[PATCH] http.c: use CURLOPT_RANGE for range requests

[PATCH] http.c: use CURLOPT_RANGE for range requests

[David Turner]

A HTTP server is permitted to return a non-range response to a HTTP
range request (and Apache httpd in fact does this in some cases).
While libcurl knows how to correctly handle this (by skipping bytes
before and after the requested range), it only turns on this handling
if it is aware that a range request is being made.  By manually
setting the range header instead of using CURLOPT_RANGE, we were
hiding the fact that this was a range request from libcurl.  This
could cause corruption.

Signed-off-by: David Turner <dturner@twopensource.com>
---
 http.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/http.c b/http.c
index 0f924a8..303b388 100644
--- a/http.c
+++ b/http.c
@@ -1202,8 +1202,9 @@ static int http_request(const char *url,
 			curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION,
 					 fwrite);
 			if (posn > 0) {
-				strbuf_addf(&buf, "Range: bytes=%ld-", posn);
-				headers = curl_slist_append(headers, buf.buf);
+				strbuf_addf(&buf, "%ld-", posn);
+				curl_easy_setopt(slot->curl, CURLOPT_RANGE,
+						 &buf.buf);
 				strbuf_reset(&buf);
 			}
 		} else
-- 
2.4.2.691.g714732c-twtrsrc

Re: [PATCH] http.c: use CURLOPT_RANGE for range requests

[David Turner]

Please disregard this; I noticed I missed a few instances.  Will reroll
shortly.


On Fri, 2015-10-30 at 18:41 -0400, David Turner wrote:
> A HTTP server is permitted to return a non-range response to a HTTP
> range request (and Apache httpd in fact does this in some cases).
> While libcurl knows how to correctly handle this (by skipping bytes
> before and after the requested range), it only turns on this handling
> if it is aware that a range request is being made.  By manually
> setting the range header instead of using CURLOPT_RANGE, we were
> hiding the fact that this was a range request from libcurl.  This
> could cause corruption.
> 
> Signed-off-by: David Turner <dturner@twopensource.com>
> ---
>  http.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/http.c b/http.c
> index 0f924a8..303b388 100644
> --- a/http.c
> +++ b/http.c
> @@ -1202,8 +1202,9 @@ static int http_request(const char *url,
>  			curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION,
>  					 fwrite);
>  			if (posn > 0) {
> -				strbuf_addf(&buf, "Range: bytes=%ld-", posn);
> -				headers = curl_slist_append(headers, buf.buf);
> +				strbuf_addf(&buf, "%ld-", posn);
> +				curl_easy_setopt(slot->curl, CURLOPT_RANGE,
> +						 &buf.buf);
>  				strbuf_reset(&buf);
>  			}
>  		} else