diff options
Diffstat (limited to 'inc/dnbd3/shared/protocol.h')
-rw-r--r-- | inc/dnbd3/shared/protocol.h | 156 |
1 files changed, 156 insertions, 0 deletions
diff --git a/inc/dnbd3/shared/protocol.h b/inc/dnbd3/shared/protocol.h new file mode 100644 index 0000000..1dd47f8 --- /dev/null +++ b/inc/dnbd3/shared/protocol.h @@ -0,0 +1,156 @@ +#ifndef _PROTOCOL_H_ +#define _PROTOCOL_H_ + +#include <dnbd3/types.h> +#include <dnbd3/shared/serialize.h> +#include <dnbd3/shared/sockhelper.h> + +#include <errno.h> +#include <sys/types.h> +#include <sys/socket.h> +#include <sys/uio.h> + +// Client tells server that it is another server +#define FLAGS8_SERVER (1) +// Client (which is a proxy) tells server that it has background-replication enabled +#define FLAGS8_BG_REP (2) + +// 2017-10-16: We now support hop-counting, macro to pass hop count conditinally to a function +#define COND_HOPCOUNT(vers,hopcount) ( (vers) >= 3 ? (hopcount) : 0 ) + +// 2017-11-02: Macro to set flags in select image message properly if we're a server, as BG_REP depends on global var +#define SI_SERVER_FLAGS ( (uint8_t)( (_pretendClient ? 0 : FLAGS8_SERVER) | (_backgroundReplication == BGR_FULL ? FLAGS8_BG_REP : 0) ) ) + +#define REPLY_OK (0) +#define REPLY_ERRNO (-1) +#define REPLY_AGAIN (-2) +#define REPLY_INTR (-3) +#define REPLY_CLOSED (-4) +#define REPLY_INCOMPLETE (-5) +#define REPLY_WRONGMAGIC (-6) + +static inline int dnbd3_read_reply(int sock, dnbd3_reply_t *reply, bool wait) +{ + ssize_t ret = recv( sock, reply, sizeof(*reply), (wait ? MSG_WAITALL : MSG_DONTWAIT) | MSG_NOSIGNAL ); + if ( ret == 0 ) return REPLY_CLOSED; + if ( ret < 0 ) { + if ( errno == EAGAIN || errno == EWOULDBLOCK ) return REPLY_AGAIN; + if ( errno == EINTR ) return REPLY_INTR; + return REPLY_ERRNO; + } + if ( !wait && ret != sizeof(*reply) ) ret += recv( sock, ((char*)reply) + ret, sizeof(*reply) - ret, MSG_WAITALL | MSG_NOSIGNAL ); + if ( ret != sizeof(*reply) ) return REPLY_INCOMPLETE; + fixup_reply( *reply ); + if ( reply->magic != dnbd3_packet_magic ) return REPLY_WRONGMAGIC; + return REPLY_OK; +} + +static inline bool dnbd3_get_reply(int sock, dnbd3_reply_t *reply) +{ + int ret; + do { + ret = dnbd3_read_reply( sock, reply, true ); + } while ( ret == REPLY_INTR ); + return ret == REPLY_OK; +} + +static inline bool dnbd3_select_image(int sock, const char *name, uint16_t rid, uint8_t flags8) +{ + serialized_buffer_t serialized; + dnbd3_request_t request; + struct iovec iov[2]; + serializer_reset_write( &serialized ); + serializer_put_uint16( &serialized, PROTOCOL_VERSION ); + serializer_put_string( &serialized, name ); + serializer_put_uint16( &serialized, rid ); + serializer_put_uint8( &serialized, flags8 ); + const ssize_t len = serializer_get_written_length( &serialized ); + request.magic = dnbd3_packet_magic; + request.cmd = CMD_SELECT_IMAGE; + request.size = (uint32_t)len; + request.handle = 0; + request.offset = 0; + fixup_request( request ); + iov[0].iov_base = &request; + iov[0].iov_len = sizeof(request); + iov[1].iov_base = &serialized; + iov[1].iov_len = len; + ssize_t ret; + do { + ret = writev( sock, iov, 2 ); + } while ( ret == -1 && errno == EINTR ); + return ret == len + (ssize_t)sizeof(request); +} + +static inline bool dnbd3_get_block(int sock, uint64_t offset, uint32_t size, uint64_t handle, uint8_t hopCount) +{ + dnbd3_request_t request; + request.magic = dnbd3_packet_magic; + request.handle = handle; + request.cmd = CMD_GET_BLOCK; + // When writing before "fixup", we can get away with assigning to offset instead of offset_small if we + // do it before assigning to .hops. Faster on 64bit machines (so, on everything) + request.offset = offset; + request.hops = hopCount; + request.size = size; + fixup_request( request ); + return sock_sendAll( sock, &request, sizeof(request), 2 ) == (ssize_t)sizeof(request); +} + +static inline bool dnbd3_get_crc32(int sock, uint32_t *master, void *buffer, size_t *bufferLen) +{ + dnbd3_request_t request; + dnbd3_reply_t reply; + request.magic = dnbd3_packet_magic; + request.handle = 0; + request.cmd = CMD_GET_CRC32; + request.offset = 0; + request.size = 0; + fixup_request( request ); + if ( sock_sendAll( sock, &request, sizeof(request), 2 ) != (ssize_t)sizeof(request) ) return false; + if ( !dnbd3_get_reply( sock, &reply ) ) return false; + if ( reply.size == 0 ) { + *bufferLen = 0; + return true; + } + if ( reply.size < 4 ) return false; + reply.size -= 4; + if ( reply.cmd != CMD_GET_CRC32 || reply.size > *bufferLen ) return false; + *bufferLen = reply.size; + if ( sock_recv( sock, master, sizeof(uint32_t) ) != (ssize_t)sizeof(uint32_t) ) return false; + return sock_recv( sock, buffer, reply.size ) == (ssize_t)reply.size; +} + +/** + * Pass a full serialized_buffer_t and a socket fd. Parsed data will be returned in further arguments. + * Note that all strings will point into the passed buffer, so there's no need to free them. + * This function will also read the header for you, as this message can only occur during connection, + * where no unrequested messages could arrive inbetween. + */ +static inline bool dnbd3_select_image_reply(serialized_buffer_t *buffer, int sock, uint16_t *protocol_version, char **name, uint16_t *rid, + uint64_t *imageSize) +{ + errno = 0; + dnbd3_reply_t reply; + if ( !dnbd3_get_reply( sock, &reply ) ) { + return false; + } + errno = 0; + if ( reply.cmd != CMD_SELECT_IMAGE || reply.size < 3 || reply.size > MAX_PAYLOAD ) { + return false; + } + // receive reply payload + ssize_t ret = sock_recv( sock, buffer, reply.size ); + if ( ret != (ssize_t)reply.size ) { + return false; + } + // handle/check reply payload + serializer_reset_read( buffer, reply.size ); + *protocol_version = serializer_get_uint16( buffer ); + *name = serializer_get_string( buffer ); + *rid = serializer_get_uint16( buffer ); + *imageSize = serializer_get_uint64( buffer ); + return true; +} + +#endif |