http.c: use CURLOPT_RANGE for range requests

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>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/http.c b/http.c
index 7da76edda16abea8a53299f2770ad2dce55c1b60..5f368464e8f3e3980b36b4692d095dd06d89a0d6 100644 (file)
--- a/http.c
+++ b/http.c
@@ -30,7 +30,6 @@ static CURL *curl_default;
 #endif
 
 #define PREV_BUF_SIZE 4096
-#define RANGE_HEADER_SIZE 30
 
 char curl_errorstr[CURL_ERROR_SIZE];
 
@@ -681,6 +680,7 @@ struct active_request_slot *get_active_slot(void)
        curl_easy_setopt(slot->curl, CURLOPT_UPLOAD, 0);
        curl_easy_setopt(slot->curl, CURLOPT_HTTPGET, 1);
        curl_easy_setopt(slot->curl, CURLOPT_FAILONERROR, 1);
+       curl_easy_setopt(slot->curl, CURLOPT_RANGE, NULL);
 #ifdef LIBCURL_CAN_HANDLE_AUTH_ANY
        curl_easy_setopt(slot->curl, CURLOPT_HTTPAUTH, http_auth_methods);
 #endif
@@ -1173,6 +1173,13 @@ static const char *get_accept_language(void)
        return cached_accept_language;
 }
 
+static void http_opt_request_remainder(CURL *curl, off_t pos)
+{
+       char buf[128];
+       xsnprintf(buf, sizeof(buf), "%"PRIuMAX"-", (uintmax_t)pos);
+       curl_easy_setopt(curl, CURLOPT_RANGE, buf);
+}
+
 /* http_request() targets */
 #define HTTP_REQUEST_STRBUF    0
 #define HTTP_REQUEST_FILE      1
@@ -1201,11 +1208,8 @@ static int http_request(const char *url,
                        long posn = ftell(result);
                        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_reset(&buf);
-                       }
+                       if (posn > 0)
+                               http_opt_request_remainder(slot->curl, posn);
                } else
                        curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION,
                                         fwrite_buffer);
@@ -1515,10 +1519,6 @@ void release_http_pack_request(struct http_pack_request *preq)
                fclose(preq->packfile);
                preq->packfile = NULL;
        }
-       if (preq->range_header != NULL) {
-               curl_slist_free_all(preq->range_header);
-               preq->range_header = NULL;
-       }
        preq->slot = NULL;
        free(preq->url);
        free(preq);
@@ -1582,7 +1582,6 @@ struct http_pack_request *new_http_pack_request(
        struct packed_git *target, const char *base_url)
 {
        long prev_posn = 0;
-       char range[RANGE_HEADER_SIZE];
        struct strbuf buf = STRBUF_INIT;
        struct http_pack_request *preq;
 
@@ -1620,10 +1619,7 @@ struct http_pack_request *new_http_pack_request(
                        fprintf(stderr,
                                "Resuming fetch of pack %s at byte %ld\n",
                                sha1_to_hex(target->sha1), prev_posn);
-               xsnprintf(range, sizeof(range), "Range: bytes=%ld-", prev_posn);
-               preq->range_header = curl_slist_append(NULL, range);
-               curl_easy_setopt(preq->slot->curl, CURLOPT_HTTPHEADER,
-                       preq->range_header);
+               http_opt_request_remainder(preq->slot->curl, prev_posn);
        }
 
        return preq;
@@ -1673,8 +1669,6 @@ struct http_object_request *new_http_object_request(const char *base_url,
        char prev_buf[PREV_BUF_SIZE];
        ssize_t prev_read = 0;
        long prev_posn = 0;
-       char range[RANGE_HEADER_SIZE];
-       struct curl_slist *range_header = NULL;
        struct http_object_request *freq;
 
        freq = xcalloc(1, sizeof(*freq));
@@ -1780,10 +1774,7 @@ struct http_object_request *new_http_object_request(const char *base_url,
                        fprintf(stderr,
                                "Resuming fetch of object %s at byte %ld\n",
                                hex, prev_posn);
-               xsnprintf(range, sizeof(range), "Range: bytes=%ld-", prev_posn);
-               range_header = curl_slist_append(range_header, range);
-               curl_easy_setopt(freq->slot->curl,
-                                CURLOPT_HTTPHEADER, range_header);
+               http_opt_request_remainder(freq->slot->curl, prev_posn);
        }
 
        return freq;

diff --git a/http.h b/http.h
index 49afe39279d02785f3567aad2fec55c623a53d5f..4f97b60b5c8abdf5ab0610382a6d6fa289df2605 100644 (file)
--- a/http.h
+++ b/http.h
@@ -190,7 +190,6 @@ struct http_pack_request {
        struct packed_git **lst;
        FILE *packfile;
        char tmpfile[PATH_MAX];
-       struct curl_slist *range_header;
        struct active_request_slot *slot;
 };