Last active
March 1, 2024 01:55
-
-
Save incebellipipo/ff914d8136844ef4c9775d0055da14cf to your computer and use it in GitHub Desktop.
Simple IP management with netlink socket
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| #include <stdlib.h> | |
| #include <unistd.h> | |
| #include <stdio.h> | |
| #include <asm/types.h> | |
| #include <sys/socket.h> | |
| #include <arpa/inet.h> | |
| #include <netinet/in.h> | |
| #include <linux/netlink.h> | |
| #include <linux/rtnetlink.h> | |
| #include <malloc.h> | |
| #include <string.h> | |
| #include <iostream> | |
| using namespace std; | |
| struct rtnl_handle | |
| { | |
| int fd; | |
| struct sockaddr_nl local; | |
| struct sockaddr_nl peer; | |
| __u32 seq; | |
| __u32 dump; | |
| }; | |
| typedef struct | |
| { | |
| __u8 family; | |
| __u8 bytelen; | |
| __s16 bitlen; | |
| __u32 flags; | |
| __u32 data[8]; | |
| } inet_prefix; | |
| // This function is to open the netlink socket as the name suggests. | |
| int netlink_open(struct rtnl_handle* rth) | |
| { | |
| int addr_len; | |
| memset(rth, 0, sizeof(rth)); | |
| // Creating the netlink socket of family NETLINK_ROUTE | |
| rth->fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE); | |
| if (rth->fd < 0) | |
| { | |
| perror("cannot open netlink socket"); | |
| return -1; | |
| } | |
| memset(&rth->local, 0, sizeof(rth->local)); | |
| rth->local.nl_family = AF_NETLINK; | |
| rth->local.nl_groups = 0; | |
| // Binding the netlink socket | |
| if (bind(rth->fd, (struct sockaddr*)&rth->local, sizeof(rth->local)) < 0) | |
| { | |
| perror("cannot bind netlink socket"); | |
| return -1; | |
| } | |
| addr_len = sizeof(rth->local); | |
| if (getsockname(rth->fd, (struct sockaddr*)&rth->local, (socklen_t*) &addr_len) < 0) | |
| { | |
| perror("cannot getsockname"); | |
| return -1; | |
| } | |
| if (addr_len != sizeof(rth->local)) | |
| { | |
| fprintf(stderr, "wrong address lenght %d\n", addr_len); | |
| return -1; | |
| } | |
| if (rth->local.nl_family != AF_NETLINK) | |
| { | |
| fprintf(stderr, "wrong address family %d\n", rth->local.nl_family); | |
| return -1; | |
| } | |
| rth->seq = time(NULL); | |
| return 0; | |
| } | |
| // This function does the actual reading and writing to the netlink socket | |
| int rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n, pid_t peer, | |
| unsigned groups, struct nlmsghdr *answer) | |
| { | |
| int status; | |
| struct nlmsghdr *h; | |
| struct sockaddr_nl nladdr; | |
| // Forming the iovector with the netlink packet. | |
| struct iovec iov = { (void*)n, n->nlmsg_len }; | |
| char buf[8192]; | |
| // Forming the message to be sent. | |
| struct msghdr msg = { (void*)&nladdr, sizeof(nladdr), &iov, 1, NULL, 0, 0 }; | |
| // Filling up the details of the netlink socket to be contacted in the | |
| // kernel. | |
| memset(&nladdr, 0, sizeof(nladdr)); | |
| nladdr.nl_family = AF_NETLINK; | |
| nladdr.nl_pid = peer; | |
| nladdr.nl_groups = groups; | |
| n->nlmsg_seq = ++rtnl->seq; | |
| if (answer == NULL) | |
| n->nlmsg_flags |= NLM_F_ACK; | |
| // Actual sending of the message, status contains success/failure | |
| status = sendmsg(rtnl->fd, &msg, 0); | |
| if (status < 0) | |
| return -1; | |
| } | |
| // This is the utility function for adding the parameters to the packet. | |
| int addattr_l(struct nlmsghdr *n, int maxlen, int type, void *data, int alen) | |
| { | |
| int len = RTA_LENGTH(alen); | |
| struct rtattr *rta; | |
| if (NLMSG_ALIGN(n->nlmsg_len) + len > maxlen) | |
| return -1; | |
| rta = (struct rtattr*)(((char*)n) + NLMSG_ALIGN(n->nlmsg_len)); | |
| rta->rta_type = type; | |
| rta->rta_len = len; | |
| memcpy(RTA_DATA(rta), data, alen); | |
| n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + len; | |
| return 0; | |
| } | |
| int get_addr_1(inet_prefix *addr, const char *name, int family) | |
| { | |
| memset(addr, 0, sizeof(*addr)); | |
| if (strcmp(name, "default") == 0 || | |
| strcmp(name, "all") == 0 || | |
| strcmp(name, "any") == 0) { | |
| if (family == AF_DECnet) | |
| return -1; | |
| addr->family = family; | |
| addr->bytelen = (family == AF_INET6 ? 16 : 4); | |
| addr->bitlen = -1; | |
| return 0; | |
| } | |
| if (strchr(name, ':')) { | |
| addr->family = AF_INET6; | |
| if (family != AF_UNSPEC && family != AF_INET6) | |
| return -1; | |
| if (inet_pton(AF_INET6, name, addr->data) <= 0) | |
| return -1; | |
| addr->bytelen = 16; | |
| addr->bitlen = -1; | |
| return 0; | |
| } | |
| addr->family = AF_INET; | |
| if (family != AF_UNSPEC && family != AF_INET) | |
| return -1; | |
| struct in_addr inAddr; | |
| inet_pton(AF_INET, name, (void*)&inAddr); | |
| memcpy(&addr->data,&inAddr.s_addr, sizeof(inAddr.s_addr)); | |
| // if (get_addr_ipv4((__u8 *)addr->data, name) <= 0) | |
| // return -1; | |
| addr->bytelen = 4; | |
| addr->bitlen = -1; | |
| return 0; | |
| } | |
| int get_prefix(inet_prefix *dst, char *arg, int family) | |
| { | |
| int err; | |
| unsigned plen; | |
| memset(dst, 0, sizeof(*dst)); | |
| if (strcmp(arg, "default") == 0 || | |
| strcmp(arg, "any") == 0 || | |
| strcmp(arg, "all") == 0) { | |
| if (family == AF_DECnet) | |
| return -1; | |
| dst->family = family; | |
| dst->bytelen = 0; | |
| dst->bitlen = 0; | |
| return 0; | |
| } | |
| err = get_addr_1(dst, arg, family); | |
| if (err == 0) { | |
| switch(dst->family) { | |
| case AF_INET6: | |
| dst->bitlen = 128; | |
| break; | |
| case AF_DECnet: | |
| dst->bitlen = 16; | |
| break; | |
| default: | |
| case AF_INET: | |
| dst->bitlen = 32; | |
| } | |
| } | |
| return err; | |
| } | |
| int add_IP_Address(char * IP, struct rtnl_handle * rth) | |
| { | |
| inet_prefix lcl; | |
| // structure of the netlink packet. | |
| struct { | |
| struct nlmsghdr n; | |
| struct ifaddrmsg ifa; | |
| char buf[1024]; | |
| } req; | |
| memset(&req, 0, sizeof(req)); | |
| req.n.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifaddrmsg)); | |
| req.n.nlmsg_type = RTM_NEWADDR; | |
| req.n.nlmsg_flags = NLM_F_CREATE | NLM_F_EXCL | NLM_F_REQUEST; | |
| req.ifa.ifa_family = AF_INET ; | |
| req.ifa.ifa_prefixlen = 32 ; | |
| req.ifa.ifa_index = 4 ; // get the loopback index | |
| req.ifa.ifa_scope = 0 ; | |
| get_prefix(&lcl, IP, req.ifa.ifa_family); | |
| if (req.ifa.ifa_family == AF_UNSPEC) | |
| req.ifa.ifa_family = lcl.family; | |
| struct in_addr inAddr; | |
| inet_pton(AF_INET, IP, (void*)&inAddr); | |
| addattr_l(&req.n, sizeof(req), IFA_LOCAL, &inAddr, sizeof(inAddr)); | |
| if (rtnl_talk(rth, &req.n, 0, 0, NULL) < 0) | |
| return -2; | |
| } | |
| int remove_IP_Address(char * IP, struct rtnl_handle * rth) | |
| { | |
| inet_prefix lcl; | |
| // structure of the netlink packet. | |
| struct { | |
| struct nlmsghdr n; | |
| struct ifaddrmsg ifa; | |
| char buf[1024]; | |
| } req; | |
| memset(&req, 0, sizeof(req)); | |
| req.n.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifaddrmsg)); | |
| // req.n.nlmsg_type = RTM_NEWADDR; | |
| // req.n.nlmsg_flags = NLM_F_CREATE | NLM_F_EXCL | NLM_F_REQUEST; | |
| req.n.nlmsg_type = RTM_DELADDR; | |
| req.n.nlmsg_flags = NLM_F_REQUEST; | |
| req.ifa.ifa_family = AF_INET ; | |
| req.ifa.ifa_prefixlen = 32 ; | |
| req.ifa.ifa_index = 4 ; // get the loopback index | |
| req.ifa.ifa_scope = 0 ; | |
| if (rtnl_talk(rth, &req.n, 0, 0, NULL) < 0) | |
| return -2; | |
| } | |
| int main(int argc, char **argv) { | |
| struct rtnl_handle * rth; | |
| rth = (rtnl_handle*)malloc(sizeof(rtnl_handle)); | |
| netlink_open(rth); | |
| if(argc < 3){ | |
| return EXIT_FAILURE; | |
| } | |
| if( strcmp(argv[1], "add") == 0 ){ | |
| add_IP_Address(argv[2], rth); | |
| } if ( strcmp (argv[1], "del") == 0){ | |
| remove_IP_Address(argv[2], rth); | |
| } else { | |
| return EXIT_FAILURE; | |
| } | |
| return EXIT_SUCCESS; | |
| } |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment