MINOR: quic: move IP_PKTINFO on send on a dedicated function

When using listener socket, source address for emission is explicitely
set using ancillary data for sendmsg(). This is useful to guarantee the
correct address is used when binding on a non-explicit address.

This code was implemented directly under qc_snd_buf(). However, it is
quite complex due to portability issue. For IPv4, two parallel
implementations coexist, defined under IP_PKTINFO or IP_RECVDSTADDR. For
IPv6, another option is defined under IPV6_RECVPKTINFO. Each variant
uses its distinct name which increase the code complexity.

Extract ancillary data filling in a dedicated function named
cmsg_set_saddr(). This reduces greatly the body of qc_snd_buf(). Such
functions can be replicated when other ancillary data type will be
implemented. This will notably be useful for GSO implementation.

diff --git a/src/quic_sock.c b/src/quic_sock.c
index 47534beb3236c3ce337c114bd95b702e1d96de7e..14db339f5b0968c2073549d6c74fa13c94a09ef4 100644 (file)
--- a/src/quic_sock.c
+++ b/src/quic_sock.c
@@ -566,6 +566,86 @@ void quic_conn_sock_fd_iocb(int fd)
        TRACE_LEAVE(QUIC_EV_CONN_RCV, qc);
 }
 
+static void cmsg_set_saddr(struct msghdr *msg, struct cmsghdr **cmsg,
+                           struct sockaddr_storage *saddr)
+{
+       struct cmsghdr *c;
+#ifdef IP_PKTINFO
+       struct in_pktinfo *in;
+#endif /* IP_PKTINFO */
+#ifdef IPV6_RECVPKTINFO
+       struct in6_pktinfo *in6;
+#endif /* IPV6_RECVPKTINFO */
+       size_t sz = 0;
+
+       /* First determine size of ancillary data depending on the system support. */
+       switch (saddr->ss_family) {
+       case AF_INET:
+#if defined(IP_PKTINFO)
+               sz = sizeof(struct in_pktinfo);
+#elif defined(IP_RECVDSTADDR)
+               sz = sizeof(struct in_addr);
+#endif /* IP_PKTINFO || IP_RECVDSTADDR */
+               break;
+       case AF_INET6:
+#ifdef IPV6_RECVPKTINFO
+               sz = sizeof(struct in6_pktinfo);
+#endif /* IPV6_RECVPKTINFO */
+               break;
+       default:
+               break;
+       }
+
+       /* Size is null if system does not support send source address setting. */
+       if (!sz)
+               return;
+
+       /* Set first msg_controllen to be able to use CMSG_* macros. */
+       msg->msg_controllen += CMSG_SPACE(sz);
+
+       *cmsg = !(*cmsg) ? CMSG_FIRSTHDR(msg) : CMSG_NXTHDR(msg, *cmsg);
+       ALREADY_CHECKED(*cmsg);
+       c = *cmsg;
+       c->cmsg_len = CMSG_LEN(sz);
+
+       switch (saddr->ss_family) {
+       case AF_INET:
+               c->cmsg_level = IPPROTO_IP;
+#if defined(IP_PKTINFO)
+               c->cmsg_type = IP_PKTINFO;
+               in = (struct in_pktinfo *)CMSG_DATA(c);
+               in->ipi_ifindex = 0;
+               in->ipi_addr.s_addr = 0;
+               memcpy(&in->ipi_spec_dst,
+                      &((struct sockaddr_in *)saddr)->sin_addr,
+                      sizeof(struct in_addr));
+#elif defined(IP_RECVDSTADDR)
+               c->cmsg_type = IP_SENDSRCADDR;
+               memcpy(CMSG_DATA(c),
+                      &((struct sockaddr_in *)saddr)->sin_addr,
+                      sizeof(struct in_addr));
+#endif /* IP_PKTINFO || IP_RECVDSTADDR */
+
+               break;
+
+       case AF_INET6:
+#ifdef IPV6_RECVPKTINFO
+               c->cmsg_level = IPPROTO_IPV6;
+               c->cmsg_type = IPV6_PKTINFO;
+               in6 = (struct in6_pktinfo *)CMSG_DATA(c);
+               in6->ipi6_ifindex = 0;
+               memcpy(&in6->ipi6_addr,
+                      &((struct sockaddr_in6 *)saddr)->sin6_addr,
+                      sizeof(struct in6_addr));
+#endif /* IPV6_RECVPKTINFO */
+
+               break;
+
+       default:
+               break;
+       }
+}
+
 /* Send a datagram stored into <buf> buffer with <sz> as size.
  * The caller must ensure there is at least <sz> bytes in this buffer.
  *
@@ -594,13 +674,7 @@ int qc_snd_buf(struct quic_conn *qc, const struct buffer *buf, size_t sz,
                else if (is_addr(&qc->local_addr)) {
                        struct msghdr msg;
                        struct iovec vec;
-                       struct cmsghdr *cmsg;
-#ifdef IP_PKTINFO
-                       struct in_pktinfo *in;
-#endif /* IP_PKTINFO */
-#ifdef IPV6_RECVPKTINFO
-                       struct in6_pktinfo *in6;
-#endif /* IPV6_RECVPKTINFO */
+                       struct cmsghdr *cmsg = NULL;
                        union {
 #ifdef IP_PKTINFO
                                char buf[CMSG_SPACE(sizeof(struct in_pktinfo))];
@@ -619,58 +693,8 @@ int qc_snd_buf(struct quic_conn *qc, const struct buffer *buf, size_t sz,
                        msg.msg_iov = &vec;
                        msg.msg_iovlen = 1;
 
-                       switch (qc->local_addr.ss_family) {
-                       case AF_INET:
-#if defined(IP_PKTINFO)
-                               msg.msg_control = u.buf;
-                               msg.msg_controllen = sizeof(u.buf);
-
-                               cmsg = CMSG_FIRSTHDR(&msg);
-                               in = (struct in_pktinfo *)CMSG_DATA(cmsg);
-                               in->ipi_ifindex = 0;
-                               in->ipi_addr.s_addr = 0;
-                               memcpy(&in->ipi_spec_dst,
-                                      &((struct sockaddr_in *)&qc->local_addr)->sin_addr,
-                                      sizeof(struct in_addr));
-
-                               cmsg->cmsg_level = IPPROTO_IP;
-                               cmsg->cmsg_type = IP_PKTINFO;
-                               cmsg->cmsg_len = CMSG_LEN(sizeof(struct in_pktinfo));
-#elif defined(IP_RECVDSTADDR)
-                               msg.msg_control = u.bufaddr;
-                               msg.msg_controllen = sizeof(u.bufaddr);
-
-                               cmsg = CMSG_FIRSTHDR(&msg);
-                               cmsg->cmsg_level = IPPROTO_IP;
-                               cmsg->cmsg_type = IP_SENDSRCADDR;
-                               cmsg->cmsg_len = CMSG_LEN(sizeof(struct in_addr));
-                               memcpy(CMSG_DATA(cmsg),
-                                      &((struct sockaddr_in *)&qc->local_addr)->sin_addr,
-                                      sizeof(struct in_addr));
-#endif /* IP_PKTINFO || IP_RECVDSTADDR */
-                               break;
-
-                       case AF_INET6:
-#ifdef IPV6_RECVPKTINFO
-                               msg.msg_control = u.buf6;
-                               msg.msg_controllen = sizeof(u.buf6);
-
-                               cmsg = CMSG_FIRSTHDR(&msg);
-                               in6 = (struct in6_pktinfo *)CMSG_DATA(cmsg);
-                               in6->ipi6_ifindex = 0;
-                               memcpy(&in6->ipi6_addr,
-                                      &((struct sockaddr_in6 *)&qc->local_addr)->sin6_addr,
-                                      sizeof(struct in6_addr));
-
-                               cmsg->cmsg_level = IPPROTO_IPV6;
-                               cmsg->cmsg_type = IPV6_PKTINFO;
-                               cmsg->cmsg_len = CMSG_LEN(sizeof(struct in6_pktinfo));
-#endif /* IPV6_RECVPKTINFO */
-                               break;
-
-                       default:
-                               break;
-                       }
+                       msg.msg_control = u.bufaddr;
+                       cmsg_set_saddr(&msg, &cmsg, &qc->local_addr);
 
                        ret = sendmsg(qc->li->rx.fd, &msg,
                                      MSG_DONTWAIT|MSG_NOSIGNAL);