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/* Copyright (c) 2010-2018 Dovecot authors, see the included COPYING file */
#include "imap-common.h"
#include "str.h"
#include "istream.h"
#include "ostream.h"
#include "module-context.h"
#include "imap-commands.h"
#include "compression.h"
#include "imap-zlib-plugin.h"
#define IMAP_COMPRESS_DEFAULT_LEVEL 6
#define IMAP_ZLIB_IMAP_CONTEXT(obj) \
MODULE_CONTEXT_REQUIRE(obj, imap_zlib_imap_module)
struct zlib_client {
union imap_module_context module_ctx;
int (*next_state_export)(struct client *client, bool internal,
buffer_t *dest, const char **error_r);
const struct compression_handler *handler;
};
const char *imap_zlib_plugin_version = DOVECOT_ABI_VERSION;
static struct module *imap_zlib_module;
static imap_client_created_func_t *next_hook_client_created;
static MODULE_CONTEXT_DEFINE_INIT(imap_zlib_imap_module,
&imap_module_register);
static void client_skip_line(struct client *client)
{
const unsigned char *data;
size_t data_size;
data = i_stream_get_data(client->input, &data_size);
i_assert(data_size > 0);
if (data[0] == '\n')
i_stream_skip(client->input, 1);
else if (data[0] == '\r' && data_size > 1 && data[1] == '\n')
i_stream_skip(client->input, 2);
else
i_unreached();
client->input_skip_line = FALSE;
}
static void client_update_imap_parser_streams(struct client *client)
{
struct client_command_context *cmd;
if (client->free_parser != NULL) {
imap_parser_set_streams(client->free_parser,
client->input, client->output);
}
for (cmd = client->command_queue; cmd != NULL; cmd = cmd->next) {
imap_parser_set_streams(cmd->parser,
client->input, client->output);
}
}
static bool cmd_compress(struct client_command_context *cmd)
{
struct client *client = cmd->client;
struct zlib_client *zclient = IMAP_ZLIB_IMAP_CONTEXT(client);
const struct compression_handler *handler;
const struct imap_arg *args;
struct istream *old_input;
struct ostream *old_output;
const char *mechanism, *value;
int level;
int ret;
/* <mechanism> */
if (!client_read_args(cmd, 0, 0, &args))
return FALSE;
if (!imap_arg_get_atom(args, &mechanism) ||
!IMAP_ARG_IS_EOL(&args[1])) {
client_send_command_error(cmd, "Invalid arguments.");
return TRUE;
}
if (zclient->handler != NULL) {
client_send_tagline(cmd, t_strdup_printf(
"NO [COMPRESSIONACTIVE] COMPRESSION=%s already enabled.",
t_str_ucase(zclient->handler->name)));
return TRUE;
}
ret = compression_lookup_handler(t_str_lcase(mechanism), &handler);
if (ret <= 0) {
const char * tagline =
t_strdup_printf("NO %s compression mechanism",
ret == 0 ? "Unsupported" : "Unknown");
client_send_tagline(cmd, tagline);
return TRUE;
}
client_skip_line(client);
client_send_tagline(cmd, "OK Begin compression.");
const char *setting = t_strdup_printf("imap_compress_%s_level",
handler->name);
value = mail_user_plugin_getenv(client->user, setting);
if (value == NULL) {
level = handler->get_default_level();
} else if (str_to_int(value, &level) < 0 ||
level < handler->get_min_level() ||
level > handler->get_max_level()) {
i_error("%s: Level must be between %d..%d",
setting,
handler->get_min_level(),
handler->get_max_level());
level = handler->get_default_level();
}
old_input = client->input;
old_output = client->output;
client->input = handler->create_istream(old_input);
client->output = handler->create_ostream(old_output, level);
/* preserve output offset so that the bytes out counter in logout
message doesn't get reset here */
client->output->offset = old_output->offset;
i_stream_unref(&old_input);
o_stream_unref(&old_output);
client_update_imap_parser_streams(client);
zclient->handler = handler;
return TRUE;
}
static int
imap_zlib_state_export(struct client *client, bool internal,
buffer_t *dest, const char **error_r)
{
struct zlib_client *zclient = IMAP_ZLIB_IMAP_CONTEXT(client);
if (zclient->handler != NULL && internal) {
*error_r = "COMPRESS enabled";
return 0;
}
return zclient->next_state_export(client, internal, dest, error_r);
}
static void imap_zlib_client_created(struct client **clientp)
{
struct client *client = *clientp;
struct zlib_client *zclient;
const struct compression_handler *handler;
if (mail_user_is_plugin_loaded(client->user, imap_zlib_module) &&
compression_lookup_handler("deflate", &handler) > 0) {
zclient = p_new(client->pool, struct zlib_client, 1);
MODULE_CONTEXT_SET(client, imap_zlib_imap_module, zclient);
zclient->next_state_export = (*clientp)->v.state_export;
(*clientp)->v.state_export = imap_zlib_state_export;
client_add_capability(*clientp, "COMPRESS=DEFLATE");
}
if (next_hook_client_created != NULL)
next_hook_client_created(clientp);
}
void imap_zlib_plugin_init(struct module *module)
{
command_register("COMPRESS", cmd_compress, 0);
imap_zlib_module = module;
next_hook_client_created =
imap_client_created_hook_set(imap_zlib_client_created);
}
void imap_zlib_plugin_deinit(void)
{
command_unregister("COMPRESS");
imap_client_created_hook_set(next_hook_client_created);
}
const char imap_zlib_plugin_binary_dependency[] = "imap";
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