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 /*

  * Gather (Read) entire SSL2 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 "sslproto.h"

 /* Forward static declarations */

 static SECStatus ssl2_HandleV3HandshakeRecord(sslSocket *ss);

 /*

 ** Gather a single record of data from the receiving stream. This code

 ** first gathers the header (2 or 3 bytes long depending on the value of

 ** the most significant bit in the first byte) then gathers up the data

 ** for the record into gs->buf. This code handles non-blocking I/O

 ** and is to be called multiple times until ss->sec.recordLen != 0.

 ** This function decrypts the gathered record in place, in gs_buf.

  *

  * Caller must hold RecvBufLock. 

  *

  * Returns +1 when it has gathered a complete SSLV2 record.

  * Returns  0 if it hits EOF.

  * Returns -1 (SECFailure)    on any error

  * Returns -2 (SECWouldBlock) when it gathers an SSL v3 client hello header.

 **

 ** The SSL2 Gather State machine has 4 states:

 ** GS_INIT   - Done reading in previous record.  Haven't begun to read in

 **             next record.  When ssl2_GatherData is called with the machine

 **             in this state, the machine will attempt to read the first 3

 **             bytes of the SSL2 record header, and will advance the state

 **             to GS_HEADER.

 **

 ** GS_HEADER - The machine is in this state while waiting for the completion

 **             of the first 3 bytes of the SSL2 record.  When complete, the

 **             machine will compute the remaining unread length of this record

 **             and will initiate a read of that many bytes.  The machine will

 **             advance to one of two states, depending on whether the record

 **             is encrypted (GS_MAC), or unencrypted (GS_DATA).

 **

 ** GS_MAC    - The machine is in this state while waiting for the remainder 

 **             of the SSL2 record to be read in.  When the read is completed,

 **             the machine checks the record for valid length, decrypts it,

 **             and checks and discards the MAC, then advances to GS_INIT.

 **

 ** GS_DATA   - The machine is in this state while waiting for the remainder

 **             of the unencrypted SSL2 record to be read in.  Upon completion,

 **             the machine advances to the GS_INIT state and returns the data.

 */

 int 

 ssl2_GatherData(sslSocket *ss, sslGather *gs, int flags)

 {

     unsigned char *  bp;

     unsigned char *  pBuf;

     int              nb, err, rv;

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

     if (gs->state == GS_INIT) {

 	/* Initialize gathering engine */

 	gs->state         = GS_HEADER;

 	gs->remainder     = 3;

 	gs->count         = 3;

 	gs->offset        = 0;

 	gs->recordLen     = 0;

 	gs->recordPadding = 0;

 	gs->hdr[2]        = 0;

 	gs->writeOffset   = 0;

 	gs->readOffset    = 0;

     }

     if (gs->encrypted) {

 	PORT_Assert(ss->sec.hash != 0);

     }

     pBuf = gs->buf.buf;

     for (;;) {

 	SSL_TRC(30, ("%d: SSL[%d]: gather state %d (need %d more)",

 		     SSL_GETPID(), ss->fd, gs->state, gs->remainder));

 	bp = ((gs->state != GS_HEADER) ? pBuf : gs->hdr) + gs->offset;

 	nb = ssl_DefRecv(ss, bp, gs->remainder, flags);

 	if (nb > 0) {

 	    PRINT_BUF(60, (ss, "raw gather data:", bp, nb));

 	}

 	if (nb == 0) {

 	    /* EOF */

 	    SSL_TRC(30, ("%d: SSL[%d]: EOF", SSL_GETPID(), ss->fd));

 	    rv = 0;

 	    break;

 	}

 	if (nb < 0) {

 	    SSL_DBG(("%d: SSL[%d]: recv error %d", SSL_GETPID(), ss->fd,

 		     PR_GetError()));

 	    rv = SECFailure;

 	    break;

 	}

 	gs->offset    += nb;

 	gs->remainder -= nb;

 	if (gs->remainder > 0) {

 	    continue;

 	}

 	/* Probably finished this piece */

 	switch (gs->state) {

 	case GS_HEADER: 

 	    if (!SSL3_ALL_VERSIONS_DISABLED(&ss->vrange) && !ss->firstHsDone) {

 		PORT_Assert( ss->opt.noLocks || ssl_Have1stHandshakeLock(ss) );

 		/* If this looks like an SSL3 handshake record, 

 		** and we're expecting an SSL2 Hello message from our peer, 

 		** handle it here.

 		*/

 		if (gs->hdr[0] == content_handshake) {

 		    if ((ss->nextHandshake == ssl2_HandleClientHelloMessage) ||

 			(ss->nextHandshake == ssl2_HandleServerHelloMessage)) {

 			rv = ssl2_HandleV3HandshakeRecord(ss);

 			if (rv == SECFailure) {

 			    return SECFailure;

 			}

 		    }

 		    /* XXX_1	The call stack to here is:

 		     * ssl_Do1stHandshake -> ssl_GatherRecord1stHandshake -> 

 		     *			ssl2_GatherRecord -> here.

 		     * We want to return all the way out to ssl_Do1stHandshake,

 		     * and have it call ssl_GatherRecord1stHandshake again. 

 		     * ssl_GatherRecord1stHandshake will call 

 		     * ssl3_GatherCompleteHandshake when it is called again.

 		     *

 		     * Returning SECWouldBlock here causes 

 		     * ssl_GatherRecord1stHandshake to return without clearing 

 		     * ss->handshake, ensuring that ssl_Do1stHandshake will 

 		     * call it again immediately.

 		     * 

 		     * If we return 1 here, ssl_GatherRecord1stHandshake will 

 		     * clear ss->handshake before returning, and thus will not 

 		     * be called again by ssl_Do1stHandshake.  

 		     */

 		    return SECWouldBlock;

 		} else if (gs->hdr[0] == content_alert) {

 		    if (ss->nextHandshake == ssl2_HandleServerHelloMessage) {

 			/* XXX This is a hack.  We're assuming that any failure

 			 * XXX on the client hello is a failure to match

 			 * XXX ciphers.

 			 */

 			PORT_SetError(SSL_ERROR_NO_CYPHER_OVERLAP);

 			return SECFailure;

 		    }

 		}

 	    }

 	    /* we've got the first 3 bytes.  The header may be two or three. */

 	    if (gs->hdr[0] & 0x80) {

 		/* This record has a 2-byte header, and no padding */

 		gs->count = ((gs->hdr[0] & 0x7f) << 8) | gs->hdr[1];

 		gs->recordPadding = 0;

 	    } else {

 		/* This record has a 3-byte header that is all read in now. */

 		gs->count = ((gs->hdr[0] & 0x3f) << 8) | gs->hdr[1];

 	    /*  is_escape =  (gs->hdr[0] & 0x40) != 0; */

 		gs->recordPadding = gs->hdr[2];

 	    }

 	    if (!gs->count) {

 		PORT_SetError(SSL_ERROR_RX_RECORD_TOO_LONG);

 		goto cleanup;

 	    }

 	    if (gs->count > gs->buf.space) {

 		err = sslBuffer_Grow(&gs->buf, gs->count);

 		if (err) {

 		    return err;

 		}

 		pBuf = gs->buf.buf;

 	    }

 	    if (gs->hdr[0] & 0x80) {

 	    	/* we've already read in the first byte of the body.

 		** Put it into the buffer.

 		*/

 		pBuf[0]        = gs->hdr[2];

 		gs->offset    = 1;

 		gs->remainder = gs->count - 1;

 	    } else {

 		gs->offset    = 0;

 		gs->remainder = gs->count;

 	    }

 	    if (gs->encrypted) {

 		gs->state     = GS_MAC;

 		gs->recordLen = gs->count - gs->recordPadding

 		                          - ss->sec.hash->length;

 	    } else {

 		gs->state     = GS_DATA;

 		gs->recordLen = gs->count;

 	    }

 	    break;

 	case GS_MAC:

 	    /* Have read in entire rest of the ciphertext.  

 	    ** Check for valid length.

 	    ** Decrypt it.

 	    ** Check the MAC.

 	    */

 	    PORT_Assert(gs->encrypted);

 	  {

 	    unsigned int     macLen;

 	    int              nout;

 	    unsigned char    mac[SSL_MAX_MAC_BYTES];

 	    ssl_GetSpecReadLock(ss); /**********************************/

 	    /* If this is a stream cipher, blockSize will be 1,

 	     * and this test will always be false.

 	     * If this is a block cipher, this will detect records

 	     * that are not a multiple of the blocksize in length.

 	     */

 	    if (gs->count & (ss->sec.blockSize - 1)) {

 		/* This is an error. Sender is misbehaving */

 		SSL_DBG(("%d: SSL[%d]: sender, count=%d blockSize=%d",

 			 SSL_GETPID(), ss->fd, gs->count,

 			 ss->sec.blockSize));

 		PORT_SetError(SSL_ERROR_BAD_BLOCK_PADDING);

 		rv = SECFailure;

 		goto spec_locked_done;

 	    }

 	    PORT_Assert(gs->count == gs->offset);

 	    if (gs->offset == 0) {

 		rv = 0;			/* means EOF. */

 		goto spec_locked_done;

 	    }

 	    /* Decrypt the portion of data that we just received.

 	    ** Decrypt it in place.

 	    */

 	    rv = (*ss->sec.dec)(ss->sec.readcx, pBuf, &nout, gs->offset,

 			     pBuf, gs->offset);

 	    if (rv != SECSuccess) {

 		goto spec_locked_done;

 	    }

 	    /* Have read in all the MAC portion of record 

 	    **

 	    ** Prepare MAC by resetting it and feeding it the shared secret

 	    */

 	    macLen = ss->sec.hash->length;

 	    if (gs->offset >= macLen) {

 		PRUint32           sequenceNumber = ss->sec.rcvSequence++;

 		unsigned char    seq[4];

 		seq[0] = (unsigned char) (sequenceNumber >> 24);

 		seq[1] = (unsigned char) (sequenceNumber >> 16);

 		seq[2] = (unsigned char) (sequenceNumber >> 8);

 		seq[3] = (unsigned char) (sequenceNumber);

 		(*ss->sec.hash->begin)(ss->sec.hashcx);

 		(*ss->sec.hash->update)(ss->sec.hashcx, ss->sec.rcvSecret.data,

 				        ss->sec.rcvSecret.len);

 		(*ss->sec.hash->update)(ss->sec.hashcx, pBuf + macLen, 

 				        gs->offset - macLen);

 		(*ss->sec.hash->update)(ss->sec.hashcx, seq, 4);

 		(*ss->sec.hash->end)(ss->sec.hashcx, mac, &macLen, macLen);

 		PORT_Assert(macLen == ss->sec.hash->length);

 		ssl_ReleaseSpecReadLock(ss);  /******************************/

 		if (NSS_SecureMemcmp(mac, pBuf, macLen) != 0) {

 		    /* MAC's didn't match... */

 		    SSL_DBG(("%d: SSL[%d]: mac check failed, seq=%d",

 			     SSL_GETPID(), ss->fd, ss->sec.rcvSequence));

 		    PRINT_BUF(1, (ss, "computed mac:", mac, macLen));

 		    PRINT_BUF(1, (ss, "received mac:", pBuf, macLen));

 		    PORT_SetError(SSL_ERROR_BAD_MAC_READ);

 		    rv = SECFailure;

 		    goto cleanup;

 		}

 	    } else {

 		ssl_ReleaseSpecReadLock(ss);  /******************************/

 	    }

 	    if (gs->recordPadding + macLen <= gs->offset) {

 		gs->recordOffset  = macLen;

 		gs->readOffset    = macLen;

 		gs->writeOffset   = gs->offset - gs->recordPadding;

 		rv = 1;

 	    } else {

 		PORT_SetError(SSL_ERROR_BAD_BLOCK_PADDING);

 cleanup:

 		/* nothing in the buffer any more. */

 		gs->recordOffset  = 0;

 		gs->readOffset    = 0;

 	    	gs->writeOffset   = 0;

 		rv = SECFailure;

 	    }

 	    gs->recordLen     = gs->writeOffset - gs->readOffset;

 	    gs->recordPadding = 0;	/* forget we did any padding. */

 	    gs->state = GS_INIT;

 	    if (rv > 0) {

 		PRINT_BUF(50, (ss, "recv clear record:", 

 		               pBuf + gs->recordOffset, gs->recordLen));

 	    }

 	    return rv;

 spec_locked_done:

 	    ssl_ReleaseSpecReadLock(ss);

 	    return rv;

 	  }

 	case GS_DATA:

 	    /* Have read in all the DATA portion of record */

 	    gs->recordOffset  = 0;

 	    gs->readOffset    = 0;

 	    gs->writeOffset   = gs->offset;

 	    PORT_Assert(gs->recordLen == gs->writeOffset - gs->readOffset);

 	    gs->recordLen     = gs->offset;

 	    gs->recordPadding = 0;

 	    gs->state         = GS_INIT;

 	    ++ss->sec.rcvSequence;

 	    PRINT_BUF(50, (ss, "recv clear record:", 

 	                   pBuf + gs->recordOffset, gs->recordLen));

 	    return 1;

 	}	/* end switch gs->state */

     }		/* end gather loop. */

     return rv;

 }

 /*

 ** Gather a single record of data from the receiving stream. This code

 ** first gathers the header (2 or 3 bytes long depending on the value of

 ** the most significant bit in the first byte) then gathers up the data

 ** for the record into the readBuf. This code handles non-blocking I/O

 ** and is to be called multiple times until ss->sec.recordLen != 0.

  *

  * Returns +1 when it has gathered a complete SSLV2 record.

  * Returns  0 if it hits EOF.

  * Returns -1 (SECFailure)    on any error

  * Returns -2 (SECWouldBlock) 

  *

  * Called by ssl_GatherRecord1stHandshake in sslcon.c, 

  * and by DoRecv in sslsecur.c

  * Caller must hold RecvBufLock.

  */

 int 

 ssl2_GatherRecord(sslSocket *ss, int flags)

 {

     return ssl2_GatherData(ss, &ss->gs, flags);

 }

 /* Caller should hold RecvBufLock. */

 SECStatus

 ssl_InitGather(sslGather *gs)

 {

     SECStatus status;

     gs->state = GS_INIT;

     gs->writeOffset = 0;

     gs->readOffset  = 0;

     gs->dtlsPacketOffset = 0;

     gs->dtlsPacket.len = 0;

     status = sslBuffer_Grow(&gs->buf, 4096);

     return status;

 }

 /* Caller must hold RecvBufLock. */

 void 

 ssl_DestroyGather(sslGather *gs)

 {

     if (gs) {	/* the PORT_*Free functions check for NULL pointers. */

 	PORT_ZFree(gs->buf.buf, gs->buf.space);

 	PORT_Free(gs->inbuf.buf);

 	PORT_Free(gs->dtlsPacket.buf);

     }

 }

 /* Caller must hold RecvBufLock. */

 static SECStatus

 ssl2_HandleV3HandshakeRecord(sslSocket *ss)

 {

     SECStatus           rv;

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

     PORT_Assert( ss->opt.noLocks || ssl_Have1stHandshakeLock(ss) );

     /* We've read in 3 bytes, there are 2 more to go in an ssl3 header. */

     ss->gs.remainder         = 2;

     ss->gs.count             = 0;

     /* Clearing these handshake pointers ensures that 

      * ssl_Do1stHandshake won't call ssl2_HandleMessage when we return.

      */

     ss->nextHandshake     = 0;

     ss->securityHandshake = 0;

     /* Setting ss->version to an SSL 3.x value will cause 

     ** ssl_GatherRecord1stHandshake to invoke ssl3_GatherCompleteHandshake() 

     ** the next time it is called.

     **/

     rv = ssl3_NegotiateVersion(ss, SSL_LIBRARY_VERSION_MAX_SUPPORTED,

 			       PR_TRUE);

     if (rv != SECSuccess) {

 	return rv;

     }

     ss->sec.send         = ssl3_SendApplicationData;

     return SECSuccess;

 }