From 102041d295d0554fa6c2b2d9fd302d9422aa426a Mon Sep 17 00:00:00 2001
From: "Jaime A. Garcia" <jaime.garcia.naranjo@intel.com>
Date: Wed, 27 Apr 2016 22:27:52 +0000
Subject: [PATCH] fix to check whether resume download is supported

When pack is going to be downloaded an option for
curl called resume is activated no matter what,
however although major http server support 'Range'
command that enables this functionality, not all
complies with this, when swupd client tries to
re-download a partial file from one of the server
that does not support 'Range' it will just throw
an error and stop to work until partial download
is deleted by hand.

This patch address that issue by checking first
whether server supports 'Range' command and if not
then disable 'resume' of packs.

Signed-off-by: Jaime A. Garcia <jaime.garcia.naranjo@intel.com>
---
 include/swupd.h |  1 +
 src/curl.c      | 59 ++++++++++++++++++++++++++++++++++++++++++++++++-
 src/version.c   |  2 ++
 3 files changed, 61 insertions(+), 1 deletion(-)

diff --git a/include/swupd.h b/include/swupd.h
index 02c81112..3e1c58ac 100644
--- a/include/swupd.h
+++ b/include/swupd.h
@@ -198,6 +198,7 @@ extern int swupd_curl_get_file(const char *url, char *filename, struct file *fil
 #define SWUPD_CURL_CONNECT_TIMEOUT 30
 #define SWUPD_CURL_RCV_TIMEOUT 120
 extern CURLcode swupd_curl_set_basic_options(CURL *curl, const char *url);
+void swupd_curl_test_resume(void);
 
 extern struct list *subs;
 extern void free_subscriptions(void);
diff --git a/src/curl.c b/src/curl.c
index 1103e324..9d20bbaa 100644
--- a/src/curl.c
+++ b/src/curl.c
@@ -50,6 +50,7 @@ static CURL *curl = NULL;
 
 static int curr_version = -1;
 static int req_version = -1;
+static bool resume_download_enabled = true;
 
 struct version_container {
 	size_t offset;
@@ -237,7 +238,7 @@ int swupd_curl_get_file(const char *url, char *filename, struct file *file,
 		local->staging = filename;
 
 		if (lstat(filename, &stat) == 0) {
-			if (pack) {
+			if (pack && resume_download_enabled) {
 				curl_ret = curl_easy_setopt(curl, CURLOPT_RESUME_FROM_LARGE, (curl_off_t)stat.st_size);
 			} else {
 				unlink(filename);
@@ -372,6 +373,62 @@ exit:
 	return err;
 }
 
+void swupd_curl_test_resume(void)
+{
+#define RESUME_BYTE_RANGE 2
+
+	CURLcode curl_ret;
+	char *version_string = NULL;
+	char *url = NULL;
+
+	if (!curl) {
+		abort();
+	}
+
+	curl_easy_reset(curl);
+	version_string = malloc(LINE_MAX);
+	if (version_string == NULL) {
+		abort();
+	}
+
+	string_or_die(&url, "%s/version/format%s/latest", version_url, format_string);
+
+	curl_ret = curl_easy_setopt(curl, CURLOPT_RESUME_FROM_LARGE, (curl_off_t)RESUME_BYTE_RANGE);
+	if (curl_ret != CURLE_OK) {
+		goto exit;
+	}
+
+	curl_ret = curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, swupd_download_version_to_memory);
+	if (curl_ret != CURLE_OK) {
+		goto exit;
+	}
+	curl_ret = curl_easy_setopt(curl, CURLOPT_WRITEDATA, (void *)version_string);
+	if (curl_ret != CURLE_OK) {
+		goto exit;
+	}
+	curl_ret = curl_easy_setopt(curl, CURLOPT_COOKIE, "request=uncached");
+	if (curl_ret != CURLE_OK) {
+		goto exit;
+	}
+
+	curl_ret = swupd_curl_set_basic_options(curl, url);
+	if (curl_ret != CURLE_OK) {
+		goto exit;
+	}
+
+	curl_ret = curl_easy_perform(curl);
+
+	if (curl_ret == CURLE_RANGE_ERROR) {
+		printf("Range command not supported by server, download resume disabled.\n");
+		resume_download_enabled = false;
+	}
+exit:
+	free(version_string);
+	free(url);
+
+	return;
+}
+
 static CURLcode swupd_curl_set_security_opts(CURL *curl)
 {
 	CURLcode curl_ret = CURLE_OK;
diff --git a/src/version.c b/src/version.c
index 23a5eab1..103440a5 100644
--- a/src/version.c
+++ b/src/version.c
@@ -76,6 +76,8 @@ bool check_network(void)
 			have_network = false;
 		} else {
 			have_network = true;
+			/* check if server supports Range command (resume) */
+			swupd_curl_test_resume();
 		}
 	}