如何调试 TCP recv()

Question

我有一个 client - server - server socket 双向通信模拟。

我的线路

recv(fd3, serv3_buf, BUFSIZE - 1, 0);

returns -1

如何使用 errno.h 调试 recv？

Answer 1

这里是recv相关错误的人工解释！

ERRORS These are some standard errors generated by the socket layer. Addi‐ tional errors may be generated and returned from the underlying proto‐ col modules; see their manual pages.

   EAGAIN or EWOULDBLOCK
          The socket is marked nonblocking and the receive operation would
          block, or a receive timeout had been set and the timeout expired
          before data was received.  POSIX.1-2001 allows either  error  to
          be  returned for this case, and does not require these constants
          to have the same value, so a portable application  should  check
          for both possibilities.

   EBADF  The argument sockfd is an invalid descriptor.

   ECONNREFUSED
          A remote host refused to allow the network connection (typically
          because it is not running the requested service).

   EFAULT The  receive  buffer  pointer(s)  point  outside  the  process's
          address space.

   EINTR  The  receive  was interrupted by delivery of a signal before any
          data were available; see signal(7).

   EINVAL Invalid argument passed.

   ENOMEM Could not allocate memory for recvmsg().

   ENOTCONN
          The socket is associated with a connection-oriented protocol and
          has not been connected (see connect(2) and accept(2)).

   ENOTSOCK
          The argument sockfd does not refer to a socket.

您可以使用 perror() 和 strerror() 来管理 recv returns -1 时的错误字符串。

见相关man(ual)解释：

perror

strerror

如何调试 TCP recv()

How to debug TCP recv()

c

sockets

tcp

errno

recv