import: fix etag detection support

Let's make sure we still look at the etags reported by http 304 (i.e.
the cache management code). Otherwise we won't properly realize we
already downloaded this before.

This fixes a bug introduced in 6792cbbcf84b730f465decbeaf247c6b1ccf1c18

1 files changed, 29 insertions, 16 deletions

diff --git a/src/import/pull-job.c b/src/import/pull-job.c
index d1e61ba601..908546b968 100644
--- a/src/import/pull-job.c
+++ b/src/import/pull-job.c
@@ -433,6 +433,16 @@ fail:
         return 0;
 }
 
+static int http_status_ok(CURLcode status) {
+        /* Consider all HTTP status code in the 2xx range as OK */
+        return status >= 200 && status <= 299;
+}
+
+static int http_status_etag_exists(CURLcode status) {
+        /* This one is special, it's triggered by our etag mgmt logic */
+        return status == 304;
+}
+
 static size_t pull_job_header_callback(void *contents, size_t size, size_t nmemb, void *userdata) {
         _cleanup_free_ char *length = NULL, *last_modified = NULL, *etag = NULL;
         size_t sz = size * nmemb;
@@ -458,28 +468,31 @@ static size_t pull_job_header_callback(void *contents, size_t size, size_t nmemb
                 goto fail;
         }
 
-        if (status < 200 || status >= 300)
-                /* If this is not HTTP 2xx, let's skip these headers, they are probably for
-                 * some redirect or so, and we are not interested in the headers of those. */
-                return sz;
+        if (http_status_ok(status) || http_status_etag_exists(status)) {
+                /* Check Etag on OK and etag exists responses. */
 
-        r = curl_header_strdup(contents, sz, "ETag:", &etag);
-        if (r < 0) {
-                log_oom();
-                goto fail;
-        }
-        if (r > 0) {
-                free_and_replace(j->etag, etag);
+                r = curl_header_strdup(contents, sz, "ETag:", &etag);
+                if (r < 0) {
+                        log_oom();
+                        goto fail;
+                }
+                if (r > 0) {
+                        free_and_replace(j->etag, etag);
+
+                        if (strv_contains(j->old_etags, j->etag)) {
+                                log_info("Image already downloaded. Skipping download. (%s)", j->etag);
+                                j->etag_exists = true;
+                                pull_job_finish(j, 0);
+                                return sz;
+                        }
 
-                if (strv_contains(j->old_etags, j->etag)) {
-                        log_info("Image already downloaded. Skipping download.");
-                        j->etag_exists = true;
-                        pull_job_finish(j, 0);
                         return sz;
                 }
+        }
 
+        if (!http_status_ok(status)) /* Let's ignore the rest here, these requests are probably redirects and
+                                      * stuff where the headers aren't interesting to us */
                 return sz;
-        }
 
         r = curl_header_strdup(contents, sz, "Content-Length:", &length);
         if (r < 0) {