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📄 x509read_c.htm

📁 阅读x.509文件的代码
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{
    int ret, len;
    unsigned char *end2;

    if( ( ret = x509_get_alg( p, end, pk_alg_oid ) ) != 0 )
        return( ret );

    /*
     * only RSA public keys handled at this time
     */
    if( pk_alg_oid->len != 9 ||
        memcmp( pk_alg_oid->p, OID_PKCS1_RSA, 9 ) != 0 )
        return( ERR_X509_CERT_UNKNOWN_PK_ALG );

    if( ( ret = asn1_get_tag( p, end, &len, ASN1_BIT_STRING ) ) != 0 )
        return( ERR_X509_CERT_INVALID_PUBKEY | ret );

    if( ( end - *p ) < 1 )
        return( ERR_X509_CERT_INVALID_PUBKEY |
                ERR_ASN1_OUT_OF_DATA );

    end2 = *p + len;

    if( *(*p)++ != 0 )
        return( ERR_X509_CERT_INVALID_PUBKEY );

    /*
     *  RSAPublicKey ::= SEQUENCE {
     *      modulus           INTEGER,  -- n
     *      publicExponent    INTEGER   -- e
     *  }
     */
    if( ( ret = asn1_get_tag( p, end2, &len,
            ASN1_CONSTRUCTED | ASN1_SEQUENCE ) ) != 0 )
        return( ERR_X509_CERT_INVALID_PUBKEY | ret );

    if( *p + len != end2 )
        return( ERR_X509_CERT_INVALID_PUBKEY |
                ERR_ASN1_LENGTH_MISMATCH );

    if( ( ret = asn1_get_mpi( p, end2, N ) ) != 0 ||
        ( ret = asn1_get_mpi( p, end2, E ) ) != 0 )
        return( ERR_X509_CERT_INVALID_PUBKEY | ret );

    if( *p != end )
        return( ERR_X509_CERT_INVALID_PUBKEY |
                ERR_ASN1_LENGTH_MISMATCH );

    return( 0 );
}

static int x509_get_sig( unsigned char **p,
                         unsigned char *end,
                         x509_buf *sig )
{
    int ret, len;

    sig->tag = **p;

    if( ( ret = asn1_get_tag( p, end, &len, ASN1_BIT_STRING ) ) != 0 )
        return( ERR_X509_CERT_INVALID_SIGNATURE | ret );

    if( --len < 1 || *(*p)++ != 0 )
        return( ERR_X509_CERT_INVALID_SIGNATURE );

    sig->len = len;
    sig->p = *p;

    *p += len;

    return( 0 );
}

/*
 * X.509 v2/v3 unique identifier (not parsed)
 */
static int x509_get_uid( unsigned char **p,
                         unsigned char *end,
                         x509_buf *uid, int n )
{
    int ret;

    if( *p == end )
        return( 0 );

    uid->tag = **p;

    if( ( ret = asn1_get_tag( p, end, &uid->len,
            ASN1_CONTEXT_SPECIFIC | ASN1_CONSTRUCTED | n ) ) != 0 )
    {
        if( ret == ERR_ASN1_UNEXPECTED_TAG )
            return( 0 );

        return( ret );
    }

    uid->p = *p;
    *p += uid->len;

    return( 0 );
}

/*
 * X.509 v3 extensions (only BasicConstraints are parsed)
 */
static int x509_get_ext( unsigned char **p,
                         unsigned char *end,
                         x509_buf *ext,
                         int *ca_istrue,
                         int *max_pathlen )
{
    int ret, len;
    int is_critical = 1;
    int is_cacert   = 0;
    unsigned char *end2;

    if( *p == end )
        return( 0 );

    ext->tag = **p;

    if( ( ret = asn1_get_tag( p, end, &ext->len,
            ASN1_CONTEXT_SPECIFIC | ASN1_CONSTRUCTED | 3 ) ) != 0 )
    {
        if( ret == ERR_ASN1_UNEXPECTED_TAG )
            return( 0 );

        return( ret );
    }

    ext->p = *p;
    end = *p + ext->len;

    /*
     * Extensions  ::=  SEQUENCE SIZE (1..MAX) OF Extension
     *
     * Extension  ::=  SEQUENCE  {
     *      extnID      OBJECT IDENTIFIER,
     *      critical    BOOLEAN DEFAULT FALSE,
     *      extnValue   OCTET STRING  }
     */
    if( ( ret = asn1_get_tag( p, end, &len,
            ASN1_CONSTRUCTED | ASN1_SEQUENCE ) ) != 0 )
        return( ERR_X509_CERT_INVALID_EXTENSIONS | ret );

    if( end != *p + len )
        return( ERR_X509_CERT_INVALID_EXTENSIONS |
                ERR_ASN1_LENGTH_MISMATCH );

    while( *p < end )
    {
        if( ( ret = asn1_get_tag( p, end, &len,
                ASN1_CONSTRUCTED | ASN1_SEQUENCE ) ) != 0 )
            return( ERR_X509_CERT_INVALID_EXTENSIONS | ret );

        if( memcmp( *p, "\x06\x03\x55\x1D\x13", 5 ) != 0 )
        {
            *p += len;
            continue;
        }

        *p += 5;

        if( ( ret = asn1_get_bool( p, end, &is_critical ) ) != 0 &&
            ( ret != ERR_ASN1_UNEXPECTED_TAG ) )
            return( ERR_X509_CERT_INVALID_EXTENSIONS | ret );

        if( ( ret = asn1_get_tag( p, end, &len,
                ASN1_OCTET_STRING ) ) != 0 )
            return( ERR_X509_CERT_INVALID_EXTENSIONS | ret );

        /*
         * BasicConstraints ::= SEQUENCE {
         *      cA                      BOOLEAN DEFAULT FALSE,
         *      pathLenConstraint       INTEGER (0..MAX) OPTIONAL }
         */
        end2 = *p + len;

        if( ( ret = asn1_get_tag( p, end2, &len,
                ASN1_CONSTRUCTED | ASN1_SEQUENCE ) ) != 0 )
            return( ERR_X509_CERT_INVALID_EXTENSIONS | ret );

        if( *p == end2 )
            continue;

        if( ( ret = asn1_get_bool( p, end2, &is_cacert ) ) != 0 )
            return( ERR_X509_CERT_INVALID_EXTENSIONS | ret );

        if( *p == end2 )
            continue;

        if( ( ret = asn1_get_int( p, end2, max_pathlen ) ) != 0 )
            return( ERR_X509_CERT_INVALID_EXTENSIONS | ret );

        if( *p != end2 )
            return( ERR_X509_CERT_INVALID_EXTENSIONS |
                    ERR_ASN1_LENGTH_MISMATCH );

        max_pathlen++;
    }

    if( *p != end )
        return( ERR_X509_CERT_INVALID_EXTENSIONS |
                ERR_ASN1_LENGTH_MISMATCH );

    *ca_istrue = is_critical & is_cacert;

    return( 0 );
}

/*
 * Parse one or more certificates and add them to the chain
 */
int x509_add_certs( x509_cert *chain, unsigned char *buf, int buflen )
{
    int ret, len;
    unsigned char *s1, *s2;
    unsigned char *p, *end;
    x509_cert *crt;

    crt = chain;

    while( crt->version != 0 )
        crt = crt->next;

    /*
     * check if the certificate is encoded in base64
     */
    s1 = (unsigned char *) strstr( (char *) buf,
        "-----BEGIN CERTIFICATE-----" );

    if( s1 != NULL )
    {
        s2 = (unsigned char *) strstr( (char *) buf,
            "-----END CERTIFICATE-----" );

        if( s2 == NULL || s2 <= s1 )
            return( ERR_X509_CERT_INVALID_PEM );

        s1 += 27;
        if( *s1 == '\r' ) s1++;
        if( *s1 == '\n' ) s1++;
            else return( ERR_X509_CERT_INVALID_PEM );

        /*
         * get the DER data length and decode the buffer
         */
        len = 0;
        ret = base64_decode( NULL, &len, s1, s2 - s1 );

        if( ret == ERR_BASE64_INVALID_CHARACTER )
            return( ERR_X509_CERT_INVALID_PEM | ret );

        if( ( p = (unsigned char *) malloc( len ) ) == NULL )
            return( 1 );
            
        if( ( ret = base64_decode( p, &len, s1, s2 - s1 ) ) != 0 )
        {
            free( p );
            return( ERR_X509_CERT_INVALID_PEM | ret );
        }

        /*
         * update the buffer size and offset
         */
        s2 += 25;
        if( *s2 == '\r' ) s2++;
        if( *s2 == '\n' ) s2++;
            else return( ERR_X509_CERT_INVALID_PEM );

        buflen -= s2 - buf;
        buf = s2;
    }
    else
    {
        /*
         * nope, copy the raw DER data
         */
        p = (unsigned char *) malloc( len = buflen );

        if( p == NULL )
            return( 1 );

        memcpy( p, buf, buflen );

        buflen = 0;
    }

    crt->raw.p = p;
    crt->raw.len = len;
    end = p + len;

    /*
     * Certificate  ::=  SEQUENCE  {
     *      tbsCertificate       TBSCertificate,
     *      signatureAlgorithm   AlgorithmIdentifier,
     *      signatureValue       BIT STRING  }
     */
    if( ( ret = asn1_get_tag( &p, end, &len,
            ASN1_CONSTRUCTED | ASN1_SEQUENCE ) ) != 0 )
    {
        x509_free_cert( crt );
        return( ERR_X509_CERT_INVALID_FORMAT );
    }

    if( len != (int) ( end - p ) )
    {
        x509_free_cert( crt );
        return( ERR_X509_CERT_INVALID_FORMAT |
                ERR_ASN1_LENGTH_MISMATCH );
    }

    /*
     * TBSCertificate  ::=  SEQUENCE  {
     */
    crt->tbs.p = p;

    if( ( ret = asn1_get_tag( &p, end, &len,
            ASN1_CONSTRUCTED | ASN1_SEQUENCE ) ) != 0 )
    {
        x509_free_cert( crt );
        return( ERR_X509_CERT_INVALID_FORMAT | ret );
    }

    end = p + len;
    crt->tbs.len = end - crt->tbs.p;

    /*
     * Version  ::=  INTEGER  {  v1(0), v2(1), v3(2)  }
     *
     * CertificateSerialNumber  ::=  INTEGER
     *
     * signature            AlgorithmIdentifier
     */
    if( ( ret = x509_get_version( &p, end, &crt->version ) ) != 0 ||
        ( ret = x509_get_serial(  &p, end, &crt->serial  ) ) != 0 ||
        ( ret = x509_get_alg(  &p, end, &crt->sig_oid1   ) ) != 0 )
    {
        x509_free_cert( crt );
        return( ret );
    }

    crt->version++;

    if( crt->version > 3 )
    {
        x509_free_cert( crt );
        return( ERR_X509_CERT_UNKNOWN_VERSION );
    }

    if( crt->sig_oid1.len != 9 ||
        memcmp( crt->sig_oid1.p, OID_PKCS1, 8 ) != 0 )
    {
        x509_free_cert( crt );
        return( ERR_X509_CERT_UNKNOWN_SIG_ALG );
    }

    if( crt->sig_oid1.p[8] < 2 ||
        crt->sig_oid1.p[8] > 5 )
    {
        x509_free_cert( crt );
        return( ERR_X509_CERT_UNKNOWN_SIG_ALG );
    }

    /*
     * issuer               Name
     */
    crt->issuer_raw.p = p;

    if( ( ret = asn1_get_tag( &p, end, &len,
            ASN1_CONSTRUCTED | ASN1_SEQUENCE ) ) != 0 )
    {
        x509_free_cert( crt );
        return( ERR_X509_CERT_INVALID_FORMAT | ret );
    }

    if( ( ret = x509_get_name( &p, p + len, &crt->issuer ) ) != 0 )
    {
        x509_free_cert( crt );
        return( ret );
    }

    crt->issuer_raw.len = p - crt->issuer_raw.p;

    /*
     * Validity ::= SEQUENCE {
     *      notBefore      Time,
     *      notAfter       Time }
     *
     */
    if( ( ret = x509_get_dates( &p, end, &crt->valid_from,
                                         &crt->valid_to ) ) != 0 )
    {
        x509_free_cert( crt );
        return( ret );
    }

    /*
     * subject              Name
     */
    crt->subject_raw.p = p;

    if( ( ret = asn1_get_tag( &p, end, &len,
            ASN1_CONSTRUCTED | ASN1_SEQUENCE ) ) != 0 )
    {
        x509_free_cert( crt );
        return( ERR_X509_CERT_INVALID_FORMAT | ret );
    }

    if( ( ret = x509_get_name( &p, p + len, &crt->subject ) ) != 0 )
    {
        x509_free_cert( crt );
        return( ret );
    }

    crt->subject_raw.len = p - crt->subject_raw.p;

    /*
     * SubjectPublicKeyInfo  ::=  SEQUENCE
     *      algorithm            AlgorithmIdentifier,
     *      subjectPublicKey     BIT STRING  }
     */
    if( ( ret = asn1_get_tag( &p, end, &len,
            ASN1_CONSTRUCTED | ASN1_SEQUENCE ) ) != 0 )
    {
        x509_free_cert( crt );
        return( ERR_X509_CERT_INVALID_FORMAT | ret );
    }

    if( ( ret = x509_get_pubkey( &p, p + len, &crt->pk_oid,
                                 &crt->rsa.N, &crt->rsa.E ) ) != 0 )
    {
        x509_free_cert( crt );
        return( ret );

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