fix some bugs in the headers and fix checksumming.

base/inet.cc:
    we can't use a uint16_t for the intermediate checksum values
    since there may be some bits that carry.
    the length that is added in the pseudo header is the length of
    the tcp portion only.
base/inet.hh:
    silly me, the ip_hlen field is in terms of 4-byte words.
    when caclulating checksum, we're dealing with network byte order,
    so don't bother doing any byteswapping.

--HG--
extra : convert_revision : 993e3413e9febea0ba2fb6ba8bf04c053cca15ed

diff --git a/base/inet.cc b/base/inet.cc
index ac0758c1f009c9fac0f614c06e566bfea7592e78..0b9e32854766ee2700de7bdec33bddb330ea3b8b 100644 (file)
--- a/base/inet.cc
+++ b/base/inet.cc
@@ -46,16 +46,17 @@ eaddr_string(const uint8_t a[6])
 uint16_t
 IpHdr::ip_cksum() const
 {
-    uint16_t sum = ip_cksum_add(this, hlen(), 0);
-    return ip_cksum_carry(sum);
+    int sum = ip_cksum_add(this, hlen(), 0);
+    sum = ip_cksum_carry(sum);
+    return sum;
 }
 
 uint16_t
 IpHdr::tu_cksum() const
 {
-    uint16_t sum = ip_cksum_add(payload(), len() - hlen(), 0);
-    sum = ip_cksum_add(&ip_src, 4, sum);
-    sum = ip_cksum_add(&ip_dst, 4, sum);
-    sum += htons(ip_p + ip_len);
-    return ip_cksum_carry(sum);
+    int sum = ip_cksum_add(payload(), len() - hlen(), 0);
+    sum = ip_cksum_add(&ip_src, 8, sum); // source and destination
+    sum += htons(ip_p + len() - hlen());
+    sum = ip_cksum_carry(sum);
+    return sum;
 }

diff --git a/base/inet.hh b/base/inet.hh
index b20c90bebf9b6e7e6689c0ea30d7701d170491f7..8a49790a779e1446a1f3c8953f125e6f589d39fb 100644 (file)
--- a/base/inet.hh
+++ b/base/inet.hh
@@ -82,7 +82,7 @@ struct EthHdr : protected eth_hdr
 struct IpHdr : protected ip_hdr
 {
     uint8_t  version() const { return ip_v; }
-    uint8_t  hlen() const { return ip_hl; }
+    uint8_t  hlen() const { return ip_hl * 4; }
     uint8_t  tos() const { return ip_tos; }
     uint16_t len() const { return ntohs(ip_len); }
     uint16_t id() const { return ntohs(ip_id); }
@@ -90,11 +90,11 @@ struct IpHdr : protected ip_hdr
     uint16_t frag_off() const { return ntohs(ip_off) & 0x1fff; }
     uint8_t  ttl() const { return ip_ttl; }
     uint8_t  proto() const { return ip_p; }
-    uint16_t sum() const { return ntohs(ip_sum); }
+    uint16_t sum() const { return ip_sum; }
     uint32_t src() const { return ntohl(ip_src); }
     uint32_t dst() const { return ntohl(ip_dst); }
 
-    void sum(uint16_t sum) { ip_sum = htons(sum); }
+    void sum(uint16_t sum) { ip_sum = sum; }
 
     uint16_t ip_cksum() const;
     uint16_t tu_cksum() const;
@@ -126,10 +126,10 @@ struct TcpHdr : protected tcp_hdr
     uint8_t  off() const { return th_off; }
     uint8_t  flags() const { return th_flags & 0x3f; }
     uint16_t win() const { return ntohs(th_win); }
-    uint16_t sum() const { return ntohs(th_sum); }
+    uint16_t sum() const { return th_sum; }
     uint16_t urp() const { return ntohs(th_urp); }
 
-    void sum(uint16_t sum) { th_sum = htons(sum); }
+    void sum(uint16_t sum) { th_sum = sum; }
 
     int size() const { return off(); }
     const uint8_t *bytes() const { return (const uint8_t *)this; }