Error 1 when makefile is executed

Question

The following code I obtained from http://ftp.cc.uoc.gr/mirrors/OpenBSD/src/usr.sbin/tcpdump/print-lldp.c to include the LLDP functionality to my project using Ubuntu as my base operating system.

/*  $OpenBSD: print-lldp.c,v 1.6 2009/11/12 00:02:16 deraadt Exp $  */

/*
 * Copyright (c) 2006 Reyk Floeter <reyk@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/param.h>
#include <sys/time.h>
#include <sys/socket.h>

#include <net/if.h>

#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/if_ether.h>
#include <arpa/inet.h>

#include <ctype.h>
#include <stdio.h>
#include <string.h>

#include "addrtoname.h"
#include "extract.h"
#include "interface.h"
#include "afnum.h"

enum {
    LLDP_TLV_END            = 0,
    LLDP_TLV_CHASSIS_ID     = 1,
    LLDP_TLV_PORT_ID        = 2,
    LLDP_TLV_TTL            = 3,
    LLDP_TLV_PORT_DESCR     = 4,
    LLDP_TLV_SYSTEM_NAME        = 5,
    LLDP_TLV_SYSTEM_DESCR       = 6,
    LLDP_TLV_SYSTEM_CAP     = 7,
    LLDP_TLV_MANAGEMENT_ADDR    = 8,
    LLDP_TLV_ORG            = 127
};

enum {
    LLDP_CHASSISID_SUBTYPE_CHASSIS  = 1,
    LLDP_CHASSISID_SUBTYPE_IFALIAS  = 2,
    LLDP_CHASSISID_SUBTYPE_PORT = 3,
    LLDP_CHASSISID_SUBTYPE_LLADDR   = 4,
    LLDP_CHASSISID_SUBTYPE_ADDR = 5,
    LLDP_CHASSISID_SUBTYPE_IFNAME   = 6,
    LLDP_CHASSISID_SUBTYPE_LOCAL    = 7
};

enum {
    LLDP_PORTID_SUBTYPE_IFALIAS = 1,
    LLDP_PORTID_SUBTYPE_PORT    = 2,
    LLDP_PORTID_SUBTYPE_LLADDR  = 3,
    LLDP_PORTID_SUBTYPE_ADDR    = 4,
    LLDP_PORTID_SUBTYPE_IFNAME  = 5,
    LLDP_PORTID_SUBTYPE_AGENTCID    = 6,
    LLDP_PORTID_SUBTYPE_LOCAL   = 7
};

#define LLDP_CAP_OTHER          0x01
#define LLDP_CAP_REPEATER       0x02
#define LLDP_CAP_BRIDGE         0x04
#define LLDP_CAP_WLAN           0x08
#define LLDP_CAP_ROUTER         0x10
#define LLDP_CAP_TELEPHONE      0x20
#define LLDP_CAP_DOCSIS         0x40
#define LLDP_CAP_STATION        0x80
#define LLDP_CAP_BITS                               \
    "\20\01OTHER\02REPEATER\03BRIDGE\04WLAN\05ROUTER\06TELEPHONE"       \
    "\07DOCSIS\10STATION"

enum {
    LLDP_MGMT_IFACE_UNKNOWN = 1,
    LLDP_MGMT_IFACE_IFINDEX = 2,
    LLDP_MGMT_IFACE_SYSPORT = 3
};

static const char *afnumber[] = AFNUM_NAME_STR;

void         lldp_print_str(u_int8_t *, int);
const char  *lldp_print_addr(int, const void *);
void         lldp_print_id(int, u_int8_t *, int);

void
lldp_print_str(u_int8_t *str, int len)
{
    int i;
    printf("\"");
    for (i = 0; i < len; i++)
        printf("%c", isprint(str[i]) ? str[i] : '.');
    printf("\"");
}

const char *
lldp_print_addr(int af, const void *addr)
{
    static char buf[48];
    if (inet_ntop(af, addr, buf, sizeof(buf)) == NULL)
        return ("?");
    return (buf);
}

void
lldp_print_id(int type, u_int8_t *ptr, int len)
{
    u_int8_t id;
    u_int8_t *data;

    id = *(u_int8_t *)ptr;
    len -= sizeof(u_int8_t);
    data = ptr + sizeof(u_int8_t);
    if (len <= 0)
        return;

    if (type == LLDP_TLV_CHASSIS_ID) {
        switch (id) {
        case LLDP_CHASSISID_SUBTYPE_CHASSIS:
            printf("chassis ");
            lldp_print_str(data, len);
            break;
        case LLDP_CHASSISID_SUBTYPE_IFALIAS:
            printf("ifalias");
            break;
        case LLDP_CHASSISID_SUBTYPE_PORT:
            printf("port");
            break;
        case LLDP_CHASSISID_SUBTYPE_LLADDR:
            printf("lladdr %s",
                ether_ntoa((struct ether_addr *)data));
            break;
        case LLDP_CHASSISID_SUBTYPE_ADDR:
            printf("addr");
            break;
        case LLDP_CHASSISID_SUBTYPE_IFNAME:
            printf("ifname ");
            lldp_print_str(data, len);
            break;
        case LLDP_CHASSISID_SUBTYPE_LOCAL:
            printf("local ");
            lldp_print_str(data, len);
            break;
        default:
            printf("unknown 0x%02x", id);
            break;
        }

    } else if (type == LLDP_TLV_PORT_ID) {
        switch (id) {
        case LLDP_PORTID_SUBTYPE_IFALIAS:
            printf("ifalias");
            break;
        case LLDP_PORTID_SUBTYPE_PORT:
            printf("port");
            break;
        case LLDP_PORTID_SUBTYPE_LLADDR:
            printf("lladdr %s",
                ether_ntoa((struct ether_addr *)data));
            break;
        case LLDP_PORTID_SUBTYPE_ADDR:
            printf("addr");
            break;
        case LLDP_PORTID_SUBTYPE_IFNAME:
            printf("ifname ");
            lldp_print_str(data, len);
            break;
        case LLDP_PORTID_SUBTYPE_AGENTCID:
            printf("agentcid");
            break;
        case LLDP_PORTID_SUBTYPE_LOCAL:
            printf("local ");
            lldp_print_str(data, len);
            break;
        default:
            printf("unknown 0x%02x", id);
            break;
        }
    }
}

void
lldp_print(const u_char *p, u_int len)
{
    u_int16_t tlv;
    u_int8_t *ptr = (u_int8_t *)p, v = 0;
    int n, type, vlen, alen;

    printf("LLDP");

#define _ptrinc(_v) ptr += (_v); vlen -= (_v);

    for (n = 0; n < len;) {
        TCHECK2(*ptr, sizeof(tlv));

        tlv = EXTRACT_16BITS(ptr);
        type = (tlv & 0xfe00) >> 9;
        vlen = tlv & 0x1ff;
        n += vlen;

        ptr += sizeof(tlv);
        TCHECK2(*ptr, vlen);

        switch (type) {
        case LLDP_TLV_END:
            goto done;
            break;

        case LLDP_TLV_CHASSIS_ID:
            printf(", ChassisId: ");
            lldp_print_id(type, ptr, vlen);
            break;

        case LLDP_TLV_PORT_ID:
            printf(", PortId: ");
            lldp_print_id(type, ptr, vlen);
            break;

        case LLDP_TLV_TTL:
            printf(", TTL: ");
            TCHECK2(*ptr, 2);
            printf("%ds", EXTRACT_16BITS(ptr));
            break;

        case LLDP_TLV_PORT_DESCR:
            printf(", PortDescr: ");
            lldp_print_str(ptr, vlen);
            break;

        case LLDP_TLV_SYSTEM_NAME:
            printf(", SysName: ");
            lldp_print_str(ptr, vlen);
            break;

        case LLDP_TLV_SYSTEM_DESCR:
            printf(", SysDescr: ");
            lldp_print_str(ptr, vlen);
            break;

        case LLDP_TLV_SYSTEM_CAP:
            printf(", CAP:");
            TCHECK2(*ptr, 4);
            printb(" available", EXTRACT_16BITS(ptr),
                LLDP_CAP_BITS);
            _ptrinc(sizeof(u_int16_t));
            printb(" enabled", EXTRACT_16BITS(ptr),
                LLDP_CAP_BITS);
            break;

        case LLDP_TLV_MANAGEMENT_ADDR:
            printf(", MgmtAddr:");
            TCHECK2(*ptr, 2);
            alen = *ptr - sizeof(u_int8_t);
            _ptrinc(sizeof(u_int8_t));
            v = *ptr;
            _ptrinc(sizeof(u_int8_t));
            if (v < AFNUM_MAX)
                printf(" %s", afnumber[v]);
            else
                printf(" type %d", v);
            TCHECK2(*ptr, alen);
            switch (v) {
            case AFNUM_INET:
                if (alen != sizeof(struct in_addr))
                    goto trunc;
                printf(" %s",
                    lldp_print_addr(AF_INET, ptr));
                break;
            case AFNUM_INET6:
                if (alen != sizeof(struct in6_addr))
                    goto trunc;
                printf(" %s",
                    lldp_print_addr(AF_INET6, ptr));
                break;
            }
            _ptrinc(alen);
            v = *(u_int8_t *)ptr;
            break;

        case LLDP_TLV_ORG:
            printf(", Org");
            break;

        default:
            printf(", type %d length %d", type, vlen);
            break;
        }
        ptr += vlen;
    }

 done:
    return;

 trunc:
    printf(" [|LLDP]");
}

The code is used in the Makefile which I used to compile the source is,

    # build helloworld executable when user executes "make"
helloworld: helloworld.o
    $(CC) $(LDFLAGS) helloworld.o -o helloworld
helloworld.o: helloworld.c
    $(CC) $(CFLAGS) -c helloworld.c

# remove object files and executable when user executes "make clean"
clean:
    rm *.o helloworld 

However, when I run the command make within the folder ~/helloworld/src$ it give the following error.

    cc  helloworld.o -o helloworld
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../x86_64-linux-gnu/crt1.o: In function `_start':
(.text+0x20): undefined reference to `main'
helloworld.o: In function `lldp_print':
helloworld.c:(.text+0x36b): undefined reference to `snapend'
helloworld.c:(.text+0x376): undefined reference to `snapend'
helloworld.c:(.text+0x386): undefined reference to `snapend'
helloworld.c:(.text+0x3e3): undefined reference to `snapend'
helloworld.c:(.text+0x3f6): undefined reference to `snapend'
helloworld.o:helloworld.c:(.text+0x406): more undefined references to `snapend' follow
helloworld.o: In function `lldp_print':
helloworld.c:(.text+0x650): undefined reference to `printb'
helloworld.c:(.text+0x691): undefined reference to `printb'
helloworld.c:(.text+0x6af): undefined reference to `snapend'
helloworld.c:(.text+0x6ba): undefined reference to `snapend'
helloworld.c:(.text+0x6ca): undefined reference to `snapend'
helloworld.c:(.text+0x758): undefined reference to `snapend'
helloworld.c:(.text+0x76b): undefined reference to `snapend'
helloworld.o:helloworld.c:(.text+0x77b): more undefined references to `snapend' follow
collect2: ld returned 1 exit status
make: *** [helloworld] Error 1

I am fairly new to C in Ubuntu and would really a[[reciate you expert's advice on how to get this code to compile successfully :)

Thanks again :)

Answer 1

The Errors:

The "main" matter is sorted out in the 1st comment.

the snapend is defined in interface.h file, be sure to have this file in the same directory as the hallo.c

The printb function is declared in interface.h and the source code for it is in util.c. Because of that the util.c also must be included in your makefile.