本人最近在学习socket程序的编写，使用sendmsg向外发送数据，但是接收端不能接收数据。代码是这样的：
#include<sys/socket.h> #include<netinet/in.h> #include<arpa/inet.h> // ntohs inet_ntoa #include<stdio.h> #include<string.h> #define MAX_LEN 100 static char *server="127.0.0.1"; static int port=1234; int parser_sender(struct sockaddr_in *addr,char *buf,int len) { printf("recv packet from %s %d\n",inet_ntoa(addr->sin_addr),ntohs(addr->sin_port)); printf("recv msg %s\n",buf); } int main() { char send[] = "hello yuna"; char buffer[MAX_LEN]; int fd; int nrec; struct sockaddr_in serv_socket,from; fd = socket(AF_INET, SOCK_DGRAM, 0); bzero(&serv_socket, sizeof(serv_socket)); serv_socket.sin_family = AF_INET; serv_socket.sin_port = htons(port); inet_pton(AF_INET, server, &serv_socket.sin_addr); struct msghdr msg; //bzero(&msg,sizeof(struct msghdr)); msg.msg_name = &serv_socket; msg.msg_namelen = sizeof(struct sockaddr_in); struct iovec io; io.iov_base = send; io.iov_len = sizeof(send); msg.msg_iov = &io; msg.msg_iovlen = 1; ssize_t send_size = sendmsg(fd, &msg, 0); msg.msg_name =&from; msg.msg_namelen =sizeof(struct sockaddr_in); io.iov_base =buffer; io.iov_len =MAX_LEN; nrec=recvmsg(fd,&msg,0); parser_sender(&from,buf,nrec); }
这是因为msg中的msg_control可能指向垃圾内存,解决办法就是加上注释掉的代码，将msg中的内存置零。至于为什么会出现这种情况，在此记录，等以后明白了，再续。
