[Winpcap-users] Which Packets Carry HTTP Info?

[Joe Merchant]

I've been reviewing packet info, winpcap, and other related stuff.
I'm overloaded and a bit confused.
I need to sniff all http traffic.If a user visits a web page, I need
to sniff that page's html.
I've got something very basic that works on one windows xp computer.
I need it to work on windows xp,vista, win7.
I need it to work if a user is on a network, a wireless connection, a
home broadband connection.  Basically, if a user visits a web page on
their pc, i need that page's details.
That being said, from sample code I've reviewed on the net, I've seen
all types of packet types (tcp, pdp, 802.11, ARP, etc.).  The sample I
have running is getting http details from tcp packets.  Enter my
confusion.  Do certain packet types carry http details?  So do I have
to check for valid http packets within 802.11 packets, arp packets,
etc?  At first I thought it was only tcp packets but the more I read,
the more I'm confused.