/* function: packet_handler
* takes a tun header and a packet and sends it down the stack
* tunnel - tun device data
* tun_header - tun header
* packet - packet
* packetsize - size of packet
*/
void packet_handler(const struct tun_data *tunnel, struct tun_pi *tun_header, const char *packet,
size_t packetsize) {
int fd;
int iov_len = 0;
// Allocate buffers for all packet headers.
struct tun_pi tun_targ;
char iphdr[sizeof(struct ip6_hdr)];
char transporthdr[MAX_TCP_HDR];
char icmp_iphdr[sizeof(struct ip6_hdr)];
char icmp_transporthdr[MAX_TCP_HDR];
// 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.
{ iphdr, 0 }, // IP header.
{ transporthdr, 0 }, // Transport layer header.
{ icmp_iphdr, 0 }, // ICMP error inner IP header.
{ icmp_transporthdr, 0 }, // ICMP error transport layer header.
{ NULL, 0 }, // Payload. No buffer, it's a pointer to the original payload.
};
if(tun_header->flags != 0) {
logmsg(ANDROID_LOG_WARN,"packet_handler: unexpected flags = %d", tun_header->flags);
}
if(ntohs(tun_header->proto) == ETH_P_IP) {
fd = tunnel->fd6;
fill_tun_header(&tun_targ, ETH_P_IPV6);
iov_len = ipv4_packet(out, CLAT_POS_IPHDR, packet, packetsize);
} else if(ntohs(tun_header->proto) == ETH_P_IPV6) {
fd = tunnel->fd4;
fill_tun_header(&tun_targ, ETH_P_IP);
iov_len = ipv6_packet(out, CLAT_POS_IPHDR, packet, packetsize);
} else {
logmsg(ANDROID_LOG_WARN,"packet_handler: unknown packet type = %x",tun_header->proto);
}
if (iov_len > 0) {
writev(fd, out, iov_len);
}
}
/* function: tcp6_to_tcp
* translate ipv6 tcp to ipv4 tcp
* fd - tun interface fd
* ip6 - source packet ipv6 header
* tcp - source packet tcp header
* payload - tcp payload
* payload_size - size of payload
* options - tcp options
* options_size - size of options
*/
void tcp6_to_tcp(int fd,const struct ip6_hdr *ip6, const struct tcphdr *tcp, const char *payload, size_t payload_size, const char *options, size_t options_size) {
struct iphdr ip_targ;
struct iovec io_targ[5];
struct tun_pi tun_header;
uint32_t checksum;
fill_tun_header(&tun_header,ETH_P_IP);
fill_ip_header(&ip_targ,payload_size+options_size+sizeof(struct tcphdr),IPPROTO_TCP,ip6);
checksum = ipv4_pseudo_header_checksum(0, &ip_targ);
io_targ[0].iov_base = &tun_header;
io_targ[0].iov_len = sizeof(tun_header);
io_targ[1].iov_base = &ip_targ;
io_targ[1].iov_len = sizeof(ip_targ);
tcp_translate(fd,tcp,payload,payload_size,io_targ,checksum,options,options_size);
}
/* function: udp6_to_udp
* translate ipv6 udp to ipv4 udp
* fd - tun interface fd
* ip6 - source packet ipv6 header
* udp - source packet udp header
* payload - udp payload
* payload_size - size of payload
*/
void udp6_to_udp(int fd, const struct ip6_hdr *ip6, const struct udphdr *udp, const char *payload, size_t payload_size) {
struct iphdr ip_targ;
struct iovec io_targ[4];
struct tun_pi tun_header;
uint32_t checksum;
fill_tun_header(&tun_header,ETH_P_IP);
fill_ip_header(&ip_targ,payload_size + sizeof(struct udphdr),IPPROTO_UDP,ip6);
checksum = ipv4_pseudo_header_checksum(0, &ip_targ);
io_targ[0].iov_base = &tun_header;
io_targ[0].iov_len = sizeof(tun_header);
io_targ[1].iov_base = &ip_targ;
io_targ[1].iov_len = sizeof(ip_targ);
udp_translate(fd,udp,payload,payload_size,io_targ,checksum);
}
/* function: icmp_to_icmp6
* translate ipv4 icmp to ipv6 icmp
* fd - tun interface fd
* ip - source packet ipv4 header
* icmp - source packet icmp header
* payload - icmp payload
* payload_size - size of payload
*/
void icmp_to_icmp6(int fd, const struct iphdr *ip, const struct icmphdr *icmp, const char *payload, size_t payload_size) {
struct ip6_hdr ip6_targ;
struct icmp6_hdr icmp6_targ;
struct iovec io_targ[4];
struct tun_pi tun_header;
uint32_t checksum_temp;
if(icmp->type != ICMP_ECHO && icmp->type != ICMP_ECHOREPLY) {
#if CLAT_DEBUG
logmsg(ANDROID_LOG_WARN,"icmp_to_icmp6/unhandled icmp type: 0x%x",icmp->type);
#endif
return;
}
fill_tun_header(&tun_header,ETH_P_IPV6);
fill_ip6_header(&ip6_targ,payload_size + sizeof(icmp6_targ),IPPROTO_ICMPV6,ip);
memset(&icmp6_targ, 0, sizeof(icmp6_targ));
icmp6_targ.icmp6_type = (icmp->type == ICMP_ECHO) ? ICMP6_ECHO_REQUEST : ICMP6_ECHO_REPLY;
icmp6_targ.icmp6_code = 0;
icmp6_targ.icmp6_cksum = 0;
icmp6_targ.icmp6_id = icmp->un.echo.id;
icmp6_targ.icmp6_seq = icmp->un.echo.sequence;
checksum_temp = ipv6_pseudo_header_checksum(0,&ip6_targ);
checksum_temp = ip_checksum_add(checksum_temp,&icmp6_targ,sizeof(icmp6_targ));
checksum_temp = ip_checksum_add(checksum_temp,payload,payload_size);
icmp6_targ.icmp6_cksum = ip_checksum_finish(checksum_temp);
io_targ[0].iov_base = &tun_header;
io_targ[0].iov_len = sizeof(tun_header);
io_targ[1].iov_base = &ip6_targ;
io_targ[1].iov_len = sizeof(ip6_targ);
io_targ[2].iov_base = &icmp6_targ;
io_targ[2].iov_len = sizeof(icmp6_targ);
io_targ[3].iov_base = (char *)payload;
io_targ[3].iov_len = payload_size;
writev(fd, io_targ, 4);
}
/* function: icmp6_to_icmp
* translate ipv6 icmp to ipv4 icmp
* fd - tun interface fd
* ip6 - source packet ipv6 header
* icmp6 - source packet icmp6 header
* payload - icmp6 payload
* payload_size - size of payload
*/
void icmp6_to_icmp(int fd, const struct ip6_hdr *ip6, const struct icmp6_hdr *icmp6, const char *payload, size_t payload_size) {
struct iphdr ip_targ;
struct icmphdr icmp_targ;
struct iovec io_targ[4];
struct tun_pi tun_header;
uint32_t temp_icmp_checksum;
if((icmp6->icmp6_type != ICMP6_ECHO_REQUEST) && (icmp6->icmp6_type != ICMP6_ECHO_REPLY)) {
#if CLAT_DEBUG
logmsg(ANDROID_LOG_WARN,"icmp6_to_icmp/unhandled icmp6 type: 0x%x",icmp6->icmp6_type);
#endif
return;
}
memset(&icmp_targ, 0, sizeof(icmp_targ));
fill_tun_header(&tun_header,ETH_P_IP);
fill_ip_header(&ip_targ,sizeof(icmp_targ) + payload_size, IPPROTO_ICMP, ip6);
icmp_targ.type = (icmp6->icmp6_type == ICMP6_ECHO_REQUEST) ? ICMP_ECHO : ICMP_ECHOREPLY;
icmp_targ.code = 0x0;
icmp_targ.checksum = 0;
icmp_targ.un.echo.id = icmp6->icmp6_id;
icmp_targ.un.echo.sequence = icmp6->icmp6_seq;
temp_icmp_checksum = ip_checksum_add(0,(void *)&icmp_targ,sizeof(icmp_targ));
temp_icmp_checksum = ip_checksum_add(temp_icmp_checksum, (void *)payload, payload_size);
icmp_targ.checksum = ip_checksum_finish(temp_icmp_checksum);
io_targ[0].iov_base = &tun_header;
io_targ[0].iov_len = sizeof(tun_header);
io_targ[1].iov_base = &ip_targ;
io_targ[1].iov_len = sizeof(ip_targ);
io_targ[2].iov_base = &icmp_targ;
io_targ[2].iov_len = sizeof(icmp_targ);
io_targ[3].iov_base = (char *)payload;
io_targ[3].iov_len = payload_size;
writev(fd, io_targ, 4);
}
