bio.go

// Copyright (C) 2014 Space Monkey, Inc.

package openssl

/*
#cgo pkg-config: openssl
#include <string.h>
#include <openssl/bio.h>

extern int cbioNew(BIO *b);
extern int cbioFree(BIO *b);

extern int writeBioWrite(BIO *b, char *buf, int size);
extern long writeBioCtrl(BIO *b, int cmd, long arg1, void *arg2);
static int writeBioPuts(BIO *b, const char *str) {
    return writeBioWrite(b, (char*)str, (int)strlen(str));
}

extern int readBioRead(BIO *b, char *buf, int size);
extern long readBioCtrl(BIO *b, int cmd, long arg1, void *arg2);

static BIO_METHOD writeBioMethod = {
    BIO_TYPE_SOURCE_SINK,
    "Go Write BIO",
    (int (*)(BIO *, const char *, int))writeBioWrite,
    NULL,
    writeBioPuts,
    NULL,
    writeBioCtrl,
    cbioNew,
    cbioFree,
    NULL};

static BIO_METHOD* BIO_s_writeBio() { return &writeBioMethod; }

static BIO_METHOD readBioMethod = {
    BIO_TYPE_SOURCE_SINK,
    "Go Read BIO",
    NULL,
    readBioRead,
    NULL,
    NULL,
    readBioCtrl,
    cbioNew,
    cbioFree,
    NULL};

static BIO_METHOD* BIO_s_readBio() { return &readBioMethod; }

static void BIO_clear_retry_flags_not_a_macro(BIO *b) {
    BIO_clear_retry_flags(b);
}

static void BIO_set_retry_read_not_a_macro(BIO *b) { BIO_set_retry_read(b); }
*/
import "C"

import (
    "errors"
    "io"
    "reflect"
    "sync"
    "unsafe"
)

const (
    SSLRecordSize = 16 * 1024
)

func nonCopyGoBytes(ptr uintptr, length int) []byte {
    var slice []byte
    header := (*reflect.SliceHeader)(unsafe.Pointer(&slice))
    header.Cap = length
    header.Len = length
    header.Data = ptr
    return slice
}

func nonCopyCString(data *C.char, size C.int) []byte {
    return nonCopyGoBytes(uintptr(unsafe.Pointer(data)), int(size))
}

//export cbioNew
func cbioNew(b *C.BIO) C.int {
    b.shutdown = 1
    b.init = 1
    b.num = -1
    b.ptr = nil
    b.flags = 0
    return 1
}

//export cbioFree
func cbioFree(b *C.BIO) C.int {
    return 1
}

type writeBio struct {
    data_mtx sync.Mutex
    op_mtx   sync.Mutex
    buf      []byte
}

func loadWritePtr(b *C.BIO) *writeBio {
    return (*writeBio)(unsafe.Pointer(b.ptr))
}

//export writeBioWrite
func writeBioWrite(b *C.BIO, data *C.char, size C.int) C.int {
    ptr := loadWritePtr(b)
    if ptr == nil || data == nil || size < 0 {
        return -1
    }
    ptr.data_mtx.Lock()
    defer ptr.data_mtx.Unlock()
    C.BIO_clear_retry_flags_not_a_macro(b)
    ptr.buf = append(ptr.buf, nonCopyCString(data, size)...)
    return size
}

//export writeBioCtrl
func writeBioCtrl(b *C.BIO, cmd C.int, arg1 C.long, arg2 unsafe.Pointer) C.long {
    switch cmd {
    case C.BIO_CTRL_WPENDING:
        return writeBioPending(b)
    case C.BIO_CTRL_DUP, C.BIO_CTRL_FLUSH:
        return 1
    default:
        return 0
    }
}

func writeBioPending(b *C.BIO) C.long {
    ptr := loadWritePtr(b)
    if ptr == nil {
        return 0
    }
    ptr.data_mtx.Lock()
    defer ptr.data_mtx.Unlock()
    return C.long(len(ptr.buf))
}

func (b *writeBio) WriteTo(w io.Writer) (rv int64, err error) {
    b.op_mtx.Lock()
    defer b.op_mtx.Unlock()

    // write whatever data we currently have
    b.data_mtx.Lock()
    data := b.buf
    b.data_mtx.Unlock()

    if len(data) == 0 {
        return 0, nil
    }
    n, err := w.Write(data)

    // subtract however much data we wrote from the buffer
    b.data_mtx.Lock()
    b.buf = b.buf[:copy(b.buf, b.buf[n:])]
    b.data_mtx.Unlock()

    return int64(n), err
}

func (self *writeBio) Disconnect(b *C.BIO) {
    if loadWritePtr(b) == self {
        b.ptr = nil
    }
}

func (b *writeBio) MakeCBIO() *C.BIO {
    rv := C.BIO_new(C.BIO_s_writeBio())
    rv.ptr = unsafe.Pointer(b)
    return rv
}

type readBio struct {
    data_mtx sync.Mutex
    op_mtx   sync.Mutex
    buf      []byte
    eof      bool
}

func loadReadPtr(b *C.BIO) *readBio {
    return (*readBio)(unsafe.Pointer(b.ptr))
}

//export readBioRead
func readBioRead(b *C.BIO, data *C.char, size C.int) C.int {
    ptr := loadReadPtr(b)
    if ptr == nil || size < 0 {
        return -1
    }
    ptr.data_mtx.Lock()
    defer ptr.data_mtx.Unlock()
    C.BIO_clear_retry_flags_not_a_macro(b)
    if len(ptr.buf) == 0 {
        if ptr.eof {
            return 0
        }
        C.BIO_set_retry_read_not_a_macro(b)
        return -1
    }
    if size == 0 || data == nil {
        return C.int(len(ptr.buf))
    }
    n := copy(nonCopyCString(data, size), ptr.buf)
    ptr.buf = ptr.buf[:copy(ptr.buf, ptr.buf[n:])]
    return C.int(n)
}

//export readBioCtrl
func readBioCtrl(b *C.BIO, cmd C.int, arg1 C.long, arg2 unsafe.Pointer) C.long {
    switch cmd {
    case C.BIO_CTRL_PENDING:
        return readBioPending(b)
    case C.BIO_CTRL_DUP, C.BIO_CTRL_FLUSH:
        return 1
    default:
        return 0
    }
}

func readBioPending(b *C.BIO) C.long {
    ptr := loadReadPtr(b)
    if ptr == nil {
        return 0
    }
    ptr.data_mtx.Lock()
    defer ptr.data_mtx.Unlock()
    return C.long(len(ptr.buf))
}

func (b *readBio) ReadFromOnce(r io.Reader) (n int, err error) {
    b.op_mtx.Lock()
    defer b.op_mtx.Unlock()

    // make sure we have a destination that fits at least one SSL record
    b.data_mtx.Lock()
    if cap(b.buf) < len(b.buf)+SSLRecordSize {
        new_buf := make([]byte, len(b.buf), len(b.buf)+SSLRecordSize)
        copy(new_buf, b.buf)
        b.buf = new_buf
    }
    dst := b.buf[len(b.buf):cap(b.buf)]
    dst_slice := b.buf
    b.data_mtx.Unlock()

    n, err = r.Read(dst)
    b.data_mtx.Lock()
    defer b.data_mtx.Unlock()
    if n > 0 {
        if len(dst_slice) != len(b.buf) {
            // someone shrunk the buffer, so we read in too far ahead and we
            // need to slide backwards
            copy(b.buf[len(b.buf):len(b.buf)+n], dst)
        }
        b.buf = b.buf[:len(b.buf)+n]
    }
    return n, err
}

func (b *readBio) MakeCBIO() *C.BIO {
    rv := C.BIO_new(C.BIO_s_readBio())
    rv.ptr = unsafe.Pointer(b)
    return rv
}

func (self *readBio) Disconnect(b *C.BIO) {
    if loadReadPtr(b) == self {
        b.ptr = nil
    }
}

func (b *readBio) MarkEOF() {
    b.data_mtx.Lock()
    defer b.data_mtx.Unlock()
    b.eof = true
}

type anyBio C.BIO

func asAnyBio(b *C.BIO) *anyBio { return (*anyBio)(b) }

func (b *anyBio) Read(buf []byte) (n int, err error) {
    n = int(C.BIO_read((*C.BIO)(b), unsafe.Pointer(&buf[0]), C.int(len(buf))))
    if n <= 0 {
        return 0, io.EOF
    }
    return n, nil
}

func (b *anyBio) Write(buf []byte) (written int, err error) {
    n := int(C.BIO_write((*C.BIO)(b), unsafe.Pointer(&buf[0]),
        C.int(len(buf))))
    if n != len(buf) {
        return n, errors.New("BIO write failed")
    }
    return n, nil
}