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Add a few comments to IP.h

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This commit is contained in:
Jon Siwek 2012-03-07 14:17:56 -06:00
parent 65307764f4
commit 76ef36e048
1 changed files with 42 additions and 1 deletions
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43
src/IP.h
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@ -260,6 +260,10 @@ public:
IPAddr DstAddr() const
{ return ip4 ? IPAddr(ip4->ip_dst) : IPAddr(ip6->ip6_dst); }
/**
* Returns a pointer to the payload of the IP packet, usually an
* upper-layer protocol.
*/
const u_char* Payload() const
{
if ( ip4 )
@ -268,6 +272,10 @@ public:
return ((const u_char*) ip6) + ip6_hdrs->TotalLength();
}
/**
* Returns the length of the IP packet's payload (length of packet minus
* header length or, for IPv6, also minus length of all extension headers).
*/
uint16 PayloadLen() const
{
if ( ip4 )
@ -276,16 +284,30 @@ public:
return ntohs(ip6->ip6_plen) + 40 - ip6_hdrs->TotalLength();
}
/**
* Returns the length of the IP packet (length of headers and payload).
*/
uint32 TotalLen() const
{ return ip4 ? ntohs(ip4->ip_len) : ntohs(ip6->ip6_plen) + 40; }
/**
* Returns length of IP packet header (includes extension headers for IPv6).
*/
uint16 HdrLen() const
{ return ip4 ? ip4->ip_hl * 4 : ip6_hdrs->TotalLength(); }
/**
* For IPv6 header chains, returns the type of the last header in the chain.
*/
uint8 LastHeader() const
{ return ip4 ? IPPROTO_RAW :
((*ip6_hdrs)[ip6_hdrs->Size()-1])->Type(); }
/**
* Returns the protocol type of the IP packet's payload, usually an
* upper-layer protocol. For IPv6, this returns the last (extension)
* header's Next Header value.
*/
unsigned char NextProto() const
{ return ip4 ? ip4->ip_p :
((*ip6_hdrs)[ip6_hdrs->Size()-1])->NextHdr(); }
@ -297,23 +319,42 @@ public:
{ return ip4 ? (ntohs(ip4->ip_off) & 0x3fff) != 0 :
ip6_hdrs->IsFragment(); }
/**
* Returns the fragment packet's offset in relation to the original
* packet in bytes.
*/
uint16 FragOffset() const
{ return ip4 ? (ntohs(ip4->ip_off) & 0x1fff) * 8 :
ip6_hdrs->FragOffset(); }
/**
* Returns the fragment packet's identification field.
*/
uint32 ID() const
{ return ip4 ? ntohs(ip4->ip_id) : ip6_hdrs->ID(); }
/**
* Returns whether a fragment packet's "More Fragments" field is set.
*/
int MF() const
{ return ip4 ? (ntohs(ip4->ip_off) & 0x2000) != 0 : ip6_hdrs->MF(); }
// IPv6 has no "Don't Fragment" flag.
/**
* Returns whether a fragment packet's "Don't Fragment" field is set.
* Note that IPv6 has no such field.
*/
int DF() const
{ return ip4 ? ((ntohs(ip4->ip_off) & 0x4000) != 0) : 0; }
/**
* Returns number of IP headers in packet (includes IPv6 extension headers).
*/
size_t NumHeaders() const
{ return ip4 ? 1 : ip6_hdrs->Size(); }
/**
* Returns an ip_hdr or ip6_hdr_chain RecordVal.
*/
RecordVal* BuildRecordVal() const;
private: