新手求教socketAPI调用错误

fhmily · 发表于 2009-4-12 12:24:58

新人到来先和大家打个招呼，请多多关照
 
接触VB是前两天的事情，平时多用的是c++，所以VB里面有很多问题感觉很困惑
 
本意是想写一个调用API的TCP，调用ws2_32.dll里面的socket/connect/recv/send函数
 
结果错误连连，最后还是卡在一个地方无论如何都过不去了，因为连最初始的socket的无法创建=.=
 
我的操作步骤如下:
建立一个带按钮的窗口，click中写
s = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)
msgbox s
(AF_INET, SOCK_STREAM, IPPROTO_TCP)这3个参数在上面已经定义过了
建立一个模块中声明socket函数
Declare Function socket Lib "ws2_32.dll" (ByVal af As Long, ByVal s_type As Long, ByVal Protocol As Long) As Long
 
结果无论怎么运行都是返回的都是创建失败的-1
 
但是跑回c++下面试却是正常的，请问这个是什么问题？

[此贴子已经被作者于2009-4-12 12:26:47编辑过]

马大哈 · 发表于 2009-4-12 13:22:55

我测试了一下,代码如下:
 
Option Explicit
Private Const AF_INET As Long = 2 Private Const SOCK_STREAM As Long = 1 Private Const IPPROTO_TCP As Long = 6
Private Const WSANOTINITIALISED As Long = 10093& Private Const WSAENETDOWN As Long = 10050& Private Const WSAEAFNOSUPPORT As Long = 10047& Private Const WSAEINPROGRESS As Long = 10036& Private Const WSAEMFILE As Long = 10024& Private Const WSAEPROTONOSUPPORT As Long = 10043& Private Const WSAEPROTOTYPE As Long = 10041& Private Const WSAENOBUFS As Long = 10055& Private Const WSAESOCKTNOSUPPORT As Long = 10044&
Private Declare Function socket Lib "ws2_32.dll" (ByVal af As Long, ByVal s_type As Long, ByVal Protocol As Long) As Long
Private Sub Command1_Click()     Dim S As Long     S = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)         MsgBox S     Debug.Print Err.LastDllError End Sub
 
Err.LastDllError返回的是10093,经查MSDN,10093是WSANOTINITIALISED:
 
<div class="msgheader">QUOTE:</div><div class="msgborder">
<h4>Error Codes</h4>
<table cellspacing="4" cols="2">
<tbody>
<tr valign="top">
<td width="46%">WSANOTINITIALISED</td>
<td width="54%">A successful WSAStartup must occur before using this function.</td></tr>
<tr valign="top">
<td width="46%">WSAENETDOWN</td>
<td width="54%">The network subsystem or the associated service provider has failed.</td></tr>
<tr valign="top">
<td width="46%">WSAEAFNOSUPPORT</td>
<td width="54%">The specified address family is not supported.</td></tr>
<tr valign="top">
<td width="46%">WSAEINPROGRESS</td>
<td width="54%">A blocking Windows Sockets 1.1 call is in progress, or the service provider is still processing a callback function.</td></tr>
<tr valign="top">
<td width="46%">WSAEMFILE</td>
<td width="54%">No more socket descriptors are available.</td></tr>
<tr valign="top">
<td width="46%">WSAENOBUFS</td>
<td width="54%">No buffer space is available. The socket cannot be created.</td></tr>
<tr valign="top">
<td width="46%">WSAEPROTONOSUPPORT</td>
<td width="54%">The specified protocol is not supported.</td></tr>
<tr valign="top">
<td width="46%">WSAEPROTOTYPE</td>
<td width="54%">The specified protocol is the wrong type for this socket.</td></tr>
<tr valign="top">
<td width="46%">WSAESOCKTNOSUPPORT</td>
<td width="54%">The specified socket type is not supported in this address family.</td></tr></tbody></table></div>
 
也就是说,看起来你需要先调用一下WSAStartup吧...

fhmily · 发表于 2009-4-12 14:40:14

我不是不想用WSAstartup
 
只是我只要调用WSAstartup整个VB6.0就直接报错关闭
 
是不是我的变量定义有问题？
 
声明：
Public Declare Function WSAStartup Lib "ws2_32.dll" (ByVal wVersionRequired As Long, lpWSAData As WSAData) As Long
 
Type WSAData    wVersion       As Integer    wHighVersion   As Integer    szDescription  As String    szSystemStatus As String    iMaxSockets    As Integer    iMaxUdpDg      As Integer    lpVendorInfo   As Long End Type
代码段：
Dim Wstart as WSAData
Dim start as long
start = WSAStartup(&H202, Wstart)

fhmily · 发表于 2009-4-12 15:08:50

又调试对了
 
不过还是不明白为什么
Dim Wstart as WSAData
call WSAStartup(&H202, Wstart)
 
和
 
Dim Wstart as WSAData
Dim start as long
start = WSAStartup(&H202, Wstart)
 
之间有什么区别么？为什么上面的那个运行就报错，下面的就正常呢？

马大哈 · 发表于 2009-4-13 02:59:41

<div class="msgheader">QUOTE:</div><div class="msgborder">以下是引用fhmily在2009-4-12 14:40:14的发言： 
我不是不想用WSAstartup
 
只是我只要调用WSAstartup整个VB6.0就直接报错关闭
 
是不是我的变量定义有问题？
 
声明：
Public Declare Function WSAStartup Lib "ws2_32.dll" (ByVal wVersionRequired As Long, lpWSAData As WSAData) As Long
 
Type WSAData    wVersion       As Integer    wHighVersion   As Integer    szDescription  As String    szSystemStatus As String    iMaxSockets    As Integer    iMaxUdpDg      As Integer    lpVendorInfo   As Long End Type
代码段：
Dim Wstart as WSAData
Dim start as long
start = WSAStartup(&H202, Wstart)</div>
你这里的这个WSAData结构声明有问题.
 
结构原型:
 
struct WSAData {     WORD             wVersion;     WORD             wHighVersion;     char             szDescription[WSADESCRIPTION_LEN+1];     char             szSystemStatus[WSASYSSTATUS_LEN+1];     unsigned short   iMaxSockets;     unsigned short   iMaxUdpDg;     char FAR *       lpVendorInfo; };
 
可见szDescription与szSystemStatus两个成员不是字符串指针,而是初始化好的两个缓冲区.
 
正确的VB6声明应该是这样:
 
Private Const WSA_DESCRIPTIONLEN = 256 Private Const WSA_DescriptionSize = WSA_DESCRIPTIONLEN + 1 Private Const WSA_SYS_STATUS_LEN = 128 Private Const WSA_SysStatusSize = WSA_SYS_STATUS_LEN + 1
 
Private Type WSADATA     wVersion As Integer     wHighVersion As Integer     szDescription As String * WSA_DescriptionSize     szSystemStatus As String * WSA_SysStatusSize     iMaxSockets As Integer     iMaxUdpDg As Integer     lpVendorInfo As Long End Type 
如果按你的那种声明,两个字符串参数传进去后,WSAStartup函数肯定会发生内存写入范围的不正常,因为变长STRING未初始化时,只有那个指针占了4字节而已....
 
那如果写入长度太长,超过了整个结构的长度,就会发生错误了;
 
假如运气好,返回的字符串短,没超过,则不会崩溃,但返回的值肯定不对头.

fhmily · 发表于 2009-4-13 19:31:28

不熟悉VB，在慢慢的摸索，经常出一些莫名其妙的问题[em53]
 
最后还是用VC先做了，不过说实话不甘心啊，还是想把这段东西弄明白
 
热心的版主再点拨我一下吧=.=
 
API中的这个函数
u_short WSAAPI htons(   __in  u_short hostshort ); 
原理其实就是把一个word中的2个16位进行颠倒
但是VB里面没有unsign类型数据，如果用integer的话会溢出，而long的话又无法带入其它函数中，这种情况该如何处理呢？

马大哈 · 发表于 2009-4-14 00:32:46

"无法带入其它函数中"作何解释呢?
 
以下是我的测试代码:
 
Option Explicit
 
Private Declare Function htons Lib "ws2_32.dll" ( _      ByVal hostshort As Integer) As Integer
 
Private Sub Command1_Click()     MsgBox Hex(htons(&H3498)) End Sub
 
INTEGER是2字节,而htons是对WORD高低位反一下,只要输入的值是2字节,理论上不会溢出的.
 
另外,欢迎讨论!

fhmily · 发表于 2009-4-15 10:01:44

&H是不是C++里面的0x？
 
如果是的话我就明白问题出在哪里了
 
等这两天忙完了好好的从头把那段程序用VB做一次
 
最后还是谢谢版主，这么热心的版主这年头太太太难见到了，以后会经常来论坛学习的[em68]

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