/*
 * Gather (Read) entire SSL3 records from socket into buffer.  
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "cert.h"
#include "ssl.h"
#include "sslimpl.h"
#include "ssl3prot.h"

/* 
 * Attempt to read in an entire SSL3 record.
 * Blocks here for blocking sockets, otherwise returns -1 with 
 * 	PR_WOULD_BLOCK_ERROR when socket would block.
 *
 * returns  1 if received a complete SSL3 record.
 * returns  0 if recv returns EOF
 * returns -1 if recv returns < 0  
 *	(The error value may have already been set to PR_WOULD_BLOCK_ERROR)
 *
 * Caller must hold the recv buf lock.
 *
 * The Gather state machine has 3 states:  GS_INIT, GS_HEADER, GS_DATA.
 * GS_HEADER: waiting for the 5-byte SSL3 record header to come in.
 * GS_DATA:   waiting for the body of the SSL3 record   to come in.
 *
 * This loop returns when either
 *      (a) an error or EOF occurs,
 *	(b) PR_WOULD_BLOCK_ERROR,
 * 	(c) data (entire SSL3 record) has been received.
 */
static int
ssl3_GatherData(sslSocket *ss, sslGather *gs, int flags)
{
    unsigned char *bp;
    unsigned char *lbp;
    int            nb;
    int            err;
    int            rv		= 1;

    PORT_Assert( ss->opt.noLocks || ssl_HaveRecvBufLock(ss) );
    if (gs->state == GS_INIT) {
	gs->state       = GS_HEADER;
	gs->remainder   = 5;
	gs->offset      = 0;
	gs->writeOffset = 0;
	gs->readOffset  = 0;
	gs->inbuf.len   = 0;
    }
    
    lbp = gs->inbuf.buf;
    for(;;) {
	SSL_TRC(30, ("%d: SSL3[%d]: gather state %d (need %d more)",
		SSL_GETPID(), ss->fd, gs->state, gs->remainder));
	bp = ((gs->state != GS_HEADER) ? lbp : gs->hdr) + gs->offset;
	nb = ssl_DefRecv(ss, bp, gs->remainder, flags);

	if (nb > 0) {
	    PRINT_BUF(60, (ss, "raw gather data:", bp, nb));
	} else if (nb == 0) {
	    /* EOF */
	    SSL_TRC(30, ("%d: SSL3[%d]: EOF", SSL_GETPID(), ss->fd));
	    rv = 0;
	    break;
	} else /* if (nb < 0) */ {
	    SSL_DBG(("%d: SSL3[%d]: recv error %d", SSL_GETPID(), ss->fd,
		     PR_GetError()));
	    rv = SECFailure;
	    break;
	}

	PORT_Assert( nb <= gs->remainder );
	if (nb > gs->remainder) {
	    /* ssl_DefRecv is misbehaving!  this error is fatal to SSL. */
	    gs->state = GS_INIT;         /* so we don't crash next time */
	    rv = SECFailure;
	    break;
	}

	gs->offset    += nb;
	gs->remainder -= nb;
	if (gs->state == GS_DATA)
	    gs->inbuf.len += nb;

	/* if there's more to go, read some more. */
	if (gs->remainder > 0) {
	    continue;
	}

	/* have received entire record header, or entire record. */
	switch (gs->state) {
	case GS_HEADER:
	    /*
	    ** Have received SSL3 record header in gs->hdr.
	    ** Now extract the length of the following encrypted data, 
	    ** and then read in the rest of the SSL3 record into gs->inbuf.
	    */
	    gs->remainder = (gs->hdr[3] << 8) | gs->hdr[4];

	    /* This is the max fragment length for an encrypted fragment
	    ** plus the size of the record header.
	    */
	    if(gs->remainder > (MAX_FRAGMENT_LENGTH + 2048 + 5)) {
		SSL3_SendAlert(ss, alert_fatal, unexpected_message);
		gs->state = GS_INIT;
		PORT_SetError(SSL_ERROR_RX_RECORD_TOO_LONG);
		return SECFailure;
	    }

	    gs->state     = GS_DATA;
	    gs->offset    = 0;
	    gs->inbuf.len = 0;

	    if (gs->remainder > gs->inbuf.space) {
		err = sslBuffer_Grow(&gs->inbuf, gs->remainder);
		if (err) {	/* realloc has set error code to no mem. */
		    return err;
		}
		lbp = gs->inbuf.buf;
	    }
	    break;	/* End this case.  Continue around the loop. */


	case GS_DATA:
	    /* 
	    ** SSL3 record has been completely received.
	    */
	    gs->state = GS_INIT;
	    return 1;
	}
    }

    return rv;
}

/*
 * Read in an entire DTLS record.
 *
 * Blocks here for blocking sockets, otherwise returns -1 with
 * 	PR_WOULD_BLOCK_ERROR when socket would block.
 *
 * This is simpler than SSL because we are reading on a datagram socket
 * and datagrams must contain >=1 complete records.
 *
 * returns  1 if received a complete DTLS record.
 * returns  0 if recv returns EOF
 * returns -1 if recv returns < 0
 *	(The error value may have already been set to PR_WOULD_BLOCK_ERROR)
 *
 * Caller must hold the recv buf lock.
 *
 * This loop returns when either
 *      (a) an error or EOF occurs,
 *	(b) PR_WOULD_BLOCK_ERROR,
 * 	(c) data (entire DTLS record) has been received.
 */
static int
dtls_GatherData(sslSocket *ss, sslGather *gs, int flags)
{
    int            nb;
    int            err;
    int            rv		= 1;

    SSL_TRC(30, ("dtls_GatherData"));

    PORT_Assert( ss->opt.noLocks || ssl_HaveRecvBufLock(ss) );

    gs->state = GS_HEADER;
    gs->offset = 0;

    if (gs->dtlsPacketOffset == gs->dtlsPacket.len) {  /* No data left */
        gs->dtlsPacketOffset = 0;
        gs->dtlsPacket.len = 0;

        /* Resize to the maximum possible size so we can fit a full datagram */
	/* This is the max fragment length for an encrypted fragment
	** plus the size of the record header.
	** This magic constant is copied from ssl3_GatherData, with 5 changed
	** to 13 (the size of the record header).
	*/
        if (gs->dtlsPacket.space < MAX_FRAGMENT_LENGTH + 2048 + 13) {
            err = sslBuffer_Grow(&gs->dtlsPacket,
				 MAX_FRAGMENT_LENGTH + 2048 + 13);
            if (err) {	/* realloc has set error code to no mem. */
                return err;
            }
        }

        /* recv() needs to read a full datagram at a time */
        nb = ssl_DefRecv(ss, gs->dtlsPacket.buf, gs->dtlsPacket.space, flags);

        if (nb > 0) {
            PRINT_BUF(60, (ss, "raw gather data:", gs->dtlsPacket.buf, nb));
        } else if (nb == 0) {
            /* EOF */
            SSL_TRC(30, ("%d: SSL3[%d]: EOF", SSL_GETPID(), ss->fd));
            rv = 0;
            return rv;
        } else /* if (nb < 0) */ {
            SSL_DBG(("%d: SSL3[%d]: recv error %d", SSL_GETPID(), ss->fd,
                     PR_GetError()));
            rv = SECFailure;
            return rv;
        }

        gs->dtlsPacket.len = nb;
    }

    /* At this point we should have >=1 complete records lined up in
     * dtlsPacket. Read off the header.
     */
    if ((gs->dtlsPacket.len - gs->dtlsPacketOffset) < 13) {
        SSL_DBG(("%d: SSL3[%d]: rest of DTLS packet "
		 "too short to contain header", SSL_GETPID(), ss->fd));
        PR_SetError(PR_WOULD_BLOCK_ERROR, 0);
        gs->dtlsPacketOffset = 0;
        gs->dtlsPacket.len = 0;
        rv = SECFailure;
        return rv;
    }
    memcpy(gs->hdr, gs->dtlsPacket.buf + gs->dtlsPacketOffset, 13);
    gs->dtlsPacketOffset += 13;

    /* Have received SSL3 record header in gs->hdr. */
    gs->remainder = (gs->hdr[11] << 8) | gs->hdr[12];

    if ((gs->dtlsPacket.len - gs->dtlsPacketOffset) < gs->remainder) {
        SSL_DBG(("%d: SSL3[%d]: rest of DTLS packet too short "
		 "to contain rest of body", SSL_GETPID(), ss->fd));
        PR_SetError(PR_WOULD_BLOCK_ERROR, 0);
        gs->dtlsPacketOffset = 0;
        gs->dtlsPacket.len = 0;
        rv = SECFailure;
        return rv;
    }

    /* OK, we have at least one complete packet, copy into inbuf */
    if (gs->remainder > gs->inbuf.space) {
	err = sslBuffer_Grow(&gs->inbuf, gs->remainder);
	if (err) {	/* realloc has set error code to no mem. */
	    return err;
	}
    }

    memcpy(gs->inbuf.buf, gs->dtlsPacket.buf + gs->dtlsPacketOffset,
	   gs->remainder);
    gs->inbuf.len = gs->remainder;
    gs->offset = gs->remainder;
    gs->dtlsPacketOffset += gs->remainder;
    gs->state = GS_INIT;

    return 1;
}

/* Gather in a record and when complete, Handle that record.
 * Repeat this until the handshake is complete, 
 * or until application data is available.
 *
 * Returns  1 when the handshake is completed without error, or 
 *                 application data is available.
 * Returns  0 if ssl3_GatherData hits EOF.
 * Returns -1 on read error, or PR_WOULD_BLOCK_ERROR, or handleRecord error.
 * Returns -2 on SECWouldBlock return from ssl3_HandleRecord.
 *
 * Called from ssl_GatherRecord1stHandshake       in sslcon.c, 
 *    and from SSL_ForceHandshake in sslsecur.c
 *    and from ssl3_GatherAppDataRecord below (<- DoRecv in sslsecur.c).
 *
 * Caller must hold the recv buf lock.
 */
int
ssl3_GatherCompleteHandshake(sslSocket *ss, int flags)
{
    SSL3Ciphertext cText;
    int            rv;
    PRBool         keepGoing = PR_TRUE;

    SSL_TRC(30, ("ssl3_GatherCompleteHandshake"));

    /* ssl3_HandleRecord may end up eventually calling ssl_FinishHandshake,
     * which requires the 1stHandshakeLock, which must be acquired before the
     * RecvBufLock.
     */
    PORT_Assert( ss->opt.noLocks || ssl_Have1stHandshakeLock(ss) );
    PORT_Assert( ss->opt.noLocks || ssl_HaveRecvBufLock(ss) );

    do {
	PRBool handleRecordNow = PR_FALSE;

	ssl_GetSSL3HandshakeLock(ss);

	/* Without this, we may end up wrongly reporting
	 * SSL_ERROR_RX_UNEXPECTED_* errors if we receive any records from the
	 * peer while we are waiting to be restarted.
	 */
	if (ss->ssl3.hs.restartTarget) {
	    ssl_ReleaseSSL3HandshakeLock(ss);
	    PORT_SetError(PR_WOULD_BLOCK_ERROR);
	    return (int) SECFailure;
	}

	/* Treat an empty msgState like a NULL msgState. (Most of the time
	 * when ssl3_HandleHandshake returns SECWouldBlock, it leaves
	 * behind a non-NULL but zero-length msgState).
	 * Test: async_cert_restart_server_sends_hello_request_first_in_separate_record
	 */
	if (ss->ssl3.hs.msgState.buf) {
	    if (ss->ssl3.hs.msgState.len == 0) {
		ss->ssl3.hs.msgState.buf = NULL;
	    } else {
		handleRecordNow = PR_TRUE;
	    }
	}

	ssl_ReleaseSSL3HandshakeLock(ss);

	if (handleRecordNow) {
	    /* ssl3_HandleHandshake previously returned SECWouldBlock and the
	     * as-yet-unprocessed plaintext of that previous handshake record.
	     * We need to process it now before we overwrite it with the next
	     * handshake record.
	     */
	    rv = ssl3_HandleRecord(ss, NULL, &ss->gs.buf);
	} else {
	    /* bring in the next sslv3 record. */
	    if (ss->recvdCloseNotify) {
		/* RFC 5246 Section 7.2.1:
		 *   Any data received after a closure alert is ignored.
		 */
		return 0;
	    }
	    if (!IS_DTLS(ss)) {
		rv = ssl3_GatherData(ss, &ss->gs, flags);
	    } else {
		rv = dtls_GatherData(ss, &ss->gs, flags);
		
		/* If we got a would block error, that means that no data was
		 * available, so we check the timer to see if it's time to
		 * retransmit */
		if (rv == SECFailure &&
		    (PORT_GetError() == PR_WOULD_BLOCK_ERROR)) {
		    ssl_GetSSL3HandshakeLock(ss);
		    dtls_CheckTimer(ss);
		    ssl_ReleaseSSL3HandshakeLock(ss);
		    /* Restore the error in case something succeeded */
		    PORT_SetError(PR_WOULD_BLOCK_ERROR);
		}
	    }

	    if (rv <= 0) {
		return rv;
	    }

	    /* decipher it, and handle it if it's a handshake.
	     * If it's application data, ss->gs.buf will not be empty upon return.
	     * If it's a change cipher spec, alert, or handshake message,
	     * ss->gs.buf.len will be 0 when ssl3_HandleRecord returns SECSuccess.
	     */
	    cText.type    = (SSL3ContentType)ss->gs.hdr[0];
	    cText.version = (ss->gs.hdr[1] << 8) | ss->gs.hdr[2];

	    if (IS_DTLS(ss)) {
		int i;

		cText.version = dtls_DTLSVersionToTLSVersion(cText.version);
		/* DTLS sequence number */
		cText.seq_num.high = 0; cText.seq_num.low = 0;
		for (i = 0; i < 4; i++) {
		    cText.seq_num.high <<= 8; cText.seq_num.low <<= 8;
		    cText.seq_num.high |= ss->gs.hdr[3 + i];
		    cText.seq_num.low |= ss->gs.hdr[7 + i];
		}
	    }

	    cText.buf     = &ss->gs.inbuf;
	    rv = ssl3_HandleRecord(ss, &cText, &ss->gs.buf);
	}
	if (rv < 0) {
	    return ss->recvdCloseNotify ? 0 : rv;
	}
	if (ss->gs.buf.len > 0) {
	    /* We have application data to return to the application. This
	     * prioritizes returning application data to the application over
	     * completing any renegotiation handshake we may be doing.
	     */
	    PORT_Assert(ss->firstHsDone);
	    PORT_Assert(cText.type == content_application_data);
	    break;
	}

	PORT_Assert(keepGoing);
	ssl_GetSSL3HandshakeLock(ss);
	if (ss->ssl3.hs.ws == idle_handshake) {
	    /* We are done with the current handshake so stop trying to
	     * handshake. Note that it would be safe to test ss->firstHsDone
	     * instead of ss->ssl3.hs.ws. By testing ss->ssl3.hs.ws instead,
	     * we prioritize completing a renegotiation handshake over sending
	     * application data.
	     */
	    PORT_Assert(ss->firstHsDone);
	    PORT_Assert(!ss->ssl3.hs.canFalseStart);
	    keepGoing = PR_FALSE;
	} else if (ss->ssl3.hs.canFalseStart) {
	    /* Prioritize sending application data over trying to complete
	     * the handshake if we're false starting.
	     *
	     * If we were to do this check at the beginning of the loop instead
	     * of here, then this function would become be a no-op after
	     * receiving the ServerHelloDone in the false start case, and we
	     * would never complete the handshake.
	     */
	    PORT_Assert(!ss->firstHsDone);

	    if (ssl3_WaitingForStartOfServerSecondRound(ss)) {
		keepGoing = PR_FALSE;
	    } else {
		ss->ssl3.hs.canFalseStart = PR_FALSE;
	    }
	}
	ssl_ReleaseSSL3HandshakeLock(ss);
    } while (keepGoing);

    ss->gs.readOffset = 0;
    ss->gs.writeOffset = ss->gs.buf.len;
    return 1;
}

/* Repeatedly gather in a record and when complete, Handle that record.
 * Repeat this until some application data is received.
 *
 * Returns  1 when application data is available.
 * Returns  0 if ssl3_GatherData hits EOF.
 * Returns -1 on read error, or PR_WOULD_BLOCK_ERROR, or handleRecord error.
 * Returns -2 on SECWouldBlock return from ssl3_HandleRecord.
 *
 * Called from DoRecv in sslsecur.c
 * Caller must hold the recv buf lock.
 */
int
ssl3_GatherAppDataRecord(sslSocket *ss, int flags)
{
    int            rv;

    /* ssl3_GatherCompleteHandshake requires both of these locks. */
    PORT_Assert( ss->opt.noLocks || ssl_Have1stHandshakeLock(ss) );
    PORT_Assert( ss->opt.noLocks || ssl_HaveRecvBufLock(ss) );

    do {
	rv = ssl3_GatherCompleteHandshake(ss, flags);
    } while (rv > 0 && ss->gs.buf.len == 0);

    return rv;
}