LXR qemu/slirp/sbuf.c

   1/*
   2 * Copyright (c) 1995 Danny Gasparovski.
   3 *
   4 * Please read the file COPYRIGHT for the
   5 * terms and conditions of the copyright.
   6 */
   7
   8#include "qemu/osdep.h"
   9#include <slirp.h>
  10#include <qemu/main-loop.h>
  11
  12static void sbappendsb(struct sbuf *sb, struct mbuf *m);
  13
  14void
  15sbfree(struct sbuf *sb)
  16{
  17        free(sb->sb_data);
  18}
  19
  20void
  21sbdrop(struct sbuf *sb, int num)
  22{
  23    int limit = sb->sb_datalen / 2;
  24
  25        /*
  26         * We can only drop how much we have
  27         * This should never succeed
  28         */
  29        if(num > sb->sb_cc)
  30                num = sb->sb_cc;
  31        sb->sb_cc -= num;
  32        sb->sb_rptr += num;
  33        if(sb->sb_rptr >= sb->sb_data + sb->sb_datalen)
  34                sb->sb_rptr -= sb->sb_datalen;
  35
  36    if (sb->sb_cc < limit && sb->sb_cc + num >= limit) {
  37        qemu_notify_event();
  38    }
  39}
  40
  41void
  42sbreserve(struct sbuf *sb, int size)
  43{
  44        if (sb->sb_data) {
  45                /* Already alloced, realloc if necessary */
  46                if (sb->sb_datalen != size) {
  47                        sb->sb_wptr = sb->sb_rptr = sb->sb_data = (char *)realloc(sb->sb_data, size);
  48                        sb->sb_cc = 0;
  49                        if (sb->sb_wptr)
  50                           sb->sb_datalen = size;
  51                        else
  52                           sb->sb_datalen = 0;
  53                }
  54        } else {
  55                sb->sb_wptr = sb->sb_rptr = sb->sb_data = (char *)malloc(size);
  56                sb->sb_cc = 0;
  57                if (sb->sb_wptr)
  58                   sb->sb_datalen = size;
  59                else
  60                   sb->sb_datalen = 0;
  61        }
  62}
  63
  64/*
  65 * Try and write() to the socket, whatever doesn't get written
  66 * append to the buffer... for a host with a fast net connection,
  67 * this prevents an unnecessary copy of the data
  68 * (the socket is non-blocking, so we won't hang)
  69 */
  70void
  71sbappend(struct socket *so, struct mbuf *m)
  72{
  73        int ret = 0;
  74
  75        DEBUG_CALL("sbappend");
  76        DEBUG_ARG("so = %p", so);
  77        DEBUG_ARG("m = %p", m);
  78        DEBUG_ARG("m->m_len = %d", m->m_len);
  79
  80        /* Shouldn't happen, but...  e.g. foreign host closes connection */
  81        if (m->m_len <= 0) {
  82                m_free(m);
  83                return;
  84        }
  85
  86        /*
  87         * If there is urgent data, call sosendoob
  88         * if not all was sent, sowrite will take care of the rest
  89         * (The rest of this function is just an optimisation)
  90         */
  91        if (so->so_urgc) {
  92                sbappendsb(&so->so_rcv, m);
  93                m_free(m);
  94                sosendoob(so);
  95                return;
  96        }
  97
  98        /*
  99         * We only write if there's nothing in the buffer,
 100         * ottherwise it'll arrive out of order, and hence corrupt
 101         */
 102        if (!so->so_rcv.sb_cc)
 103           ret = slirp_send(so, m->m_data, m->m_len, 0);
 104
 105        if (ret <= 0) {
 106                /*
 107                 * Nothing was written
 108                 * It's possible that the socket has closed, but
 109                 * we don't need to check because if it has closed,
 110                 * it will be detected in the normal way by soread()
 111                 */
 112                sbappendsb(&so->so_rcv, m);
 113        } else if (ret != m->m_len) {
 114                /*
 115                 * Something was written, but not everything..
 116                 * sbappendsb the rest
 117                 */
 118                m->m_len -= ret;
 119                m->m_data += ret;
 120                sbappendsb(&so->so_rcv, m);
 121        } /* else */
 122        /* Whatever happened, we free the mbuf */
 123        m_free(m);
 124}
 125
 126/*
 127 * Copy the data from m into sb
 128 * The caller is responsible to make sure there's enough room
 129 */
 130static void
 131sbappendsb(struct sbuf *sb, struct mbuf *m)
 132{
 133        int len, n,  nn;
 134
 135        len = m->m_len;
 136
 137        if (sb->sb_wptr < sb->sb_rptr) {
 138                n = sb->sb_rptr - sb->sb_wptr;
 139                if (n > len) n = len;
 140                memcpy(sb->sb_wptr, m->m_data, n);
 141        } else {
 142                /* Do the right edge first */
 143                n = sb->sb_data + sb->sb_datalen - sb->sb_wptr;
 144                if (n > len) n = len;
 145                memcpy(sb->sb_wptr, m->m_data, n);
 146                len -= n;
 147                if (len) {
 148                        /* Now the left edge */
 149                        nn = sb->sb_rptr - sb->sb_data;
 150                        if (nn > len) nn = len;
 151                        memcpy(sb->sb_data,m->m_data+n,nn);
 152                        n += nn;
 153                }
 154        }
 155
 156        sb->sb_cc += n;
 157        sb->sb_wptr += n;
 158        if (sb->sb_wptr >= sb->sb_data + sb->sb_datalen)
 159                sb->sb_wptr -= sb->sb_datalen;
 160}
 161
 162/*
 163 * Copy data from sbuf to a normal, straight buffer
 164 * Don't update the sbuf rptr, this will be
 165 * done in sbdrop when the data is acked
 166 */
 167void
 168sbcopy(struct sbuf *sb, int off, int len, char *to)
 169{
 170        char *from;
 171
 172        from = sb->sb_rptr + off;
 173        if (from >= sb->sb_data + sb->sb_datalen)
 174                from -= sb->sb_datalen;
 175
 176        if (from < sb->sb_wptr) {
 177                if (len > sb->sb_cc) len = sb->sb_cc;
 178                memcpy(to,from,len);
 179        } else {
 180                /* re-use off */
 181                off = (sb->sb_data + sb->sb_datalen) - from;
 182                if (off > len) off = len;
 183                memcpy(to,from,off);
 184                len -= off;
 185                if (len)
 186                   memcpy(to+off,sb->sb_data,len);
 187        }
 188}
 189