OpenSSL 3.2.0, QUIC, macOS, error 56 on connected UDP socket

current `translate_msg()` function attempts to set `->msg_name`
(and `->msg_namelen`) with `BIO`'s peer name (connection destination)
regardless if underlying socket is connected or not. Such implementation
uncovers differences in socket implementation between various OSes.

As we have learned hard way `sendmsg()` and `sendmmsg()` on `OpenBSD`
and (`MacOS` too) fail to send messages with `->msg_name` being
set on connected socket. In such case the caller receives
`EISCON` errro.

I think `translate_msg()` caller should provide a hint to indicate
whether we deal with connected (or un-connected) socket. For
connected sockets the peer's name should not be set/filled
by `translate_msg()`. On the other hand if socket is un-connected,
then `translate_msg()` must populate `->msg_name` and `->msg_namelen`
members.

The caller can use `getpeername(2)` to see if socket is
connected. If `getpeername()` succeeds then we must be dealing
with connected socket and `translate_msg()` must not set
`->msg_name` and `->msg_namelen` members. If `getpeername(2)`
fails, then `translate_msg()` must provide peer's name (destination
address) in `->msg_name` and set `->msg_namelen` accordingly.

The propposed fix introduces `is_connected()` function,
which applies `getpeername()` to socket bound to `BIO` instance.
The `dgram_sendmmsg()` uses `is_connected()` as a hint
for `translate_msg()` function, so msghdr gets initialized
with respect to socket state.

The change also modifies existing `test/quic_client_test.c`
so it also covers the case of connected socket. To keep
things simple we can introduce optional argument `connect_first`
to `./quic_client_test` function. Without `connect_first`
the test run as usual. With `connect_first` the test creates
and connects socket first. Then it passes such socket to
`BIO` sub-system to perform `QUIC` connect test as usual.

Fixes #23251

Reviewed-by: Neil Horman <nhorman@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/23396)

1 files changed, 21 insertions, 7 deletions

diff --git a/crypto/bio/bss_dgram.c b/crypto/bio/bss_dgram.c
index 7dbdfe181a..f6d688b353 100644
--- a/crypto/bio/bss_dgram.c
+++ b/crypto/bio/bss_dgram.c
@@ -560,6 +560,8 @@ static long dgram_ctrl(BIO *b, int cmd, long num, void *ptr)
     socklen_t addr_len;
     BIO_ADDR addr;
 # endif
+    struct sockaddr_storage ss;
+    socklen_t ss_len = sizeof(ss);
 
     data = (bio_dgram_data *)b->ptr;
 
@@ -577,6 +579,10 @@ static long dgram_ctrl(BIO *b, int cmd, long num, void *ptr)
         b->shutdown = (int)num;
         b->init = 1;
         dgram_update_local_addr(b);
+        if (getpeername(b->num, (struct sockaddr *)&ss, &ss_len) == 0) {
+            BIO_ADDR_make(&data->peer, BIO_ADDR_sockaddr((BIO_ADDR *)&ss));
+            data->connected = 1;
+        }
 # if defined(SUPPORT_LOCAL_ADDR)
         if (data->local_addr_enabled) {
             if (enable_local_addr(b, 1) < 1)
@@ -1067,19 +1073,27 @@ static void translate_msg_win(BIO *b, WSAMSG *mh, WSABUF *iov,
 static void translate_msg(BIO *b, struct msghdr *mh, struct iovec *iov,
                           unsigned char *control, BIO_MSG *msg)
 {
+    bio_dgram_data *data;
+
     iov->iov_base = msg->data;
     iov->iov_len  = msg->data_len;
 
-    /* macOS requires msg_namelen be 0 if msg_name is NULL */
-    mh->msg_name = msg->peer != NULL ? &msg->peer->sa : NULL;
-    if (msg->peer != NULL && dgram_get_sock_family(b) == AF_INET)
-        mh->msg_namelen = sizeof(struct sockaddr_in);
+    data = (bio_dgram_data *)b->ptr;
+    if (data->connected == 0) {
+        /* macOS requires msg_namelen be 0 if msg_name is NULL */
+        mh->msg_name = msg->peer != NULL ? &msg->peer->sa : NULL;
+        if (msg->peer != NULL && dgram_get_sock_family(b) == AF_INET)
+            mh->msg_namelen = sizeof(struct sockaddr_in);
 #  if OPENSSL_USE_IPV6
-    else if (msg->peer != NULL && dgram_get_sock_family(b) == AF_INET6)
-        mh->msg_namelen = sizeof(struct sockaddr_in6);
+        else if (msg->peer != NULL && dgram_get_sock_family(b) == AF_INET6)
+            mh->msg_namelen = sizeof(struct sockaddr_in6);
 #  endif
-    else
+        else
+            mh->msg_namelen = 0;
+    } else {
+        mh->msg_name = NULL;
         mh->msg_namelen = 0;
+    }
 
     mh->msg_iov         = iov;
     mh->msg_iovlen      = 1;