IP_RECVDSTADDR undefined

IP_RECVDSTADDR undefined

刺猬@http://blog.csdn.net/littlehedgehog

今天写一个unp上面的例子程序，被IP_RECVDSTADDR undefined难倒了，gcc老是报错说该宏未定义，最后还是在老外的一个“开源苹果”网站查到原来linux修改了相关的函数定义，包括cmsghdr及setsockopt都采用了linux系统自己的定义。顺便说一下，这个貌似并不是linux故意另辟蹊径，在solari和bsd上面也是各不相同的。这里把代码贴出来，方便后面的同学。

 

 

#include "./unix.h"#include <sys/param.h>ssize_t recvmsg_flags(int sockfd, void *buff, size_t nbytes, int *pflags, struct sockaddr *praddr, socklen_t *psocklen, struct in_addr *plocaladdr){ssize_t ret;struct msghdr msg;struct cmsghdr *cmsgptr;struct iovec iov[1];union{struct cmsghdrcmsg;charcontrol[CMSG_SPACE(sizeof(struct in_pktinfo))];}cmsg_un;msg.msg_name= praddr;msg.msg_namelen= *psocklen;iov[0].iov_base= buff;iov[0].iov_len= nbytes;msg.msg_iov= iov;msg.msg_iovlen= 1;msg.msg_control= cmsg_un.control;msg.msg_controllen= sizeof(cmsg_un.control);msg.msg_flags= 0;/*这个flags设置问题*/if ((ret = recvmsg(sockfd, &msg, 0)) < 0){perror("recvmsg");return ret;}*psocklen = msg.msg_namelen;*pflags= msg.msg_flags;if ((msg.msg_controllen < sizeof(struct cmsghdr)) || (msg.msg_flags & MSG_CTRUNC) || !plocaladdr){return ret;}for (cmsgptr = CMSG_FIRSTHDR(&msg); cmsgptr; cmsgptr = CMSG_NXTHDR(&msg, cmsgptr)){#if defined(IP_RECVDSTADDR)if (cmsgptr->cmsg_level == IPPROTO_IP && cmsgptr->cmsg_type == IP_RECVDSTADDR){memcpy(plocaladdr, CMSG_DATA(cmsgptr), sizeof(struct in_addr));}#elif defined(IP_PKTINFO)if (cmsgptr->cmsg_level == SOL_IP && cmsgptr->cmsg_type == IP_PKTINFO){struct in_pktinfo *in = (struct in_pktinfo *)CMSG_DATA(cmsgptr);memcpy(plocaladdr, &(in->ipi_addr), sizeof(struct in_addr));}#endif}return ret;}void echo(int sockfd, const struct sockaddr *pservaddr, socklen_t len, struct FILE *fp){intret;intflags = 0;const inton = 1;struct in_addrlocaladdr;charsendline[MAXLINE], recvline[MAXLINE];#if defined(IP_RECVDSTADDR)if (setsockopt(sockfd, IPPROTO_IP, IP_RECVDSTADDR, &on, sizeof(int)) < 0){perror("setsockopt");return;}#elif defined(IP_PKTINFO)if (setsockopt(sockfd, IPPROTO_IP, IP_PKTINFO, &on, sizeof(int)) < 0){perror("setsockopt");return;}#endifmemset(&localaddr, 0x00, sizeof(struct in_addr));while (fgets(sendline, MAXLINE, fp) != NULL){if (sendto(sockfd, sendline, strlen(sendline), 0x00, pservaddr, len) < 0){perror("sendto");return;}if ((ret = recvmsg_flags(sockfd, recvline, MAXLINE, &flags, pservaddr, &len, &localaddr)) < 0){return;}printf("recvmsg %d-byte datagram through %s/n", ret, inet_ntoa(localaddr));}}int main(int argc, char *argv[]){ int connfd; struct sockaddr_in servaddr; if ((connfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) { perror("socket"); exit(-1);} memset(&servaddr, 0x00, sizeof(servaddr)); servaddr.sin_family = AF_INET; servaddr.sin_port = htons(1988); servaddr.sin_addr.s_addr = inet_addr("192.168.149.95"); echo(connfd, (struct sockaddr *)&servaddr, sizeof(struct sockaddr_in), stdin); close(connfd); return 0;}