现在我正在处理c上的数据包,我已经成功创建了icmp数据包发送,但是我没有办法将它自己放入套接字中,所以我发现了多个应执行类似操作的代码。所以他们都包含我完全不了解的部分,我找不到任何有关它的信息。他们正在铸造结构与数据包到一个字符指针,如下所示:对指针施放结构
static char *packet;
ip= (struct iphdr*) packet;
icmp= (struct icmphdr*)(ip+1);
当我试过这个时,我得到了分段错误。请向我解释铸造结构的目的,以及为什么同一段代码在我的情况下不起作用。谢谢。
EDITED
struct iphdr *ip;
struct icmphdr *icmp;
ip=malloc(sizeof(*ip));
icmp=malloc(sizeof(*icmp));
int sock;
uint16_t psize = sizeof(*icmp)+sizeof(*ip);
static char *packet;
ip= (struct iphdr*) packet;
icmp= (struct icmphdr*)(ip+1);
unsigned int id = (unsigned int)rand();
unsigned int seq = (unsigned int)rand();
ip->version = 4;
ip->ihl = 5;
ip->tos = 0;
ip->tot_len = htons(psize);
ip->id = id;
ip->frag_off = 0;
ip->ttl = 255;
ip->protocol = IPPROTO_ICMP;
ip->saddr = subnet.ipDec;
icmp->type = 8;
icmp->code = 0;
icmp->un.echo.id=id;
icmp->un.echo.sequence=seq;
icmp->checksum=0;
sock=socket(AF_INET, SOCK_RAW, IPPROTO_ICMP);
struct sockaddr_in destIP;
destIP.sin_family=AF_INET;
uint32_t destIPDec=0;
ip->daddr = destIPDec;
destIP.sin_addr.s_addr=destIPDec;
sendto(sock, packet, psize, 0, (struct sockaddr*) &destIP, sizeof(destIP));
显示更多代码,我们不禁用3行代码。 –
我添加了icmp数据包的完整部分。 –