我有创建 UDP 套接字来接收多播数据包的项目代码。该代码可移植到 Linux 和 Solaris 操作系统。我的项目的一个扩展是在使用 recvmsg() 函数时检索 UDP 数据包的源 IP 地址。我曾就此事询问过一位专家,她提到 Linux 似乎能够提供源 IP 地址,但 Solaris 在使用 recvmsg() 函数时可能无法提供。所以我在这里提出问题,我能否在 Solaris 10 上使用 recvmsg() 检索源 IP 地址?
操作系统:Solaris 10、Sunstudio 12 cc(无 U1 或 U2)。代码库:C/C++
//Socket initially opened with the following options from a different function.
// This connects the socket to receive multicast:
setsockopt(data->fd, IPPROTO_IP, IP_ADD_SOURCE_MEMBERSHIP,
(char *)&mregs, sizeof(mregs) ) < 0)
//A different function performs an infinite loop reading from the socket:
struct iovec vector;
vector.iov_base = buf; //passed in param
vector.iov_len = len; //passed in param
struct msghdr msg;
char caddr[100] ;
msg.msg_name = caddr;
msg.msg_namelen = 100;
msg.msg_iov = &vector;
msg.msg_iovlen = 1;
int flags = 0;
char controlBuffer[1024];
msg.msg_control = controlBuffer;
msg.msg_controllen = 1024;
bytes = ::recvmsg(data->fd, &msg, flags);
//removed error checking
struct cmsghdr *cmsg;
struct in_pktinfo *dest_ip_ptr;
rrcp_u32_t dest_ip = 0;
cmsg = CMSG_FIRSTHDR(&msg);
for ( cmsg = CMSG_FIRSTHDR(&msg);
cmsg != NULL;
cmsg = CMSG_NXTHDR( &msg, cmsg ) )
{
//if ( cmsg->cmsg_type == IPPROTO_IP && cmsg->cmsg_level == IP_PKTINFO )
{
#ifdef Linux
struct in_pktinfo *dest_ip_ptr = (struct in_pktinfo*)CMSG_DATA(cmsg);
dest_ip = dest_ip_ptr->ipi_addr.s_addr;
#else
//in_addr only has 1 address
struct in_addr * dest_ip_ptr = (struct in_addr *)CMSG_DATA(cmsg);
dest_ip = dest_ip_ptr->_S_un._S_addr;
#endif
}
}
if( ipaddr )
ipaddr->IP = dest_ip;
//according to the Linux article mentioned below, the caddr should have the source
//socket address. In my case, the caddr field is not filled with any coherent data,
//so this does not seem to be the source address. Then again, "source socket" could
//be the interface IP on the local machine, which isn't what I need.
我也看到了以下文章,但他们似乎没有回答我的问题: Get destination address of a received UDP packet,解决方案在:Get destination address of a received UDP packet