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/* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*
* mod_data.c --- Turn the response into an rfc2397 data URL, suitable for
* displaying as inline content on a page.
*/
#include "apr.h"
#include "apr_strings.h"
#include "apr_buckets.h"
#include "apr_base64.h"
#include "apr_lib.h"
#include "ap_config.h"
#include "util_filter.h"
#include "httpd.h"
#include "http_config.h"
#include "http_log.h"
#include "http_request.h"
#include "http_protocol.h"
#define DATA_FILTER "DATA"
module AP_MODULE_DECLARE_DATA data_module;
typedef struct data_ctx
{
unsigned char overflow[3];
int count;
apr_bucket_brigade *bb;
} data_ctx;
/**
* Create a data URL as follows:
*
* data:[<mime-type>;][charset=<charset>;]base64,<payload>
*
* Where:
*
* mime-type: The mime type of the original response.
* charset: The optional character set corresponding to the mime type.
* payload: A base64 version of the response body.
*
* The content type of the response is set to text/plain.
*
* The Content-Length header, if present, is updated with the new content
* length based on the increase in size expected from the base64 conversion.
* If the Content-Length header is too large to fit into an int, we remove
* the Content-Length header instead.
*/
static apr_status_t data_out_filter(ap_filter_t *f, apr_bucket_brigade *bb)
{
apr_bucket *e, *ee;
request_rec *r = f->r;
data_ctx *ctx = f->ctx;
apr_status_t rv = APR_SUCCESS;
/* first time in? create a context */
if (!ctx) {
char *type;
char *charset = NULL;
char *end;
const char *content_length;
/* base64-ing won't work on subrequests, it would be nice if
* it did. Within subrequests, we have no EOS to check for,
* so we don't know when to flush the tail to the network.
*/
if (!ap_is_initial_req(f->r)) {
ap_remove_output_filter(f);
return ap_pass_brigade(f->next, bb);
}
ctx = f->ctx = apr_pcalloc(r->pool, sizeof(*ctx));
ctx->bb = apr_brigade_create(r->pool, f->c->bucket_alloc);
type = apr_pstrdup(r->pool, r->content_type);
if (type) {
charset = strchr(type, ' ');
if (charset) {
*charset++ = 0;
end = strchr(charset, ' ');
if (end) {
*end++ = 0;
}
}
}
apr_brigade_printf(ctx->bb, NULL, NULL, "data:%s%s;base64,",
type ? type : "", charset ? charset : "");
content_length = apr_table_get(r->headers_out, "Content-Length");
if (content_length) {
apr_off_t len, clen;
apr_brigade_length(ctx->bb, 1, &len);
if (ap_parse_strict_length(&clen, content_length)
&& clen < APR_INT32_MAX) {
ap_set_content_length(r, len +
apr_base64_encode_len((int)clen) - 1);
}
else {
apr_table_unset(r->headers_out, "Content-Length");
}
}
ap_set_content_type(r, "text/plain");
}
/* Do nothing if asked to filter nothing. */
if (APR_BRIGADE_EMPTY(bb)) {
return ap_pass_brigade(f->next, bb);
}
while (APR_SUCCESS == rv && !APR_BRIGADE_EMPTY(bb)) {
const char *data;
apr_size_t size;
apr_size_t tail;
apr_size_t len;
/* buffer big enough for 8000 encoded bytes (6000 raw bytes) and terminator */
char buffer[APR_BUCKET_BUFF_SIZE + 1];
char encoded[((sizeof(ctx->overflow)) / 3) * 4 + 1];
e = APR_BRIGADE_FIRST(bb);
/* EOS means we are done. */
if (APR_BUCKET_IS_EOS(e)) {
/* write away the tail */
if (ctx->count) {
len = apr_base64_encode_binary(encoded, ctx->overflow,
ctx->count);
apr_brigade_write(ctx->bb, NULL, NULL, encoded, len - 1);
ctx->count = 0;
}
/* pass the EOS across */
APR_BUCKET_REMOVE(e);
APR_BRIGADE_INSERT_TAIL(ctx->bb, e);
/* pass what we have down the chain */
ap_remove_output_filter(f);
rv = ap_pass_brigade(f->next, ctx->bb);
/* pass any stray buckets after the EOS down the stack */
if ((APR_SUCCESS == rv) && (!APR_BRIGADE_EMPTY(bb))) {
rv = ap_pass_brigade(f->next, bb);
}
continue;
}
/* flush what we can, we can't flush the tail until EOS */
if (APR_BUCKET_IS_FLUSH(e)) {
/* pass the flush bucket across */
APR_BUCKET_REMOVE(e);
APR_BRIGADE_INSERT_TAIL(ctx->bb, e);
/* pass what we have down the chain */
rv = ap_pass_brigade(f->next, ctx->bb);
continue;
}
/* metadata buckets are preserved as is */
if (APR_BUCKET_IS_METADATA(e)) {
/*
* Remove meta data bucket from old brigade and insert into the
* new.
*/
APR_BUCKET_REMOVE(e);
APR_BRIGADE_INSERT_TAIL(ctx->bb, e);
continue;
}
/* make sure we don't read more than 6000 bytes at a time */
apr_brigade_partition(bb, (APR_BUCKET_BUFF_SIZE / 4 * 3), &ee);
/* size will never be more than 6000 bytes */
if (APR_SUCCESS == (rv = apr_bucket_read(e, &data, &size,
APR_BLOCK_READ))) {
/* fill up and write out our overflow buffer if partially used */
while (size && ctx->count && ctx->count < sizeof(ctx->overflow)) {
ctx->overflow[ctx->count++] = *data++;
size--;
}
if (ctx->count == sizeof(ctx->overflow)) {
len = apr_base64_encode_binary(encoded, ctx->overflow,
sizeof(ctx->overflow));
apr_brigade_write(ctx->bb, NULL, NULL, encoded, len - 1);
ctx->count = 0;
}
/* write the main base64 chunk */
tail = size % sizeof(ctx->overflow);
size -= tail;
if (size) {
len = apr_base64_encode_binary(buffer,
(const unsigned char *) data, size);
apr_brigade_write(ctx->bb, NULL, NULL, buffer, len - 1);
}
/* save away any tail in the overflow buffer */
if (tail) {
memcpy(ctx->overflow, data + size, tail);
ctx->count += tail;
}
apr_bucket_delete(e);
/* pass what we have down the chain */
rv = ap_pass_brigade(f->next, ctx->bb);
if (rv) {
/* should break out of the loop, since our write to the client
* failed in some way. */
continue;
}
}
}
return rv;
}
static const command_rec data_cmds[] = { { NULL } };
static void register_hooks(apr_pool_t *p)
{
ap_register_output_filter(DATA_FILTER, data_out_filter, NULL,
AP_FTYPE_RESOURCE);
}
AP_DECLARE_MODULE(data) = { STANDARD20_MODULE_STUFF,
NULL, /* create per-directory config structure */
NULL, /* merge per-directory config structures */
NULL, /* create per-server config structure */
NULL, /* merge per-server config structures */
data_cmds, /* command apr_table_t */
register_hooks /* register hooks */
};
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