zstrm.h File Reference

Zlib compression of network traffic. More...

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Functions
void	mutt_zstrm_wrap_conn (struct Connection *conn)
	Wrap a compression layer around a Connection.

Detailed Description

Zlib compression of network traffic.

Authors

• Fabian Groffen

Copyright

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/.

Definition in file zstrm.h.

Function Documentation

mutt_zstrm_wrap_conn()

void mutt_zstrm_wrap_conn

(

struct Connection *

conn

)

Wrap a compression layer around a Connection.

Parameters

conn	Connection to wrap

Replace the read/write functions with our compression functions. After reading from the socket, we decompress and pass on the data. Before writing to a socket, we compress the data.

Definition at line 303 of file zstrm.c.

{
  struct ZstrmContext *zctx = MUTT_MEM_CALLOC(1, struct ZstrmContext);
 
  /* store wrapped stream as next stream */
  zctx->next_conn.fd = conn->fd;
  zctx->next_conn.sockdata = conn->sockdata;
  zctx->next_conn.open = conn->open;
  zctx->next_conn.close = conn->close;
  zctx->next_conn.read = conn->read;
  zctx->next_conn.write = conn->write;
  zctx->next_conn.poll = conn->poll;
 
  /* replace connection with our wrappers, where appropriate */
  conn->sockdata = zctx;
  conn->open = zstrm_open;
  conn->read = zstrm_read;
  conn->write = zstrm_write;
  conn->close = zstrm_close;
  conn->poll = zstrm_poll;
 
  /* allocate/setup (de)compression buffers */
  zctx->read.len = 8192;
  zctx->read.buf = MUTT_MEM_MALLOC(zctx->read.len, char);
  zctx->read.pos = 0;
  zctx->write.len = 8192;
  zctx->write.buf = MUTT_MEM_MALLOC(zctx->write.len, char);
  zctx->write.pos = 0;
 
  /* initialise zlib for inflate and deflate for RFC4978 */
  zctx->read.z.zalloc = zstrm_malloc;
  zctx->read.z.zfree = zstrm_free;
  zctx->read.z.opaque = NULL;
  zctx->read.z.avail_out = zctx->read.len;
  (void) inflateInit2(&zctx->read.z, -15);
  zctx->write.z.zalloc = zstrm_malloc;
  zctx->write.z.zfree = zstrm_free;
  zctx->write.z.opaque = NULL;
  zctx->write.z.avail_out = zctx->write.len;
  (void) deflateInit2(&zctx->write.z, Z_DEFAULT_COMPRESSION, Z_DEFLATED, -15, 8,
                      Z_DEFAULT_STRATEGY);
}

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