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