GopherProxy

	Refactor range-parsing - quark - quark web server
	git clone git://git.suckless.org/quark
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	---
	commit db4e35d3d5cbd5bfac61cfb8edadd47c4608a864
	parent 6b508a0e073fd4e29540f8808d919ff72c1893fb
	Author: Laslo Hunhold <[email protected]>
	Date: Thu, 23 Jul 2020 18:16:08 +0200

	Refactor range-parsing

	Quark previously didn't really handle suffix-range-requests
	(those of the form "-num", asking for the last num bytes) properly
	and also did not catch the error when the lower in the range
	"lower-upper" was actually larger than or equal to the size of the
	requested file.

	I always planned to refactor the parsing but got the motivation by
	Eric Radman <[email protected]>, who kindly reported the latter bug
	to me.

	Signed-off-by: Laslo Hunhold <[email protected]>

	Diffstat:
	M http.c \| 109 ++++++++++++++++++++++++-----…

	1 file changed, 84 insertions(+), 25 deletions(-)
	---
	diff --git a/http.c b/http.c
	@@ -562,36 +562,95 @@ http_send_response(int fd, struct request *r)
	return http_send_status(fd, S_BAD_REQUEST);
	}
	*(q++) = '\0';
	- if (p[0]) {
	+
	+ /*
	+ * byte-range=first\0last...
	+ * ^ ^
	+ * \| \|
	+ * p q
	+ */
	+
	+ /*
	+ * make sure we only have a single range,
	+ * and not a comma separated list, which we
	+ * will refuse to accept out of spite towards
	+ * this horrible part of the spec
	+ */
	+ if (strchr(q, ',')) {
	+ goto not_satisfiable;
	+ }
	+
	+ if (p[0] != '\0') {
	+ /*
	+ * Range has format "first-last" or "first-",
	+ * i.e. return bytes 'first' to 'last' (or the
	+ * last byte if 'last' is not given),
	+ * inclusively, and byte-numbering beginning at 0
	+ */
	lower = strtonum(p, 0, LLONG_MAX, &err);
	- }
	- if (!err && q[0]) {
	+ if (!err) {
	+ if (q[0] != '\0') {
	+ upper = strtonum(q, 0, LLONG_MAX,
	+ &err);
	+ } else {
	+ upper = st.st_size - 1;
	+ }
	+ }
	+ if (err) {
	+ /* one of the strtonum()'s failed */
	+ return http_send_status(fd, S_BAD_REQUEST);
	+ }
	+
	+ /* check ranges */
	+ if (lower > upper \|\| lower >= st.st_size) {
	+ goto not_satisfiable;
	+ }
	+
	+ /* adjust upper limit to be at most the last byte */
	+ upper = MIN(upper, st.st_size - 1);
	+ } else {
	+ /*
	+ * Range has format "-num", i.e. return the 'num'
	+ * last bytes
	+ */
	+
	+ /*
	+ * use upper as a temporary storage for 'num',
	+ * as we know 'upper' is st.st_size - 1
	+ */
	upper = strtonum(q, 0, LLONG_MAX, &err);
	- }
	- if (err) {
	- return http_send_status(fd, S_BAD_REQUEST);
	- }
	+ if (err) {
	+ return http_send_status(fd, S_BAD_REQUEST);
	+ }

	- /* check range */
	- if (lower < 0 \|\| upper < 0 \|\| lower > upper) {
	- if (dprintf(fd,
	- "HTTP/1.1 %d %s\r\n"
	- "Date: %s\r\n"
	- "Content-Range: bytes */%zu\r\n"
	- "Connection: close\r\n"
	- "\r\n",
	- S_RANGE_NOT_SATISFIABLE,
	- status_str[S_RANGE_NOT_SATISFIABLE],
	- timestamp(time(NULL), t),
	- st.st_size) < 0) {
	- return S_REQUEST_TIMEOUT;
	+ /* determine lower */
	+ if (upper > st.st_size) {
	+ /* more bytes requested than we have */
	+ lower = 0;
	+ } else {
	+ lower = st.st_size - upper;
	}
	- return S_RANGE_NOT_SATISFIABLE;
	- }

	- /* adjust upper limit */
	- if (upper >= st.st_size)
	- upper = st.st_size-1;
	+ /* set upper to the correct value */
	+ upper = st.st_size - 1;
	+ }
	+ goto satisfiable;
	+not_satisfiable:
	+ if (dprintf(fd,
	+ "HTTP/1.1 %d %s\r\n"
	+ "Date: %s\r\n"
	+ "Content-Range: bytes */%zu\r\n"
	+ "Connection: close\r\n"
	+ "\r\n",
	+ S_RANGE_NOT_SATISFIABLE,
	+ status_str[S_RANGE_NOT_SATISFIABLE],
	+ timestamp(time(NULL), t),
	+ st.st_size) < 0) {
	+ return S_REQUEST_TIMEOUT;
	+ }
	+ return S_RANGE_NOT_SATISFIABLE;
	+satisfiable:
	+ ;
	}

	/* mime */