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
  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 bool
  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         return true;
  37     }
  38
  39     return false;
  40 }
  41
  42 void
  43 sbreserve(struct sbuf *sb, int size)
  44 {
  45         if (sb->sb_data) {
  46                 /* Already alloced, realloc if necessary */
  47                 if (sb->sb_datalen != size) {
  48                         sb->sb_wptr = sb->sb_rptr = sb->sb_data = (char *)realloc(sb->sb_data, size);
  49                         sb->sb_cc = 0;
  50                         if (sb->sb_wptr)
  51                            sb->sb_datalen = size;
  52                         else
  53                            sb->sb_datalen = 0;
  54                 }
  55         } else {
  56                 sb->sb_wptr = sb->sb_rptr = sb->sb_data = (char *)malloc(size);
  57                 sb->sb_cc = 0;
  58                 if (sb->sb_wptr)
  59                    sb->sb_datalen = size;
  60                 else
  61                    sb->sb_datalen = 0;
  62         }
  63 }
  64
  65 /*
  66  * Try and write() to the socket, whatever doesn't get written
  67  * append to the buffer... for a host with a fast net connection,
  68  * this prevents an unnecessary copy of the data
  69  * (the socket is non-blocking, so we won't hang)
  70  */
  71 void
  72 sbappend(struct socket *so, struct mbuf *m)
  73 {
  74         int ret = 0;
  75
  76         DEBUG_CALL("sbappend");
  77         DEBUG_ARG("so = %p", so);
  78         DEBUG_ARG("m = %p", m);
  79         DEBUG_ARG("m->m_len = %d", m->m_len);
  80
  81         /* Shouldn't happen, but...  e.g. foreign host closes connection */
  82         if (m->m_len <= 0) {
  83                 m_free(m);
  84                 return;
  85         }
  86
  87         /*
  88          * If there is urgent data, call sosendoob
  89          * if not all was sent, sowrite will take care of the rest
  90          * (The rest of this function is just an optimisation)
  91          */
  92         if (so->so_urgc) {
  93                 sbappendsb(&so->so_rcv, m);
  94                 m_free(m);
  95                 (void)sosendoob(so);
  96                 return;
  97         }
  98
  99         /*
 100          * We only write if there's nothing in the buffer,
 101          * ottherwise it'll arrive out of order, and hence corrupt
 102          */
 103         if (!so->so_rcv.sb_cc)
 104            ret = slirp_send(so, m->m_data, m->m_len, 0);
 105
 106         if (ret <= 0) {
 107                 /*
 108                  * Nothing was written
 109                  * It's possible that the socket has closed, but
 110                  * we don't need to check because if it has closed,
 111                  * it will be detected in the normal way by soread()
 112                  */
 113                 sbappendsb(&so->so_rcv, m);
 114         } else if (ret != m->m_len) {
 115                 /*
 116                  * Something was written, but not everything..
 117                  * sbappendsb the rest
 118                  */
 119                 m->m_len -= ret;
 120                 m->m_data += ret;
 121                 sbappendsb(&so->so_rcv, m);
 122         } /* else */
 123         /* Whatever happened, we free the mbuf */
 124         m_free(m);
 125 }
 126
 127 /*
 128  * Copy the data from m into sb
 129  * The caller is responsible to make sure there's enough room
 130  */
 131 static void
 132 sbappendsb(struct sbuf *sb, struct mbuf *m)
 133 {
 134         int len, n,  nn;
 135
 136         len = m->m_len;
 137
 138         if (sb->sb_wptr < sb->sb_rptr) {
 139                 n = sb->sb_rptr - sb->sb_wptr;
 140                 if (n > len) n = len;
 141                 memcpy(sb->sb_wptr, m->m_data, n);
 142         } else {
 143                 /* Do the right edge first */
 144                 n = sb->sb_data + sb->sb_datalen - sb->sb_wptr;
 145                 if (n > len) n = len;
 146                 memcpy(sb->sb_wptr, m->m_data, n);
 147                 len -= n;
 148                 if (len) {
 149                         /* Now the left edge */
 150                         nn = sb->sb_rptr - sb->sb_data;
 151                         if (nn > len) nn = len;
 152                         memcpy(sb->sb_data,m->m_data+n,nn);
 153                         n += nn;
 154                 }
 155         }
 156
 157         sb->sb_cc += n;
 158         sb->sb_wptr += n;
 159         if (sb->sb_wptr >= sb->sb_data + sb->sb_datalen)
 160                 sb->sb_wptr -= sb->sb_datalen;
 161 }
 162
 163 /*
 164  * Copy data from sbuf to a normal, straight buffer
 165  * Don't update the sbuf rptr, this will be
 166  * done in sbdrop when the data is acked
 167  */
 168 void
 169 sbcopy(struct sbuf *sb, int off, int len, char *to)
 170 {
 171         char *from;
 172
 173         from = sb->sb_rptr + off;
 174         if (from >= sb->sb_data + sb->sb_datalen)
 175                 from -= sb->sb_datalen;
 176
 177         if (from < sb->sb_wptr) {
 178                 if (len > sb->sb_cc) len = sb->sb_cc;
 179                 memcpy(to,from,len);
 180         } else {
 181                 /* re-use off */
 182                 off = (sb->sb_data + sb->sb_datalen) - from;
 183                 if (off > len) off = len;
 184                 memcpy(to,from,off);
 185                 len -= off;
 186                 if (len)
 187                    memcpy(to+off,sb->sb_data,len);
 188         }
 189 }