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