我的C ++应用程序中出现了从32位Linux移植到32位FreeBSD 8.1时出现的故障。我有一个无法连接的TCP套接字连接。在对connect（）的调用中，我得到了errno == EINVAL的错误结果，其中connect（）的手册页没有覆盖。
这个错误意味着什么，哪个参数无效？消息只是说：“无效的参数”。
以下是连接的一些细节：
family: AF_INET
len: 16
port: 2357
addr: 10.34.49.13
但它并不总是失败。只有让机器空闲几个小时后，FreeBSD版本才会失败。但是在失败一次后，它会可靠地工作，直到你让它再次闲置一段时间。
以下是一些代码：
void setSocketOptions(const int skt);
void buildAddr(sockaddr_in &addr, const std::string &ip,
const ushort port);
void deepBind(const int skt, const sockaddr_in &addr);
void
test(const std::string &localHost, const std::string &remoteHost,
const ushort localPort, const ushort remotePort,
sockaddr_in &localTCPAddr, sockaddr_in &remoteTCPAddr)
{
const int skt = socket(AF_INET, SOCK_STREAM, 0);
if (0 > skt) {
clog << "Failed to create socket: (errno " << errno
<< ") " << strerror(errno) << endl;
throw;
}
setSocketOptions(skt);
// Build the localIp address and bind it to the feedback socket. Although
// it's not traditional for a client to bind the sending socket to a the
// local address, we do it to prevent connect() from using an ephemeral port
// which (our site's firewall may block). Also build the remoteIp address.
buildAddr(localTCPAddr, localHost, localPort);
deepBind(skt, localTCPAddr);
buildAddr(remoteTCPAddr, remoteHost, remotePort);
clog << "Info: Command connect family: "
<< (remoteTCPAddr.sin_family == AF_INET ? "AF_INET" : "<unknown>")
<< " len: " << int(remoteTCPAddr.sin_len)
<< " port: " << ntohs(remoteTCPAddr.sin_port)
<< " addr: " << inet_ntoa(remoteTCPAddr.sin_addr) << endl;
if (0 > ::connect(skt, (sockaddr*)& remoteTCPAddr, sizeof(sockaddr_in)))) {
switch (errno) {
case EINVAL: {
int value = -1;
socklen_t len = sizeof(value);
getsockopt(skt, SOL_SOCKET, SO_ERROR, &value, &len);
cerr << "Error: Command connect failed on local port "
<< getLocFbPort()
<< " and remote port " << remotePort
<< " to remote host '" << remoteHost
<< "' family: "
<< (remoteTCPAddr.sin_family == AF_INET ? "AF_INET" : "<unknown>")
<< " len: " << int(remoteTCPAddr.sin_len)
<< " port: " << ntohs(remoteTCPAddr.sin_port)
<< " addr: " << inet_ntoa(remoteTCPAddr.sin_addr)
<< ": Invalid argument." << endl;
cerr << "\tgetsockopt => "
<< ((value != 0) ? strerror(value): "success") << endl;
throw;
}
default: {
cerr << "Error: Command connect failed on local port "
<< localPort << " and remote port " << remotePort
<< ": (errno " << errno << ") " << strerror(errno) << endl;
throw;
}
}
}
}
void
setSocketOptions(int skt)
{
// See page 192 of UNIX Network Programming: The Sockets Networking API
// Volume 1, Third Edition by W. Richard Stevens et. al. for info on using
// ::setsockopt().
// According to "Linux Socket Programming by Example" p. 319, we must call
// setsockopt w/ SO_REUSEADDR option BEFORE calling bind.
int so_reuseaddr = 1; // Enabled.
int reuseAddrResult
= ::setsockopt(skt, SOL_SOCKET, SO_REUSEADDR, &so_reuseaddr,
sizeof(so_reuseaddr));
if (reuseAddrResult != 0) {
cerr << "Failed to set reuse addr on socket.";
throw;
}
// For every two hours of inactivity, a keepalive occurs.
int so_keepalive = 1; // Enabled. See page 200 for info on SO_KEEPALIVE.
int keepAliveResult =
::setsockopt(skt, SOL_SOCKET, SO_KEEPALIVE, &so_keepalive,
sizeof(so_keepalive));
if (keepAliveResult != 0) {
cerr << "Failed to set keep alive on socket.";
throw;
}
struct linger so_linger;
so_linger.l_onoff = 1; // Turn linger option on.
so_linger.l_linger = 5; // Linger time in seconds. (See page 202)
int lingerResult
= ::setsockopt(skt, SOL_SOCKET, SO_LINGER, &so_linger,
sizeof(so_linger));
if (lingerResult != 0) {
cerr << "Failed to set linger on socket.";
throw;
}
// Disable the Nagel algorithm on the command channel. SOL_TCP is not
// defined on FreeBSD
#ifndef SOL_TCP
#define SOL_TCP (::getprotobyname("TCP")->p_proto)
#endif
unsigned int tcpNoDelay = 1;
int noDelayResult
= ::setsockopt(skt, SOL_TCP, TCP_NODELAY, &tcpNoDelay,
sizeof(tcpNoDelay));
if (noDelayResult != 0) {
cerr << "Failed to set tcp no delay on socket.";
throw;
}
}
void
buildAddr(sockaddr_in &addr, const std::string &ip, const ushort port)
{
memset(&addr, 0, sizeof(sockaddr_in)); // Clear all fields.
addr.sin_len = sizeof(sockaddr_in);
addr.sin_family = AF_INET; // Set the address family
addr.sin_port = htons(port); // Set the port.
if (0 == inet_aton(ip.c_str(), &addr.sin_addr)) {
cerr << "BuildAddr IP.";
throw;
}
};
void
deepBind(const int skt, const sockaddr_in &addr)
{
// Bind the requested port.
if (0 <= ::bind(skt, (sockaddr *)&addr, sizeof(addr))) {
return;
}
// If the port is already in use, wait up to 100 seconds.
int count = 0;
ushort port = ntohs(addr.sin_port);
while ((errno == EADDRINUSE) && (count < 10)) {
clog << "Waiting for port " << port << " to become available..."
<< endl;
::sleep(10);
++count;
if (0 <= ::bind(skt, (sockaddr*)&addr, sizeof(addr))) {
return;
}
}
cerr << "Error: failed to bind port.";
throw;
}
以下是EINVAL的示例输出（它在这里并不总是失败，有时它会成功并且在通过套接字发送的第一个数据包失败时失败）：
Info: Command connect family: AF_INET len: 16 port: 2357 addr: 10.34.49.13
Error: Command connect failed on local port 2355 and remote port 2357 to remote host '10.34.49.13' family: AF_INET len: 16 port: 2357 addr: 10.34.49.13: Invalid argument.
getsockopt => success
答案 0 :(得分：6)
我弄清楚问题是什么，我第一次得到一个ECONNREFUSED，在Linux上我可以在短暂停顿后重试connect（）并且一切都很好，但在FreeBSD上，以下的connect（）重试失败与EINVAL。
解决方案是当ECONNREFUSED进一步备份时，而是开始重试上面的test（）定义的开始。通过此更改，代码现在可以正常运行。
答案 1 :(得分：3)
有趣的是FreeBSD connect() manpage没有列出EINVAL。 A different BSD manpage州：
[EINVAL] An invalid argument was detected (e.g., address_len is
not valid for the address family, the specified
address family is invalid).
基于不同BSD风格的不同文档，我想冒险在FreeBSD中可能存在未记录的返回代码可能性，例如参见here。
我的建议是在致电sizeof之前打印出地址长度以及套接字地址结构的connect和内容 - 这有助于您找出问题所在。
除此之外，如果您向我们展示用于设置连接的代码，则可能是最好的。这包括用于套接字地址的类型（struct sockaddr，struct sockaddr_in等），初始化它的代码以及对connect的实际调用。这将使协助变得更容易。
答案 2 :(得分：1)
当地的地址是什么？你是默默地忽略来自bind(2)的错误，这似乎不仅形式不好，而且可能导致这个问题开始！