[libvirt] [PATCH 2/2] Support IPv6 in port allocator

[Daniel P. Berrange]

On Thu, Oct 31, 2013 at 04:40:11PM +0100, Ján Tomko wrote:
> Also try to bind on IPv6 to check if the port is occupied.
> 
> https://bugzilla.redhat.com/show_bug.cgi?id=1025407
> ---
>  src/util/virportallocator.c | 45 ++++++++++++++++++++++++++++++++++++++-------
>  1 file changed, 38 insertions(+), 7 deletions(-)

Have you tested this on a system where the IPv6 kernel module is
not present, and on a system with IPv6 kmod is present, but no
interfaces have any IPv6 addresses (not even link-local ones).
I'm concerned this is going to trigger failures on IPv4 only
hosts.

> diff --git a/src/util/virportallocator.c b/src/util/virportallocator.c
> index 1922ea6..24b4bff 100644
> --- a/src/util/virportallocator.c
> +++ b/src/util/virportallocator.c
> @@ -99,21 +99,45 @@ virPortAllocatorPtr virPortAllocatorNew(const char *name,
>  }
>  
>  static int virPortAllocatorBindToPort(bool *used,
> -                                      unsigned short port)
> +                                      unsigned short port,
> +                                      int family)
>  {
> -    struct sockaddr_in addr = {
> +    struct sockaddr_in6 addr6 = {
> +        .sin6_family = AF_INET6,
> +        .sin6_port = htons(port),
> +        .sin6_addr = IN6ADDR_ANY_INIT,
> +    };
> +    struct sockaddr_in addr4 = {
>          .sin_family = AF_INET,
>          .sin_port = htons(port),
>          .sin_addr.s_addr = htonl(INADDR_ANY)
>      };
> +    struct sockaddr* addr;
> +    size_t addrlen;
> +    int v6only = 1;
>      int reuse = 1;
>      int ret = -1;
>      int fd = -1;
> +    bool ipv6 = false;
> +
> +    if (family == AF_INET6) {
> +        addr = (struct sockaddr*)&addr6;
> +        addrlen = sizeof(addr6);
> +        ipv6 = true;
> +    } else if (family == AF_INET) {
> +        addr = (struct sockaddr*)&addr4;
> +        addrlen = sizeof(addr4);

family can be AF_INET or AF_INET6 here...

> +    } else {
> +        virReportError(VIR_ERR_INTERNAL_ERROR, _("Unknown family %d"), family);
> +        return -1;
> +    }
>  
>      *used = false;
>  
>      fd = socket(PF_INET, SOCK_STREAM, 0);

...but you're hardcoding PF_INET here. I'm not sure it is valid
to use an PF_INET socket with an AF_INET6 address in bind().

>      if (fd < 0) {
> +        if (errno == EAFNOSUPPORT)
> +            return 0;
>          virReportSystemError(errno, "%s", _("Unable to open test socket"));
>          goto cleanup;
>      }
> @@ -125,7 +149,14 @@ static int virPortAllocatorBindToPort(bool *used,
>          goto cleanup;
>      }
>  
> -    if (bind(fd, (struct sockaddr*)&addr, sizeof(addr)) < 0) {
> +    if (ipv6 && setsockopt(fd, IPPROTO_IPV6, IPV6_V6ONLY, (void*)&v6only,
> +                           sizeof(v6only)) < 0) {
> +        virReportSystemError(errno, "%s",
> +                             _("Unable to set IPV6_V6ONLY flag"));
> +        goto cleanup;
> +    }
> +
> +    if (bind(fd, addr, addrlen) < 0) {
>          if (errno == EADDRINUSE) {
>              *used = true;
>              ret = 0;
> @@ -151,7 +182,7 @@ int virPortAllocatorAcquire(virPortAllocatorPtr pa,
>      virObjectLock(pa);
>  
>      for (i = pa->start; i <= pa->end && !*port; i++) {
> -        bool used = false;
> +        bool used = false, v6used = false;
>  
>          if (virBitmapGetBit(pa->bitmap,
>                              i - pa->start, &used) < 0) {
> @@ -163,10 +194,10 @@ int virPortAllocatorAcquire(virPortAllocatorPtr pa,
>          if (used)
>              continue;
>  
> -        if (virPortAllocatorBindToPort(&used, i) < 0)
> +        if (virPortAllocatorBindToPort(&v6used, i, AF_INET6) < 0 ||
> +            virPortAllocatorBindToPort(&used, i, AF_INET) < 0)
>              goto cleanup;
> -
> -        if (!used) {
> +        if (!used && !v6used) {
>              /* Add port to bitmap of reserved ports */
>              if (virBitmapSetBit(pa->bitmap,
>                                  i - pa->start) < 0) {


Daniel
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