/* proti.c The 'i' protocol. Copyright (C) 1992, 1993, 1995 Ian Lance Taylor This file is part of the Taylor UUCP package. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. The author of the program may be contacted at ian@airs.com or c/o Cygnus Support, 48 Grove Street, Somerville, MA 02144. */ #include "uucp.h" #if USE_RCS_ID const char proti_rcsid[] = "$Id: proti.c,v 1.1 1995/10/18 08:38:40 deraadt Exp $"; #endif #include #include #include "uudefs.h" #include "uuconf.h" #include "conn.h" #include "trans.h" #include "system.h" #include "prot.h" /* The 'i' protocol is a simple sliding window protocol, created by me. It is in many ways similar to the 'g' protocol. Several ideas are also taken from the paper ``A High-Throughput Message Transport System'' by P. Lauder. I don't know where the paper was published, but the author's e-mail address is piers@cs.su.oz.au. However, I haven't adopted his main idea, which is to dispense with windows entirely. This is because some links still do require flow control and, more importantly, because I want to have a limit to the amount of data I must be able to resend upon request. To reduce the costs of window acknowledgements, I use a large window and only require an ack at the halfway point. Each packet starts with a header containing the following information: Intro byte 8 bits byte 1 Packet number 5 bits byte 2 Local channel 3 bits Packet ack 5 bits byte 3 Remote channel 3 bits Packet type 3 bits bytes 4-5 Direction 1 bit Data length 12 bits Header check 8 bits byte 6 If the data length is not 0, this is followed by the data and a 32 bit CRC checksum. The following packet types are defined: SYNC Initialize the connection DATA Data packet ACK Simple acknowledgement with no data NAK Negative acknowledgement; requests resend of single packet SPOS Set file position CLOSE Close the connection */ /* The offsets of the bytes in the packet header. */ #define IHDR_INTRO (0) #define IHDR_LOCAL (1) #define IHDR_REMOTE (2) #define IHDR_CONTENTS1 (3) #define IHDR_CONTENTS2 (4) #define IHDR_CHECK (5) /* Macros to set and extract values of IHDR_LOCAL and IHDR_REMOTE. */ #define IHDRWIN_SET(iseq, ichan) (((iseq) << 3) | (ichan)) #define IHDRWIN_GETSEQ(ival) (((ival) >> 3) & 0x1f) #define IHDRWIN_GETCHAN(ival) ((ival) & 0x07) /* Macros to set and extract values of IHDR_CONTENTS fields. */ #define IHDRCON_SET1(ttype, fcaller, cbytes) \ (((ttype) << 5) | ((fcaller) ? (1 << 4) : 0) | (((cbytes) >> 8) & 0x0f)) #define IHDRCON_SET2(ttype, fcaller, cbytes) ((cbytes) & 0xff) #define THDRCON_GETTYPE(i1, i2) (((i1) >> 5) & 0x07) #define FHDRCON_GETCALLER(i1, i2) (((i1) & (1 << 4)) != 0) #define CHDRCON_GETBYTES(i1, i2) ((((i1) & 0x0f) << 8) | ((i2) & 0xff)) /* Macros for the IHDR_CHECK field. */ #define IHDRCHECK_VAL(zhdr) \ ((zhdr[IHDR_LOCAL] \ ^ zhdr[IHDR_REMOTE] \ ^ zhdr[IHDR_CONTENTS1] \ ^ zhdr[IHDR_CONTENTS2]) \ & 0xff) /* Length of the packet header. */ #define CHDRLEN (6) /* Amount of space to skip between start of packet and actual data. This is used to make the actual data longword aligned, to encourage good performance when copying data into the buffer. */ #define CHDRSKIPLEN (CHDRLEN + (sizeof (long) - CHDRLEN % sizeof (long))) /* Amount of space to skip between memory buffer and header. */ #define CHDROFFSET (CHDRSKIPLEN - CHDRLEN) /* Length of the trailing checksum. */ #define CCKSUMLEN (4) /* Macros to set and get the checksum. These multiply evaluate their arguments. */ #define ICKSUM_GET(z) \ ((((((((unsigned long) ((z)[0] & 0xff)) << 8) \ | (unsigned long) ((z)[1] & 0xff)) << 8) \ | (unsigned long) ((z)[2] & 0xff)) << 8) \ | (unsigned long) ((z)[3] & 0xff)) #define UCKSUM_SET(z, i) \ (void) ((z)[0] = (((i) >> 24) & 0xff), \ (z)[1] = (((i) >> 16) & 0xff), \ (z)[2] = (((i) >> 8) & 0xff), \ (z)[3] = ((i) & 0xff)) /* The header introduction character. */ #define IINTRO ('\007') /* The packet types. */ #define DATA (0) #define SYNC (1) #define ACK (2) #define NAK (3) #define SPOS (4) #define CLOSE (5) /* Largest possible packet size. */ #define IMAXPACKSIZE ((1 << 12) - 1) /* Largest possible sequence number (plus 1). */ #define IMAXSEQ 32 /* Get the next sequence number given a sequence number. */ #define INEXTSEQ(i) (((i) + 1) & (IMAXSEQ - 1)) /* Get the previous sequence number given a sequence number. */ #define IPREVSEQ(i) (((i) + IMAXSEQ - 1) & (IMAXSEQ - 1)) /* Compute i1 - i2 in sequence space (i.e., the number of packets from i2 to i1). */ #define CSEQDIFF(i1, i2) (((i1) + IMAXSEQ - (i2)) & (IMAXSEQ - 1)) /* Largest possible channel number (plus 1). */ #define IMAXICHAN (8) /* Default packet size to request (protocol parameter ``packet-size''). */ #define IREQUEST_PACKSIZE (1024) /* Default window size to request (protocol parameter ``window''). */ #define IREQUEST_WINSIZE (16) /* Default timeout to use when sending the SYNC packet (protocol parameter ``sync-timeout''). */ #define CSYNC_TIMEOUT (10) /* Default number of times to retry sending the SYNC packet (protocol parameter ``sync-retries''). */ #define CSYNC_RETRIES (6) /* Default timeout to use when waiting for a packet (protocol parameter ``timeout''). */ #define CTIMEOUT (10) /* Default number of times to retry sending a packet before giving up (protocol parameter ``retries''). */ #define CRETRIES (6) /* Default maximum level of errors to accept before giving up (protocol parameter ``errors''). */ #define CERRORS (100) /* Default decay rate. Each time we receive this many packets succesfully, we decrement the error level by one (protocol parameter ``error-decay''). */ #define CERROR_DECAY (10) /* The default list of characters to avoid: XON and XOFF. This string is processed as an escape sequence. This is 'j' protocol parameter ``avoid''; it is defined in this file because the 'i' and 'j' protocols share protocol parameters. */ #define ZAVOID "\\021\\023" /* Local variables. */ /* Packet size to request (protocol parameter ``packet-size''). */ static int iIrequest_packsize = IREQUEST_PACKSIZE; /* Window size to request (protocol parameter ``window''). */ static int iIrequest_winsize = IREQUEST_WINSIZE; /* Remote packet size (set from SYNC packet or from iIforced_remote_packsize). */ static int iIremote_packsize; /* Size which buffers were allocated for. */ static int iIalc_packsize; /* Forced remote packet size, used if non-zero (protocol parameter ``remote-packet-size''). There is no forced remote window size because the ACK strategy requires that both sides agree on the window size. */ static int iIforced_remote_packsize = 0; /* Remote window size (set from SYNC packet). */ static int iIremote_winsize; /* Timeout to use when sending the SYNC packet (protocol parameter ``sync-timeout''). */ int cIsync_timeout = CSYNC_TIMEOUT; /* Number of times to retry sending the SYNC packet (protocol parameter ``sync-retries''). */ static int cIsync_retries = CSYNC_RETRIES; /* Timeout to use when waiting for a packet (protocol parameter ``timeout''). */ static int cItimeout = CTIMEOUT; /* Timeout to use when waiting for an acknowledgement to open up space in the window. This is computed based on the window size and the connection speed. */ static int cIwindow_timeout = CTIMEOUT; /* Number of times to retry sending a packet before giving up (protocol parameter ``retries''). */ static int cIretries = CRETRIES; /* Maximum level of errors to accept before giving up (protocol parameter ``errors''). */ static int cIerrors = CERRORS; /* Each time we receive this many packets succesfully, we decrement the error level by one (protocol parameter ``error-decay''). */ static int cIerror_decay = CERROR_DECAY; /* The number of packets we should wait to receive before sending an ACK; this is set by default to half the window size we have requested (protocol parameter ``ack-frequency''). */ static int cIack_frequency = 0; /* The set of characters to avoid (protocol parameter ``avoid''). This is actually part of the 'j' protocol; it is defined in this file because the 'i' and 'j' protocols use the same protocol parameters. */ const char *zJavoid_parameter = ZAVOID; /* Routine to use when sending data. This is a hook for the 'j' protocol. */ static boolean (*pfIsend) P((struct sconnection *qconn, const char *zsend, size_t csend, boolean fdoread)); /* Routine to use to use when reading data. This is a hook for the 'j' protocol. */ static boolean (*pfIreceive) P((struct sconnection *qconn, size_t cneed, size_t *pcrec, int ctimeout, boolean freport)); /* Next sequence number to send. */ static int iIsendseq; /* Last sequence number received. */ static int iIrecseq; /* Last sequence number we have acknowledged. */ static int iIlocal_ack; /* Last sequence number remote system has acknowledged. */ static int iIremote_ack; /* File position we are sending from. */ static long iIsendpos; /* File position we are receiving to. */ static long iIrecpos; /* TRUE if closing the connection. */ static boolean fIclosing; /* Array of sent packets indexed by packet number. */ static char *azIsendbuffers[IMAXSEQ]; /* Array of received packets that we aren't ready to process yet, indexed by packet number. */ static char *azIrecbuffers[IMAXSEQ]; /* For each packet sequence number, record whether we sent a NAK for the packet. */ static boolean afInaked[IMAXSEQ]; /* Number of SYNC packets received (used only to detect whether one was received). */ static int cIsyncs; /* Number of packets sent. */ static long cIsent_packets; /* Number of packets received. */ static long cIreceived_packets; /* Number of packets resent. */ static long cIresent_packets; /* Number of bad packet headers received. */ static long cIbad_hdr; /* Number of out of order packets received. */ static long cIbad_order; /* Number of bad checksums received. */ static long cIbad_cksum; /* Number of packets rejected by remote system. */ static long cIremote_rejects; /* Protocol parameter commands. */ struct uuconf_cmdtab asIproto_params[] = { { "packet-size", UUCONF_CMDTABTYPE_INT, (pointer) &iIrequest_packsize, NULL }, { "window", UUCONF_CMDTABTYPE_INT, (pointer) &iIrequest_winsize, NULL }, { "remote-packet-size", UUCONF_CMDTABTYPE_INT, (pointer) &iIforced_remote_packsize, NULL }, { "sync-timeout", UUCONF_CMDTABTYPE_INT, (pointer) &cIsync_timeout, NULL }, { "sync-retries", UUCONF_CMDTABTYPE_INT, (pointer) &cIsync_retries, NULL }, { "timeout", UUCONF_CMDTABTYPE_INT, (pointer) &cItimeout, NULL }, { "retries", UUCONF_CMDTABTYPE_INT, (pointer) &cIretries, NULL }, { "errors", UUCONF_CMDTABTYPE_INT, (pointer) &cIerrors, NULL }, { "error-decay", UUCONF_CMDTABTYPE_INT, (pointer) &cIerror_decay, NULL }, { "ack-frequency", UUCONF_CMDTABTYPE_INT, (pointer) &cIack_frequency, NULL }, /* The ``avoid'' protocol parameter is part of the 'j' protocol, but it is convenient for the 'i' and 'j' protocols to share the same protocol parameter table. */ { "avoid", UUCONF_CMDTABTYPE_STRING, (pointer) &zJavoid_parameter, NULL }, { NULL, 0, NULL, NULL } }; /* Local functions. */ static boolean finak P((struct sdaemon *qdaemon, int iseq)); static boolean firesend P((struct sdaemon *qdaemon)); static boolean fiwindow_wait P((struct sdaemon *qdaemon)); static boolean fiwait_for_packet P((struct sdaemon *qdaemon, int ctimeout, int cretries, boolean fone, boolean *ftimedout)); static boolean ficheck_errors P((struct sdaemon *qdaemon)); static boolean fiprocess_data P((struct sdaemon *qdaemon, boolean *pfexit, boolean *pffound, size_t *pcneed)); static boolean fiprocess_packet P((struct sdaemon *qdaemon, const char *zhdr, const char *zfirst, int cfirst, const char *zsecond, int csecond, boolean *pfexit)); /* The 'i' protocol start routine. The work is done in a routine which is also called by the 'j' protocol start routine. */ boolean fistart (qdaemon, pzlog) struct sdaemon *qdaemon; char **pzlog; { return fijstart (qdaemon, pzlog, IMAXPACKSIZE, fsend_data, freceive_data); } /* Start the protocol. This routine is called by both the 'i' and 'j' protocol start routines. We keep transmitting a SYNC packet containing the window and packet size we would like to receive until we receive a SYNC packet from the remote system. The first two bytes of the data contents of a SYNC packet are the maximum packet size we want to receive (high byte, low byte), and the next byte is the maximum window size we want to use. */ boolean fijstart (qdaemon, pzlog, imaxpacksize, pfsend, pfreceive) struct sdaemon *qdaemon; char **pzlog; int imaxpacksize; boolean (*pfsend) P((struct sconnection *qconn, const char *zsend, size_t csend, boolean fdoread)); boolean (*pfreceive) P((struct sconnection *qconn, size_t cneed, size_t *pcrec, int ctimeout, boolean freport)); { char ab[CHDRLEN + 4 + CCKSUMLEN]; unsigned long icksum; int ctries; int csyncs; long ibaud; *pzlog = NULL; pfIsend = pfsend; pfIreceive = pfreceive; if (iIforced_remote_packsize <= 0 || iIforced_remote_packsize > imaxpacksize) iIforced_remote_packsize = 0; else iIremote_packsize = iIforced_remote_packsize; iIalc_packsize = 0; iIsendseq = 1; iIrecseq = 0; iIlocal_ack = 0; iIremote_ack = 0; iIsendpos = 0; iIrecpos = 0; fIclosing = FALSE; cIsent_packets = 0; cIreceived_packets = 0; cIresent_packets = 0; cIbad_hdr = 0; cIbad_order = 0; cIbad_cksum = 0; cIremote_rejects = 0; if (iIrequest_packsize < 0 || iIrequest_packsize > imaxpacksize) { ulog (LOG_ERROR, "Illegal protocol '%c' packet size; using %d", qdaemon->qproto->bname, imaxpacksize); iIrequest_packsize = imaxpacksize; } /* The maximum permissible window size is 16. Otherwise the protocol can get confused because a duplicated packet may arrive out of order. If the window size is large in such a case, the duplicate packet may be treated as a packet in the upcoming window, causing the protocol to assume that all intermediate packets have been lost, leading to immense confusion. */ if (iIrequest_winsize < 0 || iIrequest_winsize > IMAXSEQ / 2) { ulog (LOG_ERROR, "Illegal protocol '%c' window size; using %d", qdaemon->qproto->bname, IREQUEST_WINSIZE); iIrequest_winsize = IREQUEST_WINSIZE; } /* The default for the ACK frequency is half the window size. */ if (cIack_frequency <= 0 || cIack_frequency >= iIrequest_winsize) cIack_frequency = iIrequest_winsize / 2; ab[IHDR_INTRO] = IINTRO; ab[IHDR_LOCAL] = ab[IHDR_REMOTE] = IHDRWIN_SET (0, 0); ab[IHDR_CONTENTS1] = IHDRCON_SET1 (SYNC, qdaemon->fcaller, 4); ab[IHDR_CONTENTS2] = IHDRCON_SET2 (SYNC, qdaemon->fcaller, 4); ab[IHDR_CHECK] = IHDRCHECK_VAL (ab); ab[CHDRLEN + 0] = (iIrequest_packsize >> 8) & 0xff; ab[CHDRLEN + 1] = iIrequest_packsize & 0xff; ab[CHDRLEN + 2] = iIrequest_winsize; ab[CHDRLEN + 3] = qdaemon->cchans; icksum = icrc (ab + CHDRLEN, 4, ICRCINIT); UCKSUM_SET (ab + CHDRLEN + 4, icksum); /* The static cIsyncs is incremented each time a SYNC packet is received. */ csyncs = cIsyncs; ctries = 0; while (TRUE) { boolean ftimedout; DEBUG_MESSAGE3 (DEBUG_PROTO, "fistart: Sending SYNC packsize %d winsize %d channels %d", iIrequest_packsize, iIrequest_winsize, qdaemon->cchans); if (! (*pfIsend) (qdaemon->qconn, ab, CHDRLEN + 4 + CCKSUMLEN, TRUE)) return FALSE; if (fiwait_for_packet (qdaemon, cIsync_timeout, 0, FALSE, &ftimedout)) { if (csyncs != cIsyncs) break; } else { if (! ftimedout) return FALSE; ++ctries; if (ctries > cIsync_retries) { ulog (LOG_ERROR, "Protocol startup failed"); return FALSE; } } } /* Calculate the window timeout. */ ibaud = iconn_baud (qdaemon->qconn); if (ibaud == 0) cIwindow_timeout = cItimeout; else { /* We expect to receive an ACK about halfway through each window. In principle, an entire window might be sitting in a modem buffer while we are waiting for an ACK. Therefore, the minimum time we should wait for an ACK is (1/2 window size) * (seconds / byte) + (roundtrip time) == (1/2 window size) * (1 / (baud / 10)) + (roundtrip time) == (1/2 window size) * (10 / baud) + (roundtrip time) == (5 * (window size)) / baud + (roundtrip time) The window size is iIremote_packsize * iIremote_winsize. For typical settings of packsize == 1024, winsize == 16, baud == 9600, this equation works out to (5 * 1024 * 16) / 9600 == 8 seconds We then take cItimeout as the round trip time, which gives us some flexibility. We get more flexibility because it is quite likely that by the time we have finished sending out the last packet in a window, the first one has already been received by the remote system. */ cIwindow_timeout = ((5 * iIremote_packsize * iIremote_winsize) / ibaud + cItimeout); } /* If we are the callee, bump both timeouts by one, to make it less likely that both systems will timeout simultaneously. */ if (! qdaemon->fcaller) { ++cItimeout; ++cIwindow_timeout; } /* We got a SYNC packet; set up packet buffers to use. */ if (iIremote_packsize > imaxpacksize) iIremote_packsize = imaxpacksize; do { int iseq; for (iseq = 0; iseq < IMAXSEQ; iseq++) { azIrecbuffers[iseq] = NULL; afInaked[iseq] = FALSE; azIsendbuffers[iseq] = (char *) malloc (iIremote_packsize + CHDRSKIPLEN + CCKSUMLEN); if (azIsendbuffers[iseq] == NULL) { int ifree; for (ifree = 0; ifree < iseq; ifree++) free ((pointer) azIsendbuffers[ifree]); break; } } if (iseq >= IMAXSEQ) { *pzlog = zbufalc (sizeof "protocol '' sending packet/window / receiving /" + 64); sprintf (*pzlog, "protocol '%c' sending packet/window %d/%d receiving %d/%d", qdaemon->qproto->bname, (int) iIremote_packsize, (int) iIremote_winsize, (int) iIrequest_packsize, (int) iIrequest_winsize); iIalc_packsize = iIremote_packsize; return TRUE; } iIremote_packsize >>= 1; } while (iIremote_packsize > 200); ulog (LOG_ERROR, "'%c' protocol startup failed; insufficient memory for packets", qdaemon->qproto->bname); return FALSE; } /* Shut down the protocol. We can be fairly informal about this, since we know that the upper level protocol has already exchanged hangup messages. If we didn't know that, we would have to make sure that all packets before the CLOSE had been received. */ boolean fishutdown (qdaemon) struct sdaemon *qdaemon; { char *z; size_t clen; fIclosing = TRUE; z = zigetspace (qdaemon, &clen) - CHDRLEN; z[IHDR_INTRO] = IINTRO; z[IHDR_LOCAL] = IHDRWIN_SET (iIsendseq, 0); z[IHDR_REMOTE] = IHDRWIN_SET (iIrecseq, 0); iIlocal_ack = iIrecseq; z[IHDR_CONTENTS1] = IHDRCON_SET1 (CLOSE, qdaemon->fcaller, 0); z[IHDR_CONTENTS2] = IHDRCON_SET2 (CLOSE, qdaemon->fcaller, 0); z[IHDR_CHECK] = IHDRCHECK_VAL (z); DEBUG_MESSAGE0 (DEBUG_PROTO, "fishutdown: Sending CLOSE"); if (! (*pfIsend) (qdaemon->qconn, z, CHDRLEN, FALSE)) return FALSE; ulog (LOG_NORMAL, "Protocol '%c' packets: sent %ld, resent %ld, received %ld", qdaemon->qproto->bname, cIsent_packets, cIresent_packets, cIreceived_packets); if (cIbad_hdr != 0 || cIbad_cksum != 0 || cIbad_order != 0 || cIremote_rejects != 0) ulog (LOG_NORMAL, "Errors: header %ld, checksum %ld, order %ld, remote rejects %ld", cIbad_hdr, cIbad_cksum, cIbad_order, cIremote_rejects); /* Reset the protocol parameters to their default values. */ iIrequest_packsize = IREQUEST_PACKSIZE; iIrequest_winsize = IREQUEST_WINSIZE; iIforced_remote_packsize = 0; cIsync_timeout = CSYNC_TIMEOUT; cIsync_retries = CSYNC_RETRIES; cItimeout = CTIMEOUT; cIwindow_timeout = CTIMEOUT; cIretries = CRETRIES; cIerrors = CERRORS; cIerror_decay = CERROR_DECAY; cIack_frequency = 0; zJavoid_parameter = ZAVOID; return TRUE; } /* Send a command string. These are just sent as normal packets, ending in a packet containing a null byte. */ boolean fisendcmd (qdaemon, z, ilocal, iremote) struct sdaemon *qdaemon; const char *z; int ilocal; int iremote; { size_t clen; DEBUG_MESSAGE1 (DEBUG_UUCP_PROTO, "fisendcmd: Sending command \"%s\"", z); clen = strlen (z); while (TRUE) { char *zpacket; size_t csize; zpacket = zigetspace (qdaemon, &csize); if (clen < csize) { memcpy (zpacket, z, clen + 1); return fisenddata (qdaemon, zpacket, clen + 1, ilocal, iremote, (long) -1); } memcpy (zpacket, z, csize); z += csize; clen -= csize; if (! fisenddata (qdaemon, zpacket, csize, ilocal, iremote, (long) -1)) return FALSE; } /*NOTREACHED*/ } /* Send a NAK. */ static boolean finak (qdaemon, iseq) struct sdaemon *qdaemon; int iseq; { char abnak[CHDRLEN]; abnak[IHDR_INTRO] = IINTRO; abnak[IHDR_LOCAL] = IHDRWIN_SET (iseq, 0); abnak[IHDR_REMOTE] = IHDRWIN_SET (iIrecseq, 0); iIlocal_ack = iIrecseq; abnak[IHDR_CONTENTS1] = IHDRCON_SET1 (NAK, qdaemon->fcaller, 0); abnak[IHDR_CONTENTS2] = IHDRCON_SET2 (NAK, qdaemon->fcaller, 0); abnak[IHDR_CHECK] = IHDRCHECK_VAL (abnak); afInaked[iseq] = TRUE; DEBUG_MESSAGE1 (DEBUG_PROTO | DEBUG_ABNORMAL, "finak: Sending NAK %d", iseq); return (*pfIsend) (qdaemon->qconn, abnak, CHDRLEN, TRUE); } /* Resend the latest packet the remote has not acknowledged. */ static boolean firesend (qdaemon) struct sdaemon *qdaemon; { int iseq; char *zhdr; size_t clen; iseq = INEXTSEQ (iIremote_ack); if (iseq == iIsendseq) { /* Everything has been ACKed and there is nothing to resend. */ return TRUE; } DEBUG_MESSAGE1 (DEBUG_PROTO | DEBUG_ABNORMAL, "firesend: Resending packet %d", iseq); /* Update the received sequence number. */ zhdr = azIsendbuffers[iseq] + CHDROFFSET; if (IHDRWIN_GETSEQ (zhdr[IHDR_REMOTE]) != iIrecseq) { int iremote; iremote = IHDRWIN_GETCHAN (zhdr[IHDR_REMOTE]); zhdr[IHDR_REMOTE] = IHDRWIN_SET (iIrecseq, iremote); zhdr[IHDR_CHECK] = IHDRCHECK_VAL (zhdr); iIlocal_ack = iIrecseq; } ++cIresent_packets; clen = CHDRCON_GETBYTES (zhdr[IHDR_CONTENTS1], zhdr[IHDR_CONTENTS2]); return (*pfIsend) (qdaemon->qconn, zhdr, CHDRLEN + clen + (clen > 0 ? CCKSUMLEN : 0), TRUE); } /* Wait until there is an opening in the receive window of the remote system. */ static boolean fiwindow_wait (qdaemon) struct sdaemon *qdaemon; { /* iIsendseq is the sequence number we are sending, and iIremote_ack is the last sequence number acknowledged by the remote. */ while (CSEQDIFF (iIsendseq, iIremote_ack) > iIremote_winsize) { /* If a NAK is lost, it is possible for the other side to be sending a stream of packets while we are waiting for an ACK. This should be caught in fiprocess_data; if it is about to send an ACK, but it has an unacknowledged packet to send, it sends the entire packet. Hopefully that will trigger an ACK or a NAK and get us going again. */ DEBUG_MESSAGE0 (DEBUG_PROTO, "fiwindow_wait: Waiting for ACK"); if (! fiwait_for_packet (qdaemon, cIwindow_timeout, cIretries, TRUE, (boolean *) NULL)) return FALSE; } return TRUE; } /* Get buffer space to use for packet data. We return a pointer to the space to be used for the actual data, leaving room for the header. */ /*ARGSUSED*/ char * zigetspace (qdaemon, pclen) struct sdaemon *qdaemon; size_t *pclen; { *pclen = iIremote_packsize; return azIsendbuffers[iIsendseq] + CHDRSKIPLEN; } /* Send a data packet. The zdata argument will always point to value returned by zigetspace, so we know that we have room before it for the header information. */ boolean fisenddata (qdaemon, zdata, cdata, ilocal, iremote, ipos) struct sdaemon *qdaemon; char *zdata; size_t cdata; int ilocal; int iremote; long ipos; { char *zhdr; unsigned long icksum; boolean fret; #if DEBUG > 0 if (ilocal < 0 || ilocal >= IMAXICHAN || iremote < 0 || iremote >= IMAXICHAN) ulog (LOG_FATAL, "fisenddata: ilocal %d iremote %d", ilocal, iremote); #endif /* If we are changing the file position, we must send an SPOS packet. */ if (ipos != iIsendpos && ipos != (long) -1) { int inext; char *zspos; /* We need to get a buffer to hold the SPOS packet, and it needs to be next sequence number. However, the data we have been given is currently in the next sequence number buffer. So we shuffle the buffers around. */ inext = INEXTSEQ (iIsendseq); zspos = azIsendbuffers[inext]; azIsendbuffers[inext] = zdata - CHDRSKIPLEN; azIsendbuffers[iIsendseq] = zspos; zspos += CHDROFFSET; zspos[IHDR_INTRO] = IINTRO; zspos[IHDR_LOCAL] = IHDRWIN_SET (iIsendseq, 0); zspos[IHDR_REMOTE] = IHDRWIN_SET (iIrecseq, 0); iIlocal_ack = iIrecseq; zspos[IHDR_CONTENTS1] = IHDRCON_SET1 (SPOS, qdaemon->fcaller, CCKSUMLEN); zspos[IHDR_CONTENTS2] = IHDRCON_SET2 (SPOS, qdaemon->fcaller, CCKSUMLEN); zspos[IHDR_CHECK] = IHDRCHECK_VAL (zspos); UCKSUM_SET (zspos + CHDRLEN, (unsigned long) ipos); icksum = icrc (zspos + CHDRLEN, CCKSUMLEN, ICRCINIT); UCKSUM_SET (zspos + CHDRLEN + CCKSUMLEN, icksum); /* Wait for an opening in the window. */ if (iIremote_winsize > 0 && CSEQDIFF (iIsendseq, iIremote_ack) > iIremote_winsize) { if (! fiwindow_wait (qdaemon)) return FALSE; } DEBUG_MESSAGE1 (DEBUG_PROTO, "fisenddata: Sending SPOS %ld", ipos); if (! (*pfIsend) (qdaemon->qconn, zspos, CHDRLEN + CCKSUMLEN + CCKSUMLEN, TRUE)) return FALSE; iIsendseq = INEXTSEQ (iIsendseq); iIsendpos = ipos; } zhdr = zdata - CHDRLEN; zhdr[IHDR_INTRO] = IINTRO; zhdr[IHDR_LOCAL] = IHDRWIN_SET (iIsendseq, ilocal); zhdr[IHDR_CONTENTS1] = IHDRCON_SET1 (DATA, qdaemon->fcaller, cdata); zhdr[IHDR_CONTENTS2] = IHDRCON_SET2 (DATA, qdaemon->fcaller, cdata); /* Compute and set the checksum. */ if (cdata > 0) { icksum = icrc (zdata, cdata, ICRCINIT); UCKSUM_SET (zdata + cdata, icksum); } /* Wait until there is an opening in the window (we hope to not have to wait here at all, actually; ideally the window should be large enough to avoid a wait). */ if (iIremote_winsize > 0 && CSEQDIFF (iIsendseq, iIremote_ack) > iIremote_winsize) { if (! fiwindow_wait (qdaemon)) return FALSE; } /* We only fill in IHDR_REMOTE now, since only now do know the correct value of iIrecseq. */ zhdr[IHDR_REMOTE] = IHDRWIN_SET (iIrecseq, iremote); iIlocal_ack = iIrecseq; zhdr[IHDR_CHECK] = IHDRCHECK_VAL (zhdr); DEBUG_MESSAGE4 (DEBUG_PROTO, "fisenddata: Sending packet %d size %d local %d remote %d", iIsendseq, (int) cdata, ilocal, iremote); iIsendseq = INEXTSEQ (iIsendseq); ++cIsent_packets; fret = (*pfIsend) (qdaemon->qconn, zhdr, cdata + CHDRLEN + (cdata > 0 ? CCKSUMLEN : 0), TRUE); iIsendpos += cdata; if (fret && iPrecstart != iPrecend) { boolean fexit; fret = fiprocess_data (qdaemon, &fexit, (boolean *) NULL, (size_t *) NULL); } return fret; } /* Wait for data to come in. */ boolean fiwait (qdaemon) struct sdaemon *qdaemon; { return fiwait_for_packet (qdaemon, cItimeout, cIretries, FALSE, (boolean *) NULL); } /* Wait for a packet. Either there is no data to send, or the remote window is full. */ static boolean fiwait_for_packet (qdaemon, ctimeout, cretries, fone, pftimedout) struct sdaemon *qdaemon; int ctimeout; int cretries; boolean fone; boolean *pftimedout; { int cshort; int ctimeouts; if (pftimedout != NULL) *pftimedout = FALSE; cshort = 0; ctimeouts = 0; while (TRUE) { boolean fexit, ffound; size_t cneed; size_t crec; if (! fiprocess_data (qdaemon, &fexit, &ffound, &cneed)) return FALSE; if (fexit || (fone && ffound)) return TRUE; if (cneed == 0) continue; DEBUG_MESSAGE1 (DEBUG_PROTO, "fiwait_for_packet: Need %d bytes", (int) cneed); if (! (*pfIreceive) (qdaemon->qconn, cneed, &crec, ctimeout, TRUE)) return FALSE; if (crec != 0) { /* If we didn't get enough data twice in a row, we may have dropped some data and be waiting for the end of a large packet. Incrementing iPrecstart will force fiprocess_data to skip the current packet and try to find the next one. */ if (crec >= cneed) cshort = 0; else { ++cshort; if (cshort > 1) { iPrecstart = (iPrecstart + 1) % CRECBUFLEN; cshort = 0; } } } else { int i; /* We timed out on the read. */ ++ctimeouts; if (ctimeouts > cretries) { if (cretries > 0) ulog (LOG_ERROR, "Timed out waiting for packet"); if (pftimedout != NULL) *pftimedout = TRUE; return FALSE; } /* Clear out the list of packets we have sent NAKs for. We should have seen some sort of response by now. */ for (i = 0; i < IMAXSEQ; i++) afInaked[i] = FALSE; /* Send a NAK for the packet we want, and, if we have an unacknowledged packet, send it again. */ if (! finak (qdaemon, INEXTSEQ (iIrecseq)) || ! firesend (qdaemon)) return FALSE; } } /*NOTREACHED*/ } /* Make sure we haven't overflowed the permissible error level. */ static boolean ficheck_errors (qdaemon) struct sdaemon *qdaemon; { if (cIerrors < 0) return TRUE; if (((cIbad_order + cIbad_hdr + cIbad_cksum + cIremote_rejects) - (cIreceived_packets / cIerror_decay)) > cIerrors) { /* Try shrinking the packet size. */ if (iIrequest_packsize > 400) { char absync[CHDRLEN + 3 + CCKSUMLEN]; unsigned long icksum; /* Don't bother sending the number of channels in this packet. */ iIrequest_packsize /= 2; absync[IHDR_INTRO] = IINTRO; absync[IHDR_LOCAL] = IHDRWIN_SET (0, 0); absync[IHDR_REMOTE] = IHDRWIN_SET (iIrecseq, 0); iIlocal_ack = iIrecseq; absync[IHDR_CONTENTS1] = IHDRCON_SET1 (SYNC, qdaemon->fcaller, 3); absync[IHDR_CONTENTS2] = IHDRCON_SET2 (SYNC, qdaemon->fcaller, 3); absync[IHDR_CHECK] = IHDRCHECK_VAL (absync); absync[CHDRLEN + 0] = (iIrequest_packsize >> 8) & 0xff; absync[CHDRLEN + 1] = iIrequest_packsize & 0xff; absync[CHDRLEN + 2] = iIrequest_winsize; icksum = icrc (absync + CHDRLEN, 3, ICRCINIT); UCKSUM_SET (absync + CHDRLEN + 3, icksum); cIerrors *= 2; DEBUG_MESSAGE2 (DEBUG_PROTO | DEBUG_ABNORMAL, "ficheck_errors: Sending SYNC packsize %d winsize %d", iIrequest_packsize, iIrequest_winsize); return (*pfIsend) (qdaemon->qconn, absync, CHDRLEN + 3 + CCKSUMLEN, TRUE); } ulog (LOG_ERROR, "Too many '%c' protocol errors", qdaemon->qproto->bname); return FALSE; } return TRUE; } /* Process data waiting in the receive buffer, passing to the fgot_data function. */ static boolean fiprocess_data (qdaemon, pfexit, pffound, pcneed) struct sdaemon *qdaemon; boolean *pfexit; boolean *pffound; size_t *pcneed; { boolean fbadhdr; if (pfexit != NULL) *pfexit = FALSE; if (pffound != NULL) *pffound = FALSE; fbadhdr = FALSE; while (iPrecstart != iPrecend) { char ab[CHDRLEN]; int cfirst, csecond; char *zfirst, *zsecond; int i; int iget; int ttype; int iseq; int csize; int iack; /* If we're closing the connection, ignore any data remaining in the input buffer. */ if (fIclosing) { if (pfexit != NULL) *pfexit = TRUE; if (pcneed != NULL) *pcneed = 0; return TRUE; } /* Look for the IINTRO character. */ if (abPrecbuf[iPrecstart] != IINTRO) { char *zintro; int cintro; cintro = iPrecend - iPrecstart; if (cintro < 0) cintro = CRECBUFLEN - iPrecstart; zintro = memchr (abPrecbuf + iPrecstart, IINTRO, (size_t) cintro); if (zintro == NULL) { iPrecstart = (iPrecstart + cintro) % CRECBUFLEN; continue; } /* We don't need % CRECBUFLEN here because zintro - (abPrecbuf + iPrecstart) < cintro <= CRECBUFLEN - iPrecstart. */ iPrecstart += zintro - (abPrecbuf + iPrecstart); } /* Get the header into ab. */ for (i = 0, iget = iPrecstart; i < CHDRLEN && iget != iPrecend; i++, iget = (iget + 1) % CRECBUFLEN) ab[i] = abPrecbuf[iget]; if (i < CHDRLEN) { if (pcneed != NULL) *pcneed = CHDRLEN - i; return TRUE; } if ((ab[IHDR_CHECK] & 0xff) != IHDRCHECK_VAL (ab) || (FHDRCON_GETCALLER (ab[IHDR_CONTENTS1], ab[IHDR_CONTENTS2]) ? qdaemon->fcaller : ! qdaemon->fcaller)) { /* We only report a single bad header message per call, to avoid generating many errors if we get many INTRO bytes in a row. */ if (! fbadhdr) { DEBUG_MESSAGE0 (DEBUG_PROTO | DEBUG_ABNORMAL, "fiprocess_data: Bad header"); ++cIbad_hdr; if (! ficheck_errors (qdaemon)) return FALSE; fbadhdr = TRUE; } iPrecstart = (iPrecstart + 1) % CRECBUFLEN; continue; } zfirst = zsecond = NULL; cfirst = csecond = 0; ttype = THDRCON_GETTYPE (ab[IHDR_CONTENTS1], ab[IHDR_CONTENTS2]); if (ttype == DATA || ttype == SPOS || ttype == CLOSE) iseq = IHDRWIN_GETSEQ (ab[IHDR_LOCAL]); else iseq = -1; csize = CHDRCON_GETBYTES (ab[IHDR_CONTENTS1], ab[IHDR_CONTENTS2]); if (iseq != -1) { /* Make sure this packet is in our receive window. The last packet we have acked is iIlocal_ack. */ if (iIrequest_winsize > 0 && CSEQDIFF (iseq, iIlocal_ack) > iIrequest_winsize) { DEBUG_MESSAGE2 (DEBUG_PROTO | DEBUG_ABNORMAL, "fiprocess_data: Out of order packet %d (ack %d)", iseq, iIlocal_ack); ++cIbad_order; if (! ficheck_errors (qdaemon)) return FALSE; iPrecstart = (iPrecstart + 1) % CRECBUFLEN; continue; } } if (csize > 0) { int cinbuf; char abcksum[CCKSUMLEN]; unsigned long ickdata; cinbuf = iPrecend - iPrecstart; if (cinbuf < 0) cinbuf += CRECBUFLEN; if (cinbuf < CHDRLEN + csize + CCKSUMLEN) { if (pcneed != NULL) *pcneed = CHDRLEN + csize + CCKSUMLEN - cinbuf; return TRUE; } if (iPrecend > iPrecstart) { cfirst = csize; zfirst = abPrecbuf + iPrecstart + CHDRLEN; } else { cfirst = CRECBUFLEN - (iPrecstart + CHDRLEN); if (cfirst <= 0) { /* Here cfirst is non-positive, so subtracting from abPrecbuf will actually skip the appropriate number of bytes at the start of abPrecbuf. */ zfirst = abPrecbuf - cfirst; cfirst = csize; } else { if (cfirst >= csize) cfirst = csize; else { zsecond = abPrecbuf; csecond = csize - cfirst; } zfirst = abPrecbuf + iPrecstart + CHDRLEN; } } /* Get the checksum into abcksum. */ for (i = 0, iget = (iPrecstart + CHDRLEN + csize) % CRECBUFLEN; i < CCKSUMLEN; i++, iget = (iget + 1) % CRECBUFLEN) abcksum[i] = abPrecbuf[iget]; ickdata = icrc (zfirst, (size_t) cfirst, ICRCINIT); if (csecond > 0) ickdata = icrc (zsecond, (size_t) csecond, ickdata); if (ICKSUM_GET (abcksum) != ickdata) { DEBUG_MESSAGE2 (DEBUG_PROTO | DEBUG_ABNORMAL, "fiprocess_data: Bad checksum; data %lu, frame %lu", ickdata, ICKSUM_GET (abcksum)); ++cIbad_cksum; if (! ficheck_errors (qdaemon)) return FALSE; /* If this sequence number is in our receive window, send a NAK. iIrecseq is the last sequence number we have succesfully received. */ if (iseq != -1 && iseq != iIrecseq && (iIrequest_winsize <= 0 || CSEQDIFF (iseq, iIrecseq) <= iIrequest_winsize) && azIrecbuffers[iseq] == NULL) { if (! finak (qdaemon, iseq)) return FALSE; } iPrecstart = (iPrecstart + 1) % CRECBUFLEN; continue; } } /* Here we know that this is a valid packet, so we can adjust iPrecstart accordingly. */ if (csize == 0) iPrecstart = (iPrecstart + CHDRLEN) % CRECBUFLEN; else { iPrecstart = ((iPrecstart + CHDRLEN + csize + CCKSUMLEN) % CRECBUFLEN); ++cIreceived_packets; } /* Get the ack from the packet, if appropriate. iIsendseq is the next sequence number we are going to send, and iIremote_ack is the last sequence number acknowledged by the remote system. */ iack = IHDRWIN_GETSEQ (ab[IHDR_REMOTE]); if (iIremote_winsize > 0 && iack != iIsendseq && CSEQDIFF (iack, iIremote_ack) <= iIremote_winsize && CSEQDIFF (iIsendseq, iack) <= iIremote_winsize) { /* Call uwindow_acked each time packet 0 is acked. */ if (iack < iIremote_ack) uwindow_acked (qdaemon, FALSE); iIremote_ack = iack; } if (iseq != -1) { /* If we already sent a NAK for this packet, and we have not seen the previous packet, then forget that we sent a NAK for this and any preceding packets. This is to handle the following sequence: receive packet 0 packets 1 and 2 lost receive packet 3 send NAK 1 send NAK 2 packet 1 lost receive packet 2 At this point we want to send NAK 1. */ if (afInaked[iseq] && azIrecbuffers[IPREVSEQ (iseq)] == NULL) { for (i = INEXTSEQ (iIrecseq); i != iseq; i = INEXTSEQ (i)) afInaked[i] = FALSE; afInaked[iseq] = FALSE; } /* If we haven't handled all previous packets, we must save off this packet and deal with it later. */ if (iseq != INEXTSEQ (iIrecseq)) { if (iseq == iIrecseq || (iIrequest_winsize > 0 && CSEQDIFF (iseq, iIrecseq) > iIrequest_winsize)) { DEBUG_MESSAGE2 (DEBUG_PROTO | DEBUG_ABNORMAL, "fiprocess_data: Ignoring out of order packet %d (recseq %d)", iseq, iIrecseq); continue; } else { DEBUG_MESSAGE2 (DEBUG_PROTO | DEBUG_ABNORMAL, "fiprocess_data: Saving unexpected packet %d (recseq %d)", iseq, iIrecseq); if (azIrecbuffers[iseq] == NULL) { azIrecbuffers[iseq] = zbufalc ((size_t) (CHDRLEN + csize)); memcpy (azIrecbuffers[iseq], ab, CHDRLEN); if (csize > 0) { memcpy (azIrecbuffers[iseq] + CHDRLEN, zfirst, (size_t) cfirst); if (csecond > 0) memcpy (azIrecbuffers[iseq] + CHDRLEN + cfirst, zsecond, (size_t) csecond); } } } /* Send NAK's for each packet between the last one we received and this one, avoiding any packets for which we've already sent NAK's or which we've already received. */ for (i = INEXTSEQ (iIrecseq); i != iseq; i = INEXTSEQ (i)) { if (! afInaked[i] && azIrecbuffers[i] == NULL) { if (! finak (qdaemon, i)) return FALSE; } } continue; } iIrecseq = iseq; } if (pffound != NULL) *pffound = TRUE; if (! fiprocess_packet (qdaemon, ab, zfirst, cfirst, zsecond, csecond, pfexit)) return FALSE; if (iseq != -1) { int inext; /* If we've already received the next packet(s), process them. */ inext = INEXTSEQ (iIrecseq); while (azIrecbuffers[inext] != NULL) { char *z; int c; z = azIrecbuffers[inext]; c = CHDRCON_GETBYTES (z[IHDR_CONTENTS1], z[IHDR_CONTENTS2]); iIrecseq = inext; if (! fiprocess_packet (qdaemon, z, z + CHDRLEN, c, (char *) NULL, 0, pfexit)) return FALSE; ubuffree (azIrecbuffers[inext]); azIrecbuffers[inext] = NULL; inext = INEXTSEQ (inext); } } /* If we have received half of our window size or more since the last ACK, send one now. Sending an ACK for half the window at a time should significantly cut the acknowledgement traffic when only one side is sending. We should normally not have to send an ACK if we have data to send, since each packet sent will ACK the most recently received packet. However, it can happen if we receive a burst of short packets, such as a set of command acknowledgements. */ if (iIrequest_winsize > 0 && CSEQDIFF (iIrecseq, iIlocal_ack) >= cIack_frequency) { char aback[CHDRLEN]; aback[IHDR_INTRO] = IINTRO; aback[IHDR_LOCAL] = IHDRWIN_SET (0, 0); aback[IHDR_REMOTE] = IHDRWIN_SET (iIrecseq, 0); iIlocal_ack = iIrecseq; aback[IHDR_CONTENTS1] = IHDRCON_SET1 (ACK, qdaemon->fcaller, 0); aback[IHDR_CONTENTS2] = IHDRCON_SET2 (ACK, qdaemon->fcaller, 0); aback[IHDR_CHECK] = IHDRCHECK_VAL (aback); DEBUG_MESSAGE1 (DEBUG_PROTO, "fiprocess_data: Sending ACK %d", iIrecseq); if (! (*pfIsend) (qdaemon->qconn, aback, CHDRLEN, TRUE)) return FALSE; } } if (pcneed != NULL) *pcneed = CHDRLEN; return TRUE; } /* Process a single packet. */ static boolean fiprocess_packet (qdaemon, zhdr, zfirst, cfirst, zsecond, csecond, pfexit) struct sdaemon *qdaemon; const char *zhdr; const char *zfirst; int cfirst; const char *zsecond; int csecond; boolean *pfexit; { int ttype; ttype = THDRCON_GETTYPE (zhdr[IHDR_CONTENTS1], zhdr[IHDR_CONTENTS2]); switch (ttype) { case DATA: { int iseq; boolean fret; iseq = IHDRWIN_GETSEQ (zhdr[IHDR_LOCAL]); DEBUG_MESSAGE4 (DEBUG_PROTO, "fiprocess_packet: Got DATA packet %d size %d local %d remote %d", iseq, cfirst + csecond, IHDRWIN_GETCHAN (zhdr[IHDR_REMOTE]), IHDRWIN_GETCHAN (zhdr[IHDR_LOCAL])); fret = fgot_data (qdaemon, zfirst, (size_t) cfirst, zsecond, (size_t) csecond, IHDRWIN_GETCHAN (zhdr[IHDR_REMOTE]), IHDRWIN_GETCHAN (zhdr[IHDR_LOCAL]), iIrecpos, INEXTSEQ (iIremote_ack) == iIsendseq, pfexit); iIrecpos += cfirst + csecond; return fret; } case SYNC: { int ipack, iwin, cchans; /* We accept a SYNC packet to adjust the packet and window sizes at any time. */ if (cfirst + csecond < 3) { ulog (LOG_ERROR, "Bad SYNC packet"); return FALSE; } ipack = (zfirst[0] & 0xff) << 8; if (cfirst > 1) ipack |= zfirst[1] & 0xff; else ipack |= zsecond[0]; if (cfirst > 2) iwin = zfirst[2]; else iwin = zsecond[2 - cfirst]; /* The fourth byte in a SYNC packet is the number of channels to use. This is optional. Switching the number of channels in the middle of a conversation may cause problems. */ if (cfirst + csecond <= 3) cchans = 0; else { if (cfirst > 3) cchans = zfirst[3]; else cchans = zsecond[3 - cfirst]; if (cchans > 0 && cchans < 8) qdaemon->cchans = cchans; } DEBUG_MESSAGE3 (DEBUG_PROTO, "fiprocess_packet: Got SYNC packsize %d winsize %d channels %d", ipack, iwin, cchans); if (iIforced_remote_packsize == 0 && (iIalc_packsize == 0 || ipack <= iIalc_packsize)) iIremote_packsize = ipack; iIremote_winsize = iwin; /* We increment a static variable to tell the initialization code that a SYNC was received, and we set *pfexit to TRUE to get out to the initialization code (this will do no harm if we are called from elsewhere). */ ++cIsyncs; *pfexit = TRUE; return TRUE; } case ACK: /* There is nothing to do here, since the ack was already handled in fiprocess_data. */ DEBUG_MESSAGE1 (DEBUG_PROTO, "fiprocess_packet: Got ACK %d", IHDRWIN_GETSEQ (zhdr[IHDR_REMOTE])); return TRUE; case NAK: /* We must resend the requested packet. */ { int iseq; char *zsend; size_t clen; ++cIremote_rejects; if (! ficheck_errors (qdaemon)) return FALSE; iseq = IHDRWIN_GETSEQ (zhdr[IHDR_LOCAL]); /* If the remote side times out while waiting for a packet, it will send a NAK for the next packet it wants to see. If we have not sent that packet yet, and we have no unacknowledged data, it implies that the remote side has a window full of data to send, which implies that our ACK has been lost. Therefore, we send an ACK. */ if (iseq == iIsendseq && INEXTSEQ (iIremote_ack) == iIsendseq) { char aback[CHDRLEN]; aback[IHDR_INTRO] = IINTRO; aback[IHDR_LOCAL] = IHDRWIN_SET (0, 0); aback[IHDR_REMOTE] = IHDRWIN_SET (iIrecseq, 0); iIlocal_ack = iIrecseq; aback[IHDR_CONTENTS1] = IHDRCON_SET1 (ACK, qdaemon->fcaller, 0); aback[IHDR_CONTENTS2] = IHDRCON_SET2 (ACK, qdaemon->fcaller, 0); aback[IHDR_CHECK] = IHDRCHECK_VAL (aback); DEBUG_MESSAGE1 (DEBUG_PROTO, "fiprocess_packet: Sending ACK %d", iIrecseq); return (*pfIsend) (qdaemon->qconn, aback, CHDRLEN, TRUE); } else { if (iseq == iIsendseq || (iIremote_winsize > 0 && (CSEQDIFF (iseq, iIremote_ack) > iIremote_winsize || CSEQDIFF (iIsendseq, iseq) > iIremote_winsize))) { DEBUG_MESSAGE2 (DEBUG_PROTO | DEBUG_ABNORMAL, "fiprocess_packet: Ignoring out of order NAK %d (sendseq %d)", iseq, iIsendseq); return TRUE; } DEBUG_MESSAGE1 (DEBUG_PROTO | DEBUG_ABNORMAL, "fiprocess_packet: Got NAK %d; resending packet", iseq); /* Update the received sequence number. */ zsend = azIsendbuffers[iseq] + CHDROFFSET; if (IHDRWIN_GETSEQ (zsend[IHDR_REMOTE]) != iIrecseq) { int iremote; iremote = IHDRWIN_GETCHAN (zsend[IHDR_REMOTE]); zsend[IHDR_REMOTE] = IHDRWIN_SET (iIrecseq, iremote); zsend[IHDR_CHECK] = IHDRCHECK_VAL (zsend); iIlocal_ack = iIrecseq; } ++cIresent_packets; clen = CHDRCON_GETBYTES (zsend[IHDR_CONTENTS1], zsend[IHDR_CONTENTS2]); return (*pfIsend) (qdaemon->qconn, zsend, CHDRLEN + clen + (clen > 0 ? CCKSUMLEN : 0), TRUE); } } case SPOS: /* Set the file position. */ { char abpos[CCKSUMLEN]; const char *zpos; if (cfirst >= CCKSUMLEN) zpos = zfirst; else { memcpy (abpos, zfirst, (size_t) cfirst); memcpy (abpos + cfirst, zsecond, (size_t) (CCKSUMLEN - cfirst)); zpos = abpos; } iIrecpos = (long) ICKSUM_GET (zpos); DEBUG_MESSAGE1 (DEBUG_PROTO, "fiprocess_packet: Got SPOS %ld", iIrecpos); return TRUE; } case CLOSE: { boolean fexpected; fexpected = ! fLog_sighup || fIclosing; if (! fexpected) ulog (LOG_ERROR, "Received unexpected CLOSE packet"); else DEBUG_MESSAGE0 (DEBUG_PROTO, "fiprocess_packet: Got CLOSE packet"); fIclosing = TRUE; *pfexit = TRUE; return fexpected; } default: /* Just ignore unrecognized packet types, for future protocol enhancements. */ DEBUG_MESSAGE1 (DEBUG_PROTO, "fiprocess_packet: Got packet type %d", ttype); return TRUE; } /*NOTREACHED*/ }