n2n_keyfile.c

/* (c) 2009 Richard Andrews <andrews@ntop.org> */
/* Contributions from:
 *     - Jozef Kralik
 */

#include "n2n.h"
#include "n2n_keyfile.h"
#include <errno.h>
#include <stdio.h>
#include <time.h>
#include <string.h>


#ifdef WIN32
char *strsep(char **ppsz_string, const char *psz_delimiters)
{
    char *p;
    char *psz_string = *ppsz_string;
    if (!psz_string)
        return NULL;

    p = strpbrk(psz_string, psz_delimiters);
    if (!p)
    {
        *ppsz_string = NULL;
        return psz_string;
    }
    *p++ = '\0';

    *ppsz_string = p;
    return psz_string;
}
#endif


/* Parse hex nibbles in ascii until a non-nibble character is found. Nibble
 * characters are 0-9, a-f and A-F. 
 *
 * Return number of bytes parsed into keyBuf or a negative error code.
 */
ssize_t n2n_parse_hex(uint8_t *keyBuf,
                      size_t keyLen,
                      const char *textKey,
                      size_t textLen)
{
    ssize_t       retval = 0;
    uint8_t      *pout = keyBuf;
    size_t        octet = 0;
    const char   *textEnd;
    const char   *pbeg;

    textEnd = textKey + textLen;
    pbeg = textKey;

    while ((pbeg + 1 < textEnd) && (retval < (ssize_t) keyLen))
    {
        if (1 != sscanf(pbeg, "%02x", (unsigned int*) &octet))
        {
            retval = -1;
            break;
        }

        *pout = (octet & 0xff);
        ++pout;
        ++retval;
        pbeg += 2;
    }

    return retval;
}


static int parseKeyLine(n2n_cipherspec_t *spec,
                        const char *linein)
{
    /* parameters are separated by whitespace */
    char line[N2N_KEYFILE_LINESIZE];
    char *lp = line;
    const char *token;
    strncpy(line, linein, N2N_KEYFILE_LINESIZE);

    memset(spec, 0, sizeof(n2n_cipherspec_t));

    /* decode valid_from time */
    token = strsep(&lp, DELIMITERS);
    if (!token)
    {
        goto error;
    }
    spec->valid_from = atol(token);

    /* decode valid_until time */
    token = strsep(&lp, DELIMITERS);
    if (!token)
    {
        goto error;
    }
    spec->valid_until = atol(token);

    /* decode the transform number */
    token = strsep(&lp, DELIMITERS);
    if (!token)
    {
        goto error;
    }
    spec->t = atoi(token);

    /* The reset if opaque key data */
    token = strsep(&lp, DELIMITERS);
    if (!token)
    {
        goto error;
    }
    strncpy((char *) spec->opaque, token, N2N_MAX_KEYSIZE);
    spec->opaque_size = strlen((char *) spec->opaque);

    return 0;

    error: return -1;
}


#define SEP "/"


int validCipherSpec(const n2n_cipherspec_t *k,
                    time_t now)
{
    if (k->valid_until < k->valid_from)
    {
        goto bad;
    }
    if (k->valid_from > now)
    {
        goto bad;
    }
    if (k->valid_until < now)
    {
        goto bad;
    }

    return 0;

    bad: return -1;
}

/* Read key control file and return the number of specs stored or a negative
 * error code.
 *
 * As the specs are read in the from and until time values are compared to
 * present time. Only those keys which are valid are stored.
 */
int n2n_read_keyfile(n2n_cipherspec_t *specs,    /* fill out this array of cipherspecs */
                     size_t numspecs,            /* number of slots in the array. */
                     const char *ctrlfile_path)  /* path to control file */
{
    /* Each line contains one cipherspec. */

    int       retval = 0;
    FILE     *fp = NULL;
    size_t    idx = 0;
    time_t    now = time(NULL);

    traceDebug("Reading '%s'\n", ctrlfile_path);

    fp = fopen(ctrlfile_path, "r");
    if (fp)
    {
        /* Read the file a line a time with fgets. */
        char line[N2N_KEYFILE_LINESIZE];
        size_t lineNum = 0;

        while (idx < numspecs)
        {
            n2n_cipherspec_t *k = &(specs[idx]);
            fgets(line, N2N_KEYFILE_LINESIZE, fp);
            ++lineNum;

            if (strlen(line) > 1)
            {
                if (0 == parseKeyLine(k, line))
                {
                    if (k->valid_until > now)
                    {
                        traceInfo(" --> [%u] from %lu, until %lu, transform=%hu, data=%s\n",
                                   idx, k->valid_from, k->valid_until, k->t, k->opaque);

                        ++retval;
                        ++idx;
                    }
                    else
                    {
                        traceInfo(" --X [%u] from %lu, until %lu, transform=%hu, data=%s\n",
                                   idx, k->valid_from, k->valid_until, k->t, k->opaque);

                    }
                }
                else
                {
                    traceWarning("Failed to decode line %u\n", lineNum);
                }
            }

            if (feof(fp))
            {
                break;
            }

            line[0] = 0; /* this line has been consumed */
        }

        fclose(fp);
        fp = NULL;
    }
    else
    {
        traceError("Failed to open '%s'\n", ctrlfile_path);
        retval = -1;
    }

    return retval;
}