+
+#ifndef OPENSSL_NO_HEARTBEATS
+int
+dtls1_process_heartbeat(SSL *s)
+ {
+ unsigned char *p = &s->s3->rrec.data[0], *pl;
+ unsigned short hbtype;
+ unsigned int payload;
+ unsigned int padding = 16; /* Use minimum padding */
+
+ /* Read type and payload length first */
+ hbtype = *p++;
+ n2s(p, payload);
+ pl = p;
+
+ if (s->msg_callback)
+ s->msg_callback(0, s->version, TLS1_RT_HEARTBEAT,
+ &s->s3->rrec.data[0], s->s3->rrec.length,
+ s, s->msg_callback_arg);
+
+ if (hbtype == TLS1_HB_REQUEST)
+ {
+ unsigned char *buffer, *bp;
+ int r;
+
+ /* Allocate memory for the response, size is 1 byte
+ * message type, plus 2 bytes payload length, plus
+ * payload, plus padding
+ */
+ buffer = OPENSSL_malloc(1 + 2 + payload + padding);
+ bp = buffer;
+
+ /* Enter response type, length and copy payload */
+ *bp++ = TLS1_HB_RESPONSE;
+ s2n(payload, bp);
+ memcpy(bp, pl, payload);
+ /* Random padding */
+ RAND_pseudo_bytes(p, padding);
+
+ r = dtls1_write_bytes(s, TLS1_RT_HEARTBEAT, buffer, 3 + payload + padding);
+
+ if (r >= 0 && s->msg_callback)
+ s->msg_callback(1, s->version, TLS1_RT_HEARTBEAT,
+ buffer, 3 + payload + padding,
+ s, s->msg_callback_arg);
+
+ OPENSSL_free(buffer);
+
+ if (r < 0)
+ return r;
+ }
+ else if (hbtype == TLS1_HB_RESPONSE)
+ {
+ unsigned int seq;
+
+ /* We only send sequence numbers (2 bytes unsigned int),
+ * and 16 random bytes, so we just try to read the
+ * sequence number */
+ n2s(pl, seq);
+
+ if (payload == 18 && seq == s->tlsext_hb_seq)
+ {
+ dtls1_stop_timer(s);
+ s->tlsext_hb_seq++;
+ s->tlsext_hb_pending = 0;
+ }
+ }
+
+ return 0;
+ }
+
+int
+dtls1_heartbeat(SSL *s)
+ {
+ unsigned char *buf, *p;
+ int ret;
+ unsigned int payload = 18; /* Sequence number + random bytes */
+ unsigned int padding = 16; /* Use minimum padding */
+
+ /* Only send if peer supports and accepts HB requests... */
+ if (!(s->tlsext_heartbeat & SSL_TLSEXT_HB_ENABLED) ||
+ s->tlsext_heartbeat & SSL_TLSEXT_HB_DONT_SEND_REQUESTS)
+ {
+ SSLerr(SSL_F_DTLS1_HEARTBEAT,SSL_R_TLS_HEARTBEAT_PEER_DOESNT_ACCEPT);
+ return -1;
+ }
+
+ /* ...and there is none in flight yet... */
+ if (s->tlsext_hb_pending)
+ {
+ SSLerr(SSL_F_DTLS1_HEARTBEAT,SSL_R_TLS_HEARTBEAT_PENDING);
+ return -1;
+ }
+
+ /* ...and no handshake in progress. */
+ if (SSL_in_init(s) || s->in_handshake)
+ {
+ SSLerr(SSL_F_DTLS1_HEARTBEAT,SSL_R_UNEXPECTED_MESSAGE);
+ return -1;
+ }
+
+ /* Check if padding is too long, payload and padding
+ * must not exceed 2^14 - 3 = 16381 bytes in total.
+ */
+ OPENSSL_assert(payload + padding <= 16381);
+
+ /* Create HeartBeat message, we just use a sequence number
+ * as payload to distuingish different messages and add
+ * some random stuff.
+ * - Message Type, 1 byte
+ * - Payload Length, 2 bytes (unsigned int)
+ * - Payload, the sequence number (2 bytes uint)
+ * - Payload, random bytes (16 bytes uint)
+ * - Padding
+ */
+ buf = OPENSSL_malloc(1 + 2 + payload + padding);
+ p = buf;
+ /* Message Type */
+ *p++ = TLS1_HB_REQUEST;
+ /* Payload length (18 bytes here) */
+ s2n(payload, p);
+ /* Sequence number */
+ s2n(s->tlsext_hb_seq, p);
+ /* 16 random bytes */
+ RAND_pseudo_bytes(p, 16);
+ p += 16;
+ /* Random padding */
+ RAND_pseudo_bytes(p, padding);
+
+ ret = dtls1_write_bytes(s, TLS1_RT_HEARTBEAT, buf, 3 + payload + padding);
+ if (ret >= 0)
+ {
+ if (s->msg_callback)
+ s->msg_callback(1, s->version, TLS1_RT_HEARTBEAT,
+ buf, 3 + payload + padding,
+ s, s->msg_callback_arg);
+
+ dtls1_start_timer(s);
+ s->tlsext_hb_pending = 1;
+ }
+
+ OPENSSL_free(buf);
+
+ return ret;
+ }
+#endif
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