pptp_gre_header
struct pptp_gre_header *grehdr;
grehdr = (struct pptp_gre_header *)opkt;
opkt += sizeof(struct pptp_gre_header);
struct pptp_gre_header *grehdr;
iphdr->ip_len < hlen + sizeof(struct pptp_gre_header)) {
grehdr = (struct pptp_gre_header *)pkt;
pkt += sizeof(struct pptp_gre_header);
lpkt -= sizeof(struct pptp_gre_header);
static void pptp_gre_header_string (struct pptp_gre_header *, char *, int);
pptp_gre_header_string(struct pptp_gre_header *grehdr, char *buf, int lbuf)