newroute

netlink.cpp

@@ -10,6 +10,7 @@
 #include <linux/netlink.h>
 #include <linux/rtnetlink.h>
 #include <net/if.h>
+#include <arpa/inet.h>
 
 #include "ip4.h"
 #include "rtnetlink.h"
@@ -103,5 +104,22 @@ int main()
     }
   }
 
+  // newroute
+  {
+    printf("newroute\n");
+    uint32_t gateway;
+    int ret = inet_pton(AF_INET, "192.168.1.1", (void *)&gateway);
+    assert(ret == 1);
+
+    int dret = rtnetlink::send_newroute(fd, if_index.ifr_ifindex, gateway);
+    if (dret < 0) {
+      exit(EXIT_FAILURE);
+    }
+    int eret = rtnetlink::handle_error(fd);
+    if (eret < 0) {
+      exit(EXIT_FAILURE);
+    }
+  }
+
   return 0;
 }

rtnetlink.cpp

@@ -18,7 +18,7 @@ static inline int align4(int len)
   return (len + 3) & (~3);
 }
 
-struct newaddr_msg {
+struct getaddr_msg {
   struct nlmsghdr nl;
   struct ifaddrmsg ifaddr;
 };
@@ -32,6 +32,15 @@ struct deladdr_msg {
   } attr[2];
 };
 
+struct newroute_msg {
+  struct nlmsghdr nl;
+  struct rtmsg rt;
+  struct {
+    struct rtattr rtattr;
+    uint32_t value;
+  } attr[2];
+};
+
 namespace rtnetlink {
 
   bool parse_newaddr(uint8_t const * buf, ssize_t length,
@@ -127,9 +136,9 @@ namespace rtnetlink {
 
   int send_getaddr(int fd, uint32_t ifa_index)
   {
-    const size_t message_length = (sizeof (struct newaddr_msg));
+    const size_t message_length = (sizeof (struct getaddr_msg));
 
-    struct newaddr_msg rtmmsg = {
+    struct getaddr_msg rtmmsg = {
       .nl = {
         .nlmsg_len = message_length,
         .nlmsg_type = RTM_GETADDR,
@@ -218,6 +227,59 @@ namespace rtnetlink {
     return 0;
   }
 
+  int send_newroute(int fd, uint32_t ifa_index, uint32_t gateway)
+  {
+    const size_t message_length = (sizeof (struct newroute_msg));
+
+    struct newroute_msg rtmmsg = {
+      .nl = {
+        .nlmsg_len = message_length,
+        .nlmsg_type = RTM_NEWROUTE,
+        .nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK | NLM_F_EXCL | NLM_F_CREATE,
+        .nlmsg_seq = 123456,
+      },
+      .rt = {
+        .rtm_family = AF_INET,
+        .rtm_table = RT_TABLE_MAIN,
+        .rtm_protocol = RTPROT_BOOT,
+        .rtm_scope = RT_SCOPE_UNIVERSE,
+        .rtm_type = RTN_UNICAST,
+      },
+      .attr = {
+        {
+          .rtattr = { .rta_len = 8, .rta_type = RTA_GATEWAY },
+          .value = gateway,
+        },
+        {
+          .rtattr = { .rta_len = 8, .rta_type = RTA_OIF },
+          .value = ifa_index,
+        }
+      }
+    };
+
+    struct iovec iov[1] = {
+      {
+        .iov_base = &rtmmsg,
+        .iov_len = message_length,
+      }
+    };
+    struct sockaddr_nl addr = { .nl_family = AF_NETLINK };
+    struct msghdr msg = {
+      .msg_name = (void *)&addr,
+      .msg_namelen = (sizeof (sockaddr_nl)),
+      .msg_iov = iov,
+      .msg_iovlen = 1,
+    };
+
+    ssize_t sret = sendmsg(fd, &msg, 0);
+    if (sret < 0) {
+      perror("sendmsg");
+      return -1;
+    }
+
+    return 0;
+  }
+
   int handle_error(int fd)
   {
     struct sockaddr_nl addr = { .nl_family = AF_NETLINK };

rtnetlink.h

@@ -19,5 +19,7 @@ namespace rtnetlink {
   int send_getaddr(int fd, uint32_t ifa_index);
 
   int send_typeaddr(int fd, uint16_t nlmsg_type, uint32_t ifa_index, uint8_t ifa_prefixlen, uint32_t local, uint32_t address);
+  int send_newroute(int fd, uint32_t ifa_index, uint32_t gateway);
+
   int handle_error(int fd);
 }