CURL driver requests partial data from server on guest IO req. For HTTP and HTTPS, it uses "Range: ***" in requests, and this will not work if server not accepting range. This patch does this check when open.
* Removed curl_size_cb, which is not used: On one hand it's registered to libcurl as CURLOPT_WRITEFUNCTION, instead of CURLOPT_HEADERFUNCTION, which will get called with *data*, not *header*. On the other hand the s->len is assigned unconditionally later. In this gone function, the sscanf for "Content-Length: %zd", on (void *)ptr, which is not guaranteed to be zero-terminated, is potentially a security bug. So this patch fixes it as a side-effect. The bug is reported as: https://bugs.launchpad.net/qemu/+bug/1188943 (Note the bug is marked "private" so you might not be able to see it) * Introduced curl_header_cb, which is used to parse header and mark the server as accepting range if "Accept-Ranges: bytes" line is seen from response header. If protocol is HTTP or HTTPS, but server response has no not this support, refuse to open this URL. Note that python builtin module SimpleHTTPServer is an example of not supporting range, if you need to test this driver, get a better server or use internet URLs. Cc: "Richard W.M. Jones" <rjo...@redhat.com> Signed-off-by: Fam Zheng <f...@redhat.com> --- v2: Fix the case that header data is shorter than accept_line length. [stefan] --- block/curl.c | 23 +++++++++++++++++------ 1 file changed, 17 insertions(+), 6 deletions(-) diff --git a/block/curl.c b/block/curl.c index b8935fd..7d8644a 100644 --- a/block/curl.c +++ b/block/curl.c @@ -81,6 +81,7 @@ typedef struct BDRVCURLState { CURLState states[CURL_NUM_STATES]; char *url; size_t readahead_size; + bool accept_range; } BDRVCURLState; static void curl_clean_state(CURLState *s); @@ -110,14 +111,15 @@ static int curl_sock_cb(CURL *curl, curl_socket_t fd, int action, return 0; } -static size_t curl_size_cb(void *ptr, size_t size, size_t nmemb, void *opaque) +static size_t curl_header_cb(void *ptr, size_t size, size_t nmemb, void *opaque) { - CURLState *s = ((CURLState*)opaque); + BDRVCURLState *s = opaque; size_t realsize = size * nmemb; - size_t fsize; + const char *accept_line = "Accept-Ranges: bytes"; - if(sscanf(ptr, "Content-Length: %zd", &fsize) == 1) { - s->s->len = fsize; + if (real_size >= strlen(accept_len) + && strncmp((char *)ptr, accept_line, strlen(accept_line)) == 0) { + s->accept_range = true; } return realsize; @@ -441,8 +443,11 @@ static int curl_open(BlockDriverState *bs, QDict *options, int flags) // Get file size + s->accept_range = false; curl_easy_setopt(state->curl, CURLOPT_NOBODY, 1); - curl_easy_setopt(state->curl, CURLOPT_WRITEFUNCTION, (void *)curl_size_cb); + curl_easy_setopt(state->curl, CURLOPT_HEADERFUNCTION, + curl_header_cb); + curl_easy_setopt(state->curl, CURLOPT_HEADERDATA, s); if (curl_easy_perform(state->curl)) goto out; curl_easy_getinfo(state->curl, CURLINFO_CONTENT_LENGTH_DOWNLOAD, &d); @@ -452,6 +457,12 @@ static int curl_open(BlockDriverState *bs, QDict *options, int flags) s->len = (size_t)d; else if(!s->len) goto out; + if ((!strncasecmp(s->url, "http://";, strlen("http://";)) + || !strncasecmp(s->url, "https://";, strlen("https://";))) + && !s->accept_range) { + pstrcpy(state->errmsg, CURL_ERROR_SIZE, "Server not supporting range."); + goto out; + } DPRINTF("CURL: Size = %zd\n", s->len); curl_clean_state(state); -- 1.8.3.1
