Use a raw socket to send IPv6 packets instead of a tun.
This will allow us to bind the socket to a particular network.
Bug: 15340961
Change-Id: I50857d372955f2b6f7035157c2968cda72c32585
diff --git a/translate.c b/translate.c
index 958ce2f..487468b 100644
--- a/translate.c
+++ b/translate.c
@@ -465,6 +465,30 @@
return CLAT_POS_PAYLOAD + 1;
}
+void send_tun(int fd, clat_packet out, int iov_len) {
+ writev(fd, out, iov_len);
+}
+
+// Weak symbol so we can override it in the unit test.
+void send_rawv6(int fd, clat_packet out, int iov_len) __attribute__((weak));
+
+void send_rawv6(int fd, clat_packet out, int iov_len) {
+ // A send on a raw socket requires a destination address to be specified even if the socket's
+ // protocol is IPPROTO_RAW. This is the address that will be used in routing lookups; the
+ // destination address in the packet header only affects what appears on the wire, not where the
+ // packet is sent to.
+ static struct sockaddr_in6 sin6 = { AF_INET6, 0, 0, { { { 0, 0, 0, 0 } } }, 0 };
+ static struct msghdr msg = {
+ .msg_name = &sin6,
+ .msg_namelen = sizeof(sin6),
+ };
+
+ msg.msg_iov = out,
+ msg.msg_iovlen = iov_len,
+ sin6.sin6_addr = ((struct ip6_hdr *) out[CLAT_POS_IPHDR].iov_base)->ip6_dst;
+ sendmsg(fd, &msg, 0);
+}
+
/* function: translate_packet
* takes a packet, translates it, and writes it to fd
* fd - fd to write translated packet to
@@ -486,7 +510,7 @@
// iovec of the packets we'll send. This gets passed down to the translation functions.
clat_packet out = {
- { &tun_targ, sizeof(tun_targ) }, // Tunnel header.
+ { &tun_targ, 0 }, // Tunnel header.
{ iphdr, 0 }, // IP header.
{ fraghdr, 0 }, // Fragment header.
{ transporthdr, 0 }, // Transport layer header.
@@ -498,12 +522,15 @@
if (to_ipv6) {
iov_len = ipv4_packet(out, CLAT_POS_IPHDR, packet, packetsize);
+ if (iov_len > 0) {
+ send_rawv6(fd, out, iov_len);
+ }
} else {
iov_len = ipv6_packet(out, CLAT_POS_IPHDR, packet, packetsize);
- }
-
- if (iov_len > 0) {
- fill_tun_header(&tun_targ, to_ipv6 ? ETH_P_IPV6 : ETH_P_IP);
- writev(fd, out, iov_len);
+ if (iov_len > 0) {
+ fill_tun_header(&tun_targ, ETH_P_IP);
+ out[CLAT_POS_TUNHDR].iov_len = sizeof(tun_targ);
+ send_tun(fd, out, iov_len);
+ }
}
}