Question

First of all I am showing the code for my c file ..

#include <stdlib.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <memory.h>
#include <string.h>
#include <ctype.h>
#include "sendip_module.h"
#include "ipv6ext.h"
#include "../ipv6.h"
#include "../ipv4.h"
#include "ah.h"
#include "esp.h"
#include "crypto_module.h"

#include <openssl/hmac.h>
#include <openssl/md5.h>

/*
code for hmac_md5 here....

void
hmac_md5(text, text_len, key, key_len, digest)
unsigned char*  text;                /* pointer to data stream */
int text_len;            /* length of data stream */
unsigned char* key;                 /* pointer to authentication key */
int key_len;             /* length of authentication key */
caddr_t digest;              /* caller digest to be filled in */

{
    MD5_CTX context;
    unsigned char k_ipad[65];    /* inner padding -
                                  * key XORd with ipad
                                  */
    unsigned char k_opad[65];    /* outer padding -
                                  * key XORd with opad
                                  */
    unsigned char tk[16];
    int i;
    /* if key is longer than 64 bytes reset it to key=MD5(key) */
    if (key_len > 64) {

            MD5_CTX      tctx;

            MD5Init(&tctx);
            MD5Update(&tctx, key, key_len);
            MD5Final(tk, &tctx);

            key = tk;
            key_len = 16;
    }

    /*
     * the HMAC_MD5 transform looks like:
     *
     * MD5(K XOR opad, MD5(K XOR ipad, text))
     *
     * where K is an n byte key
     * ipad is the byte 0x36 repeated 64 times
     * opad is the byte 0x5c repeated 64 times
     * and text is the data being protected
     */

    /* start out by storing key in pads */
    bzero( k_ipad, sizeof k_ipad);
    bzero( k_opad, sizeof k_opad);
    bcopy( key, k_ipad, key_len);
    bcopy( key, k_opad, key_len);

    /* XOR key with ipad and opad values */
    for (i=0; i<64; i++) {
            k_ipad[i] ^= 0x36;
            k_opad[i] ^= 0x5c;
    }
    /*
     * perform inner MD5
     */
    MD5Init(&context);                   /* init context for 1st
                                          * pass */
    MD5Update(&context, k_ipad, 64);      /* start with inner pad */
    MD5Update(&context, text, text_len); /* then text of datagram */
    MD5Final(digest, &context);          /* finish up 1st pass */
    /*
     * perform outer MD5
     */
    MD5Init(&context);                   /* init context for 2nd
                                          * pass */
    MD5Update(&context, k_opad, 64);     /* start with outer pad */
    MD5Update(&context, digest, 16);     /* then results of 1st
                                          * hash */
    MD5Final(digest, &context);          /* finish up 2nd pass */

}

*/

/*
rest of the program logic...
*/

I have already included …<.path where openssl is installed…..>../openssl/include to C_INCLUDE_PATH and exported it.

and now when i try to compile it getting error :

 $ make

gcc -o xorauth.so -I.. -fPIC -fsigned-char -pipe -Wall -Wpointer-arith -Wwrite-strings
wstrict-prototypes -Wnested-externs -Winline -Werror -g -Wcast-align -  
DSENDIP_LIBS=\"/usr/local/lib/sendip\" -shared xorauth.c ../libsendipaux.a  
../libsendipaux.a

cc1: warnings being treated as errors

xorauth.c:34:1: error: function declaration isn’t a prototype
xorauth.c: In function ‘hmac_md5’:
xorauth.c:56:17: error: implicit declaration of function ‘MD5Init’
xorauth.c:56:17: error: nested extern declaration of ‘MD5Init’
xorauth.c:57:17: error: implicit declaration of function ‘MD5Update’
xorauth.c:57:17: error: nested extern declaration of ‘MD5Update’ 
xorauth.c:58:17: error: implicit declaration of function ‘MD5Final’
xorauth.c:58:17: error: nested extern declaration of ‘MD5Final’
make: *** [xorauth.so] Error 1

if required I will edit the other implementation details I have skiped them just to make the post small because I think there is something which i need to do regarding include path and header files and i am unaware of it.

What is going wrong please help me ???

Answer 1

There is no MD5Init function in OpenSSL. (There is in the BSD implementation.)

man MD5_Init (note the underscore), or see here.

EDIT:

Now that you’ve shown us the offending code, I can also help with the “not a prototype” message.

You have (edited a bit):

void hmac_md5(text, text_len, key, key_len, digest)
unsigned char*  text;                
int text_len;            
unsigned char* key;                 
int key_len;             
caddr_t digest;              
{
    /* ... */
}

That’s an old-style, or “K&R”, function definition. It’s still valid, but only for backward compatibility, and it means that the compiler won’t be able to warn you about calls with the wrong number or type(s) of arguments. The modern (since 1989) version is:

void hmac_md5(unsigned char *text, 
              int text_len, 
              unsigned char *key, 
              int key_len, 
              caddr_t digest)
{
    /* ... */
}

When converting old-style function declarations and definitions to use prototypes, you sometimes have to be careful about parameters with narrow types (float, and integer types narrower than int or unsigned int) due to the promotion rules. That doesn’t apply in this particular case.

Note that you can leave the definition as it is if you like. Since you got the code from an internet draft, that might even be a good idea (if it ain’t broke, don’t fix it) — but as I said you’ll get no help from the compiler if you call it with the wrong number or type(s) of arguments.