block/curl: rewrite http header parsing function

Existing code was long, unclear and twisty.

This also relaxes the rules a tiny bit: allows to have
whitespace before header name and colon and makes the
header value match to be case-insensitive.

Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
This commit is contained in:
Michael Tokarev 2024-06-29 16:27:00 +03:00
parent e2f346aa98
commit 2abc22e639

View File

@ -210,37 +210,29 @@ static size_t curl_header_cb(void *ptr, size_t size, size_t nmemb, void *opaque)
{
BDRVCURLState *s = opaque;
size_t realsize = size * nmemb;
const char *header = (char *)ptr;
const char *end = header + realsize;
const char *accept_ranges = "accept-ranges:";
const char *bytes = "bytes";
const char *p = ptr;
const char *end = p + realsize;
const char *t = "accept-ranges : bytes "; /* A lowercase template */
if (realsize >= strlen(accept_ranges)
&& g_ascii_strncasecmp(header, accept_ranges,
strlen(accept_ranges)) == 0) {
char *p = strchr(header, ':') + 1;
/* Skip whitespace between the header name and value. */
while (p < end && *p && g_ascii_isspace(*p)) {
p++;
}
if (end - p >= strlen(bytes)
&& strncmp(p, bytes, strlen(bytes)) == 0) {
/* Check that there is nothing but whitespace after the value. */
p += strlen(bytes);
while (p < end && *p && g_ascii_isspace(*p)) {
p++;
}
if (p == end || !*p) {
s->accept_range = true;
/* check if header matches the "t" template */
for (;;) {
if (*t == ' ') { /* space in t matches any amount of isspace in p */
if (p < end && g_ascii_isspace(*p)) {
++p;
} else {
++t;
}
} else if (*t && p < end && *t == g_ascii_tolower(*p)) {
++p, ++t;
} else {
break;
}
}
if (!*t && p == end) { /* if we managed to reach ends of both strings */
s->accept_range = true;
}
return realsize;
}