#include <stdio.h>
#include <string.h>
#include <linux/bpf.h>
#include <unistd.h>
#include <asm/unistd.h>
#include <net/if.h>
#include "l3lb.h"

static inline int sys_bpf(enum bpf_cmd cmd, union bpf_attr *attr, unsigned int size)
{
	return syscall(__NR_bpf, cmd, attr, size);
}

static inline __u64 ptr_to_u64(const void *ptr)
{
	return (__u64) (unsigned long) ptr;
}

unsigned int parse_ipnetwork(char *p) {
    int k, i=0, b;
    unsigned int ip=0, mk=0xffffffff;
    for (k=0; k<4; k++) {
        b=0;
        if (p[i]<'0'||p[i]>'9') return 0;
        while(p[i]>='0'&&p[i]<='9') {
            b=b*10+p[i++]-'0';
            if (b>256) return 0;
        }
        if (k<3&&p[i]!='.') return 0;
        if (k==3&&p[i]!=0&&p[i]!='/') return 0;
        ip = (ip<<8) | b;
        if (k==3) break;
        i++;
    }
    if (p[i]==0) mk=0xffffffff;
    else if (p[i]=='/') {
        i++; b=0;
        while(p[i]>='0'&&p[i]<='9') {
            b=b*10+p[i++]-'0';
            if (b>32) return 0;
        }
        if (p[i]!=0||b>32||b<1) return 0;
        b=32-b;
        mk>>=b; mk<<=b;
    } else return 0;
    return ip&mk;
}

int main(int argc, char *argv[]) {
    unsigned int ip;
    BNode value;
    union bpf_attr attr_pin, attr_elem;
    int fd, rc;
    memset(&attr_pin, 0, sizeof(attr_pin));
    memset(&attr_elem, 0, sizeof(attr_elem));
    attr_pin.pathname = ptr_to_u64("/sys/fs/bpf/l3bindings");
    fd = sys_bpf(BPF_OBJ_GET, &attr_pin, sizeof(attr_pin));
    if (fd<0) {
        printf("bpf map /sys/fs/bpf/l3bindings not exist yet, need to start bpf prog first\n");
        return 1;
    }
    attr_elem.map_fd = fd;
    attr_elem.key = ptr_to_u64(&ip);
    attr_elem.value = ptr_to_u64(&value);
    if (argc != 6) {
        printf("usage: %s [sip] [if_from] [ip_from] [if_to] [ip_to]\n", argv[0]);
        return 1;
    }
    ip = parse_ipnetwork(argv[1]);
    if (ip == 0) {
        printf("ip network %s not valid\n", argv[1]);
        return 1;
    }
    value.ifin = if_nametoindex(argv[2]);
    if (!value.ifin) {
        printf("interface %s not found\n", argv[2]);
        return 1;
    }
    value.saddr  = parse_ip(argv[3]);
    if (value.saddr == 0) {
        printf("source ip %s not valid\n", argv[3]);
        return 1;
    }
    value.ifout = if_nametoindex(argv[4]);
    if (!value.ifout) {
        printf("interface %s not found\n", argv[4]);
        return 1;
    }
    value.daddr  = parse_ip(argv[5]);
    if (value.daddr == 0) {
        printf("target ip %s not valid\n", argv[5]);
        return 1;
    }
    rc = sys_bpf(BPF_MAP_UPDATE_ELEM, &attr_elem, sizeof(attr_elem));
    if (rc<0) {
        printf("fail to register the L3 binding rule\n");
        return 1;
    }
    return 0;
}