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-rw-r--r--ipv4.c30
-rw-r--r--ipv6.c30
-rw-r--r--translate.c77
-rw-r--r--translate.h6
4 files changed, 61 insertions, 82 deletions
diff --git a/ipv4.c b/ipv4.c
index 784f10c..243f9d0 100644
--- a/ipv4.c
+++ b/ipv4.c
@@ -64,40 +64,30 @@ void icmp_packet(int fd, const char *packet, size_t len, struct iphdr *ip) {
* ip - ip header
*/
void tcp_packet(int fd, const char *packet, size_t len, struct iphdr *ip) {
- struct tcphdr tcp;
+ const struct tcphdr *tcp = (const struct tcphdr *) packet;
const char *payload;
- const char *options;
- size_t payload_size, options_size;
+ size_t payload_size, header_size;
if(len < sizeof(tcp)) {
logmsg_dbg(ANDROID_LOG_ERROR,"tcp_packet/(too small)");
return;
}
- memcpy(&tcp, packet, sizeof(tcp));
-
- if(tcp.doff < 5) {
- logmsg_dbg(ANDROID_LOG_ERROR,"tcp_packet/tcp header length set to less than 5: %x",tcp.doff);
+ if(tcp->doff < 5) {
+ logmsg_dbg(ANDROID_LOG_ERROR,"tcp_packet/tcp header length set to less than 5: %x", tcp->doff);
return;
}
- if((size_t)tcp.doff*4 > len) {
- logmsg_dbg(ANDROID_LOG_ERROR,"tcp_packet/tcp header length set too large: %x",tcp.doff);
+ if((size_t) tcp->doff*4 > len) {
+ logmsg_dbg(ANDROID_LOG_ERROR,"tcp_packet/tcp header length set too large: %x", tcp->doff);
return;
}
- if(tcp.doff > 5) {
- options = packet + sizeof(tcp);
- options_size = tcp.doff*4 - sizeof(tcp);
- } else {
- options = NULL;
- options_size = 0;
- }
-
- payload = packet + tcp.doff*4;
- payload_size = len - tcp.doff*4;
+ header_size = tcp->doff * 4;
+ payload = packet + header_size;
+ payload_size = len - header_size;
- tcp_to_tcp6(fd,ip,&tcp,payload,payload_size,options,options_size);
+ tcp_to_tcp6(fd, ip, tcp, header_size, payload, payload_size);
}
/* function: udp_packet
diff --git a/ipv6.c b/ipv6.c
index 8fc36a4..61013f2 100644
--- a/ipv6.c
+++ b/ipv6.c
@@ -66,40 +66,30 @@ void icmp6_packet(int fd, const char *packet, size_t len, struct ip6_hdr *ip6) {
* ip6 - ip6 header
*/
void tcp6_packet(int fd, const char *packet, size_t len, struct ip6_hdr *ip6) {
- struct tcphdr tcp;
+ const struct tcphdr *tcp = (const struct tcphdr *) packet;
const char *payload;
- const char *options;
- size_t payload_size, options_size;
+ size_t payload_size, header_size;
if(len < sizeof(tcp)) {
logmsg_dbg(ANDROID_LOG_ERROR,"tcp6_packet/(too small)");
return;
}
- memcpy(&tcp, packet, sizeof(tcp));
-
- if(tcp.doff < 5) {
- logmsg_dbg(ANDROID_LOG_ERROR,"tcp6_packet/tcp header length set to less than 5: %x",tcp.doff);
+ if(tcp->doff < 5) {
+ logmsg_dbg(ANDROID_LOG_ERROR,"tcp6_packet/tcp header length set to less than 5: %x", tcp->doff);
return;
}
- if((size_t)tcp.doff*4 > len) {
- logmsg_dbg(ANDROID_LOG_ERROR,"tcp6_packet/tcp header length set too large: %x",tcp.doff);
+ if((size_t) tcp->doff*4 > len) {
+ logmsg_dbg(ANDROID_LOG_ERROR,"tcp6_packet/tcp header length set too large: %x", tcp->doff);
return;
}
- if(tcp.doff > 5) {
- options = packet + sizeof(tcp);
- options_size = tcp.doff*4 - sizeof(tcp);
- } else {
- options = NULL;
- options_size = 0;
- }
-
- payload = packet + tcp.doff*4;
- payload_size = len - tcp.doff*4;
+ header_size = tcp->doff * 4;
+ payload = packet + header_size;
+ payload_size = len - header_size;
- tcp6_to_tcp(fd,ip6,&tcp,payload,payload_size,options,options_size);
+ tcp6_to_tcp(fd, ip6, tcp, header_size, payload, payload_size);
}
/* function: udp6_packet
diff --git a/translate.c b/translate.c
index 89a7e7b..936c781 100644
--- a/translate.c
+++ b/translate.c
@@ -303,44 +303,41 @@ void udp6_to_udp(int fd, const struct ip6_hdr *ip6, const struct udphdr *udp, co
* array position 0 - tun header
* array position 1 - ipv4/ipv6 header
* array position 2 - empty (will be tcp header)
- * array position 3 - empty (will be tcp options or payload)
- * array position 4 - empty (can be payload)
+ * array position 3 - empty (will be payload)
* checksum - partial checksum covering ipv4/ipv6 header
- * options - pointer to tcp option buffer
- * options_size - size of tcp option buffer
*
* TODO: mss rewrite
* TODO: hosts without pmtu discovery - non DF packets will rely on fragmentation (unimplemented)
*/
-void tcp_translate(int fd, const struct tcphdr *tcp, const char *payload, size_t payload_size, struct iovec *io_targ, uint32_t checksum, const char *options, size_t options_size) {
- struct tcphdr tcp_targ;
- int targ_index = 2;
-
- memcpy(&tcp_targ, tcp, sizeof(tcp_targ));
- tcp_targ.check = 0;
-
- checksum = ip_checksum_add(checksum, &tcp_targ, sizeof(tcp_targ));
- if(options) {
- checksum = ip_checksum_add(checksum, options, options_size);
+void tcp_translate(int fd, const struct tcphdr *tcp, size_t header_size, const char *payload,
+ size_t payload_size, struct iovec *io_targ, uint32_t checksum) {
+ union {
+ // Reserve space for the maximum size of the TCP header, including options. The TCP header
+ // length field is 4 bits long and counts 4-byte words, so it can be at most 60 bytes.
+ char buf[15 * 4];
+ struct tcphdr tcp;
+ } header;
+
+ if (header_size > sizeof(header.buf)) {
+ // A TCP header cannot be more than 60 bytes long, so this can never happen unless there is a
+ // bug in the caller.
+ logmsg(ANDROID_LOG_ERROR, "tcp_translate: header too long %d > %d, truncating",
+ header_size, sizeof(header.buf));
+ header_size = sizeof(header.buf);
}
- checksum = ip_checksum_add(checksum, payload, payload_size);
- tcp_targ.check = ip_checksum_finish(checksum);
- io_targ[targ_index].iov_base = &tcp_targ;
- io_targ[targ_index].iov_len = sizeof(tcp_targ);
- targ_index++;
+ memcpy(&header, tcp, header_size);
- if(options) {
- io_targ[targ_index].iov_base = (char *)options;
- io_targ[targ_index].iov_len = options_size;
- targ_index++;
- }
+ header.tcp.check = 0;
+ checksum = ip_checksum_add(checksum, &header, header_size);
+ checksum = ip_checksum_add(checksum, payload, payload_size);
+ header.tcp.check = ip_checksum_finish(checksum);
- io_targ[targ_index].iov_base = (char *)payload;
- io_targ[targ_index].iov_len = payload_size;
- targ_index++;
+ io_targ[2].iov_base = &header;
+ io_targ[2].iov_len = header_size;
- writev(fd, io_targ, targ_index);
+ io_targ[3].iov_base = (char *)payload;
+ io_targ[3].iov_len = payload_size;
}
/* function: tcp_to_tcp6
@@ -348,12 +345,12 @@ void tcp_translate(int fd, const struct tcphdr *tcp, const char *payload, size_t
* fd - tun interface fd
* ip - source packet ipv4 header
* tcp - source packet tcp header
+ * header_size - size of tcp header including options
* payload - tcp payload
* payload_size - size of payload
- * options - tcp options
- * options_size - size of options
*/
-void tcp_to_tcp6(int fd,const struct iphdr *ip, const struct tcphdr *tcp, const char *payload, size_t payload_size, const char *options, size_t options_size) {
+void tcp_to_tcp6(int fd, const struct iphdr *ip, const struct tcphdr *tcp, size_t header_size,
+ const char *payload, size_t payload_size) {
struct ip6_hdr ip6_targ;
struct iovec io_targ[5];
struct tun_pi tun_header;
@@ -361,16 +358,16 @@ void tcp_to_tcp6(int fd,const struct iphdr *ip, const struct tcphdr *tcp, const
fill_tun_header(&tun_header,ETH_P_IPV6);
- fill_ip6_header(&ip6_targ,payload_size+options_size+sizeof(struct tcphdr),IPPROTO_TCP,ip);
+ fill_ip6_header(&ip6_targ, header_size + payload_size, IPPROTO_TCP, ip);
- checksum = ipv6_pseudo_header_checksum(0, &ip6_targ, sizeof(*tcp) + options_size + payload_size);
+ checksum = ipv6_pseudo_header_checksum(0, &ip6_targ, header_size + payload_size);
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);
- tcp_translate(fd,tcp,payload,payload_size,io_targ,checksum,options,options_size);
+ tcp_translate(fd, tcp, header_size, payload, payload_size, io_targ, checksum);
}
/* function: tcp6_to_tcp
@@ -378,12 +375,12 @@ void tcp_to_tcp6(int fd,const struct iphdr *ip, const struct tcphdr *tcp, const
* fd - tun interface fd
* ip6 - source packet ipv6 header
* tcp - source packet tcp header
+ * header_size - size of tcp header including options
* 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) {
+void tcp6_to_tcp(int fd, const struct ip6_hdr *ip6, const struct tcphdr *tcp, size_t header_size,
+ const char *payload, size_t payload_size) {
struct iphdr ip_targ;
struct iovec io_targ[5];
struct tun_pi tun_header;
@@ -391,14 +388,14 @@ void tcp6_to_tcp(int fd,const struct ip6_hdr *ip6, const struct tcphdr *tcp, con
fill_tun_header(&tun_header,ETH_P_IP);
- fill_ip_header(&ip_targ,payload_size+options_size+sizeof(struct tcphdr),IPPROTO_TCP,ip6);
+ fill_ip_header(&ip_targ, header_size + payload_size, IPPROTO_TCP, ip6);
- checksum = ipv4_pseudo_header_checksum(0, &ip_targ, sizeof(*tcp) + payload_size + options_size);
+ checksum = ipv4_pseudo_header_checksum(0, &ip_targ, header_size + payload_size);
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);
+ tcp_translate(fd, tcp, header_size, payload, payload_size, io_targ, checksum);
}
diff --git a/translate.h b/translate.h
index 6fc3c79..641768e 100644
--- a/translate.h
+++ b/translate.h
@@ -24,7 +24,9 @@ void icmp6_to_icmp(int fd, const struct ip6_hdr *ip6, const struct icmp6_hdr *ic
void udp_to_udp6(int fd, const struct iphdr *ip, const struct udphdr *udp, const char *payload, size_t payload_size);
void udp6_to_udp(int fd, const struct ip6_hdr *ip6, const struct udphdr *udp, const char *payload, size_t payload_size);
-void tcp_to_tcp6(int fd,const struct iphdr *ip, const struct tcphdr *tcp, const char *payload, size_t payload_size, const char *options, size_t options_size);
-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);
+void tcp_to_tcp6(int fd,const struct iphdr *ip, const struct tcphdr *tcp, size_t header_size,
+ const char *payload, size_t payload_size);
+void tcp6_to_tcp(int fd,const struct ip6_hdr *ip6, const struct tcphdr *tcp, size_t header_size,
+ const char *payload, size_t payload_size);
#endif /* __TRANSLATE_H__ */
generated by cgit v1.2.3 (git 2.25.1) at 2024-09-28 00:08:53 +0000