Treat the options as part of the TCP header.

This simplifies the code and makes UDP and TCP look the same. It
will also make it easier to implement nested translation in the
future because there will only be one iovec array entry for the
transport layer header, regardless of whether we are translating
UDP or TCP and regardless of the presence of options.

Also get rid of a couple of memcpy statements by pointing to the
original data instead.

Bug: 8276725
Change-Id: I6a702aefdf3a070eedfc6f7d3ebec21880ecc22b

1 files changed, 10 insertions, 20 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