ref: 7f224a8f6d343cf0aaf162cc9b9f7d4d62ac78ac
dir: /sys/src/liboventi/venti.txt/
protocol version id both client and server send '\n' terminated ascii of the form venti-<versions>-<software> <software> = is a software id which is ignored but may be useful for debugging If the server and client have the same version number then this version is used. Otherwise backup to the greatest common major version number, e.g. 1.00 2.00 etc. If no version in common then abort. The idea is both client and server should support a continusous range of major versions. The minor version numbers are used for development purposes. After protocol negotiation switch to binary format all numbers sent big endian strings are sent with 2 byte length without nulls and in utf-8 max size of 1K RPC protocol header op[1] byte op tid[2] transation id client manages the tid space. Until session is established tid must equal 0. i.e. only one outstanding op. CipherStrength None, Auth, Weak, Strong CipherAlgorithms None SSL3 TLS1 CompressionAlgorithms None Deflate Thwack? BlockTypes Root Pointer Data ============================================== TPing RPing RError error: string THello version:string; know to be supported by both uid: string uhash[20] use for cipher boot strapping cipherstrength[1] ncipher[1]; cipher[ncipher]; ncompressor[1]; compressor[ncompressor]; RHello sid: string shash[20]; use for cipher bott strapping cipher[1]; compressor[1]; use srp style authentication g=2 N is safe prime 1024 bits - find a good prime! x = H("venti" H(sid) H(uid) H(password)) v = g^x a = random b = random B = (v + g^b) A = g^a u = first four bytes of H(B) S = (B - g^x) ^ (a + u*x) = (A * v^u) ^ b K = H(S) M1 = H(H(versions) H(THello) H(RHello) A B K) M2 = H(A M1 K) TAuth0 A[128] RAuth0 B[128] TAuth1 M1[20] RAuth1 M2[20] push cipher push compression TWrite length[2] max 56*1024 type[1] data[length] RWrite hash[20] TRead hash[20] type[1] length[2] RRead length[2] data[length] ============================================================ simplified access when trusting the server reduces network bandwidth since pointer blocks are not sent to the client - can also enable permission checking RReadRoot root[20] TReadRoot name: string type: string blocksize[2] nblock[8] time[4] uid: string; gid: string RReadData root[20] block[8] length[2] TReadData length[2] collision[1] data[length] ============================================== maybe some clients should be required to navigate to block via root nodes. This would enable permission checking via access to the root node. RTagOpen tag[2] root[20] TTagOpen QTagRead tag[2] type[1] length[2] RTagRead length[2] data[length] QTagWalkRead tag[2] ntag[2] can reuse a tag to do an implict clunk index[2] type[1] length[2] RTagWalkRead length[2] data[length] RTagClunk tag[2] TTagClunk ============================ Types of blocks Data Root name[128] type[128] score[20] - DirBlock Pointer score[20]* the number of hashes can be less than fanout when the tree is not full DirBlock DirEntry[32]* DirEntry pointersize[2] - pointer block size datasize[2] - data blocks size flag[1] directory size[7] in bytes - determines pointer depth - intermidate truncated block count as full score[20] root of pointer blocks or data block ============================ mode flags (1<<0) ModeOtherExec (1<<1) ModeOtherWrite (1<<2) ModeOtherRead (1<<3) ModeGroupExec (1<<4) ModeGroupWrite (1<<5) ModeGroupRead (1<<6) ModeOwnerExec (1<<7) ModeOwnerWrite (1<<8) ModeOwnerRead (1<<9) ModeSticky (1<<10) ModeSetUid (1<<11) ModeSetGid (1<<12) ModeAppend (1<<13) ModeExclusive (1<<14) ModeLink (1<<15) ModeDir - duplicates dir entry (1<<16) ModeHidden (1<<17) ModeSystem (1<<18) ModeArchive (1<<19) ModeTemporary (1<<18) ModeCompressed (1<<19) ModeEncrypted extraType 2 Plan9 version[4] muid: string 3 NT Time createTime[8]; modifyTime[8]; accessTime[8] MetaEntry name: string /* must be first */ direntry[4] id[8] uid: string gui: string mtime[4] ctime[4] atime[4] mode[4] extratype; extrasize[2] extra:[nextra] MetaEntry Block magic[4] size[2] free[2] - used to determine if work compacting maxindex[2] - size of index table in bytes nindex[2] index[2*nindex] per OS directory entries? inode...