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 /* Done as a macro in socket.h */
  13 /* int
  14  * sbspace(struct sockbuff *sb)
  15  * {
  16  *      return SB_DATALEN - sb->sb_cc;
  17  * }
  18  */
  19
  20 void
  21 sbfree(sb)
  22         struct sbuf *sb;
  23 {
  24         free(sb->sb_data);
  25 }
  26
  27 void
  28 sbdrop(sb, num)
  29         struct sbuf *sb;
  30         int num;
  31 {
  32         /*
  33          * We can only drop how much we have
  34          * This should never succeed
  35          */
  36         if(num > sb->sb_cc)
  37                 num = sb->sb_cc;
  38         sb->sb_cc -= num;
  39         sb->sb_rptr += num;
  40         if(sb->sb_rptr >= sb->sb_data + sb->sb_datalen)
  41                 sb->sb_rptr -= sb->sb_datalen;
  42
  43 }
  44
  45 void
  46 sbreserve(sb, size)
  47         struct sbuf *sb;
  48         int size;
  49 {
  50         if (sb->sb_data) {
  51                 /* Already alloced, realloc if necessary */
  52                 if (sb->sb_datalen != size) {
  53                         sb->sb_wptr = sb->sb_rptr = sb->sb_data = (char *)realloc(sb->sb_data, size);
  54                         sb->sb_cc = 0;
  55                         if (sb->sb_wptr)
  56                            sb->sb_datalen = size;
  57                         else
  58                            sb->sb_datalen = 0;
  59                 }
  60         } else {
  61                 sb->sb_wptr = sb->sb_rptr = sb->sb_data = (char *)malloc(size);
  62                 sb->sb_cc = 0;
  63                 if (sb->sb_wptr)
  64                    sb->sb_datalen = size;
  65                 else
  66                    sb->sb_datalen = 0;
  67         }
  68 }
  69
  70 /*
  71  * Try and write() to the socket, whatever doesn't get written
  72  * append to the buffer... for a host with a fast net connection,
  73  * this prevents an unnecessary copy of the data
  74  * (the socket is non-blocking, so we won't hang)
  75  */
  76 void
  77 sbappend(so, m)
  78         struct socket *so;
  79         struct mbuf *m;
  80 {
  81         int ret = 0;
  82
  83         DEBUG_CALL("sbappend");
  84         DEBUG_ARG("so = %lx", (long)so);
  85         DEBUG_ARG("m = %lx", (long)m);
  86         DEBUG_ARG("m->m_len = %d", m->m_len);
  87
  88         /* Shouldn't happen, but...  e.g. foreign host closes connection */
  89         if (m->m_len <= 0) {
  90                 m_free(m);
  91                 return;
  92         }
  93
  94         /*
  95          * If there is urgent data, call sosendoob
  96          * if not all was sent, sowrite will take care of the rest
  97          * (The rest of this function is just an optimisation)
  98          */
  99         if (so->so_urgc) {
 100                 sbappendsb(&so->so_rcv, m);
 101                 m_free(m);
 102                 sosendoob(so);
 103                 return;
 104         }
 105
 106         /*
 107          * We only write if there's nothing in the buffer,
 108          * ottherwise it'll arrive out of order, and hence corrupt
 109          */
 110         if (!so->so_rcv.sb_cc)
 111            ret = slirp_send(so, m->m_data, m->m_len, 0);
 112
 113         if (ret <= 0) {
 114                 /*
 115                  * Nothing was written
 116                  * It's possible that the socket has closed, but
 117                  * we don't need to check because if it has closed,
 118                  * it will be detected in the normal way by soread()
 119                  */
 120                 sbappendsb(&so->so_rcv, m);
 121         } else if (ret != m->m_len) {
 122                 /*
 123                  * Something was written, but not everything..
 124                  * sbappendsb the rest
 125                  */
 126                 m->m_len -= ret;
 127                 m->m_data += ret;
 128                 sbappendsb(&so->so_rcv, m);
 129         } /* else */
 130         /* Whatever happened, we free the mbuf */
 131         m_free(m);
 132 }
 133
 134 /*
 135  * Copy the data from m into sb
 136  * The caller is responsible to make sure there's enough room
 137  */
 138 static void
 139 sbappendsb(struct sbuf *sb, struct mbuf *m)
 140 {
 141         int len, n,  nn;
 142
 143         len = m->m_len;
 144
 145         if (sb->sb_wptr < sb->sb_rptr) {
 146                 n = sb->sb_rptr - sb->sb_wptr;
 147                 if (n > len) n = len;
 148                 memcpy(sb->sb_wptr, m->m_data, n);
 149         } else {
 150                 /* Do the right edge first */
 151                 n = sb->sb_data + sb->sb_datalen - sb->sb_wptr;
 152                 if (n > len) n = len;
 153                 memcpy(sb->sb_wptr, m->m_data, n);
 154                 len -= n;
 155                 if (len) {
 156                         /* Now the left edge */
 157                         nn = sb->sb_rptr - sb->sb_data;
 158                         if (nn > len) nn = len;
 159                         memcpy(sb->sb_data,m->m_data+n,nn);
 160                         n += nn;
 161                 }
 162         }
 163
 164         sb->sb_cc += n;
 165         sb->sb_wptr += n;
 166         if (sb->sb_wptr >= sb->sb_data + sb->sb_datalen)
 167                 sb->sb_wptr -= sb->sb_datalen;
 168 }
 169
 170 /*
 171  * Copy data from sbuf to a normal, straight buffer
 172  * Don't update the sbuf rptr, this will be
 173  * done in sbdrop when the data is acked
 174  */
 175 void
 176 sbcopy(sb, off, len, to)
 177         struct sbuf *sb;
 178         int off;
 179         int len;
 180         char *to;
 181 {
 182         char *from;
 183
 184         from = sb->sb_rptr + off;
 185         if (from >= sb->sb_data + sb->sb_datalen)
 186                 from -= sb->sb_datalen;
 187
 188         if (from < sb->sb_wptr) {
 189                 if (len > sb->sb_cc) len = sb->sb_cc;
 190                 memcpy(to,from,len);
 191         } else {
 192                 /* re-use off */
 193                 off = (sb->sb_data + sb->sb_datalen) - from;
 194                 if (off > len) off = len;
 195                 memcpy(to,from,off);
 196                 len -= off;
 197                 if (len)
 198                    memcpy(to+off,sb->sb_data,len);
 199         }
 200 }