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/*
* libwebsockets - small server side websockets and web server implementation
*
* RFC7233 ranges parser
*
* Copyright (C) 2016 Andy Green <andy@warmcat.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation:
* version 2.1 of the License.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301 USA
*/
#include "private-libwebsockets.h"
/*
* RFC7233 examples
*
* o The first 500 bytes (byte offsets 0-499, inclusive):
*
* bytes=0-499
*
* o The second 500 bytes (byte offsets 500-999, inclusive):
*
* bytes=500-999
*
* o The final 500 bytes (byte offsets 9500-9999, inclusive):
*
* bytes=-500
*
* Or:
*
* bytes=9500-
*
* o The first and last bytes only (bytes 0 and 9999):
*
* bytes=0-0,-1
*
* o Other valid (but not canonical) specifications of the second 500
* bytes (byte offsets 500-999, inclusive):
*
* bytes=500-600,601-999
* bytes=500-700,601-999
*/
/*
* returns 1 if the range struct represents a usable range
* if no ranges header, you get one of these for the whole
* file. Otherwise you get one for each valid range in the
* header.
*
* returns 0 if no further valid range forthcoming; rp->state
* may be LWSRS_SYNTAX or LWSRS_COMPLETED
*/
int
lws_ranges_next(struct lws_range_parsing *rp)
{
static const char * const beq = "bytes=";
char c;
while (1) {
c = rp->buf[rp->pos];
switch (rp->state) {
case LWSRS_SYNTAX:
case LWSRS_COMPLETED:
return 0;
case LWSRS_NO_ACTIVE_RANGE:
rp->state = LWSRS_COMPLETED;
return 0;
case LWSRS_BYTES_EQ: // looking for "bytes="
if (c != beq[rp->pos]) {
rp->state = LWSRS_SYNTAX;
return -1;
}
if (rp->pos == 5)
rp->state = LWSRS_FIRST;
break;
case LWSRS_FIRST:
rp->start = 0;
rp->end = 0;
rp->start_valid = 0;
rp->end_valid = 0;
rp->state = LWSRS_STARTING;
// fallthru
case LWSRS_STARTING:
if (c == '-') {
rp->state = LWSRS_ENDING;
break;
}
if (!(c >= '0' && c <= '9')) {
rp->state = LWSRS_SYNTAX;
return 0;
}
rp->start = (rp->start * 10) + (c - '0');
rp->start_valid = 1;
break;
case LWSRS_ENDING:
if (c == ',' || c == '\0') {
rp->state = LWSRS_FIRST;
if (c == ',')
rp->pos++;
/*
* By the end of this, start and end are
* always valid if the range still is
*/
if (!rp->start_valid) { /* eg, -500 */
if (rp->end > rp->extent)
rp->end = rp->extent;
rp->start = rp->extent - rp->end;
rp->end = rp->extent - 1;
} else
if (!rp->end_valid)
rp->end = rp->extent - 1;
rp->did_try = 1;
/* end must be >= start or ignore it */
if (rp->end < rp->start) {
if (c == ',')
break;
rp->state = LWSRS_COMPLETED;
return 0;
}
return 1; /* issue range */
}
if (!(c >= '0' && c <= '9')) {
rp->state = LWSRS_SYNTAX;
return 0;
}
rp->end = (rp->end * 10) + (c - '0');
rp->end_valid = 1;
break;
}
rp->pos++;
}
}
void
lws_ranges_reset(struct lws_range_parsing *rp)
{
rp->pos = 0;
rp->ctr = 0;
rp->start = 0;
rp->end = 0;
rp->start_valid = 0;
rp->end_valid = 0;
rp->state = LWSRS_BYTES_EQ;
}
/*
* returns count of valid ranges
*/
int
lws_ranges_init(struct lws *wsi, struct lws_range_parsing *rp,
unsigned long long extent)
{
rp->agg = 0;
rp->send_ctr = 0;
rp->inside = 0;
rp->count_ranges = 0;
rp->did_try = 0;
lws_ranges_reset(rp);
rp->state = LWSRS_COMPLETED;
rp->extent = extent;
if (lws_hdr_copy(wsi, (char *)rp->buf, sizeof(rp->buf),
WSI_TOKEN_HTTP_RANGE) <= 0)
return 0;
rp->state = LWSRS_BYTES_EQ;
while (lws_ranges_next(rp)) {
rp->count_ranges++;
rp->agg += rp->end - rp->start + 1;
}
lwsl_debug("%s: count %d\n", __func__, rp->count_ranges);
lws_ranges_reset(rp);
if (rp->did_try && !rp->count_ranges)
return -1; /* "not satisfiable */
lws_ranges_next(rp);
return rp->count_ranges;
}
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