[i];
+ break;
+ }
+ }
+ ssh2_pkt_getstring(&str, &len); /* server->client mac */
+ for (i = 0; i < nmacs; i++) {
+ if (in_commasep_string(maclist[i]->name, str, len)) {
+ scmac_tobe = maclist[i];
+ break;
+ }
+ }
+ ssh2_pkt_getstring(&str, &len); /* client->server compression */
+ for (i = 0; i < lenof(compressions)+1; i++) {
+ const struct ssh_compress *c = i==0 ? preferred_comp : compressions[i-1];
+ if (in_commasep_string(c->name, str, len)) {
+ cscomp_tobe = c;
+ break;
+ }
+ }
+ ssh2_pkt_getstring(&str, &len); /* server->client compression */
+ for (i = 0; i < lenof(compressions)+1; i++) {
+ const struct ssh_compress *c = i==0 ? preferred_comp : compressions[i-1];
+ if (in_commasep_string(c->name, str, len)) {
+ sccomp_tobe = c;
+ break;
+ }
+ }
+
+ /*
+ * Currently we only support Diffie-Hellman and DSS, so let's
+ * bomb out if those aren't selected.
+ */
+ if (kex != &ssh_diffiehellman || hostkey != &ssh_dss) {
+ bombout(("internal fault: chaos in SSH 2 transport layer"));
+ crReturn(0);
+ }
+
+ /*
+ * Now we begin the fun. Generate and send e for Diffie-Hellman.
+ */
+ e = dh_create_e();
+ ssh2_pkt_init(SSH2_MSG_KEXDH_INIT);
+ ssh2_pkt_addmp(e);
+ ssh2_pkt_send();
+
+ crWaitUntil(ispkt);
+ if (pktin.type != SSH2_MSG_KEXDH_REPLY) {
+ bombout(("expected key exchange packet from server"));
+ crReturn(0);
+ }
+ ssh2_pkt_getstring(&hostkeydata, &hostkeylen);
+ f = ssh2_pkt_getmp();
+ ssh2_pkt_getstring(&sigdata, &siglen);
+
+ K = dh_find_K(f);
+
+ sha_string(&exhash, hostkeydata, hostkeylen);
+ sha_mpint(&exhash, e);
+ sha_mpint(&exhash, f);
+ sha_mpint(&exhash, K);
+ SHA_Final(&exhash, exchange_hash);
+
+#if 0
+ debug(("Exchange hash is:\r\n"));
+ for (i = 0; i < 20; i++)
+ debug((" %02x", exchange_hash[i]));
+ debug(("\r\n"));