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 #include "qemu/main-loop.h"
  11
  12 static void sbappendsb(struct sbuf *sb, struct mbuf *m);
  13
  14 void
  15 sbfree(struct sbuf *sb)
  16 {
  17         free(sb->sb_data);
  18 }
  19
  20 bool
  21 sbdrop(struct sbuf *sb, int num)
  22 {
  23     int limit = sb->sb_datalen / 2;
  24
  25         /*
  26          * We can only drop how much we have
  27          * This should never succeed
  28          */
  29         if(num > sb->sb_cc)
  30                 num = sb->sb_cc;
  31         sb->sb_cc -= num;
  32         sb->sb_rptr += num;
  33         if(sb->sb_rptr >= sb->sb_data + sb->sb_datalen)
  34                 sb->sb_rptr -= sb->sb_datalen;
  35
  36     if (sb->sb_cc < limit && sb->sb_cc + num >= limit) {
  37         return true;
  38     }
  39
  40     return false;
  41 }
  42
  43 void
  44 sbreserve(struct sbuf *sb, int size)
  45 {
  46         if (sb->sb_data) {
  47                 /* Already alloced, realloc if necessary */
  48                 if (sb->sb_datalen != size) {
  49                         sb->sb_wptr = sb->sb_rptr = sb->sb_data = (char *)realloc(sb->sb_data, size);
  50                         sb->sb_cc = 0;
  51                         if (sb->sb_wptr)
  52                            sb->sb_datalen = size;
  53                         else
  54                            sb->sb_datalen = 0;
  55                 }
  56         } else {
  57                 sb->sb_wptr = sb->sb_rptr = sb->sb_data = (char *)malloc(size);
  58                 sb->sb_cc = 0;
  59                 if (sb->sb_wptr)
  60                    sb->sb_datalen = size;
  61                 else
  62                    sb->sb_datalen = 0;
  63         }
  64 }
  65
  66 /*
  67  * Try and write() to the socket, whatever doesn't get written
  68  * append to the buffer... for a host with a fast net connection,
  69  * this prevents an unnecessary copy of the data
  70  * (the socket is non-blocking, so we won't hang)
  71  */
  72 void
  73 sbappend(struct socket *so, struct mbuf *m)
  74 {
  75         int ret = 0;
  76
  77         DEBUG_CALL("sbappend");
  78         DEBUG_ARG("so = %p", so);
  79         DEBUG_ARG("m = %p", m);
  80         DEBUG_ARG("m->m_len = %d", m->m_len);
  81
  82         /* Shouldn't happen, but...  e.g. foreign host closes connection */
  83         if (m->m_len <= 0) {
  84                 m_free(m);
  85                 return;
  86         }
  87
  88         /*
  89          * If there is urgent data, call sosendoob
  90          * if not all was sent, sowrite will take care of the rest
  91          * (The rest of this function is just an optimisation)
  92          */
  93         if (so->so_urgc) {
  94                 sbappendsb(&so->so_rcv, m);
  95                 m_free(m);
  96                 (void)sosendoob(so);
  97                 return;
  98         }
  99
 100         /*
 101          * We only write if there's nothing in the buffer,
 102          * ottherwise it'll arrive out of order, and hence corrupt
 103          */
 104         if (!so->so_rcv.sb_cc)
 105            ret = slirp_send(so, m->m_data, m->m_len, 0);
 106
 107         if (ret <= 0) {
 108                 /*
 109                  * Nothing was written
 110                  * It's possible that the socket has closed, but
 111                  * we don't need to check because if it has closed,
 112                  * it will be detected in the normal way by soread()
 113                  */
 114                 sbappendsb(&so->so_rcv, m);
 115         } else if (ret != m->m_len) {
 116                 /*
 117                  * Something was written, but not everything..
 118                  * sbappendsb the rest
 119                  */
 120                 m->m_len -= ret;
 121                 m->m_data += ret;
 122                 sbappendsb(&so->so_rcv, m);
 123         } /* else */
 124         /* Whatever happened, we free the mbuf */
 125         m_free(m);
 126 }
 127
 128 /*
 129  * Copy the data from m into sb
 130  * The caller is responsible to make sure there's enough room
 131  */
 132 static void
 133 sbappendsb(struct sbuf *sb, struct mbuf *m)
 134 {
 135         int len, n,  nn;
 136
 137         len = m->m_len;
 138
 139         if (sb->sb_wptr < sb->sb_rptr) {
 140                 n = sb->sb_rptr - sb->sb_wptr;
 141                 if (n > len) n = len;
 142                 memcpy(sb->sb_wptr, m->m_data, n);
 143         } else {
 144                 /* Do the right edge first */
 145                 n = sb->sb_data + sb->sb_datalen - sb->sb_wptr;
 146                 if (n > len) n = len;
 147                 memcpy(sb->sb_wptr, m->m_data, n);
 148                 len -= n;
 149                 if (len) {
 150                         /* Now the left edge */
 151                         nn = sb->sb_rptr - sb->sb_data;
 152                         if (nn > len) nn = len;
 153                         memcpy(sb->sb_data,m->m_data+n,nn);
 154                         n += nn;
 155                 }
 156         }
 157
 158         sb->sb_cc += n;
 159         sb->sb_wptr += n;
 160         if (sb->sb_wptr >= sb->sb_data + sb->sb_datalen)
 161                 sb->sb_wptr -= sb->sb_datalen;
 162 }
 163
 164 /*
 165  * Copy data from sbuf to a normal, straight buffer
 166  * Don't update the sbuf rptr, this will be
 167  * done in sbdrop when the data is acked
 168  */
 169 void
 170 sbcopy(struct sbuf *sb, int off, int len, char *to)
 171 {
 172         char *from;
 173
 174         from = sb->sb_rptr + off;
 175         if (from >= sb->sb_data + sb->sb_datalen)
 176                 from -= sb->sb_datalen;
 177
 178         if (from < sb->sb_wptr) {
 179                 if (len > sb->sb_cc) len = sb->sb_cc;
 180                 memcpy(to,from,len);
 181         } else {
 182                 /* re-use off */
 183                 off = (sb->sb_data + sb->sb_datalen) - from;
 184                 if (off > len) off = len;
 185                 memcpy(to,from,off);
 186                 len -= off;
 187                 if (len)
 188                    memcpy(to+off,sb->sb_data,len);
 189         }
 190 }