+ * Helper function to add an SSH2 signature blob to a packet.
+ * Expects to be shown the public key blob as well as the signature
+ * blob. Normally works just like ssh2_pkt_addstring, but will
+ * fiddle with the signature packet if necessary for
+ * BUG_SSH2_RSA_PADDING.
+ */
+static void ssh2_add_sigblob(void *pkblob_v, int pkblob_len,
+ void *sigblob_v, int sigblob_len)
+{
+ unsigned char *pkblob = (unsigned char *)pkblob_v;
+ unsigned char *sigblob = (unsigned char *)sigblob_v;
+
+ /* dmemdump(pkblob, pkblob_len); */
+ /* dmemdump(sigblob, sigblob_len); */
+
+ /*
+ * See if this is in fact an ssh-rsa signature and a buggy
+ * server; otherwise we can just do this the easy way.
+ */
+ if ((ssh_remote_bugs & BUG_SSH2_RSA_PADDING) &&
+ (GET_32BIT(pkblob) == 7 && !memcmp(pkblob+4, "ssh-rsa", 7))) {
+ int pos, len, siglen;
+
+ /*
+ * Find the byte length of the modulus.
+ */
+
+ pos = 4+7; /* skip over "ssh-rsa" */
+ pos += 4 + GET_32BIT(pkblob+pos); /* skip over exponent */
+ len = GET_32BIT(pkblob+pos); /* find length of modulus */
+ pos += 4; /* find modulus itself */
+ while (len > 0 && pkblob[pos] == 0)
+ len--, pos++;
+ /* debug(("modulus length is %d\n", len)); */
+
+ /*
+ * Now find the signature integer.
+ */
+ pos = 4+7; /* skip over "ssh-rsa" */
+ siglen = GET_32BIT(sigblob+pos);
+ /* debug(("signature length is %d\n", siglen)); */
+
+ if (len != siglen) {
+ unsigned char newlen[4];
+ ssh2_pkt_addstring_start();
+ ssh2_pkt_addstring_data(sigblob, pos);
+ /* dmemdump(sigblob, pos); */
+ pos += 4; /* point to start of actual sig */
+ PUT_32BIT(newlen, len);
+ ssh2_pkt_addstring_data(newlen, 4);
+ /* dmemdump(newlen, 4); */
+ newlen[0] = 0;
+ while (len-- > siglen) {
+ ssh2_pkt_addstring_data(newlen, 1);
+ /* dmemdump(newlen, 1); */
+ }
+ ssh2_pkt_addstring_data(sigblob+pos, siglen);
+ /* dmemdump(sigblob+pos, siglen); */
+ return;
+ }
+
+ /* Otherwise fall through and do it the easy way. */
+ }
+
+ ssh2_pkt_addstring_start();
+ ssh2_pkt_addstring_data(sigblob, sigblob_len);
+}
+
+/*