[pacman-dev] [PATCH v2 1/2] only use effective url for urls containing .db or .pkg

[morganamilo]

Github and other sites redirect their downloads to a cdn. So the
download http://foo.org/myrepo.db may redirect to something like
https://cdn.foo.org/83749327439.

This then causes pacman to try and download the sig as
https://cdn.foo.org/83749327439.sig which is incorrect. In this case
pacman should append .sig to the original url.

However urls like https://archlinux.org/packages/community/x86_64/0ad/download/
Redirect to the mirror, so .sig has to appended after the redirects and
not before.

So we decide if we should append .sig on the original or effective url
based on if the effective url (minus the query part) has .db or .pkg in it.

Fixes FS#71148

---

v2: move variable decleration to start of block
---
 lib/libalpm/dload.c | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/lib/libalpm/dload.c b/lib/libalpm/dload.c
index 2c14841f..88351780 100644
--- a/lib/libalpm/dload.c
+++ b/lib/libalpm/dload.c
@@ -613,11 +613,31 @@ static int curl_check_finished_download(CURLM *curlm, CURLMsg *msg,
 	/* Let's check if client requested downloading accompanion *.sig file */
 	if(!payload->signature && payload->download_signature && curlerr == CURLE_OK && payload->respcode < 400) {
 		struct dload_payload *sig = NULL;
+		char *url = payload->fileurl;
+		char *_effective_filename;
+		const char *effective_filename;
+		char *query;
+		int len;
+
+		STRDUP(_effective_filename, effective_url, GOTO_ERR(handle, ALPM_ERR_MEMORY, cleanup));
+		effective_filename = get_filename(_effective_filename);
+		query = strrchr(effective_filename, '?');
+
+		if(query) {
+			query[0] = '\0';
+		}
+
+		/* Only use the effective url for sig downloads if the effective_url contains .db or .pkg */
+		if(strstr(effective_filename, ".db") || strstr(effective_filename, ".pkg")) {
+			url = effective_url;
+		}
+
+		free(_effective_filename);
 
-		int len = strlen(effective_url) + 5;
+		len = strlen(url) + 5;
 		CALLOC(sig, 1, sizeof(*sig), GOTO_ERR(handle, ALPM_ERR_MEMORY, cleanup));
 		MALLOC(sig->fileurl, len, FREE(sig); GOTO_ERR(handle, ALPM_ERR_MEMORY, cleanup));
-		snprintf(sig->fileurl, len, "%s.sig", effective_url);
+		snprintf(sig->fileurl, len, "%s.sig", url);
 
 		if(payload->trust_remote_name) {
 			/* In this case server might provide a new name for the main payload.
-- 
2.32.0