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
  10 static void sbappendsb(struct sbuf *sb, struct mbuf *m);
  11
  12 void
  13 sbfree(struct sbuf *sb)
  14 {
  15         free(sb->sb_data);
  16 }
  17
  18 bool
  19 sbdrop(struct sbuf *sb, int num)
  20 {
  21     int limit = sb->sb_datalen / 2;
  22
  23         /*
  24          * We can only drop how much we have
  25          * This should never succeed
  26          */
  27         if(num > sb->sb_cc)
  28                 num = sb->sb_cc;
  29         sb->sb_cc -= num;
  30         sb->sb_rptr += num;
  31         if(sb->sb_rptr >= sb->sb_data + sb->sb_datalen)
  32                 sb->sb_rptr -= sb->sb_datalen;
  33
  34     if (sb->sb_cc < limit && sb->sb_cc + num >= limit) {
  35         return true;
  36     }
  37
  38     return false;
  39 }
  40
  41 void
  42 sbreserve(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  */
  70 void
  71 sbappend(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                 (void)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  */
 130 static void
 131 sbappendsb(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  */
 167 void
 168 sbcopy(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 }