创建socket时的协议参数的疑问~~~

[wuzhiwenk3001]

SOCKET socket( int af, int type, int protocol );中, protocol参数是这个socket所用的协议.
我所理解这个参数的意思是: 你的数据是基于这个协议的( 比如:TCP,那么我发送的数据的TCP头不用你构造,接收到的数据也不包含TCP头,内核已经帮你去掉了).

但最近看到的程序与我的理解不同.比如这个从网上找到的ping程序:
sock = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP);
它用原始套接字,发送数据时不用自已写IP头,但要自已填ICMP头,当收到数据时,能收到IP头!当然也能收到ICMP头!

晕死,搞到我都弄不同白这个 protocol参数是搞什么的,MSDN也只有这句 "Protocol to be used with the socket that is specific to the indicated address family. "

请大牛指点~~~这个protocol的真正用意是什么~

[矫情狗_____]

套接字指定协议...(即TCP/UDP/等)...0为自动选定...

[wuzhiwenk3001]

我也看过TCP/IP 详解 ,我是懂协议的,我就是问单单在这具socket函数里那个协议参数的意义.

[wuzhiwenk3001]

[Quote=引用 4 楼 的回复:]

C/C++ code

The protocol specifies a particular protocol to be used with the socket. Normally only a single protocol exists to support a particular socket type
within a given p……
[/Quote]

英语刚过4级,很吃力

[cobra_chen]

可以理解为语种（比如中文，英文，德文，法文）么？
报文协议相当于A语言。
流协议相当于B语言。
底层协议相当于C语言。
不同的语言用于不同的沟通。
socket的也是。
-
协议只是一个规定，遵循就好。

[luciferisnotsatan]

[Quote=引用 2 楼 的回复:]

可以理解为语种（比如中文，英文，德文，法文）么？
报文协议相当于A语言。
流协议相当于B语言。
底层协议相当于C语言。
不同的语言用于不同的沟通。
socket的也是。
-
协议只是一个规定，遵循就好。
[/Quote]
type看成语言，中文，英文。
protocol 看成文章类型，记叙文，诗歌。

想要具体理解，还是找书看下吧。
TCP/IP 详解 卷一
unix网络编程

[qq120848369]

       The protocol specifies a particular protocol to be used with the socket.  Normally only a single protocol exists to support  a  particular  socket  type
       within  a  given  protocol family, in which case protocol can be specified as 0.  However, it is possible that many protocols may exist, in which case a
       particular protocol must be specified in this manner.  The protocol number to use is specific to the “communication domain” in which communication is to
       take place; see protocols(5).  See getprotoent(3) on how to map protocol name strings to protocol numbers.

AME
       protocols - protocols definition file

DESCRIPTION
       This  file  is a plain ASCII file, describing the various DARPA internet protocols that are available from the TCP/IP subsystem.  It should be consulted
       instead of using the numbers in the ARPA include files, or, even worse, just guessing them.  These numbers will occur in the protocol field  of  any  IP
       header.

       Keep  this  file untouched since changes would result in incorrect IP packages.  Protocol numbers and names are specified by the IANA (Internet Assigned
       Numbers Authority).

       Each line is of the following format:

              protocol number aliases ...

       where the fields are delimited by spaces or tabs.  Empty lines are ignored.  If a line contains a hash mark (#), the hash mark and the part of the  line
       following it are ignored.

       The field descriptions are:

       protocol
              the native name for the protocol.  For example ip, tcp, or udp.

       number the official number for this protocol as it will appear within the IP header.

       aliases
              optional aliases for the protocol.
FILES
       /etc/protocols
              The protocols definition file.

# /etc/protocols:
# $Id: protocols,v 1.9 2009/09/29 15:11:55 ovasik Exp $
#
# Internet (IP) protocols
#
#       from: @(#)protocols     5.1 (Berkeley) 4/17/89
#
# Updated for NetBSD based on RFC 1340, Assigned Numbers (July 1992).
# Last IANA update included dated 2009-06-18
#
# See also http://www.iana.org/assignments/protocol-numbers

ip      0       IP              # internet protocol, pseudo protocol number
hopopt  0       HOPOPT          # hop-by-hop options for ipv6
icmp    1       ICMP            # internet control message protocol
igmp    2       IGMP            # internet group management protocol
ggp     3       GGP             # gateway-gateway protocol
ipencap 4       IP-ENCAP        # IP encapsulated in IP (officially ``IP'')
st      5       ST              # ST datagram mode
tcp     6       TCP             # transmission control protocol
cbt     7       CBT             # CBT, Tony Ballardie <[e-mail]>
egp     8       EGP             # exterior gateway protocol
igp     9       IGP             # any private interior gateway (Cisco: for IGRP)
bbn-rcc 10      BBN-RCC-MON     # BBN RCC Monitoring
nvp     11      NVP-II          # Network Voice Protocol
pup     12      PUP             # PARC universal packet protocol
argus   13      ARGUS           # ARGUS
emcon   14      EMCON           # EMCON
xnet    15      XNET            # Cross Net Debugger
chaos   16      CHAOS           # Chaos
udp     17      UDP             # user datagram protocol