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udp: Add udp_pktinfo() helper
Currently we open code parsing the control message for IP_PKTINFO in udp_peek_addr(). We have an upcoming case where we want to parse PKTINFO in another place, so split this out into a helper function. While we're there, make the parsing a bit more robust: scan all cmsgs to look for the one we want, rather than assuming there's only one. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> [sbrivio: udp_pktinfo(): Fix typo in comment and change err() to debug()] Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
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parent
04984578b0
commit
f107a86cc0
1 changed files with 36 additions and 16 deletions
52
udp.c
52
udp.c
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@ -464,6 +464,41 @@ static void udp_send_tap_icmp6(const struct ctx *c,
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tap_icmp6_send(c, saddr, eaddr, &msg, msglen);
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tap_icmp6_send(c, saddr, eaddr, &msg, msglen);
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}
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}
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/**
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* udp_pktinfo() - Retrieve packet destination address from cmsg
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* @msg: msghdr into which message has been received
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* @dst: (Local) destination address of message in @mh (output)
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*
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* Return: 0 on success, -1 if the information was missing (@dst is set to
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* inany_any6).
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*/
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static int udp_pktinfo(struct msghdr *msg, union inany_addr *dst)
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{
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struct cmsghdr *hdr;
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for (hdr = CMSG_FIRSTHDR(msg); hdr; hdr = CMSG_NXTHDR(msg, hdr)) {
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if (hdr->cmsg_level == IPPROTO_IP &&
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hdr->cmsg_type == IP_PKTINFO) {
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const struct in_pktinfo *i4 = (void *)CMSG_DATA(hdr);
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*dst = inany_from_v4(i4->ipi_addr);
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return 0;
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}
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if (hdr->cmsg_level == IPPROTO_IPV6 &&
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hdr->cmsg_type == IPV6_PKTINFO) {
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const struct in6_pktinfo *i6 = (void *)CMSG_DATA(hdr);
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dst->a6 = i6->ipi6_addr;
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return 0;
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}
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}
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debug("Missing PKTINFO cmsg on datagram");
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*dst = inany_any6;
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return -1;
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}
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/**
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/**
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* udp_sock_recverr() - Receive and clear an error from a socket
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* udp_sock_recverr() - Receive and clear an error from a socket
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* @c: Execution context
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* @c: Execution context
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@ -607,7 +642,6 @@ static int udp_peek_addr(int s, union sockaddr_inany *src,
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union inany_addr *dst)
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union inany_addr *dst)
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{
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{
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char sastr[SOCKADDR_STRLEN], dstr[INANY_ADDRSTRLEN];
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char sastr[SOCKADDR_STRLEN], dstr[INANY_ADDRSTRLEN];
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const struct cmsghdr *hdr;
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char cmsg[PKTINFO_SPACE];
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char cmsg[PKTINFO_SPACE];
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struct msghdr msg = {
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struct msghdr msg = {
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.msg_name = src,
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.msg_name = src,
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@ -624,21 +658,7 @@ static int udp_peek_addr(int s, union sockaddr_inany *src,
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return -errno;
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return -errno;
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}
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}
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hdr = CMSG_FIRSTHDR(&msg);
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udp_pktinfo(&msg, dst);
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if (hdr && hdr->cmsg_level == IPPROTO_IP &&
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hdr->cmsg_type == IP_PKTINFO) {
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const struct in_pktinfo *info4 = (void *)CMSG_DATA(hdr);
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*dst = inany_from_v4(info4->ipi_addr);
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} else if (hdr && hdr->cmsg_level == IPPROTO_IPV6 &&
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hdr->cmsg_type == IPV6_PKTINFO) {
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const struct in6_pktinfo *info6 = (void *)CMSG_DATA(hdr);
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dst->a6 = info6->ipi6_addr;
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} else {
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debug("Unexpected cmsg on UDP datagram");
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*dst = inany_any6;
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}
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trace("Peeked UDP datagram: %s -> %s",
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trace("Peeked UDP datagram: %s -> %s",
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sockaddr_ntop(src, sastr, sizeof(sastr)),
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sockaddr_ntop(src, sastr, sizeof(sastr)),
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