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2b68cb77cd
All users of genl have the same code to open a genl socket and resolve the family for their specific protocol. Introduce a helper to initialize the handle, and use it in all the genl code. Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
81 lines
1.8 KiB
C
81 lines
1.8 KiB
C
/*
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* libgenl.c GENL library
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <linux/genetlink.h>
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#include "libgenl.h"
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static int genl_parse_getfamily(struct nlmsghdr *nlh)
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{
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struct rtattr *tb[CTRL_ATTR_MAX + 1];
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struct genlmsghdr *ghdr = NLMSG_DATA(nlh);
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int len = nlh->nlmsg_len;
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struct rtattr *attrs;
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if (nlh->nlmsg_type != GENL_ID_CTRL) {
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fprintf(stderr, "Not a controller message, nlmsg_len=%d "
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"nlmsg_type=0x%x\n", nlh->nlmsg_len, nlh->nlmsg_type);
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return -1;
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}
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len -= NLMSG_LENGTH(GENL_HDRLEN);
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if (len < 0) {
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fprintf(stderr, "wrong controller message len %d\n", len);
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return -1;
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}
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if (ghdr->cmd != CTRL_CMD_NEWFAMILY) {
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fprintf(stderr, "Unknown controller command %d\n", ghdr->cmd);
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return -1;
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}
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attrs = (struct rtattr *) ((char *) ghdr + GENL_HDRLEN);
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parse_rtattr(tb, CTRL_ATTR_MAX, attrs, len);
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if (tb[CTRL_ATTR_FAMILY_ID] == NULL) {
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fprintf(stderr, "Missing family id TLV\n");
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return -1;
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}
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return rta_getattr_u16(tb[CTRL_ATTR_FAMILY_ID]);
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}
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int genl_resolve_family(struct rtnl_handle *grth, const char *family)
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{
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GENL_REQUEST(req, 1024, GENL_ID_CTRL, 0, 0, CTRL_CMD_GETFAMILY,
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NLM_F_REQUEST);
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addattr_l(&req.n, sizeof(req), CTRL_ATTR_FAMILY_NAME,
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family, strlen(family) + 1);
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if (rtnl_talk(grth, &req.n, &req.n, sizeof(req)) < 0) {
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fprintf(stderr, "Error talking to the kernel\n");
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return -2;
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}
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return genl_parse_getfamily(&req.n);
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}
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int genl_init_handle(struct rtnl_handle *grth, const char *family,
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int *genl_family)
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{
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if (*genl_family >= 0)
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return 0;
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if (rtnl_open_byproto(grth, 0, NETLINK_GENERIC) < 0) {
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fprintf(stderr, "Cannot open generic netlink socket\n");
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return -1;
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}
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*genl_family = genl_resolve_family(grth, family);
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if (*genl_family < 0)
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return -1;
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return 0;
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}
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