1 /* ssl/statem/statem.c */
3 * Written by Matt Caswell for the OpenSSL project.
5 /* ====================================================================
6 * Copyright (c) 1998-2015 The OpenSSL Project. All rights reserved.
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in
17 * the documentation and/or other materials provided with the
20 * 3. All advertising materials mentioning features or use of this
21 * software must display the following acknowledgment:
22 * "This product includes software developed by the OpenSSL Project
23 * for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
25 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
26 * endorse or promote products derived from this software without
27 * prior written permission. For written permission, please contact
28 * openssl-core@openssl.org.
30 * 5. Products derived from this software may not be called "OpenSSL"
31 * nor may "OpenSSL" appear in their names without prior written
32 * permission of the OpenSSL Project.
34 * 6. Redistributions of any form whatsoever must retain the following
36 * "This product includes software developed by the OpenSSL Project
37 * for use in the OpenSSL Toolkit (http://www.openssl.org/)"
39 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
40 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
41 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
42 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
43 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
44 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
45 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
46 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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48 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
49 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
50 * OF THE POSSIBILITY OF SUCH DAMAGE.
51 * ====================================================================
53 * This product includes cryptographic software written by Eric Young
54 * (eay@cryptsoft.com). This product includes software written by Tim
55 * Hudson (tjh@cryptsoft.com).
59 #include <openssl/rand.h>
60 #include "../ssl_locl.h"
61 #include "statem_locl.h"
64 * This file implements the SSL/TLS/DTLS state machines.
66 * There are two primary state machines:
68 * 1) Message flow state machine
69 * 2) Handshake state machine
71 * The Message flow state machine controls the reading and sending of messages
72 * including handling of non-blocking IO events, flushing of the underlying
73 * write BIO, handling unexpected messages, etc. It is itself broken into two
74 * separate sub-state machines which control reading and writing respectively.
76 * The Handshake state machine keeps track of the current SSL/TLS handshake
77 * state. Transitions of the handshake state are the result of events that
78 * occur within the Message flow state machine.
80 * Overall it looks like this:
82 * --------------------------------------------- -------------------
84 * | Message flow state machine | | |
86 * | -------------------- -------------------- | Transition | Handshake state |
87 * | | MSG_FLOW_READING | | MSG_FLOW_WRITING | | Event | machine |
88 * | | sub-state | | sub-state | |----------->| |
89 * | | machine for | | machine for | | | |
90 * | | reading messages | | writing messages | | | |
91 * | -------------------- -------------------- | | |
93 * --------------------------------------------- -------------------
97 /* Sub state machine return values */
98 enum SUB_STATE_RETURN {
99 /* Something bad happened or NBIO */
101 /* Sub state finished go to the next sub state */
103 /* Sub state finished and handshake was completed */
104 SUB_STATE_END_HANDSHAKE
107 static int state_machine(SSL *s, int server);
108 static void init_read_state_machine(SSL *s);
109 static enum SUB_STATE_RETURN read_state_machine(SSL *s);
110 static void init_write_state_machine(SSL *s);
111 static enum SUB_STATE_RETURN write_state_machine(SSL *s);
113 OSSL_HANDSHAKE_STATE SSL_state(const SSL *ssl)
115 return ssl->statem.hand_state;
118 void SSL_set_state(SSL *ssl, OSSL_HANDSHAKE_STATE state)
121 * This function seems like a really bad idea. Should we remove it
124 ssl->statem.hand_state = state;
127 int SSL_in_init(SSL *s)
129 return s->statem.in_init;
132 int SSL_is_init_finished(SSL *s)
134 return !(s->statem.in_init) && (s->statem.hand_state == TLS_ST_OK);
137 int SSL_in_before(SSL *s)
140 * Historically being "in before" meant before anything had happened. In the
141 * current code though we remain in the "before" state for a while after we
142 * have started the handshake process (e.g. as a server waiting for the
143 * first message to arrive). There "in before" is taken to mean "in before"
144 * and not started any handshake process yet.
146 return (s->statem.hand_state == TLS_ST_BEFORE)
147 && (s->statem.state == MSG_FLOW_UNINITED);
151 * Clear the state machine state and reset back to MSG_FLOW_UNINITED
153 void ossl_statem_clear(SSL *s)
155 s->statem.state = MSG_FLOW_UNINITED;
156 s->statem.hand_state = TLS_ST_BEFORE;
157 s->statem.in_init = 1;
158 s->statem.no_cert_verify = 0;
162 * Set the state machine up ready for a renegotiation handshake
164 void ossl_statem_set_renegotiate(SSL *s)
166 s->statem.state = MSG_FLOW_RENEGOTIATE;
167 s->statem.in_init = 1;
171 * Put the state machine into an error state. This is a permanent error for
172 * the current connection.
174 void ossl_statem_set_error(SSL *s)
176 s->statem.state = MSG_FLOW_ERROR;
180 * Discover whether the current connection is in the error state.
182 * Valid return values are:
186 int ossl_statem_in_error(const SSL *s)
188 if (s->statem.state == MSG_FLOW_ERROR)
194 void ossl_statem_set_in_init(SSL *s, int init)
196 s->statem.in_init = init;
199 int ossl_statem_connect(SSL *s) {
200 return state_machine(s, 0);
203 int ossl_statem_accept(SSL *s)
205 return state_machine(s, 1);
209 * The main message flow state machine. We start in the MSG_FLOW_UNINITED or
210 * MSG_FLOW_RENEGOTIATE state and finish in MSG_FLOW_FINISHED. Valid states and
211 * transitions are as follows:
213 * MSG_FLOW_UNINITED MSG_FLOW_RENEGOTIATE
215 * +-----------------------+
217 * MSG_FLOW_WRITING <---> MSG_FLOW_READING
225 * We may exit at any point due to an error or NBIO event. If an NBIO event
226 * occurs then we restart at the point we left off when we are recalled.
227 * MSG_FLOW_WRITING and MSG_FLOW_READING have sub-state machines associated with them.
229 * In addition to the above there is also the MSG_FLOW_ERROR state. We can move
230 * into that state at any point in the event that an irrecoverable error occurs.
232 * Valid return values are:
236 static int state_machine(SSL *s, int server) {
238 unsigned long Time = (unsigned long)time(NULL);
239 void (*cb) (const SSL *ssl, int type, int val) = NULL;
240 STATEM *st = &s->statem;
244 if (st->state == MSG_FLOW_ERROR) {
245 /* Shouldn't have been called if we're already in the error state */
249 RAND_add(&Time, sizeof(Time), 0);
253 if (s->info_callback != NULL)
254 cb = s->info_callback;
255 else if (s->ctx->info_callback != NULL)
256 cb = s->ctx->info_callback;
259 if (!SSL_in_init(s) || SSL_in_before(s)) {
264 #ifndef OPENSSL_NO_SCTP
265 if (SSL_IS_DTLS(s)) {
267 * Notify SCTP BIO socket to enter handshake mode and prevent stream
268 * identifier other than 0. Will be ignored if no SCTP is used.
270 BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SET_IN_HANDSHAKE,
271 s->in_handshake, NULL);
275 #ifndef OPENSSL_NO_HEARTBEATS
277 * If we're awaiting a HeartbeatResponse, pretend we already got and
278 * don't await it anymore, because Heartbeats don't make sense during
281 if (s->tlsext_hb_pending) {
284 s->tlsext_hb_pending = 0;
289 /* Initialise state machine */
291 if (st->state == MSG_FLOW_RENEGOTIATE) {
294 s->ctx->stats.sess_connect_renegotiate++;
297 if (st->state == MSG_FLOW_UNINITED || st->state == MSG_FLOW_RENEGOTIATE) {
298 if (st->state == MSG_FLOW_UNINITED) {
299 st->hand_state = TLS_ST_BEFORE;
304 cb(s, SSL_CB_HANDSHAKE_START, 1);
306 if (SSL_IS_DTLS(s)) {
307 if ((s->version & 0xff00) != (DTLS1_VERSION & 0xff00) &&
309 || (s->version & 0xff00) != (DTLS1_BAD_VER & 0xff00))) {
310 SSLerr(SSL_F_STATE_MACHINE, ERR_R_INTERNAL_ERROR);
314 if ((s->version >> 8) != SSL3_VERSION_MAJOR
315 && s->version != TLS_ANY_VERSION) {
316 SSLerr(SSL_F_STATE_MACHINE, ERR_R_INTERNAL_ERROR);
321 if (!SSL_IS_DTLS(s)) {
322 if (s->version != TLS_ANY_VERSION &&
323 !ssl_security(s, SSL_SECOP_VERSION, 0, s->version, NULL)) {
324 SSLerr(SSL_F_STATE_MACHINE, SSL_R_VERSION_TOO_LOW);
329 if (s->init_buf == NULL) {
330 if ((buf = BUF_MEM_new()) == NULL) {
333 if (!BUF_MEM_grow(buf, SSL3_RT_MAX_PLAIN_LENGTH)) {
340 if (!ssl3_setup_buffers(s)) {
346 * Should have been reset by tls_process_finished, too.
348 s->s3->change_cipher_spec = 0;
350 if (!server || st->state != MSG_FLOW_RENEGOTIATE) {
352 * Ok, we now need to push on a buffering BIO ...but not with
355 #ifndef OPENSSL_NO_SCTP
356 if (!SSL_IS_DTLS(s) || !BIO_dgram_is_sctp(SSL_get_wbio(s)))
358 if (!ssl_init_wbio_buffer(s, server ? 1 : 0)) {
362 ssl3_init_finished_mac(s);
366 if (st->state != MSG_FLOW_RENEGOTIATE) {
367 s->ctx->stats.sess_accept++;
368 } else if (!s->s3->send_connection_binding &&
370 SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION)) {
372 * Server attempting to renegotiate with client that doesn't
373 * support secure renegotiation.
375 SSLerr(SSL_F_STATE_MACHINE,
376 SSL_R_UNSAFE_LEGACY_RENEGOTIATION_DISABLED);
377 ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
378 ossl_statem_set_error(s);
382 * st->state == MSG_FLOW_RENEGOTIATE, we will just send a
385 s->ctx->stats.sess_accept_renegotiate++;
388 s->ctx->stats.sess_connect++;
390 /* mark client_random uninitialized */
391 memset(s->s3->client_random, 0, sizeof(s->s3->client_random));
394 s->s3->tmp.cert_request = 0;
396 if (SSL_IS_DTLS(s)) {
401 st->state = MSG_FLOW_WRITING;
402 init_write_state_machine(s);
403 st->read_state_first_init = 1;
406 while(st->state != MSG_FLOW_FINISHED) {
407 if(st->state == MSG_FLOW_READING) {
408 ssret = read_state_machine(s);
409 if (ssret == SUB_STATE_FINISHED) {
410 st->state = MSG_FLOW_WRITING;
411 init_write_state_machine(s);
416 } else if (st->state == MSG_FLOW_WRITING) {
417 ssret = write_state_machine(s);
418 if (ssret == SUB_STATE_FINISHED) {
419 st->state = MSG_FLOW_READING;
420 init_read_state_machine(s);
421 } else if (ssret == SUB_STATE_END_HANDSHAKE) {
422 st->state = MSG_FLOW_FINISHED;
429 ossl_statem_set_error(s);
434 st->state = MSG_FLOW_UNINITED;
440 #ifndef OPENSSL_NO_SCTP
441 if (SSL_IS_DTLS(s)) {
443 * Notify SCTP BIO socket to leave handshake mode and allow stream
444 * identifier other than 0. Will be ignored if no SCTP is used.
446 BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SET_IN_HANDSHAKE,
447 s->in_handshake, NULL);
454 cb(s, SSL_CB_ACCEPT_EXIT, ret);
456 cb(s, SSL_CB_CONNECT_EXIT, ret);
462 * Initialise the MSG_FLOW_READING sub-state machine
464 static void init_read_state_machine(SSL *s)
466 STATEM *st = &s->statem;
468 st->read_state = READ_STATE_HEADER;
472 * This function implements the sub-state machine when the message flow is in
473 * MSG_FLOW_READING. The valid sub-states and transitions are:
475 * READ_STATE_HEADER <--+<-------------+
478 * READ_STATE_BODY -----+-->READ_STATE_POST_PROCESS
480 * +----------------------------+
482 * [SUB_STATE_FINISHED]
484 * READ_STATE_HEADER has the responsibility for reading in the message header
485 * and transitioning the state of the handshake state machine.
487 * READ_STATE_BODY reads in the rest of the message and then subsequently
490 * READ_STATE_POST_PROCESS is an optional step that may occur if some post
491 * processing activity performed on the message may block.
493 * Any of the above states could result in an NBIO event occuring in which case
494 * control returns to the calling application. When this function is recalled we
495 * will resume in the same state where we left off.
497 static enum SUB_STATE_RETURN read_state_machine(SSL *s) {
498 STATEM *st = &s->statem;
501 int (*transition)(SSL *s, int mt);
503 enum MSG_PROCESS_RETURN (*process_message)(SSL *s, PACKET *pkt);
504 enum WORK_STATE (*post_process_message)(SSL *s, enum WORK_STATE wst);
505 unsigned long (*max_message_size)(SSL *s);
506 void (*cb) (const SSL *ssl, int type, int val) = NULL;
508 if (s->info_callback != NULL)
509 cb = s->info_callback;
510 else if (s->ctx->info_callback != NULL)
511 cb = s->ctx->info_callback;
514 transition = server_read_transition;
515 process_message = server_process_message;
516 max_message_size = server_max_message_size;
517 post_process_message = server_post_process_message;
519 transition = client_read_transition;
520 process_message = client_process_message;
521 max_message_size = client_max_message_size;
522 post_process_message = client_post_process_message;
525 if (st->read_state_first_init) {
527 st->read_state_first_init = 0;
531 switch(st->read_state) {
532 case READ_STATE_HEADER:
534 /* Get the state the peer wants to move to */
535 if (SSL_IS_DTLS(s)) {
537 * In DTLS we get the whole message in one go - header and body
539 ret = dtls_get_message(s, &mt, &len);
541 ret = tls_get_message_header(s, &mt);
545 /* Could be non-blocking IO */
546 return SUB_STATE_ERROR;
550 /* Notify callback of an impending state change */
552 cb(s, SSL_CB_ACCEPT_LOOP, 1);
554 cb(s, SSL_CB_CONNECT_LOOP, 1);
557 * Validate that we are allowed to move to the new state and move
558 * to that state if so
560 if(!transition(s, mt)) {
561 ssl3_send_alert(s, SSL3_AL_FATAL, SSL3_AD_UNEXPECTED_MESSAGE);
562 SSLerr(SSL_F_READ_STATE_MACHINE, SSL_R_UNEXPECTED_MESSAGE);
563 return SUB_STATE_ERROR;
566 if (s->s3->tmp.message_size > max_message_size(s)) {
567 ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
568 SSLerr(SSL_F_READ_STATE_MACHINE, SSL_R_EXCESSIVE_MESSAGE_SIZE);
569 return SUB_STATE_ERROR;
572 st->read_state = READ_STATE_BODY;
575 case READ_STATE_BODY:
576 if (!SSL_IS_DTLS(s)) {
577 /* We already got this above for DTLS */
578 ret = tls_get_message_body(s, &len);
580 /* Could be non-blocking IO */
581 return SUB_STATE_ERROR;
586 if (!PACKET_buf_init(&pkt, s->init_msg, len)) {
587 ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
588 SSLerr(SSL_F_READ_STATE_MACHINE, ERR_R_INTERNAL_ERROR);
589 return SUB_STATE_ERROR;
591 ret = process_message(s, &pkt);
592 if (ret == MSG_PROCESS_ERROR) {
593 return SUB_STATE_ERROR;
596 if (ret == MSG_PROCESS_FINISHED_READING) {
597 if (SSL_IS_DTLS(s)) {
600 return SUB_STATE_FINISHED;
603 if (ret == MSG_PROCESS_CONTINUE_PROCESSING) {
604 st->read_state = READ_STATE_POST_PROCESS;
605 st->read_state_work = WORK_MORE_A;
607 st->read_state = READ_STATE_HEADER;
611 case READ_STATE_POST_PROCESS:
612 st->read_state_work = post_process_message(s, st->read_state_work);
613 switch(st->read_state_work) {
615 return SUB_STATE_ERROR;
617 case WORK_FINISHED_CONTINUE:
618 st->read_state = READ_STATE_HEADER;
621 case WORK_FINISHED_STOP:
622 if (SSL_IS_DTLS(s)) {
625 return SUB_STATE_FINISHED;
630 /* Shouldn't happen */
631 ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
632 SSLerr(SSL_F_READ_STATE_MACHINE, ERR_R_INTERNAL_ERROR);
633 ossl_statem_set_error(s);
634 return SUB_STATE_ERROR;
640 * Send a previously constructed message to the peer.
642 static int statem_do_write(SSL *s)
644 STATEM *st = &s->statem;
646 if (st->hand_state == TLS_ST_CW_CHANGE
647 || st->hand_state == TLS_ST_SW_CHANGE) {
649 return dtls1_do_write(s, SSL3_RT_CHANGE_CIPHER_SPEC);
651 return ssl3_do_write(s, SSL3_RT_CHANGE_CIPHER_SPEC);
653 return ssl_do_write(s);
658 * Initialise the MSG_FLOW_WRITING sub-state machine
660 static void init_write_state_machine(SSL *s)
662 STATEM *st = &s->statem;
664 st->write_state = WRITE_STATE_TRANSITION;
668 * This function implements the sub-state machine when the message flow is in
669 * MSG_FLOW_WRITING. The valid sub-states and transitions are:
671 * +-> WRITE_STATE_TRANSITION ------> [SUB_STATE_FINISHED]
674 * | WRITE_STATE_PRE_WORK -----> [SUB_STATE_END_HANDSHAKE]
680 * | WRITE_STATE_POST_WORK
684 * WRITE_STATE_TRANSITION transitions the state of the handshake state machine
686 * WRITE_STATE_PRE_WORK performs any work necessary to prepare the later
687 * sending of the message. This could result in an NBIO event occuring in
688 * which case control returns to the calling application. When this function
689 * is recalled we will resume in the same state where we left off.
691 * WRITE_STATE_SEND sends the message and performs any work to be done after
694 * WRITE_STATE_POST_WORK performs any work necessary after the sending of the
695 * message has been completed. As for WRITE_STATE_PRE_WORK this could also
696 * result in an NBIO event.
698 static enum SUB_STATE_RETURN write_state_machine(SSL *s)
700 STATEM *st = &s->statem;
702 enum WRITE_TRAN (*transition)(SSL *s);
703 enum WORK_STATE (*pre_work)(SSL *s, enum WORK_STATE wst);
704 enum WORK_STATE (*post_work)(SSL *s, enum WORK_STATE wst);
705 int (*construct_message)(SSL *s);
706 void (*cb) (const SSL *ssl, int type, int val) = NULL;
708 if (s->info_callback != NULL)
709 cb = s->info_callback;
710 else if (s->ctx->info_callback != NULL)
711 cb = s->ctx->info_callback;
714 transition = server_write_transition;
715 pre_work = server_pre_work;
716 post_work = server_post_work;
717 construct_message = server_construct_message;
719 transition = client_write_transition;
720 pre_work = client_pre_work;
721 post_work = client_post_work;
722 construct_message = client_construct_message;
726 switch(st->write_state) {
727 case WRITE_STATE_TRANSITION:
729 /* Notify callback of an impending state change */
731 cb(s, SSL_CB_ACCEPT_LOOP, 1);
733 cb(s, SSL_CB_CONNECT_LOOP, 1);
735 switch(transition(s)) {
736 case WRITE_TRAN_CONTINUE:
737 st->write_state = WRITE_STATE_PRE_WORK;
738 st->write_state_work = WORK_MORE_A;
741 case WRITE_TRAN_FINISHED:
742 return SUB_STATE_FINISHED;
746 return SUB_STATE_ERROR;
750 case WRITE_STATE_PRE_WORK:
751 switch(st->write_state_work = pre_work(s, st->write_state_work)) {
753 return SUB_STATE_ERROR;
755 case WORK_FINISHED_CONTINUE:
756 st->write_state = WRITE_STATE_SEND;
759 case WORK_FINISHED_STOP:
760 return SUB_STATE_END_HANDSHAKE;
762 if(construct_message(s) == 0)
763 return SUB_STATE_ERROR;
767 case WRITE_STATE_SEND:
768 if (SSL_IS_DTLS(s) && st->use_timer) {
769 dtls1_start_timer(s);
771 ret = statem_do_write(s);
773 return SUB_STATE_ERROR;
775 st->write_state = WRITE_STATE_POST_WORK;
776 st->write_state_work = WORK_MORE_A;
779 case WRITE_STATE_POST_WORK:
780 switch(st->write_state_work = post_work(s, st->write_state_work)) {
782 return SUB_STATE_ERROR;
784 case WORK_FINISHED_CONTINUE:
785 st->write_state = WRITE_STATE_TRANSITION;
788 case WORK_FINISHED_STOP:
789 return SUB_STATE_END_HANDSHAKE;
794 return SUB_STATE_ERROR;
800 * Flush the write BIO
802 int statem_flush(SSL *s)
804 s->rwstate = SSL_WRITING;
805 if (BIO_flush(s->wbio) <= 0) {
808 s->rwstate = SSL_NOTHING;
814 * Called by the record layer to determine whether application data is
815 * allowed to be sent in the current handshake state or not.
818 * 1: Yes (application data allowed)
819 * 0: No (application data not allowed)
821 int ossl_statem_app_data_allowed(SSL *s)
823 STATEM *st = &s->statem;
825 if (st->state == MSG_FLOW_UNINITED || st->state == MSG_FLOW_RENEGOTIATE)
828 if (!s->s3->in_read_app_data || (s->s3->total_renegotiations == 0))
833 * If we're a server and we haven't got as far as writing our
834 * ServerHello yet then we allow app data
836 if (st->hand_state == TLS_ST_BEFORE
837 || st->hand_state == TLS_ST_SR_CLNT_HELLO)
841 * If we're a client and we haven't read the ServerHello yet then we
844 if (st->hand_state == TLS_ST_CW_CLNT_HELLO)
851 #ifndef OPENSSL_NO_SCTP
853 * Set flag used by SCTP to determine whether we are in the read sock state
855 void ossl_statem_set_sctp_read_sock(SSL *s, int read_sock)
857 s->statem.in_sctp_read_sock = read_sock;
861 * Called by the record layer to determine whether we are in the read sock
865 * 1: Yes (we are in the read sock state)
866 * 0: No (we are not in the read sock state)
868 int statem_in_sctp_read_sock(SSL *s)
870 return s->statem.in_sctp_read_sock;