source: branches/samba-3.3.x/source/libsmb/asn1.c

/* 
   Unix SMB/CIFS implementation.
   simple SPNEGO routines
   Copyright (C) Andrew Tridgell 2001
   
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.
   
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "includes.h"

/* free an asn1 structure */
void asn1_free(ASN1_DATA *data)
{
        struct nesting *nesting = data->nesting;

        while (nesting) {
                struct nesting *nnext = nesting->next;
                free(nesting);
                nesting = nnext;
        };
        data->nesting = NULL;
        SAFE_FREE(data->data);
}

/* write to the ASN1 buffer, advancing the buffer pointer */
bool asn1_write(ASN1_DATA *data, const void *p, int len)
{
        if (data->has_error) return false;
        if (data->length < data->ofs+len) {
                data->data = SMB_REALLOC_ARRAY(data->data, unsigned char,
                                               data->ofs+len);
                if (!data->data) {
                        data->has_error = true;
                        return false;
                }
                data->length = data->ofs+len;
        }
        memcpy(data->data + data->ofs, p, len);
        data->ofs += len;
        return true;
}

/* useful fn for writing a uint8 */
bool asn1_write_uint8(ASN1_DATA *data, uint8 v)
{
        return asn1_write(data, &v, 1);
}

/* push a tag onto the asn1 data buffer. Used for nested structures */
bool asn1_push_tag(ASN1_DATA *data, uint8 tag)
{
        struct nesting *nesting;

        asn1_write_uint8(data, tag);
        nesting = SMB_MALLOC_P(struct nesting);
        if (!nesting) {
                data->has_error = true;
                return false;
        }

        nesting->start = data->ofs;
        nesting->next = data->nesting;
        data->nesting = nesting;
        return asn1_write_uint8(data, 0xff);
}

/* pop a tag */
bool asn1_pop_tag(ASN1_DATA *data)
{
        struct nesting *nesting;
        size_t len;

        if (data->has_error) {
                return false;
        }

        nesting = data->nesting;

        if (!nesting) {
                data->has_error = true;
                return false;
        }
        len = data->ofs - (nesting->start+1);
        /* yes, this is ugly. We don't know in advance how many bytes the length
           of a tag will take, so we assumed 1 byte. If we were wrong then we 
           need to correct our mistake */
        if (len > 0xFFFF) {
                data->data[nesting->start] = 0x83;
                if (!asn1_write_uint8(data, 0)) return false;
                if (!asn1_write_uint8(data, 0)) return false;
                if (!asn1_write_uint8(data, 0)) return false;
                memmove(data->data+nesting->start+4, data->data+nesting->start+1, len);
                data->data[nesting->start+1] = (len>>16) & 0xFF;
                data->data[nesting->start+2] = (len>>8) & 0xFF;
                data->data[nesting->start+3] = len&0xff;
        } else if (len > 255) {
                data->data[nesting->start] = 0x82;
                if (!asn1_write_uint8(data, 0)) return false;
                if (!asn1_write_uint8(data, 0)) return false;
                memmove(data->data+nesting->start+3, data->data+nesting->start+1, len);
                data->data[nesting->start+1] = len>>8;
                data->data[nesting->start+2] = len&0xff;
        } else if (len > 127) {
                data->data[nesting->start] = 0x81;
                if (!asn1_write_uint8(data, 0)) return false;
                memmove(data->data+nesting->start+2, data->data+nesting->start+1, len);
                data->data[nesting->start+1] = len;
        } else {
                data->data[nesting->start] = len;
        }

        data->nesting = nesting->next;
        free(nesting);
        return true;
}


/* write an integer */
bool asn1_write_Integer(ASN1_DATA *data, int i)
{
        if (!asn1_push_tag(data, ASN1_INTEGER)) return false;
        do {
                asn1_write_uint8(data, i);
                i = i >> 8;
        } while (i);
        return asn1_pop_tag(data);
}

/* write an object ID to a ASN1 buffer */
bool asn1_write_OID(ASN1_DATA *data, const char *OID)
{
        unsigned v, v2;
        const char *p = (const char *)OID;
        char *newp;

        if (!asn1_push_tag(data, ASN1_OID))
                return false;
        v = strtol(p, &newp, 10);
        p = newp;
        v2 = strtol(p, &newp, 10);
        p = newp;
        if (!asn1_write_uint8(data, 40*v + v2))
                return false;

        while (*p) {
                v = strtol(p, &newp, 10);
                p = newp;
                if (v >= (1<<28)) asn1_write_uint8(data, 0x80 | ((v>>28)&0xff));
                if (v >= (1<<21)) asn1_write_uint8(data, 0x80 | ((v>>21)&0xff));
                if (v >= (1<<14)) asn1_write_uint8(data, 0x80 | ((v>>14)&0xff));
                if (v >= (1<<7)) asn1_write_uint8(data, 0x80 | ((v>>7)&0xff));
                if (!asn1_write_uint8(data, v&0x7f))
                        return false;
        }
        return asn1_pop_tag(data);
}

/* write an octet string */
bool asn1_write_OctetString(ASN1_DATA *data, const void *p, size_t length)
{
        asn1_push_tag(data, ASN1_OCTET_STRING);
        asn1_write(data, p, length);
        asn1_pop_tag(data);
        return !data->has_error;
}

/* write a general string */
bool asn1_write_GeneralString(ASN1_DATA *data, const char *s)
{
        asn1_push_tag(data, ASN1_GENERAL_STRING);
        asn1_write(data, s, strlen(s));
        asn1_pop_tag(data);
        return !data->has_error;
}

/* write a BOOLEAN */
bool asn1_write_BOOLEAN(ASN1_DATA *data, bool v)
{
        asn1_write_uint8(data, ASN1_BOOLEAN);
        asn1_write_uint8(data, v);
        return !data->has_error;
}

/* write a BOOLEAN - hmm, I suspect this one is the correct one, and the 
   above boolean is bogus. Need to check */
bool asn1_write_BOOLEAN2(ASN1_DATA *data, bool v)
{
        asn1_push_tag(data, ASN1_BOOLEAN);
        asn1_write_uint8(data, v);
        asn1_pop_tag(data);
        return !data->has_error;
}

/* check a BOOLEAN */
bool asn1_check_BOOLEAN(ASN1_DATA *data, bool v)
{
        uint8 b = 0;

        asn1_read_uint8(data, &b);
        if (b != ASN1_BOOLEAN) {
                data->has_error = true;
                return false;
        }
        asn1_read_uint8(data, &b);
        if (b != v) {
                data->has_error = true;
                return false;
        }
        return !data->has_error;
}


/* load a ASN1_DATA structure with a lump of data, ready to be parsed */
bool asn1_load(ASN1_DATA *data, DATA_BLOB blob)
{
        ZERO_STRUCTP(data);
        data->data = (unsigned char *)memdup(blob.data, blob.length);
        if (!data->data) {
                data->has_error = true;
                return false;
        }
        data->length = blob.length;
        return true;
}

/* read from a ASN1 buffer, advancing the buffer pointer */
bool asn1_read(ASN1_DATA *data, void *p, int len)
{
        if (data->has_error)
                return false;

        if (len < 0 || data->ofs + len < data->ofs || data->ofs + len < len) {
                data->has_error = true;
                return false;
        }

        if (data->ofs + len > data->length) {
                data->has_error = true;
                return false;
        }
        memcpy(p, data->data + data->ofs, len);
        data->ofs += len;
        return true;
}

/* read a uint8 from a ASN1 buffer */
bool asn1_read_uint8(ASN1_DATA *data, uint8 *v)
{
        return asn1_read(data, v, 1);
}

/*
 * Check thta the value of the ASN1 buffer at the current offset equals tag.
 */
bool asn1_check_tag(ASN1_DATA *data, uint8 tag)
{
        if (data->has_error || data->ofs >= data->length || data->ofs < 0) {
                data->has_error = true;
                return false;
        }

        return (tag == data->data[data->ofs]);
}

/* start reading a nested asn1 structure */
bool asn1_start_tag(ASN1_DATA *data, uint8 tag)
{
        uint8 b;
        struct nesting *nesting;
        
        if (!asn1_read_uint8(data, &b))
                return false;

        if (b != tag) {
                data->has_error = true;
                return false;
        }
        nesting = SMB_MALLOC_P(struct nesting);
        if (!nesting) {
                data->has_error = true;
                return false;
        }

        if (!asn1_read_uint8(data, &b)) {
                SAFE_FREE(nesting);
                return false;
        }

        if (b & 0x80) {
                int n = b & 0x7f;
                if (!asn1_read_uint8(data, &b)) {
                        SAFE_FREE(nesting);
                        return false;
                }
                nesting->taglen = b;
                while (n > 1) {
                        if (!asn1_read_uint8(data, &b)) {
                                SAFE_FREE(nesting);
                                return false;
                        }
                        nesting->taglen = (nesting->taglen << 8) | b;
                        n--;
                }
        } else {
                nesting->taglen = b;
        }
        nesting->start = data->ofs;
        nesting->next = data->nesting;
        data->nesting = nesting;
        return !data->has_error;
}


/* stop reading a tag */
bool asn1_end_tag(ASN1_DATA *data)
{
        struct nesting *nesting;

        /* make sure we read it all */
        if (asn1_tag_remaining(data) != 0) {
                data->has_error = true;
                return false;
        }

        nesting = data->nesting;

        if (!nesting) {
                data->has_error = true;
                return false;
        }

        data->nesting = nesting->next;
        free(nesting);
        return true;
}

/* work out how many bytes are left in this nested tag */
int asn1_tag_remaining(ASN1_DATA *data)
{
        if (data->has_error)
                return 0;

        if (!data->nesting) {
                data->has_error = true;
                return -1;
        }
        return data->nesting->taglen - (data->ofs - data->nesting->start);
}

/* read an object ID from a ASN1 buffer */
bool asn1_read_OID(ASN1_DATA *data, char **OID)
{
        uint8 b = 0;
        char *oid_str = NULL;

        *OID = NULL;

        if (!asn1_start_tag(data, ASN1_OID)) {
                return false;
        }
        asn1_read_uint8(data, &b);

        oid_str = talloc_asprintf(NULL,
                        "%u",
                        b/40);
        if (!oid_str) {
                data->has_error = true;
                goto out;
        }
        oid_str = talloc_asprintf_append(oid_str,
                        " %u",
                        b%40);
        if (!oid_str) {
                data->has_error = true;
                goto out;
        }

        while (asn1_tag_remaining(data) > 0) {
                unsigned v = 0;
                do {
                        asn1_read_uint8(data, &b);
                        v = (v<<7) | (b&0x7f);
                } while (!data->has_error && b & 0x80);
                oid_str = talloc_asprintf_append(oid_str,
                                        " %u",
                                        v);
                if (!oid_str) {
                        data->has_error = true;
                        goto out;
                }
        }

  out:

        asn1_end_tag(data);

        if (!data->has_error) {
                *OID = SMB_STRDUP(oid_str);
        }

        TALLOC_FREE(oid_str);

        return !data->has_error;
}

/* check that the next object ID is correct */
bool asn1_check_OID(ASN1_DATA *data, const char *OID)
{
        char *id;

        if (!asn1_read_OID(data, &id)) {
                return false;
        }

        if (strcmp(id, OID) != 0) {
                data->has_error = true;
                free(id);
                return false;
        }
        free(id);
        return true;
}

/* read a GeneralString from a ASN1 buffer */
bool asn1_read_GeneralString(ASN1_DATA *data, char **s)
{
        int len;
        char *str;

        *s = NULL;

        if (!asn1_start_tag(data, ASN1_GENERAL_STRING)) {
                return false;
        }
        len = asn1_tag_remaining(data);
        if (len < 0) {
                data->has_error = true;
                return false;
        }
        str = SMB_MALLOC_ARRAY(char, len+1);
        if (!str) {
                data->has_error = true;
                return false;
        }
        asn1_read(data, str, len);
        str[len] = 0;
        asn1_end_tag(data);

        if (!data->has_error) {
                *s = str;
        }
        return !data->has_error;
}

/* read a octet string blob */
bool asn1_read_OctetString(ASN1_DATA *data, DATA_BLOB *blob)
{
        int len;
        ZERO_STRUCTP(blob);
        if (!asn1_start_tag(data, ASN1_OCTET_STRING)) return false;
        len = asn1_tag_remaining(data);
        if (len < 0) {
                data->has_error = true;
                return false;
        }
        *blob = data_blob(NULL, len);
        asn1_read(data, blob->data, len);
        asn1_end_tag(data);
        return !data->has_error;
}

/* read an interger */
bool asn1_read_Integer(ASN1_DATA *data, int *i)
{
        uint8 b;
        *i = 0;
        
        if (!asn1_start_tag(data, ASN1_INTEGER)) return false;
        while (asn1_tag_remaining(data)>0) {
                asn1_read_uint8(data, &b);
                *i = (*i << 8) + b;
        }
        return asn1_end_tag(data);      
        
}

/* check a enumarted value is correct */
bool asn1_check_enumerated(ASN1_DATA *data, int v)
{
        uint8 b;
        if (!asn1_start_tag(data, ASN1_ENUMERATED)) return false;
        asn1_read_uint8(data, &b);
        asn1_end_tag(data);

        if (v != b)
                data->has_error = false;

        return !data->has_error;
}

/* write an enumarted value to the stream */
bool asn1_write_enumerated(ASN1_DATA *data, uint8 v)
{
        if (!asn1_push_tag(data, ASN1_ENUMERATED)) return false;
        asn1_write_uint8(data, v);
        asn1_pop_tag(data);
        return !data->has_error;
}

bool ber_write_OID_String(DATA_BLOB *blob, const char *OID)
{
        uint_t v, v2;
        const char *p = (const char *)OID;
        char *newp;
        int i;

        v = strtoul(p, &newp, 10);
        if (newp[0] != '.') return false;
        p = newp + 1;

        v2 = strtoul(p, &newp, 10);
        if (newp[0] != '.') return false;
        p = newp + 1;

        /*the ber representation can't use more space then the string one */
        *blob = data_blob(NULL, strlen(OID));
        if (!blob->data) return false;

        blob->data[0] = 40*v + v2;

        i = 1;
        while (*p) {
                v = strtoul(p, &newp, 10);
                if (newp[0] == '.') {
                        p = newp + 1;
                } else if (newp[0] == '\0') {
                        p = newp;
                } else {
                        data_blob_free(blob);
                        return false;
                }
                if (v >= (1<<28)) blob->data[i++] = (0x80 | ((v>>28)&0x7f));
                if (v >= (1<<21)) blob->data[i++] = (0x80 | ((v>>21)&0x7f));
                if (v >= (1<<14)) blob->data[i++] = (0x80 | ((v>>14)&0x7f));
                if (v >= (1<<7)) blob->data[i++] = (0x80 | ((v>>7)&0x7f));
                blob->data[i++] = (v&0x7f);
        }

        blob->length = i;

        return true;
}

/* read an object ID from a data blob */
bool ber_read_OID_String(TALLOC_CTX *mem_ctx, DATA_BLOB blob, const char **OID)
{
        int i;
        uint8_t *b;
        uint_t v;
        char *tmp_oid = NULL;

        if (blob.length < 2) return false;

        b = blob.data;

        tmp_oid = talloc_asprintf(mem_ctx, "%u",  b[0]/40);
        if (!tmp_oid) goto nomem;
        tmp_oid = talloc_asprintf_append_buffer(tmp_oid, ".%u",  b[0]%40);
        if (!tmp_oid) goto nomem;

        for(i = 1, v = 0; i < blob.length; i++) {
                v = (v<<7) | (b[i]&0x7f);
                if ( ! (b[i] & 0x80)) {
                        tmp_oid = talloc_asprintf_append_buffer(tmp_oid, ".%u",  v);
                        v = 0;
                }
                if (!tmp_oid) goto nomem;
        }

        if (v != 0) {
                talloc_free(tmp_oid);
                return false;
        }

        *OID = tmp_oid;
        return true;

nomem:
        return false;
}