[Openvpn-devel,2/8] implement networking API for iproute2

diff --git a/src/openvpn/Makefile.am b/src/openvpn/Makefile.am
index c94296d3..6d9cde3e 100644
--- a/src/openvpn/Makefile.am
+++ b/src/openvpn/Makefile.am
@@ -80,7 +80,7 @@  openvpn_SOURCES = \
 	mtu.c mtu.h \
 	mudp.c mudp.h \
 	multi.c multi.h \
-	networking.h \
+	networking_ip.c networking.h \
 	ntlm.c ntlm.h \
 	occ.c occ.h occ-inline.h \
 	openssl_compat.h \
diff --git a/src/openvpn/networking_ip.c b/src/openvpn/networking_ip.c
new file mode 100644
index 00000000..bfe7b459
--- /dev/null
+++ b/src/openvpn/networking_ip.c
@@ -0,0 +1,369 @@ 
+/*
+ *  Networking API implementation for iproute2
+ *
+ *  Copyright (C) 2018 Antonio Quartulli <a@unstable.cc>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program (see the file COPYING included with this
+ *  distribution); if not, write to the Free Software Foundation, Inc.,
+ *  59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#if defined(TARGET_LINUX) && defined(ENABLE_IPROUTE)
+
+#include "syshead.h"
+
+#include "networking.h"
+#include "networking_ip.h"
+#include "misc.h"
+#include "socket.h"
+
+#include <stdbool.h>
+#include <netinet/in.h>
+
+static struct env_set *es = NULL;
+
+int
+net_iface_up(const char *iface, bool up)
+{
+    struct argv argv = argv_new();
+
+    argv_printf(&argv, "%s link set dev %s %s", iproute_path, iface,
+                up ? "up" : "down");
+    argv_msg(M_INFO, &argv);
+    openvpn_execve_check(&argv, es, S_FATAL, "Linux ip link set failed");
+
+    argv_reset(&argv);
+
+    return 0;
+}
+
+int
+net_iface_mtu_set(const char *iface, uint32_t mtu)
+{
+    struct argv argv = argv_new();
+
+    argv_printf(&argv, "%s link set dev %s up mtu %d", iproute_path, iface,
+                mtu);
+    argv_msg(M_INFO, &argv);
+    openvpn_execve_check(&argv, es, S_FATAL, "Linux ip link set failed");
+
+    return 0;
+}
+
+int
+net_addr_v4_add(const char *iface, const in_addr_t *addr, int prefixlen,
+                  const in_addr_t *broadcast)
+{
+    struct argv argv = argv_new();
+
+    char *addr_str = (char *)print_in_addr_t(*addr, 0, NULL);
+    char *brd_str = (char *)print_in_addr_t(*broadcast, 0, NULL);
+
+    argv_printf(&argv, "%s addr add dev %s %s/%d broadcast %s", iproute_path,
+                iface, addr_str, prefixlen, brd_str);
+    argv_msg(M_INFO, &argv);
+    openvpn_execve_check(&argv, es, S_FATAL, "Linux ip addr add failed");
+
+    free(addr_str);
+    free(brd_str);
+
+    argv_reset(&argv);
+
+    return 0;
+}
+
+int
+net_addr_v6_add(const char *iface, const struct in6_addr *addr, int prefixlen)
+{
+    struct argv argv = argv_new();
+    char *addr_str = (char *)print_in6_addr(*addr, 0, NULL);
+
+    argv_printf(&argv, "%s -6 addr add %s/%d dev %s", iproute_path, addr_str,
+                prefixlen, iface);
+    argv_msg(M_INFO, &argv);
+    openvpn_execve_check(&argv, es, S_FATAL, "Linux ip -6 addr add failed");
+
+    free(addr_str);
+
+    argv_reset(&argv);
+
+    return 0;
+}
+
+int
+net_addr_v4_del(const char *iface, const in_addr_t *addr, int prefixlen)
+{
+    struct argv argv = argv_new();
+    char *addr_str = (char *)print_in_addr_t(*addr, 0, NULL);
+
+    argv_printf(&argv, "%s addr del dev %s %s/%d", iproute_path, iface,
+                addr_str, prefixlen);
+
+    argv_msg(M_INFO, &argv);
+    openvpn_execve_check(&argv, NULL, 0, "Linux ip addr del failed");
+
+    free(addr_str);
+
+    argv_reset(&argv);
+
+    return 0;
+}
+
+int
+net_addr_v6_del(const char *iface, const struct in6_addr *addr, int prefixlen)
+{
+    struct argv argv = argv_new();
+    char *addr_str = (char *)print_in6_addr(*addr, 0, NULL);
+
+    argv_printf(&argv, "%s -6 addr del %s/%d dev %s", iproute_path,
+                addr_str, prefixlen, iface);
+    argv_msg(M_INFO, &argv);
+    openvpn_execve_check(&argv, NULL, 0, "Linux ip -6 addr del failed");
+
+    free(addr_str);
+
+    argv_reset(&argv);
+
+    return 0;
+}
+
+int
+net_addr_ptp_v4_add(const char *iface, const in_addr_t *local,
+                      const in_addr_t *remote)
+{
+    struct argv argv = argv_new();
+    char *local_str = (char *)print_in_addr_t(*local, 0, NULL);
+    char *remote_str = (char *)print_in_addr_t(*remote, 0, NULL);
+
+    argv_printf(&argv, "%s addr add dev %s local %s peer %s", iproute_path,
+                iface, local_str, remote_str);
+    argv_msg(M_INFO, &argv);
+    openvpn_execve_check(&argv, es, S_FATAL, "Linux ip addr add failed");
+
+    free(local_str);
+    free(remote_str);
+
+    argv_reset(&argv);
+
+    return 0;
+}
+
+int
+net_addr_ptp_v4_del(const char *iface, const in_addr_t *local,
+                      const in_addr_t *remote)
+{
+    struct argv argv = argv_new();
+    char *local_str = (char *)print_in_addr_t(*local, 0, NULL);
+    char *remote_str = (char *)print_in_addr_t(*remote, 0, NULL);
+
+    argv_printf(&argv, "%s addr del dev %s local %s peer %s", iproute_path,
+                iface, local_str, remote_str);
+    argv_msg(M_INFO, &argv);
+    openvpn_execve_check(&argv, NULL, 0, "Linux ip addr del failed");
+
+    free(local_str);
+    free(remote_str);
+
+    argv_reset(&argv);
+
+    return 0;
+}
+
+int
+net_route_v4_add(const in_addr_t *dst, int prefixlen, const in_addr_t *gw,
+                   const char *iface, uint32_t table, int metric)
+{
+    struct argv argv = argv_new();
+    char *dst_str = (char *)print_in_addr_t(*dst, 0, NULL);
+
+    argv_printf(&argv, "%s route add %s/%d", iproute_path, dst_str, prefixlen);
+
+    if (metric > 0)
+        argv_printf_cat(&argv, "metric %d", metric);
+
+    if (iface)
+        argv_printf_cat(&argv, "dev %s", iface);
+
+    if (gw)
+    {
+        char *gw_str = (char *)print_in_addr_t(*gw, 0, NULL);
+
+        argv_printf_cat(&argv, "via %s", gw_str);
+
+        free(gw_str);
+    }
+
+    argv_msg(D_ROUTE, &argv);
+    openvpn_execve_check(&argv, es, 0, "ERROR: Linux route add command failed");
+
+    free(dst_str);
+
+    argv_reset(&argv);
+
+    return 0;
+}
+
+int
+net_route_v6_add(const struct in6_addr *dst, int prefixlen,
+                 const struct in6_addr *gw, const char *iface, uint32_t table,
+                 int metric)
+{
+    struct argv argv = argv_new();
+    char *dst_str = (char *)print_in6_addr(*dst, 0, NULL);
+
+    argv_printf(&argv, "%s -6 route add %s/%d dev %s", iproute_path, dst_str,
+                prefixlen, iface);
+
+    if (gw)
+    {
+        char *gw_str = (char *)print_in6_addr(*gw, 0, NULL);
+
+        argv_printf_cat(&argv, "via %s", gw_str);
+
+        free(gw_str);
+    }
+
+    if (metric > 0)
+        argv_printf_cat(&argv, "metric %d", metric);
+
+    argv_msg(D_ROUTE, &argv);
+    openvpn_execve_check(&argv, es, 0, "ERROR: Linux route -6 add command failed");
+
+    free(dst_str);
+
+    argv_reset(&argv);
+
+    return 0;
+}
+
+int
+net_route_v4_del(const in_addr_t *dst, int prefixlen, const in_addr_t *gw,
+                 const char *iface, uint32_t table, int metric)
+{
+    struct argv argv = argv_new();
+    char *dst_str = (char *)print_in_addr_t(*dst, 0, NULL);
+
+    argv_printf(&argv, "%s route del %s/%d", iproute_path, dst_str, prefixlen);
+
+    if (metric > 0)
+        argv_printf_cat(&argv, "metric %d", metric);
+
+    argv_msg(D_ROUTE, &argv);
+    openvpn_execve_check(&argv, es, 0, "ERROR: Linux route delete command failed");
+
+    free(dst_str);
+
+    argv_reset(&argv);
+
+    return 0;
+}
+
+int
+net_route_v6_del(const struct in6_addr *dst, int prefixlen,
+                 const struct in6_addr *gw, const char *iface, uint32_t table,
+                 int metric)
+{
+    struct argv argv = argv_new();
+    char *dst_str = (char *)print_in6_addr(*dst, 0, NULL);
+
+    argv_printf(&argv, "%s -6 route del %s/%d dev %s", iproute_path, dst_str,
+                prefixlen, iface);
+
+    if (gw)
+    {
+        char *gw_str = (char *)print_in6_addr(*gw, 0, NULL);
+
+        argv_printf_cat(&argv, "via %s", gw_str);
+
+        free(gw_str);
+    }
+
+    if (metric > 0)
+        argv_printf_cat(&argv, "metric %d", metric);
+
+    argv_msg(D_ROUTE, &argv);
+    openvpn_execve_check(&argv, es, 0, "ERROR: Linux route -6 del command failed");
+
+    free(dst_str);
+
+    argv_reset(&argv);
+
+    return 0;
+}
+
+int
+net_route_v4_best_gw(const in_addr_t *dst, int prefixlen,
+                     in_addr_t *best_gw, char *best_iface)
+{
+    best_iface[0] = '\0';
+
+    FILE *fp = fopen("/proc/net/route", "r");
+    if (!fp)
+        return -1;
+
+    char line[256];
+    int count = 0;
+    unsigned int lowest_metric = UINT_MAX;
+    while (fgets(line, sizeof(line), fp) != NULL)
+    {
+        if (count)
+        {
+            unsigned int net_x = 0;
+            unsigned int mask_x = 0;
+            unsigned int gw_x = 0;
+            unsigned int metric = 0;
+            unsigned int flags = 0;
+            char name[16];
+            name[0] = '\0';
+
+            const int np = sscanf(line, "%15s\t%x\t%x\t%x\t%*s\t%*s\t%d\t%x",
+                                  name, &net_x, &gw_x, &flags, &metric,
+                                  &mask_x);
+
+            if (np == 6 && (flags & IFF_UP))
+            {
+                const in_addr_t net = ntohl(net_x);
+                const in_addr_t mask = ntohl(mask_x);
+                const in_addr_t gw = ntohl(gw_x);
+
+                if (!net && !mask && metric < lowest_metric)
+                {
+                    *best_gw = gw;
+                    strcpy(best_iface, name);
+                    lowest_metric = metric;
+                }
+            }
+        }
+        ++count;
+    }
+    fclose(fp);
+
+    return 0;
+}
+
+/*
+ * The following function is not implemented in the iproute backend as it
+ * already uses netlink in route.c.
+ *
+ * int
+ * net_route_v6_best_gw(const struct in6_addr *dst, int prefixlen,
+ *                      struct in6_addr *best_gw, char *best_iface)
+ */
+
+#endif /* ENABLE_IPROUTE && TARGET_LINUX */