Re: [Qemu-devel] [PATCH v3 2/2] qga: win32 implementation of qmp_guest_network_get_interfaces

[Olga Krishtal <okrishtal@parallels.com>]

[-- Attachment #1: Type: text/plain, Size: 15893 bytes --]

On 28/05/15 23:54, Denis V. Lunev wrote:
> On 28/05/15 21:41, Kirk Allan wrote:
>> By default, IP addresses and prefixes will be derived from information
>> obtained by various calls and structures.  IPv4 prefixes can be found
>> by matching the address to those returned by GetAdaptersInfo. IPv6
>> prefixes can not be matched this way due to the unpredictable order of
>> entries.
>>
>> In Windows Visa/2008 guests and newer, it is possible to use inet_ntop()
>> and  OnLinkPrefixLength to get  IPv4 and IPv6 addresses and prefixes.
>> Setting –extra-cflags in the build configuration to
>> ”- D_WIN32_WINNT-0x600 -DWINVER=0x600” or greater enables this 
>> functionality
>> for those guests.  Setting –ectra-cflags is not required and if not 
>> used,
>> the default approach will be taken.
>>
>> Signed-off-by: Kirk Allan <kallan@suse.com>
>> ---
>>   qga/commands-win32.c | 292 
>> ++++++++++++++++++++++++++++++++++++++++++++++++++-
>>   1 file changed, 290 insertions(+), 2 deletions(-)
>>
>> diff --git a/qga/commands-win32.c b/qga/commands-win32.c
>> index 3ef0549..3bf9011 100644
>> --- a/qga/commands-win32.c
>> +++ b/qga/commands-win32.c
>> @@ -16,11 +16,17 @@
>>   #include <powrprof.h>
>>   #include <stdio.h>
>>   #include <string.h>
>> +#include <winsock2.h>
>> +#include <ws2tcpip.h>
>> +#include <ws2ipdef.h>
>> +#include <iptypes.h>
>> +#include <iphlpapi.h>
>>   #include "qga/guest-agent-core.h"
>>   #include "qga/vss-win32.h"
>>   #include "qga-qmp-commands.h"
>>   #include "qapi/qmp/qerror.h"
>>   #include "qemu/queue.h"
>> +#include "qemu/host-utils.h"
>>
>>   #ifndef SHTDN_REASON_FLAG_PLANNED
>>   #define SHTDN_REASON_FLAG_PLANNED 0x80000000
>> @@ -589,9 +595,291 @@ void qmp_guest_suspend_hybrid(Error **errp)
>>       error_set(errp, QERR_UNSUPPORTED);
>>   }
>>
>> +static DWORD guest_get_adapters_addresses(IP_ADAPTER_ADDRESSES 
>> **adptr_addrs)
>> +{
>> +    ULONG adptr_addrs_len = 0;
>> +    DWORD ret = ERROR_SUCCESS;
>> +
>> +    /* Call the first time to get the adptr_addrs_len. */
>> +    *adptr_addrs = NULL;
>> +    GetAdaptersAddresses(AF_UNSPEC, GAA_FLAG_INCLUDE_PREFIX,
>> +                         NULL, *adptr_addrs, &adptr_addrs_len);
>> +
>> +    *adptr_addrs = g_malloc(adptr_addrs_len);
>> +    if (*adptr_addrs == NULL) {
>> +        ret = ERROR_NOT_ENOUGH_MEMORY;
>> +    } else {
>> +        ret = GetAdaptersAddresses(AF_UNSPEC, GAA_FLAG_INCLUDE_PREFIX,
>> +                                   NULL, *adptr_addrs, 
>> &adptr_addrs_len);
>> +        if (ret != ERROR_SUCCESS) {
>> +            g_free(*adptr_addrs);
>> +            *adptr_addrs = NULL;
>> +        }
>> +    }
>> +    return ret;
>
> https://developer.gnome.org/glib/2.28/glib-Memory-Allocation.html#g-malloc 
>
>
> g_malloc never fail
>
> If any call to allocate memory fails, the application is terminated. 
> This also means that there is no need to check if the call succeeded.
>
> this means that IP_ADAPTER_ADDRESSES could be returned from function
I think that check is still necessary, because we may suffer some other 
problems:
*ERROR_ADDRESS_NOT_ASSOCIATED*
*ERROR_INVALID_PARAMETER*
and even *Other*, according to MSDN.

 From my point of view, the prototype of function should be smth like this:
static IP_ADAPTER_ADDRESSES *guest_get_adapters_addresses()
{

	PIP_ADAPTER_ADDRESSES ip_add = NULL;
	/* Memory allocation, etc */
	......
	if (GetAdaptersAddresses(....)) {
		error_setg_win32(errp, GetLastError(), "Failed smth");
		.....
	}

     return ip_add;

}
**
>
>> +}
>> +
>> +#if (_WIN32_WINNT < 0x0600)
> are you correct with the condition? according to MSDN
>
> On Windows XP and later:  Use the GetAdaptersAddresses function 
> instead of GetAdaptersInfo.
>
> Thus you should have above branch of code undefined.
>
It is better to use #ifdef (smth), #else and #endif to separate win version.
Den is right, the first func will be compiled always, and the winxp 
variation
will be compiled for winserver 2003, and winxp. Have you tested if for 
2003 server?
>
>> +static DWORD guest_get_adapters_info(IP_ADAPTER_INFO **adptr_info)
>> +{
>> +    ULONG adptr_info_len = 0;
>> +    DWORD ret = ERROR_SUCCESS;
>> +
>> +    /* Call the first time to get the adptr_info_len. */
>> +    *adptr_info = NULL;
>> +    GetAdaptersInfo(*adptr_info, &adptr_info_len);
>> +
>> +    *adptr_info = g_malloc(adptr_info_len);
>> +    if (*adptr_info == NULL) {
>> +        ret = ERROR_NOT_ENOUGH_MEMORY;
>> +    } else {
>> +        ret = GetAdaptersInfo(*adptr_info, &adptr_info_len);
>> +        if (ret != ERROR_SUCCESS) {
>> +            g_free(*adptr_info);
>> +            *adptr_info = NULL;
>> +        }
>> +    }
>
> same note about the allocation
Same prototype as before.
>
>> +    return ret;
>> +}
>> +#endif
>> +
>> +static char *guest_wctomb_dup(WCHAR *wstr)
>> +{
>> +    char *str;
>> +    size_t i;
>> +
>> +    i = wcslen(wstr) + 1;
>> +    str = g_malloc(i);
>> +    if (str) {
>> +        WideCharToMultiByte(CP_ACP, WC_COMPOSITECHECK,
>> +                            wstr, -1, str, i, NULL, NULL);
>> +    }
>
> same allocation
>
>> +    return str;
>> +}
>> +
>> +static char *guest_inet_ntop(int af, void *cp, char *buf, size_t len)
>> +{
>> +#if (_WIN32_WINNT >= 0x0600) && defined(ARCH_x86_64)
>> +    /* If built for 64 bit Windows Vista/2008 or newer, inet_ntop() is
>> +     * available for use.  Otherwise, do our best to derive it.
>> +     */
>
> nothing about 64bit only is present here. This seems strange to me
> https://msdn.microsoft.com/ru-ru/library/windows/desktop/cc805843(v=vs.85).aspx 
>
>
If you will use glib utility: nm_utils_inet4/6_ntop() you won't need 
this separation.
>> +    return (char *)InetNtop(af, cp, buf, len);
>> +#else
>> +    u_char *p;
>> +
>> +    p = (u_char *)cp;
>> +    if (af == AF_INET) {
>> +        snprintf(buf, len, "%u.%u.%u.%u", p[0], p[1], p[2], p[3]);
>> +    } else if (af == AF_INET6) {
>> +        int i, compressed_zeros, added_to_buf;
>> +        char t[sizeof "::ffff"];
>
> sizeof without braces and from string could be tricky but I am not
> quite sure
>
>> +
>> +        buf[0] = '\0';
>> +        compressed_zeros = 0;
>> +        added_to_buf = 0;
>> +        for (i = 0; i < 16; i += 2) {
>> +            if (p[i] != 0 || p[i + 1] != 0) {
>> +                if (compressed_zeros) {
>> +                    if (len > sizeof "::") {
>> +                        strcat(buf, "::");
>> +                        len -= sizeof "::" - 1;
>
> with len == 1 you will definitely have problem with wrong conversion
>
>> +                    }
>> +                    added_to_buf++;
>> +                } else {
>> +                    if (added_to_buf) {
>> +                        if (len > 1) {
>> +                            strcat(buf, ":");
>> +                            len--;
>> +                        }
>> +                    }
>> +                    added_to_buf++;
>> +                }
>> +
>> +                /* Take into account leading zeros. */
>> +                if (p[i]) {
>> +                    len -= snprintf(t, sizeof(t), "%x%02x", p[i], 
>> p[i+1]);
>> +                } else {
>> +                    len -= snprintf(t, sizeof(t), "%x", p[i+1]);
>> +                }
>
> snprintf can produce non-zero terminated character arrays
> and the same problem with length...
>
>> +
>> +                /* Ensure there's enough room for the NULL. */
>> +                if (len > 0) {
>> +                    strcat(buf, t);
>> +                }
>> +                compressed_zeros = 0;
>> +            } else {
>> +                compressed_zeros++;
>> +            }
>> +        }
>> +        if (compressed_zeros && !added_to_buf) {
>> +            /* The address was all zeros. */
>> +            strcat(buf, "::");
> there is not length check here
>
>> +        }
>> +    }
>> +    return buf;
>> +#endif
>> +}
>> +
I still recommend to think over this function, here useful link
https://developer.gnome.org/glib/stable/glib-String-Utility-Functions.html
glib provides a lot of function to work with strings, and there you do 
not need think
about memory allocations and etc. Pls, look.

>> +static int64_t guest_ip_prefix(IP_ADAPTER_UNICAST_ADDRESS *ip_addr)
>> +{
>> +#if (_WIN32_WINNT >= 0x0600)
>> +    /* If built for Windows Vista/2008 or newer, use the 
>> OnLinkPrefixLength
>> +     * field to obtain the prefix.  Otherwise, do our best to figure 
>> it out.
>> +     */
>> +    return ip_addr->OnLinkPrefixLength;
>> +#else
>> +    int64_t prefix = -1; /* Use for AF_INET6 and 
>> unknown/undetermined values. */
>> +    IP_ADAPTER_INFO *adptr_info, *info;
>> +    IP_ADDR_STRING *ip;
>> +    struct in_addr *p;
>> +
>> +    if (ip_addr->Address.lpSockaddr->sa_family == AF_INET) {
>
> why not to return immediately? You will have 1 less indent
>
>> +        if (guest_get_adapters_info(&adptr_info) != ERROR_SUCCESS) {
>> +            return prefix;
>> +        }
adptr_info = guest_get_adapters_info();
if(adptr_info == NULL )
     goto out;
If you will use the prototypes, I have written before it will be easier.


>> +        /* Match up the passed in ip_addr with one found in 
>> adaptr_info.
>> +         * The matching one in adptr_info will have the netmask.
>> +         */
>> +        p = &((struct sockaddr_in 
>> *)ip_addr->Address.lpSockaddr)->sin_addr;
>> +        for (info = adptr_info; info && prefix == -1; info = 
>> info->Next) {
>> +            for (ip = &info->IpAddressList; ip; ip = ip->Next) {
>> +                if (p->S_un.S_addr == 
>> inet_addr(ip->IpAddress.String)) {
>> +                    prefix = ctpop32(inet_addr(ip->IpMask.String));
>> +                    break;
> why not goto here. Moving out from inner loop with goto is a good thing.
> There is no necessity to use prefix == -1 above in this case
>
>> +                }
>> +            }
>> +        }
>> +        g_free(adptr_info);
>> +    }
>> +    return prefix;
>> +#endif
>> +}
>> +
>>   GuestNetworkInterfaceList *qmp_guest_network_get_interfaces(Error 
>> **errp)
>>   {
>> -    error_set(errp, QERR_UNSUPPORTED);
>> +    IP_ADAPTER_ADDRESSES *adptr_addrs, *addr;
>> +    IP_ADAPTER_UNICAST_ADDRESS *ip_addr = NULL;
>> +    GuestNetworkInterfaceList *head = NULL, *cur_item = NULL;
>> +    GuestIpAddressList *head_addr, *cur_addr;
>> +    GuestNetworkInterfaceList *info;
>> +    GuestIpAddressList *address_item = NULL;
>> +    unsigned char *mac_addr;
>> +    void *p;
>> +    char addr4[INET_ADDRSTRLEN];
>> +    char addr6[INET6_ADDRSTRLEN];
>> +    DWORD ret;
>> +
May be you should return  pointer to structure by 
guest_get_adapters_addresses, and
make this function take void? As the result you won't need if (ret != 
ERROR_SUCCESS)
It will be smth like this:
adptr_addrs = guest_get_adapters_addresses();
if (adptr_addrs == NULL)
     goto out;
And all error, that may happen in guest_get_adapters_addresses will be 
held there.
>> +    ret = guest_get_adapters_addresses(&adptr_addrs);
>> +    if (ret != ERROR_SUCCESS) {
>> +        error_setg(errp, "failed to get adapter addresses %lu", ret);
>> +        return NULL;
>> +    }
>> +
>> +    for (addr = adptr_addrs; addr; addr = addr->Next) {
>> +        info = g_malloc0(sizeof(*info));
>> +        if (!info) {
>
> no need to check, see above
>
>> +            error_setg(errp, "failed to alloc a network interface 
>> list");
>> +            goto error;
>> +        }
>> +
>> +        if (!cur_item) {
> it is better to reserve ! condition to logical checks. For pointers it 
> is better to check using != NULL
>
>
>> +            head = cur_item = info;
>> +        } else {
>> +            cur_item->next = info;
>> +            cur_item = info;
>> +        }
>> +
>> +        info->value = g_malloc0(sizeof(*info->value));
>> +        if (!info->value) {
> same
>
>> +            error_setg(errp, "failed to alloc a network interface");
>> +            goto error;
>> +        }
>> +        info->value->name = guest_wctomb_dup(addr->FriendlyName);
>> +
>> +        if (addr->PhysicalAddressLength) {
>
> same for check
>
>> +            mac_addr = addr->PhysicalAddress;
>> +
>> +            info->value->hardware_address =
>> + g_strdup_printf("%02x:%02x:%02x:%02x:%02x:%02x",
>> +                    (int) mac_addr[0], (int) mac_addr[1],
>> +                    (int) mac_addr[2], (int) mac_addr[3],
>> +                    (int) mac_addr[4], (int) mac_addr[5]);
>> +
>> +            info->value->has_hardware_address = true;
>> +        }
>> +
>> +        head_addr = NULL;
>> +        cur_addr = NULL;
>> +        for (ip_addr = addr->FirstUnicastAddress;
>> +                ip_addr;
>> +                ip_addr = ip_addr->Next) {
>> +            address_item = g_malloc0(sizeof(*address_item));
>> +            if (!address_item) {
>> +                error_setg(errp, "failed to alloc an Ip address list");
>> +                goto error;
>> +            }
>> +
no need check if (!address_item), as Den had explained before.
>> +            if (!cur_addr) {
>> +                head_addr = cur_addr = address_item;
>> +            } else {
>> +                cur_addr->next = address_item;
>> +                cur_addr = address_item;
>> +            }
>> +
>> +            address_item->value = 
>> g_malloc0(sizeof(*address_item->value));
>> +            if (!address_item->value) {
>> +                error_setg(errp, "failed to alloc an Ip address");
>> +                goto error;
>> +            }
>> +
>> +            if (ip_addr->Address.lpSockaddr->sa_family == AF_INET) {
>> +                p = &((struct sockaddr_in *)
>> + ip_addr->Address.lpSockaddr)->sin_addr;
>> +
>> +                if (!guest_inet_ntop(AF_INET, p, addr4, 
>> sizeof(addr4))) {
>> +                    error_setg_win32(errp, WSAGetLastError(),
>> +                        "failed address presentation form conversion");
>> +                    goto error;
>> +                }
>> +
>> +                address_item->value->ip_address = g_strdup(addr4);
>> +                address_item->value->ip_address_type =
>> +                    GUEST_IP_ADDRESS_TYPE_IPV4;
>> +            } else if (ip_addr->Address.lpSockaddr->sa_family == 
>> AF_INET6) {
>> +                p = &((struct sockaddr_in6 *)
>> + ip_addr->Address.lpSockaddr)->sin6_addr;
>> +
>> +                if (!guest_inet_ntop(AF_INET6, p, addr6, 
>> sizeof(addr6))) {
>> +                    error_setg_win32(errp, WSAGetLastError(),
>> +                        "failed address presentation form conversion");
>> +                    goto error;
>> +                }
>> +
>> +                address_item->value->ip_address = g_strdup(addr6);
>> +                address_item->value->ip_address_type =
>> +                    GUEST_IP_ADDRESS_TYPE_IPV6;
>> +            }
>> +            address_item->value->prefix = guest_ip_prefix(ip_addr);
>> +        }
>> +        if (head_addr) {
>> +            info->value->has_ip_addresses = true;
>> +            info->value->ip_addresses = head_addr;
>> +        }
>> +    }
>> +
>> +    if (adptr_addrs) {
>> +        g_free(adptr_addrs);
>
> if is not needed
>
> https://developer.gnome.org/glib/stable/glib-Memory-Allocation.html#g-free 
>
>
>> +    }
>> +    return head;
>> +
>> +error:
>> +    if (adptr_addrs) {
>> +        g_free(adptr_addrs);
>> +    }
>> +    if (head) {
>> +        qapi_free_GuestNetworkInterfaceList(head);
>> +    }
>>       return NULL;
>>   }
>>
>> @@ -707,7 +995,7 @@ GuestMemoryBlockInfo 
>> *qmp_guest_get_memory_block_info(Error **errp)
>>   GList *ga_command_blacklist_init(GList *blacklist)
>>   {
>>       const char *list_unsupported[] = {
>> -        "guest-suspend-hybrid", "guest-network-get-interfaces",
>> +        "guest-suspend-hybrid",
>>           "guest-get-vcpus", "guest-set-vcpus",
>>           "guest-set-user-password",
>>           "guest-get-memory-blocks", "guest-set-memory-blocks",
>>
>


[-- Attachment #2: Type: text/html, Size: 31214 bytes --]