connectivity: fix constructing hosts list for CURLOPT_RESOLVEth/curl-resolve-list

Curl's CURLOPT_RESOLVE expects one list entry per host. That
documentation ([1]) also makes that clear that the form is
"[+]HOST:PORT:ADDRESS[,ADDRESS]".

The way we constructed the list, only the last entry was honored:

  <trace> [1647551393.5362] connectivity: (eth0,IPv4,25) adding 'fedoraproject.org:80:18.159.254.57' to curl resolve list
  <trace> [1647551393.5363] connectivity: (eth0,IPv4,25) adding 'fedoraproject.org:80:152.19.134.142' to curl resolve list
  <trace> [1647551393.5363] connectivity: (eth0,IPv4,25) adding 'fedoraproject.org:80:18.192.40.85' to curl resolve list
  ...
  <trace> [1647551393.5366] connectivity: (eth0,IPv4,25) adding 'fedoraproject.org:80:85.236.55.6' to curl resolve list
  <trace> [1647551393.5366] connectivity: (eth0,IPv4,25) adding 'fedoraproject.org:80:38.145.60.20' to curl resolve list
  ...
  <trace> [1647551393.5415] connectivity: (eth0,IPv4,25) libcurl: == Info: Added fedoraproject.org:80:18.159.254.57 to DNS cache\012
  <trace> [1647551393.5416] connectivity: (eth0,IPv4,25) libcurl: == Info: RESOLVE fedoraproject.org:80 is - old addresses discarded!\012
  <trace> [1647551393.5416] connectivity: (eth0,IPv4,25) libcurl: == Info: Added fedoraproject.org:80:152.19.134.142 to DNS cache\012
  <trace> [1647551393.5417] connectivity: (eth0,IPv4,25) libcurl: == Info: RESOLVE fedoraproject.org:80 is - old addresses discarded!\012
  ...
  <trace> [1647551393.5422] connectivity: (eth0,IPv4,25) libcurl: == Info: RESOLVE fedoraproject.org:80 is - old addresses discarded!\012
  <trace> [1647551393.5423] connectivity: (eth0,IPv4,25) libcurl: == Info: Added fedoraproject.org:80:38.145.60.20 to DNS cache\012
  <trace> [1647551393.5424] connectivity: (eth0,IPv4,25) libcurl: == Info: Hostname fedoraproject.org was found in DNS cache\012
  <trace> [1647551393.5424] connectivity: (eth0,IPv4,25) libcurl: == Info:   Trying 38.145.60.20:80...\012

There are two possible fixes. Either join all addresses in one
entry, or use the '+' modifier. Do the former.

Now we get:

  <trace> [1647551967.0378] connectivity: (eth0,IPv4,25) set curl resolve list to 'fedoraproject.org:80:38.145.60.21,152.19.134.142,152...
  ...
  <trace> [1647551967.0559] connectivity: (eth0,IPv4,25) libcurl: == Info: Added fedoraproject.org:80:38.145.60.21,152.19.134.142,152.1...
  <trace> [1647551967.0560] connectivity: (eth0,IPv4,25) libcurl: == Info: Hostname fedoraproject.org was found in DNS cache\012
  <trace> [1647551967.0561] connectivity: (eth0,IPv4,25) libcurl: == Info:   Trying 38.145.60.21:80...\012

[1] https://curl.se/libcurl/c/CURLOPT_RESOLVE.html

Reported-by: Bastien Nocera <hadess@hadess.net>

Fixes: 2cec94bacce4 ('connectivity: use systemd-resolved for resolving the check endpoint')

1 files changed, 16 insertions, 7 deletions

diff --git a/src/core/nm-connectivity.c b/src/core/nm-connectivity.c
index ad20d1ee28..8a79e45d67 100644
--- a/src/core/nm-connectivity.c
+++ b/src/core/nm-connectivity.c
@@ -15,6 +15,7 @@
 #include <linux/rtnetlink.h>
 
 #include "c-list/src/c-list.h"
+#include "libnm-glib-aux/nm-str-buf.h"
 #include "libnm-platform/nmp-object.h"
 #include "libnm-core-intern/nm-core-internal.h"
 #include "nm-config.h"
@@ -758,7 +759,8 @@ resolve_cb(GObject *object, GAsyncResult *res, gpointer user_data)
     int                        addr_family;
     gsize                      len = 0;
     gsize                      i;
-    gs_free_error GError      *error = NULL;
+    gs_free_error GError      *error        = NULL;
+    nm_auto_str_buf NMStrBuf   strbuf_hosts = NM_STR_BUF_INIT(0, FALSE);
 
     result = g_dbus_connection_call_finish(G_DBUS_CONNECTION(object), res, &error);
     if (g_error_matches(error, G_IO_ERROR, G_IO_ERROR_CANCELLED))
@@ -781,7 +783,6 @@ resolve_cb(GObject *object, GAsyncResult *res, gpointer user_data)
     for (i = 0; i < no_addresses; i++) {
         gs_unref_variant GVariant *address = NULL;
         char                       str_addr[NM_UTILS_INET_ADDRSTRLEN];
-        gs_free char              *host_entry = NULL;
         const guchar              *address_buf;
 
         g_variant_get_child(addresses, i, "(ii@ay)", &ifindex, &addr_family, &address);
@@ -796,13 +797,21 @@ resolve_cb(GObject *object, GAsyncResult *res, gpointer user_data)
         if (len != nm_utils_addr_family_to_size(addr_family))
             continue;
 
-        host_entry = g_strdup_printf("%s:%s:%s",
+        if (strbuf_hosts.len == 0) {
+            nm_str_buf_append_printf(&strbuf_hosts,
+                                     "%s:%s:",
                                      cb_data->concheck.con_config->host,
-                                     cb_data->concheck.con_config->port ?: "80",
-                                     nm_utils_inet_ntop(addr_family, address_buf, str_addr));
+                                     cb_data->concheck.con_config->port ?: "80");
+        } else
+            nm_str_buf_append_c(&strbuf_hosts, ',');
+
+        nm_str_buf_append(&strbuf_hosts, nm_utils_inet_ntop(addr_family, address_buf, str_addr));
+    }
+    if (strbuf_hosts.len > 0) {
+        const char *s = nm_str_buf_get_str(&strbuf_hosts);
 
-        cb_data->concheck.hosts = curl_slist_append(cb_data->concheck.hosts, host_entry);
-        _LOG2T("adding '%s' to curl resolve list", host_entry);
+        cb_data->concheck.hosts = curl_slist_append(NULL, s);
+        _LOG2T("set curl resolve list to '%s'", s);
     }
 
     do_curl_request(cb_data);