From: Lev Stipakov <l...@openvpn.net> When adding host route for IPv4, we use the default gateway. There are cases, however, when this does not work - for example when remote is not accessible via default gateway but via dedicated route.
Factor out code to look for the best gateway to reach the host from get_default_gateway_ipv6() and generalize is for IPv4/6. Change-Id: I6c7e1cef637fe9fb3f3bc6ff4fb2c65599cd86fb Signed-off-by: Lev Stipakov <l...@openvpn.net> Acked-by: Gert Doering <g...@greenie.muc.de> --- This change was reviewed on Gerrit and approved by at least one developer. I request to merge it to master. Gerrit URL: https://gerrit.openvpn.net/c/openvpn/+/879 This mail reflects revision 5 of this Change. Acked-by according to Gerrit (reflected above): Gert Doering <g...@greenie.muc.de> diff --git a/src/openvpn/route.c b/src/openvpn/route.c index dd37fb9..d895e1c 100644 --- a/src/openvpn/route.c +++ b/src/openvpn/route.c @@ -2732,40 +2732,105 @@ return ret; } +/** + * @brief Determines the best route to a destination for both IPv4 and IPv6. + * + * Uses `GetBestInterfaceEx` and `GetBestRoute2` to find the optimal route + * and network interface for the specified destination address. + * + * @param gc Pointer to struct gc_arena for internal string allocation. + * @param dest The destination IP address (IPv4 or IPv6). + * @param best_route Pointer to a `MIB_IPFORWARD_ROW2` structure to store the best route. + * @return DWORD `NO_ERROR` on success, or an error code. + */ +static DWORD +get_best_route(struct gc_arena *gc, SOCKADDR_INET *dest, MIB_IPFORWARD_ROW2 *best_route) +{ + DWORD best_if_index; + DWORD status; + + CLEAR(*best_route); + + /* get the best interface index to reach dest */ + status = GetBestInterfaceEx((struct sockaddr *)dest, &best_if_index); + if (status != NO_ERROR) + { + msg(D_ROUTE, "NOTE: GetBestInterfaceEx returned error: %s (code=%u)", + strerror_win32(status, gc), + (unsigned int)status); + goto done; + } + + msg(D_ROUTE_DEBUG, "GetBestInterfaceEx() returned if=%d", (int)best_if_index); + + /* get the routing information (such as NextHop) for the destination and interface */ + NET_LUID luid; + CLEAR(luid); + SOCKADDR_INET best_src; + CLEAR(best_src); + status = GetBestRoute2(&luid, best_if_index, NULL, + dest, 0, best_route, &best_src); + if (status != NO_ERROR) + { + msg(D_ROUTE, "NOTE: GetIpForwardEntry2 returned error: %s (code=%u)", + strerror_win32(status, gc), + (unsigned int)status); + goto done; + } + +done: + return status; +} + void get_default_gateway(struct route_gateway_info *rgi, in_addr_t dest, openvpn_net_ctx_t *ctx) { - struct gc_arena gc = gc_new(); - - const IP_ADAPTER_INFO *adapters = get_adapter_info_list(&gc); - const MIB_IPFORWARDTABLE *routes = get_windows_routing_table(&gc); - const MIB_IPFORWARDROW *row = get_default_gateway_row(routes); - DWORD a_index; - const IP_ADAPTER_INFO *ai; - CLEAR(*rgi); - if (row) + struct gc_arena gc = gc_new(); + + /* convert in_addr_t into SOCKADDR_INET */ + SOCKADDR_INET sa; + CLEAR(sa); + sa.si_family = AF_INET; + sa.Ipv4.sin_addr.s_addr = htonl(dest); + + /* get the best route to the destination */ + MIB_IPFORWARD_ROW2 best_route; + CLEAR(best_route); + DWORD status = get_best_route(&gc, &sa, &best_route); + if (status != NO_ERROR) { - rgi->gateway.addr = ntohl(row->dwForwardNextHop); - if (rgi->gateway.addr) + goto done; + } + + rgi->flags = RGI_ADDR_DEFINED | RGI_IFACE_DEFINED; + rgi->gateway.addr = ntohl(best_route.NextHop.Ipv4.sin_addr.S_un.S_addr); + rgi->adapter_index = best_route.InterfaceIndex; + + if (rgi->gateway.addr == INADDR_ANY) + { + rgi->flags |= RGI_ON_LINK; + } + + /* get netmask and MAC address */ + const IP_ADAPTER_INFO *adapters = get_adapter_info_list(&gc); + const IP_ADAPTER_INFO *ai = get_adapter(adapters, rgi->adapter_index); + if (ai) + { + memcpy(rgi->hwaddr, ai->Address, 6); + rgi->flags |= RGI_HWADDR_DEFINED; + + /* get netmask for non-onlink routes */ + in_addr_t nm = inet_addr(ai->IpAddressList.IpMask.String); + if (!(rgi->flags & RGI_ON_LINK) && (nm != INADDR_NONE)) { - rgi->flags |= RGI_ADDR_DEFINED; - a_index = adapter_index_of_ip(adapters, rgi->gateway.addr, NULL, &rgi->gateway.netmask); - if (a_index != TUN_ADAPTER_INDEX_INVALID) - { - rgi->adapter_index = a_index; - rgi->flags |= (RGI_IFACE_DEFINED|RGI_NETMASK_DEFINED); - ai = get_adapter(adapters, a_index); - if (ai) - { - memcpy(rgi->hwaddr, ai->Address, 6); - rgi->flags |= RGI_HWADDR_DEFINED; - } - } + rgi->gateway.netmask = ntohl(nm); + rgi->flags |= RGI_NETMASK_DEFINED; } } +done: gc_free(&gc); } @@ -2823,43 +2888,22 @@ const struct in6_addr *dest, openvpn_net_ctx_t *ctx) { struct gc_arena gc = gc_new(); - MIB_IPFORWARD_ROW2 BestRoute; - SOCKADDR_INET DestinationAddress, BestSourceAddress; - DWORD BestIfIndex; - DWORD status; - NET_LUID InterfaceLuid; - CLEAR(*rgi6); - CLEAR(InterfaceLuid); /* cleared = not used for lookup */ - CLEAR(DestinationAddress); + SOCKADDR_INET DestinationAddress; + CLEAR(DestinationAddress); DestinationAddress.si_family = AF_INET6; if (dest) { DestinationAddress.Ipv6.sin6_addr = *dest; } - status = GetBestInterfaceEx( (struct sockaddr *)&DestinationAddress, &BestIfIndex ); + MIB_IPFORWARD_ROW2 BestRoute; + CLEAR(BestRoute); + DWORD status = get_best_route(&gc, &DestinationAddress, &BestRoute); if (status != NO_ERROR) { - msg(D_ROUTE, "NOTE: GetBestInterfaceEx returned error: %s (code=%u)", - strerror_win32(status, &gc), - (unsigned int)status); - goto done; - } - - msg( D_ROUTE, "GetBestInterfaceEx() returned if=%d", (int) BestIfIndex ); - - status = GetBestRoute2( &InterfaceLuid, BestIfIndex, NULL, - &DestinationAddress, 0, - &BestRoute, &BestSourceAddress ); - - if (status != NO_ERROR) - { - msg(D_ROUTE, "NOTE: GetIpForwardEntry2 returned error: %s (code=%u)", - strerror_win32(status, &gc), - (unsigned int)status); goto done; } diff --git a/src/openvpn/route.h b/src/openvpn/route.h index 0bbedbb..98ea79e 100644 --- a/src/openvpn/route.h +++ b/src/openvpn/route.h @@ -334,6 +334,13 @@ bool is_special_addr(const char *addr_str); +/** + * @brief Retrieves the best gateway for a given destination based on the routing table. + * + * @param rgi Pointer to a struct to store the gateway information. + * @param dest Destination IP address in host byte order. + * @param ctx Pointer to a platform-specific network context struct. + */ void get_default_gateway(struct route_gateway_info *rgi, in_addr_t dest, openvpn_net_ctx_t *ctx); _______________________________________________ Openvpn-devel mailing list Openvpn-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/openvpn-devel
