UDP WSARecvMsg返回WSAEWOULDBLOCK但Wireshark捕获数据包

Question

从UDP套接字（端口7078）读取数据时出现问题。我已经调用了WSARecvMsg函数并收到了WSAEWOULDBLOCK错误。但是，Wireshark在端口7078上捕获传入的UDP数据包！请帮帮我！

这是我创建和绑定套接字

的代码

static ortp_socket_t create_and_bind(const char *addr, int *port, int *sock_family, bool_t reuse_addr){
    int err;
    int optval = 1;
    ortp_socket_t sock=-1;
    char num[8];
    struct addrinfo hints, *res0, *res;

    if (*port==-1) *port=0;
    if (*port==0) reuse_addr=FALSE;

    memset(&hints, 0, sizeof(hints));
    hints.ai_family = PF_UNSPEC;
    hints.ai_socktype = SOCK_DGRAM;
    snprintf(num, sizeof(num), "%d",*port);
    err = getaddrinfo(addr,num, &hints, &res0);
    if (err!=0) {
        ortp_warning ("Error in getaddrinfo on (addr=%s port=%i): %s", addr, *port, gai_strerror(err));
        return -1;
    }

    for (res = res0; res; res = res->ai_next) {
        sock = socket(res->ai_family, res->ai_socktype, 0);
        if (sock==-1)
            continue;

        if (reuse_addr){
            err = setsockopt (sock, SOL_SOCKET, SO_REUSEADDR,
                    (SOCKET_OPTION_VALUE)&optval, sizeof (optval));
            if (err < 0)
            {
                ortp_warning ("Fail to set rtp address reusable: %s.", getSocketError());
            }
        }
        err = 0;
        switch (res->ai_family) {
            default:
            case AF_INET:
                break;
            case AF_INET6:
                break;
        }
        if (err < 0) {
            ortp_warning("Fail to set recv TTL/HL socket option: %s.", getSocketError());
        }

        *sock_family=res->ai_family;
        err = bind (sock, res->ai_addr, res->ai_addrlen);
        if (err != 0){
            ortp_debug ("Fail to bind rtp socket to (addr=%s port=%i) : %s.", addr, *port, getSocketError());
            close_socket (sock);
            sock=-1;
            continue;
        }
        switch (res->ai_family)
          {
            case AF_INET:
              if (IN_MULTICAST(ntohl(((struct sockaddr_in *) res->ai_addr)->sin_addr.s_addr)))
            {
                  struct ip_mreq mreq;
              mreq.imr_multiaddr.s_addr = ((struct sockaddr_in *) res->ai_addr)->sin_addr.s_addr;
              mreq.imr_interface.s_addr = INADDR_ANY;
              err = setsockopt(sock, IPPROTO_IP, IP_ADD_MEMBERSHIP, (SOCKET_OPTION_VALUE) &mreq, sizeof(mreq));
              if (err < 0){
                ortp_warning ("Fail to join address group: %s.", getSocketError());
                close_socket (sock);
                sock=-1;
                continue;
                }
            }
              break;
            case AF_INET6:
              if (IN6_IS_ADDR_MULTICAST(&(((struct sockaddr_in6 *) res->ai_addr)->sin6_addr)))
            {
              struct ipv6_mreq mreq;
              mreq.ipv6mr_multiaddr = ((struct sockaddr_in6 *) res->ai_addr)->sin6_addr;
              mreq.ipv6mr_interface = 0;
              err = setsockopt(sock, IPPROTO_IPV6, IPV6_JOIN_GROUP, (SOCKET_OPTION_VALUE)&mreq, sizeof(mreq));
              if (err < 0)
                {
                  ortp_warning ("Fail to join address group: %s.", getSocketError());
                  close_socket (sock);
                  sock=-1;
                  continue;
                }
            }
              break;
          }
        break;
    }
    freeaddrinfo(res0);

#if defined(WIN32) || defined(_WIN32_WCE)
    if (ortp_WSARecvMsg == NULL) {
        GUID guid = WSAID_WSARECVMSG;
        DWORD bytes_returned;
        if (WSAIoctl(sock, SIO_GET_EXTENSION_FUNCTION_POINTER, &guid, sizeof(guid),
            &ortp_WSARecvMsg, sizeof(ortp_WSARecvMsg), &bytes_returned, NULL, NULL) == SOCKET_ERROR) {
            ortp_warning("WSARecvMsg function not found.");
        }
    }
#endif
    if (sock!=-1){
        set_non_blocking_socket (sock);
        if (*port==0){
            struct sockaddr_storage saddr;
            socklen_t slen=sizeof(saddr);
            err=getsockname(sock,(struct sockaddr*)&saddr,&slen);
            if (err==-1){
                ortp_error("getsockname(): %s",getSocketError());
                close(sock);
                return (ortp_socket_t)-1;
            }
            err=getnameinfo((struct sockaddr*)&saddr, slen, NULL, 0, num, sizeof(num), NI_NUMERICHOST | NI_NUMERICSERV);
            if (err!=0){
                ortp_error("getnameinfo(): %s",gai_strerror(err));
                close(sock);
                return (ortp_socket_t)-1;
            }
            *port=atoi(num);
        }

    }
    return sock;

}

我使用WSAIoctl来获取WSARECVMSG函数指针

typedef INT  (WINAPI * LPFN_WSARECVMSG)(SOCKET, LPWSAMSG, LPDWORD, LPWSAOVERLAPPED, LPWSAOVERLAPPED_COMPLETION_ROUTINE);
static LPFN_WSARECVMSG ortp_WSARecvMsg = NULL;
if (ortp_WSARecvMsg == NULL) {
        GUID guid = WSAID_WSARECVMSG;
        DWORD bytes_returned;
        if (WSAIoctl(sock, SIO_GET_EXTENSION_FUNCTION_POINTER, &guid, sizeof(guid),
            &ortp_WSARecvMsg, sizeof(ortp_WSARecvMsg), &bytes_returned, NULL, NULL) == SOCKET_ERROR) {
            ortp_warning("WSARecvMsg function not found.");
        }
}

我接收数据的代码

int rtp_session_rtp_recv_abstract(ortp_socket_t socket, mblk_t *msg, int flags, struct sockaddr *from, socklen_t *fromlen) {
    int ret;
    int bufsz = (int) (msg->b_datap->db_lim - msg->b_datap->db_base);
    char control[512];
    WSAMSG msghdr;
    WSACMSGHDR *cmsghdr;
    WSABUF data_buf;
    DWORD bytes_received;
    if (ortp_WSARecvMsg == NULL) {
        return recvfrom(socket, (char *)msg->b_wptr, bufsz, flags, from, fromlen);
    }

    memset(&msghdr, 0, sizeof(msghdr));
    memset(control, 0, sizeof(control));
    if(from != NULL && fromlen != NULL) {
        msghdr.name = from;
        msghdr.namelen = *fromlen;
    }
    data_buf.buf = (char *)msg->b_wptr;
    data_buf.len = bufsz;
    msghdr.lpBuffers = &data_buf;
    msghdr.dwBufferCount = 1;
    msghdr.Control.buf = control;
    msghdr.Control.len = sizeof(control);
    msghdr.dwFlags = flags;
    ret = ortp_WSARecvMsg(socket, &msghdr, &bytes_received, NULL, NULL);
    if(fromlen != NULL)
        *fromlen = msghdr.namelen;
    if(ret >= 0) {
        ret = bytes_received;
    }
    else 
    {
        int i;
        long m_ErrorCode = WSAGetLastError();
        i = 0;
    }
    return ret;
}