package yggdrasil // This file contains the version metadata struct // Used in the inital connection setup and key exchange // Some of this could arguably go in wire.go instead // This is the version-specific metadata exchanged at the start of a connection. // It must always beign with the 4 bytes "meta" and a wire formatted uint64 major version number. // The current version also includes a minor version number, and the box/sig/link keys that need to be exchanged to open an connection. type version_metadata struct { meta [4]byte ver uint64 // 1 byte in this version // Everything after this point potentially depends on the version number, and is subject to change in future versions minorVer uint64 // 1 byte in this version box boxPubKey sig sigPubKey link boxPubKey } // Gets a base metadata with no keys set, but with the correct version numbers. func version_getBaseMetadata() version_metadata { return version_metadata{ meta: [4]byte{'m', 'e', 't', 'a'}, ver: 0, minorVer: 2, } } // Gest the length of the metadata for this version, used to know how many bytes to read from the start of a connection. func version_getMetaLength() (mlen int) { mlen += 4 // meta mlen += 1 // ver, as long as it's < 127, which it is in this version mlen += 1 // minorVer, as long as it's < 127, which it is in this version mlen += boxPubKeyLen // box mlen += sigPubKeyLen // sig mlen += boxPubKeyLen // link return } // Encodes version metadata into its wire format. func (m *version_metadata) encode() []byte { bs := make([]byte, 0, version_getMetaLength()) bs = append(bs, m.meta[:]...) bs = append(bs, wire_encode_uint64(m.ver)...) bs = append(bs, wire_encode_uint64(m.minorVer)...) bs = append(bs, m.box[:]...) bs = append(bs, m.sig[:]...) bs = append(bs, m.link[:]...) if len(bs) != version_getMetaLength() { panic("Inconsistent metadata length") } return bs } // Decodes version metadata from its wire format into the struct. func (m *version_metadata) decode(bs []byte) bool { switch { case !wire_chop_slice(m.meta[:], &bs): return false case !wire_chop_uint64(&m.ver, &bs): return false case !wire_chop_uint64(&m.minorVer, &bs): return false case !wire_chop_slice(m.box[:], &bs): return false case !wire_chop_slice(m.sig[:], &bs): return false case !wire_chop_slice(m.link[:], &bs): return false } return true } // Checks that the "meta" bytes and the version numbers are the expected values. func (m *version_metadata) check() bool { base := version_getBaseMetadata() return base.meta == m.meta && base.ver == m.ver && base.minorVer == m.minorVer }