/*
 * Copyright (c) 1995 Danny Gasparovski.
 *
 * Please read the file COPYRIGHT for the
 * terms and conditions of the copyright.
 */

#include <stdlib.h>
#include "slirp/slirp.h"

/* Done as a macro in socket.h */
/* int
 * sbspace(struct sockbuff *sb)
 * {
 *	return SB_DATALEN - sb->sb_cc;
 * }
 */

void sbfree(sb) struct sbuf *sb;
{ free(sb->sb_data); }

void sbdrop(sb, num) struct sbuf *sb;
int num;
{
        /*
         * We can only drop how much we have
         * This should never succeed
         */
        if (num > sb->sb_cc)
                num = sb->sb_cc;
        sb->sb_cc -= num;
        sb->sb_rptr += num;
        if (sb->sb_rptr >= sb->sb_data + sb->sb_datalen)
                sb->sb_rptr -= sb->sb_datalen;
}

void sbreserve(sb, size) struct sbuf *sb;
int size;
{
        if (sb->sb_data) {
                /* Already alloced, realloc if necessary */
                if (sb->sb_datalen != size) {
                        sb->sb_wptr = sb->sb_rptr = sb->sb_data = (char *)realloc(sb->sb_data, size);
                        sb->sb_cc = 0;
                        if (sb->sb_wptr)
                                sb->sb_datalen = size;
                        else
                                sb->sb_datalen = 0;
                }
        } else {
                sb->sb_wptr = sb->sb_rptr = sb->sb_data = (char *)malloc(size);
                sb->sb_cc = 0;
                if (sb->sb_wptr)
                        sb->sb_datalen = size;
                else
                        sb->sb_datalen = 0;
        }
}

/*
 * Try and write() to the socket, whatever doesn't get written
 * append to the buffer... for a host with a fast net connection,
 * this prevents an unnecessary copy of the data
 * (the socket is non-blocking, so we won't hang)
 */
void sbappend(so, m) struct SLIRPsocket *so;
struct SLIRPmbuf *m;
{
        int ret = 0;

        DEBUG_CALL("sbappend");
        DEBUG_ARG("so = %lx", (long)so);
        DEBUG_ARG("m = %lx", (long)m);
        DEBUG_ARG("m->m_len = %d", m->m_len);

        /* Shouldn't happen, but...  e.g. foreign host closes connection */
        if (m->m_len <= 0) {
                m_free(m);
                return;
        }

        /*
         * If there is urgent data, call sosendoob
         * if not all was sent, sowrite will take care of the rest
         * (The rest of this function is just an optimisation)
         */
        if (so->so_urgc) {
                sbappendsb(&so->so_rcv, m);
                m_free(m);
                sosendoob(so);
                return;
        }

        /*
         * We only write if there's nothing in the buffer,
         * ottherwise it'll arrive out of order, and hence corrupt
         */
        if (!so->so_rcv.sb_cc)
                ret = send(so->s, m->m_data, m->m_len, 0);

        if (ret <= 0) {
                /*
                 * Nothing was written
                 * It's possible that the socket has closed, but
                 * we don't need to check because if it has closed,
                 * it will be detected in the normal way by soread()
                 */
                sbappendsb(&so->so_rcv, m);
        } else if (ret != m->m_len) {
                /*
                 * Something was written, but not everything..
                 * sbappendsb the rest
                 */
                m->m_len -= ret;
                m->m_data += ret;
                sbappendsb(&so->so_rcv, m);
        } /* else */
        /* Whatever happened, we free the SLIRPmbuf */
        m_free(m);
}

/*
 * Copy the data from m into sb
 * The caller is responsible to make sure there's enough room
 */
void sbappendsb(sb, m) struct sbuf *sb;
struct SLIRPmbuf *m;
{
        int len, n, nn;

        len = m->m_len;

        if (sb->sb_wptr < sb->sb_rptr) {
                n = sb->sb_rptr - sb->sb_wptr;
                if (n > len)
                        n = len;
                memcpy(sb->sb_wptr, m->m_data, n);
        } else {
                /* Do the right edge first */
                n = sb->sb_data + sb->sb_datalen - sb->sb_wptr;
                if (n > len)
                        n = len;
                memcpy(sb->sb_wptr, m->m_data, n);
                len -= n;
                if (len) {
                        /* Now the left edge */
                        nn = sb->sb_rptr - sb->sb_data;
                        if (nn > len)
                                nn = len;
                        memcpy(sb->sb_data, m->m_data + n, nn);
                        n += nn;
                }
        }

        sb->sb_cc += n;
        sb->sb_wptr += n;
        if (sb->sb_wptr >= sb->sb_data + sb->sb_datalen)
                sb->sb_wptr -= sb->sb_datalen;
}

/*
 * Copy data from sbuf to a normal, straight buffer
 * Don't update the sbuf rptr, this will be
 * done in sbdrop when the data is acked
 */
void sbcopy(sb, off, len, to) struct sbuf *sb;
int off;
int len;
char *to;
{
        char *from;

        from = sb->sb_rptr + off;
        if (from >= sb->sb_data + sb->sb_datalen)
                from -= sb->sb_datalen;

        if (from < sb->sb_wptr) {
                if (len > sb->sb_cc)
                        len = sb->sb_cc;
                memcpy(to, from, len);
        } else {
                /* re-use off */
                off = (sb->sb_data + sb->sb_datalen) - from;
                if (off > len)
                        off = len;
                memcpy(to, from, off);
                len -= off;
                if (len)
                        memcpy(to + off, sb->sb_data, len);
        }
}
