/* Copyright (C) 2000-1 drscholl@users.sourceforge.net
   This is free software distributed under the terms of the
   GNU Public License.  See the file COPYING for details.

   $Id: buffer.c,v 1.65 2001/02/15 08:39:45 drscholl Exp $ */

#ifndef WIN32
#include <unistd.h>
#include <sys/time.h>
#else
#include <windows.h>
#endif /* !WIN32 */
#include <string.h>
#include <errno.h>
#include <stdlib.h>
#include "opennap.h"
#include "debug.h"

static BUFFER *
buffer_new (void)
{
    BUFFER *r = CALLOC (1, sizeof (BUFFER));

    if (!r)
    {
	OUTOFMEMORY ("buffer_new");
	return 0;
    }
#if DEBUG
    r->magic = MAGIC_BUFFER;
#endif
    r->data = MALLOC (BUFFER_SIZE);
    if (!r->data)
    {
	OUTOFMEMORY ("buffer_new");
	FREE (r);
	return 0;
    }
    r->datamax = BUFFER_SIZE;
    return r;
}

/* append bytes to the buffer */
static BUFFER *
buffer_queue (BUFFER * b, char *d, int dsize)
{
    BUFFER *r = b;
    int     count;

    if (b)
	while (b->next)
	    b = b->next;
    while (dsize > 0)
    {
	if (!b)
	    r = b = buffer_new ();
	else if (b->datasize == b->datamax)
	{
	    b->next = buffer_new ();
	    b = b->next;
	}
	if (!b)
	{
	    /*something really bad just happened!  no choice but to close
	       this connection since it will be out of sync */
	    buffer_free (r);
	    return 0;
	}
	count = dsize;
	/* dsize could be greater than what is allocated */
	if (count > b->datamax - b->datasize)
	    count = b->datamax - b->datasize;
	memcpy (b->data + b->datasize, d, count);
	b->datasize += count;
	dsize -= count;
	d += count;
    }
    return r;
}

/* consume some bytes from the buffer */
BUFFER *
buffer_consume (BUFFER * b, int n)
{
    ASSERT (buffer_validate (b));
    ASSERT (b->consumed + n <= b->datasize);
    b->consumed += n;
    if (b->consumed >= b->datasize)
    {
	BUFFER *p = b;

	b = b->next;
	FREE (p->data);
	FREE (p);
    }
    return b;
}

BUFFER *
buffer_append (BUFFER * a, BUFFER * b)
{
    BUFFER *r = a;

    ASSERT (b != 0);
    if (!a)
	return b;
    ASSERT (buffer_validate (a));
    while (a->next)
	a = a->next;
    a->next = b;
    return r;
}

int
buffer_size (BUFFER * b)
{
    int     n = 0;

    ASSERT (b == 0 || buffer_validate (b));
    for (; b; b = b->next)
	n += b->datasize - b->consumed;
    return n;
}

void
buffer_free (BUFFER * b)
{
    BUFFER *p;

    ASSERT (b == 0 || buffer_validate (b));
    while (b)
    {
	p = b;
	b = b->next;
	FREE (p->data);
	FREE (p);
    }
}

#if DEBUG
int
buffer_validate (BUFFER * b)
{
    ASSERT_RETURN_IF_FAIL (VALID_LEN (b, sizeof (BUFFER)), 0);
    ASSERT_RETURN_IF_FAIL (b->magic == MAGIC_BUFFER, 0);
    ASSERT_RETURN_IF_FAIL (b->datasize <= b->datamax, 0);
    ASSERT_RETURN_IF_FAIL (b->data == 0
			   || VALID_LEN (b->data, b->datasize), 0);
    ASSERT_RETURN_IF_FAIL (b->consumed == 0 || b->consumed < b->datasize, 0);
    ASSERT_RETURN_IF_FAIL (b->next == 0
			   || VALID_LEN (b->next, sizeof (BUFFER *)), 0);
    return 1;
}
#endif /* DEBUG */

static BUFFER *
buffer_compress (z_streamp zip, BUFFER ** b)
{
    BUFFER *r = 0, **pr;
    int     n, bytes, flush;

    ASSERT (buffer_validate (*b));

    /* set up the input */
    bytes = (*b)->datasize - (*b)->consumed;
    zip->next_in = (u_char *) (*b)->data + (*b)->consumed;
    zip->avail_in = bytes;
    /* force a flush if this is the last input to compress */
    flush = ((*b)->next == 0) ? Z_SYNC_FLUSH : Z_NO_FLUSH;
    /* set to 0 so we allocate in the loop */
    zip->avail_out = 0;

    pr = &r;

    do
    {
	if (zip->avail_out == 0)
	{
	    /* allocate a new buffer to hold the rest of the compressed data */
	    *pr = buffer_new ();
	    if (!*pr)
		break;
	    /* mark the buffer as completely full then remove unused data
	       when we exit this loop */
	    (*pr)->datasize = (*pr)->datamax;
	    zip->next_out = (unsigned char *) (*pr)->data;
	    zip->avail_out = (*pr)->datasize;
	}
	n = deflate (zip, flush);
	if (n != Z_OK)
	{
	    log ("buffer_compress: deflate: %s (error %d)",
		 NONULL (zip->msg), n);
	    break;
	}
	pr = &(*pr)->next;
    }
    while (zip->avail_out == 0 && flush == Z_SYNC_FLUSH);

    /* subtract any uncompressed bytes */
    bytes -= zip->avail_in;
    *b = buffer_consume (*b, bytes);

    if (r)
    {
	pr = &r;
	while ((*pr)->next)
	    pr = &(*pr)->next;
	(*pr)->datasize -= zip->avail_out;
	/* this should only happen for the first created buffer if the
	   input was small and there was a second buffer in the list */
	if ((*pr)->datasize == 0)
	{
	    ASSERT (r->next == 0);
	    if (r->next != 0)
		log ("buffer_compress: ERROR! r->next was not NULL");
	    FREE (r->data);
	    FREE (r);
	    r = 0;
	}
    }

    return r;
}

/* assuming that we receive relatively short blocks via the network (less
   than 16kb), we uncompress all data when we receive it and don't worry
   about blocking.

   NOTE: this is the only buffer_*() function that does not use the memory
   pool.  each server gets its own real input buffer */
int
buffer_decompress (BUFFER * b, z_streamp zip, char *in, int insize)
{
    int     n;

    ASSERT (buffer_validate (b));
    ASSERT (insize > 0);
    zip->next_in = (unsigned char *) in;
    zip->avail_in = insize;
    zip->next_out = (unsigned char *) b->data + b->datasize;
    zip->avail_out = b->datamax - b->datasize;
    /* set this to the max size and subtract what is left after the inflate */
    b->datasize = b->datamax;
    do
    {
	/* if there is no more output space left, create some more */
	if (zip->avail_out == 0)
	{
	    /* allocate one extra byte to write a \0 char */
	    if (safe_realloc ((void **) &b->data, b->datamax + 2049))
	    {
		OUTOFMEMORY ("buffer_decompress");
		return -1;
	    }
	    b->datamax += 2048;
	    zip->next_out = (unsigned char *) b->data + b->datasize;
	    zip->avail_out = b->datamax - b->datasize;
	    /* set this to the max size and subtract what is left after the
	       inflate */
	    b->datasize = b->datamax;
	}
	n = inflate (zip, Z_SYNC_FLUSH);
	if (n != Z_OK)
	{
	    log ("buffer_decompress: inflate: %s (error %d)",
		 NONULL (zip->msg), n);
	    return -1;
	}
    }
    while (zip->avail_out == 0);
    /* subtract unused bytes */
    b->datasize -= zip->avail_out;
    return 0;
}

void
init_compress (CONNECTION * con, int level)
{
    int     n;

    ASSERT (validate_connection (con));
    ASSERT (ISSERVER (con));
    con->sopt->zin = CALLOC (1, sizeof (z_stream));
    if (!con->sopt->zin)
    {
	OUTOFMEMORY ("init_compress");
	return;
    }
    con->sopt->zout = CALLOC (1, sizeof (z_stream));
    if (!con->sopt->zout)
    {
	FREE (con->sopt->zin);
	OUTOFMEMORY ("init_compress");
	return;
    }

    n = inflateInit (con->sopt->zin);
    if (n != Z_OK)
    {
	log ("init_compress: inflateInit: %s (%d)",
	     NONULL (con->sopt->zin->msg), n);
    }
    n = deflateInit (con->sopt->zout, level);
    if (n != Z_OK)
    {
	log ("init_compress: deflateInit: %s (%d)",
	     NONULL (con->sopt->zout->msg), n);
    }

    log ("init_compress: compressing server stream at level %d", level);
}

void
finalize_compress (SERVER * serv)
{
    int     n;

    n = deflateEnd (serv->zout);
    if (n != Z_OK)
	log ("finalize_compress: deflateEnd: %s (%d)",
	     NONULL (serv->zout->msg), n);
    n = inflateEnd (serv->zin);
    if (n != Z_OK)
	log ("finalize_compress: inflateEnd: %s (%d)",
	     NONULL (serv->zin->msg), n);
    FREE (serv->zin);
    FREE (serv->zout);
}

int
send_queued_data (CONNECTION * con)
{
    int     n;
    BUFFER *r;

    ASSERT (validate_connection (con));

    if (con->destroy)
    {
	/* connection is being shut down, just ignore it */
	clear_write (con->fd);	/* just to be sure */
	return -1;
    }

    if (ISSERVER (con))
    {
	/* compress server output until we have at least 16k waiting (about
	 * the size of the tcp buffer for the socket)
	 */
	while (con->sopt->outbuf && buffer_size (con->sendbuf) < 16384)
	{
	    /* buffer_compress will only compress the first buffer in the
	     * list, so we possibly need to call it multiple times.
	     */
	    r = buffer_compress (con->sopt->zout, &con->sopt->outbuf);
	    if (!r)
		break;
	    con->sendbuf = buffer_append (con->sendbuf, r);
	}

	/* for large networks, it might be desirable not to send data every
	 * time through the main loop.  this adds support for queuing up
	 * a larger amount of data before actually doing a write()
	 */
	if (Server_Chunk > 0)
	{
	    /* check to see if enough data has been accumulated to send */
	    if (buffer_size (con->sendbuf) < Server_Chunk)
	    {
		clear_write (con->fd);	/* turn off check for write */
		return 0;	/* wait until more data is recv'd */
	    }
	}
    }

    /* write until the queue is consumed, or we would block */
    while (con->sendbuf)
    {
	n = WRITE (con->fd, con->sendbuf->data + con->sendbuf->consumed,
		   con->sendbuf->datasize - con->sendbuf->consumed);
	if (n == -1)
	{
	    if (N_ERRNO != EWOULDBLOCK && N_ERRNO != EDEADLK &&
		    N_ERRNO != ENOBUFS)
	    {
		clear_write (con->fd);	/* just to be sure */
		log ("send_queued_data: write: %s (errno %d) for host %s",
		     strerror (N_ERRNO), N_ERRNO, con->host);
		return -1;
	    }
	    break;
	}
	else if (n == 0)
	{
	    log ("send_queued_data: wrote 0 bytes to fd %d", con->fd);
	    break;
	}

	/* mark data as written */
	con->sendbuf = buffer_consume (con->sendbuf, n);

	/* keep track of the outgoing bandwidth */
	global.bytes_out += n;
    }

    /* check to make sure the queue hasn't gotten too big */

    if (ISSERVER (con))
    {
	/* for a server, we will have up to 16k in con->sendbuf, and then
	 * possibly a lot more in con->sopt->outbuf.  the latter
	 * is uncompressed data.
	 */
	if (buffer_size (con->sopt->outbuf) > Server_Queue_Length)
	{
	    log ("send_queued_data: output buffer for %s exceeded %u bytes",
		 con->host, Server_Queue_Length);
	    return -1;
	}
    }
    else if (buffer_size (con->sendbuf) > Client_Queue_Length)
    {
	log ("send_queued_data: output buffer for %s exceeded %u bytes",
	     con->host, Client_Queue_Length);
	return -1;
    }

    if (con->sendbuf || (ISSERVER (con) && con->sopt->outbuf))
	/* still need to write */
	set_write (con->fd);
    else
	/* output queue is empty, clear the write bit */
	clear_write (con->fd);

    return 0;
}

void
queue_data (CONNECTION * con, char *s, int ssize)
{
    ASSERT (validate_connection (con));
    if (ISSERVER (con))
    {
	/* always queue server data so we can compress it more effciently */
	con->sopt->outbuf = buffer_queue (con->sopt->outbuf, s, ssize);
	if (!con->sopt->outbuf)
	    destroy_connection (con);
	/* server connections are always flushed at the end of the main
	 * event loop, so we don't need to call set_write() here
	 */
    }
    else if (!con->destroy)
    {
	/* if no output is queued, immediately attempt to send it now to
	 * avoid copying
	 */
	if (!con->sendbuf)
	{
#ifndef ALWAYS_QUEUE
	    int     n = WRITE (con->fd, s, ssize);

	    if (n == -1)
	    {
		if (N_ERRNO != EWOULDBLOCK)
		{
		    log ("queue_data: %s: write: %s (errno %d)",
			 con->host, strerror (N_ERRNO), N_ERRNO);
		    destroy_connection (con);
		    return;
		}
		/* queue the data */
	    }
	    else if (n == ssize)
		return;		/* all written, nothing else to do */
	    else
	    {
		/* queue the portion that didn't get written */
		s += n;
		ssize -= n;
	    }
#endif /* ! ALWAYS_QUEUE */
	    /* we want to know when the socket becomes writable again */
	    set_write (con->fd);
	}

	con->sendbuf = buffer_queue (con->sendbuf, s, ssize);
	if (!con->sendbuf)
	    destroy_connection (con);
    }
}