This is a fix for commit db488c79173b240459c7754f38c3c6af9b432970 dnsmasq main process exits without waiting for DAD, this is dnsmasq daemon's task. So we periodically poll the kernel using netlink and check whether there are any IPv6 addresses assigned to bridge which have 'tentative' state. After DAD is finished, execution continues. I guess that is what dnsmasq was assumed to do. --- Difference to v1: fixed syntax (comments and alignment). Difference to v2: moved to virnetdev. src/libvirt_private.syms | 1 + src/network/bridge_driver.c | 35 +++++++++- src/util/virnetdev.c | 160 ++++++++++++++++++++++++++++++++++++++++++++ src/util/virnetdev.h | 2 + 4 files changed, 197 insertions(+), 1 deletion(-) diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms index c87efa1..514560b 100644 --- a/src/libvirt_private.syms +++ b/src/libvirt_private.syms @@ -1791,6 +1791,7 @@ virNetDevSetRcvMulti; virNetDevSetupControl; virNetDevSysfsFile; virNetDevValidateConfig; +virNetDevWaitDadFinish; # util/virnetdevbandwidth.h diff --git a/src/network/bridge_driver.c b/src/network/bridge_driver.c index c343e5b..0a93678 100644 --- a/src/network/bridge_driver.c +++ b/src/network/bridge_driver.c @@ -2026,6 +2026,33 @@ networkAddRouteToBridge(virNetworkObjPtr network, } static int +networkWaitDadFinish(virNetworkObjPtr network) +{ + virNetworkIpDefPtr ipdef; + virSocketAddrPtr *addrs = NULL; + size_t i; + int ret; + for (i = 0; + (ipdef = virNetworkDefGetIpByIndex(network->def, AF_INET6, i)); + i++) {} + + if (i == 0) + return 0; + if (VIR_ALLOC_N(addrs, i)) + return -1; + + for (i = 0; + (ipdef = virNetworkDefGetIpByIndex(network->def, AF_INET6, i)); + i++) { + addrs[i] = &ipdef->address; + } + + ret = virNetDevWaitDadFinish(addrs, i); + VIR_FREE(addrs); + return ret; +} + +static int networkStartNetworkVirtual(virNetworkDriverStatePtr driver, virNetworkObjPtr network) { @@ -2159,7 +2186,13 @@ networkStartNetworkVirtual(virNetworkDriverStatePtr driver, if (v6present && networkStartRadvd(driver, network) < 0) goto err4; - /* DAD has happened (dnsmasq waits for it), dnsmasq is now bound to the + /* dnsmasq main process does not wait for DAD to complete, + * so we need to wait for it ourselves. + */ + if (v6present && networkWaitDadFinish(network) < 0) + goto err4; + + /* DAD has happened, dnsmasq is now bound to the * bridge's IPv6 address, so we can now set the dummy tun down. */ if (tapfd >= 0) { diff --git a/src/util/virnetdev.c b/src/util/virnetdev.c index 579ff3b..3d77b37 100644 --- a/src/util/virnetdev.c +++ b/src/util/virnetdev.c @@ -96,6 +96,7 @@ VIR_LOG_INIT("util.netdev"); # define FEATURE_BIT_IS_SET(blocks, index, field) \ (FEATURE_WORD(blocks, index, field) & FEATURE_FIELD_FLAG(index)) #endif +# define IP_BUF_SIZE 4096 typedef enum { VIR_MCAST_TYPE_INDEX_TOKEN, @@ -1305,6 +1306,103 @@ int virNetDevClearIPAddress(const char *ifname, return ret; } +/* return whether there is a known address with 'tentative' flag set */ +static int +virNetDevParseDadStatus(struct nlmsghdr *nlh, int len, + virSocketAddrPtr *addrs, size_t count) +{ + struct ifaddrmsg *ifaddrmsg_ptr; + unsigned int ifaddrmsg_len; + struct rtattr *rtattr_ptr; + size_t i; + struct in6_addr *addr; + for (; NLMSG_OK(nlh, len); nlh = NLMSG_NEXT(nlh, len)) { + if (NLMSG_PAYLOAD(nlh, 0) < sizeof(struct ifaddrmsg)) { + /* Message without payload is the last one. */ + break; + } + + ifaddrmsg_ptr = (struct ifaddrmsg *)NLMSG_DATA(nlh); + if (!(ifaddrmsg_ptr->ifa_flags & IFA_F_TENTATIVE)) { + /* Not tentative: we are not interested in this entry. */ + continue; + } + + ifaddrmsg_len = IFA_PAYLOAD(nlh); + rtattr_ptr = (struct rtattr *) IFA_RTA(ifaddrmsg_ptr); + for (; RTA_OK(rtattr_ptr, ifaddrmsg_len); + rtattr_ptr = RTA_NEXT(rtattr_ptr, ifaddrmsg_len)) { + if (RTA_PAYLOAD(rtattr_ptr) != sizeof(struct in6_addr)) { + /* No address: ignore. */ + continue; + } + + /* We check only known addresses. */ + for (i = 0; i < count; i++) { + addr = &addrs[i]->data.inet6.sin6_addr; + if (!memcmp(addr, RTA_DATA(rtattr_ptr), + sizeof(struct in6_addr))) { + /* We found matching tentative address. */ + return 1; + } + } + } + } + return 0; +} + +/* return after DAD finishes for all known IPv6 addresses or an error */ +int +virNetDevWaitDadFinish(virSocketAddrPtr *addrs, size_t count) +{ + struct nl_msg *nlmsg = NULL; + struct ifaddrmsg ifa; + struct nlmsghdr *resp = NULL; + unsigned int recvbuflen; + int ret = -1, dad = 1; + + if (!(nlmsg = nlmsg_alloc_simple(RTM_GETADDR, + NLM_F_REQUEST | NLM_F_DUMP))) { + virReportOOMError(); + return -1; + } + + memset(&ifa, 0, sizeof(ifa)); + /* DAD is for IPv6 adresses only. */ + ifa.ifa_family = AF_INET6; + if (nlmsg_append(nlmsg, &ifa, sizeof(ifa), NLMSG_ALIGNTO) < 0) { + virReportError(VIR_ERR_INTERNAL_ERROR, "%s", + _("allocated netlink buffer is too small")); + goto cleanup; + } + + /* Periodically query netlink until DAD finishes on all known addresses. */ + while (dad) { + if (virNetlinkCommand(nlmsg, &resp, &recvbuflen, 0, 0, + NETLINK_ROUTE, 0) < 0) + goto cleanup; + + if (virNetlinkGetErrorCode(resp, recvbuflen) < 0) { + virReportError(VIR_ERR_SYSTEM_ERROR, "%s", + _("error reading DAD state information")); + goto cleanup; + } + + /* Parse response. */ + dad = virNetDevParseDadStatus(resp, recvbuflen, addrs, count); + if (dad) + usleep(1000 * 10); + + VIR_FREE(resp); + } + ret = 0; + + cleanup: + VIR_FREE(resp); + nlmsg_free(nlmsg); + return ret; +} + #else /* defined(__linux__) && defined(HAVE_LIBNL) */ int virNetDevSetIPAddress(const char *ifname, @@ -1424,6 +1522,68 @@ int virNetDevClearIPAddress(const char *ifname, return ret; } +/* return whether there is a known address with 'tentative' flag set */ +static int +virNetDevParseDadStatus(char *outbuf, + virSocketAddrPtr *addrs, size_t count) +{ + virSocketAddr sockaddr; + size_t i, j; + int ret = 0; + char **addr_strings = virStringSplit(outbuf, "\n", 0); + for (j = 0; addr_strings[j] != NULL; ++j) { + if (virSocketParseAddr(strings[j], &sockaddr, AF_INET6) < 0) + continue; + for (i = 0; i < count; i++) { + if (virSocketAddrEqual(addrs[i], &sockaddr)) { + ret = 1; + goto cleanup; + } + } + } + + cleanup: + virStringFreeList(addr_strings); + return ret; +} + +/* return after DAD finishes for all known IPv6 addresses or an error */ +int +virNetDevWaitDadFinish(virSocketAddrPtr *addrs, size_t count) +{ + int ret = -1, dad = 1; + char *outbuf = NULL; + virCommandPtr cmd = NULL; + +# ifdef IP_PATH + while (dad) { + cmd = virCommandNew(POSIX_SHELL); + virCommandAddArgList(cmd, "-c", + IP_PATH "-6 addr show tentative | \ + awk '/inet6/{split(\\$2, a, \\\"/\\\"); \ + print a[1]}'", NULL); + virCommandSetOutputBuffer(cmd, &outbuf); + if (virCommandRun(cmd, NULL)) + goto cleanup; + virCommandFree(cmd); + + dad = virNetDevParseDadStatus(outbuf, addrs, count); + if (dad) + usleep(1000 * 10); + + VIR_FREE(outbuf); + } + ret = 0; +# else + virReportSystemError(ENOSYS, "%s", _("Unable to check IPv6 DAD")); +# endif + + cleanup: + virCommandFree(cmd); + VIR_FREE(outbuf); + return ret; +} + #endif /* defined(__linux__) && defined(HAVE_LIBNL) */ /** diff --git a/src/util/virnetdev.h b/src/util/virnetdev.h index a27504b..9108be6 100644 --- a/src/util/virnetdev.h +++ b/src/util/virnetdev.h @@ -105,6 +105,8 @@ int virNetDevClearIPAddress(const char *ifname, ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2) ATTRIBUTE_RETURN_CHECK; int virNetDevGetIPAddress(const char *ifname, virSocketAddrPtr addr) ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2) ATTRIBUTE_RETURN_CHECK; +int virNetDevWaitDadFinish(virSocketAddrPtr *addrs, size_t count) + ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2); int virNetDevSetMAC(const char *ifname, -- 1.8.3.1

Such messages do not have NLMSG_ERROR or NLMSG_DONE type but they are valid responses. We test 'multi-partness' by looking for NLM_F_MULTI flag. --- Difference to v1: fixed comment style. src/util/virnetlink.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/src/util/virnetlink.c b/src/util/virnetlink.c index 0276522..679b48e 100644 --- a/src/util/virnetlink.c +++ b/src/util/virnetlink.c @@ -394,7 +394,9 @@ virNetlinkGetErrorCode(struct nlmsghdr *resp, unsigned int recvbuflen) break; default: - goto malformed_resp; + /* We allow multipart messages. */ + if (!(resp->nlmsg_flags & NLM_F_MULTI)) + goto malformed_resp; } return result; -- 1.8.3.1