1 /* 2 * libgenl.c GENL library 3 */ 4 5 #include <stdio.h> 6 #include <stdlib.h> 7 #include <unistd.h> 8 9 #include <linux/genetlink.h> 10 #include "libgenl.h" 11 12 static int genl_parse_getfamily(struct nlmsghdr *nlh) 13 { 14 struct rtattr *tb[CTRL_ATTR_MAX + 1]; 15 struct genlmsghdr *ghdr = NLMSG_DATA(nlh); 16 int len = nlh->nlmsg_len; 17 struct rtattr *attrs; 18 19 if (nlh->nlmsg_type != GENL_ID_CTRL) { 20 fprintf(stderr, "Not a controller message, nlmsg_len=%d " 21 "nlmsg_type=0x%x\n", nlh->nlmsg_len, nlh->nlmsg_type); 22 return -1; 23 } 24 25 len -= NLMSG_LENGTH(GENL_HDRLEN); 26 27 if (len < 0) { 28 fprintf(stderr, "wrong controller message len %d\n", len); 29 return -1; 30 } 31 32 if (ghdr->cmd != CTRL_CMD_NEWFAMILY) { 33 fprintf(stderr, "Unknown controller command %d\n", ghdr->cmd); 34 return -1; 35 } 36 37 attrs = (struct rtattr *) ((char *) ghdr + GENL_HDRLEN); 38 parse_rtattr(tb, CTRL_ATTR_MAX, attrs, len); 39 40 if (tb[CTRL_ATTR_FAMILY_ID] == NULL) { 41 fprintf(stderr, "Missing family id TLV\n"); 42 return -1; 43 } 44 45 return rta_getattr_u16(tb[CTRL_ATTR_FAMILY_ID]); 46 } 47 48 int genl_resolve_family(struct rtnl_handle *grth, const char *family) 49 { 50 GENL_REQUEST(req, 1024, GENL_ID_CTRL, 0, 0, CTRL_CMD_GETFAMILY, 51 NLM_F_REQUEST); 52 53 addattr_l(&req.n, sizeof(req), CTRL_ATTR_FAMILY_NAME, 54 family, strlen(family) + 1); 55 56 if (rtnl_talk(grth, &req.n, &req.n, sizeof(req)) < 0) { 57 fprintf(stderr, "Error talking to the kernel\n"); 58 return -2; 59 } 60 61 return genl_parse_getfamily(&req.n); 62 } 63 64 int genl_init_handle(struct rtnl_handle *grth, const char *family, 65 int *genl_family) 66 { 67 if (*genl_family >= 0) 68 return 0; 69 70 if (rtnl_open_byproto(grth, 0, NETLINK_GENERIC) < 0) { 71 fprintf(stderr, "Cannot open generic netlink socket\n"); 72 return -1; 73 } 74 75 *genl_family = genl_resolve_family(grth, family); 76 if (*genl_family < 0) 77 return -1; 78 79 return 0; 80 } 81
