imapclient: first step towards making package usable as imap client with other imap servers, and minor imapserver bug fix

The imapclient needs more changes, like more strict parsing, before it can be a
generally usable IMAP client, these are a few steps towards that.

- Fix a bug in the imapserver METADATA responses for TOOMANY and MAXSIZE.
- Split low-level IMAP protocol handling (new Proto type) from the higher-level
  client command handling (existing Conn type). The idea is that some simple
  uses of IMAP can get by with just using these commands, while more intricate
  uses of IMAP (like a synchronizing client that needs to talk to all kinds of
  servers with different behaviours and implemented extensions) can write custom
  commands and read untagged responses or command completion results
  explicitly. The lower-level method names have clearer names now, like
  ReadResponse instead of Response.
- Merge the untagged responses and (command completion) "Result" into a new
  type Response. Makes function signatures simpler. And make Response implement
  the error interface, and change command methods to return the Response as error
  if the result is NO or BAD. Simplifies error handling, and still provides the
  option to continue after a NO or BAD.
- Add UIDSearch/MSNSearch commands, with a custom "search program", so mostly
  to indicate these commands exist.
- More complete coverage of types for response codes, for easier handling.
- Automatically handle any ENABLED or CAPABILITY untagged response or response
  code for IMAP command methods on type Conn.
- Make difference between MSN vs UID versions of
  FETCH/STORE/SEARCH/COPY/MOVE/REPLACE commands more clear. The original MSN
  commands now have MSN prefixed to their name, so they are grouped together in
  the documentation.
- Document which capabilities are needed for a command.
This commit is contained in:
Mechiel Lukkien
2025-04-14 21:53:18 +02:00
parent 2c1283f032
commit e7b562e3f2
31 changed files with 3198 additions and 1525 deletions

View File

@ -2,48 +2,57 @@ package imapclient
import (
"bufio"
"errors"
"fmt"
"strings"
"time"
)
// Capability is a known string for with the ENABLED and CAPABILITY command.
// Capability is a known string for with the ENABLED command and response and
// CAPABILITY responses. Servers could send unknown values. Always in upper case.
type Capability string
const (
CapIMAP4rev1 Capability = "IMAP4rev1"
CapIMAP4rev2 Capability = "IMAP4rev2"
CapLoginDisabled Capability = "LOGINDISABLED"
CapStarttls Capability = "STARTTLS"
CapAuthPlain Capability = "AUTH=PLAIN"
CapLiteralPlus Capability = "LITERAL+"
CapLiteralMinus Capability = "LITERAL-"
CapIdle Capability = "IDLE"
CapNamespace Capability = "NAMESPACE"
CapBinary Capability = "BINARY"
CapUnselect Capability = "UNSELECT"
CapUidplus Capability = "UIDPLUS"
CapEsearch Capability = "ESEARCH"
CapEnable Capability = "ENABLE"
CapSave Capability = "SAVE"
CapListExtended Capability = "LIST-EXTENDED"
CapSpecialUse Capability = "SPECIAL-USE"
CapMove Capability = "MOVE"
CapUTF8Only Capability = "UTF8=ONLY"
CapUTF8Accept Capability = "UTF8=ACCEPT"
CapID Capability = "ID" // ../rfc/2971:80
CapMetadata Capability = "METADATA" // ../rfc/5464:124
CapMetadataServer Capability = "METADATA-SERVER" // ../rfc/5464:124
CapSaveDate Capability = "SAVEDATE" // ../rfc/8514
CapCreateSpecialUse Capability = "CREATE-SPECIAL-USE" // ../rfc/6154:296
CapCompressDeflate Capability = "COMPRESS=DEFLATE" // ../rfc/4978:65
CapListMetadata Capability = "LIST-METADTA" // ../rfc/9590:73
CapMultiAppend Capability = "MULTIAPPEND" // ../rfc/3502:33
CapReplace Capability = "REPLACE" // ../rfc/8508:155
CapPreview Capability = "PREVIEW" // ../rfc/8970:114
CapMultiSearch Capability = "MULTISEARCH" // ../rfc/7377:187
CapNotify Capability = "NOTIFY" // ../rfc/5465:195
CapUIDOnly Capability = "UIDONLY" // ../rfc/9586:129
CapIMAP4rev1 Capability = "IMAP4REV1" // ../rfc/3501:1310
CapIMAP4rev2 Capability = "IMAP4REV2" // ../rfc/9051:1219
CapLoginDisabled Capability = "LOGINDISABLED" // ../rfc/3501:3792 ../rfc/9051:5436
CapStartTLS Capability = "STARTTLS" // ../rfc/3501:1327 ../rfc/9051:1238
CapAuthPlain Capability = "AUTH=PLAIN" // ../rfc/3501:1327 ../rfc/9051:1238
CapAuthExternal Capability = "AUTH=EXTERNAL" // ../rfc/4422:1575
CapAuthSCRAMSHA256Plus Capability = "AUTH=SCRAM-SHA-256-PLUS" // ../rfc/7677:80
CapAuthSCRAMSHA256 Capability = "AUTH=SCRAM-SHA-256"
CapAuthSCRAMSHA1Plus Capability = "AUTH=SCRAM-SHA-1-PLUS" // ../rfc/5802:465
CapAuthSCRAMSHA1 Capability = "AUTH=SCRAM-SHA-1"
CapAuthCRAMMD5 Capability = "AUTH=CRAM-MD5" // ../rfc/2195:80
CapLiteralPlus Capability = "LITERAL+" // ../rfc/2088:45
CapLiteralMinus Capability = "LITERAL-" // ../rfc/7888:26 ../rfc/9051:847 Default since IMAP4rev2
CapIdle Capability = "IDLE" // ../rfc/2177:69 ../rfc/9051:3542 Default since IMAP4rev2
CapNamespace Capability = "NAMESPACE" // ../rfc/2342:130 ../rfc/9051:135 Default since IMAP4rev2
CapBinary Capability = "BINARY" // ../rfc/3516:100
CapUnselect Capability = "UNSELECT" // ../rfc/3691:78 ../rfc/9051:3667 Default since IMAP4rev2
CapUidplus Capability = "UIDPLUS" // ../rfc/4315:36 ../rfc/9051:8015 Default since IMAP4rev2
CapEsearch Capability = "ESEARCH" // ../rfc/4731:69 ../rfc/9051:8016 Default since IMAP4rev2
CapEnable Capability = "ENABLE" // ../rfc/5161:52 ../rfc/9051:8016 Default since IMAP4rev2
CapListExtended Capability = "LIST-EXTENDED" // ../rfc/5258:150 ../rfc/9051:7987 Syntax except multiple mailboxes default since IMAP4rev2
CapSpecialUse Capability = "SPECIAL-USE" // ../rfc/6154:156 ../rfc/9051:8021 Special-use attributes in LIST responses by default since IMAP4rev2
CapMove Capability = "MOVE" // ../rfc/6851:87 ../rfc/9051:8018 Default since IMAP4rev2
CapUTF8Only Capability = "UTF8=ONLY"
CapUTF8Accept Capability = "UTF8=ACCEPT"
CapCondstore Capability = "CONDSTORE" // ../rfc/7162:411
CapQresync Capability = "QRESYNC" // ../rfc/7162:1376
CapID Capability = "ID" // ../rfc/2971:80
CapMetadata Capability = "METADATA" // ../rfc/5464:124
CapMetadataServer Capability = "METADATA-SERVER" // ../rfc/5464:124
CapSaveDate Capability = "SAVEDATE" // ../rfc/8514
CapCreateSpecialUse Capability = "CREATE-SPECIAL-USE" // ../rfc/6154:296
CapCompressDeflate Capability = "COMPRESS=DEFLATE" // ../rfc/4978:65
CapListMetadata Capability = "LIST-METADATA" // ../rfc/9590:73
CapMultiAppend Capability = "MULTIAPPEND" // ../rfc/3502:33
CapReplace Capability = "REPLACE" // ../rfc/8508:155
CapPreview Capability = "PREVIEW" // ../rfc/8970:114
CapMultiSearch Capability = "MULTISEARCH" // ../rfc/7377:187
CapNotify Capability = "NOTIFY" // ../rfc/5465:195
CapUIDOnly Capability = "UIDONLY" // ../rfc/9586:129
)
// Status is the tagged final result of a command.
@ -55,63 +64,134 @@ const (
OK Status = "OK" // Command succeeded.
)
// Response is a response to an IMAP command including any preceding untagged
// responses. Response implements the error interface through result.
//
// See [UntaggedResponseGet] and [UntaggedResponseList] to retrieve specific types
// of untagged responses.
type Response struct {
Untagged []Untagged
Result
}
var (
ErrMissing = errors.New("no response of type") // Returned by UntaggedResponseGet.
ErrMultiple = errors.New("multiple responses of type") // Idem.
)
// UntaggedResponseGet returns the single untagged response of type T. Only
// [ErrMissing] or [ErrMultiple] can be returned as error.
func UntaggedResponseGet[T Untagged](resp Response) (T, error) {
var t T
var have bool
for _, e := range resp.Untagged {
if tt, ok := e.(T); ok {
if have {
return t, ErrMultiple
}
t = tt
}
}
if !have {
return t, ErrMissing
}
return t, nil
}
// UntaggedResponseList returns all untagged responses of type T.
func UntaggedResponseList[T Untagged](resp Response) []T {
var l []T
for _, e := range resp.Untagged {
if tt, ok := e.(T); ok {
l = append(l, tt)
}
}
return l
}
// Result is the final response for a command, indicating success or failure.
type Result struct {
Status Status
RespText
Code Code // Set if response code is present.
Text string // Any remaining text.
}
// CodeArg represents a response code with arguments, i.e. the data between [] in the response line.
type CodeArg interface {
CodeString() string
}
// CodeOther is a valid but unrecognized response code.
type CodeOther struct {
Code string
Args []string
}
func (c CodeOther) CodeString() string {
return c.Code + " " + strings.Join(c.Args, " ")
}
// CodeWords is a code with space-separated string parameters. E.g. CAPABILITY.
type CodeWords struct {
Code string
Args []string
}
func (c CodeWords) CodeString() string {
s := c.Code
for _, w := range c.Args {
s += " " + w
func (r Result) Error() string {
s := fmt.Sprintf("IMAP result %s", r.Status)
if r.Code != nil {
s += "[" + r.Code.CodeString() + "]"
}
if r.Text != "" {
s += " " + r.Text
}
return s
}
// CodeList is a code with a list with space-separated strings as parameters. E.g. BADCHARSET, PERMANENTFLAGS.
type CodeList struct {
Code string
Args []string // If nil, no list was present. List can also be empty.
// Code represents a response code with optional arguments, i.e. the data between [] in the response line.
type Code interface {
CodeString() string
}
func (c CodeList) CodeString() string {
s := c.Code
if c.Args == nil {
// CodeWord is a response code without parameters, always in upper case.
type CodeWord string
func (c CodeWord) CodeString() string {
return string(c)
}
// CodeOther is an unrecognized response code with parameters.
type CodeParams struct {
Code string // Always in upper case.
Args []string
}
func (c CodeParams) CodeString() string {
return c.Code + " " + strings.Join(c.Args, " ")
}
// CodeCapability is a CAPABILITY response code with the capabilities supported by the server.
type CodeCapability []Capability
func (c CodeCapability) CodeString() string {
var s string
for _, c := range c {
s += " " + string(c)
}
return "CAPABILITY" + s
}
type CodeBadCharset []string
func (c CodeBadCharset) CodeString() string {
s := "BADCHARSET"
if len(c) == 0 {
return s
}
return s + "(" + strings.Join(c.Args, " ") + ")"
return s + " (" + strings.Join([]string(c), " ") + ")"
}
// CodeUint is a code with a uint32 parameter, e.g. UIDNEXT and UIDVALIDITY.
type CodeUint struct {
Code string
Num uint32
type CodePermanentFlags []string
func (c CodePermanentFlags) CodeString() string {
return "PERMANENTFLAGS (" + strings.Join([]string(c), " ") + ")"
}
func (c CodeUint) CodeString() string {
return fmt.Sprintf("%s %d", c.Code, c.Num)
type CodeUIDNext uint32
func (c CodeUIDNext) CodeString() string {
return fmt.Sprintf("UIDNEXT %d", c)
}
type CodeUIDValidity uint32
func (c CodeUIDValidity) CodeString() string {
return fmt.Sprintf("UIDVALIDITY %d", c)
}
type CodeUnseen uint32
func (c CodeUnseen) CodeString() string {
return fmt.Sprintf("UNSEEN %d", c)
}
// "APPENDUID" response code.
@ -196,11 +276,32 @@ func (c CodeBadEvent) CodeString() string {
return fmt.Sprintf("BADEVENT (%s)", strings.Join([]string(c), " "))
}
// RespText represents a response line minus the leading tag.
type RespText struct {
Code string // The first word between [] after the status.
CodeArg CodeArg // Set if code has a parameter.
More string // Any remaining text.
// "METADATA LONGENTRIES number" response for GETMETADATA command.
type CodeMetadataLongEntries uint32
func (c CodeMetadataLongEntries) CodeString() string {
return fmt.Sprintf("METADATA LONGENTRIES %d", c)
}
// "METADATA (MAXSIZE number)" response for SETMETADATA command.
type CodeMetadataMaxSize uint32
func (c CodeMetadataMaxSize) CodeString() string {
return fmt.Sprintf("METADATA (MAXSIZE %d)", c)
}
// "METADATA (TOOMANY)" response for SETMETADATA command.
type CodeMetadataTooMany struct{}
func (c CodeMetadataTooMany) CodeString() string {
return "METADATA (TOOMANY)"
}
// "METADATA (NOPRIVATE)" response for SETMETADATA command.
type CodeMetadataNoPrivate struct{}
func (c CodeMetadataNoPrivate) CodeString() string {
return "METADATA (NOPRIVATE)"
}
// atom or string.
@ -241,17 +342,30 @@ func syncliteral(s string) string {
// todo: make an interface that the untagged responses implement?
type Untagged any
type UntaggedBye RespText
type UntaggedPreauth RespText
type UntaggedBye struct {
Code Code // Set if response code is present.
Text string // Any remaining text.
}
type UntaggedPreauth struct {
Code Code // Set if response code is present.
Text string // Any remaining text.
}
type UntaggedExpunge uint32
type UntaggedExists uint32
type UntaggedRecent uint32
type UntaggedCapability []string
type UntaggedEnabled []string
// UntaggedCapability lists all capabilities the server implements.
type UntaggedCapability []Capability
// UntaggedEnabled indicates the capabilities that were enabled on the connection
// by the server, typically in response to an ENABLE command.
type UntaggedEnabled []Capability
type UntaggedResult Result
type UntaggedFlags []string
type UntaggedList struct {
// ../rfc/9051:6690
Flags []string
Separator byte // 0 for NIL
Mailbox string
@ -272,8 +386,9 @@ type UntaggedUIDFetch struct {
}
type UntaggedSearch []uint32
// ../rfc/7162:1101
type UntaggedSearchModSeq struct {
// ../rfc/7162:1101
Nums []uint32
ModSeq int64
}
@ -282,8 +397,10 @@ type UntaggedStatus struct {
Attrs map[StatusAttr]int64 // Upper case status attributes.
}
// ../rfc/5464:716 Unsolicited response, indicating an annotation has changed.
// Unsolicited response, indicating an annotation has changed.
type UntaggedMetadataKeys struct {
// ../rfc/5464:716
Mailbox string // Empty means not specific to mailbox.
// Keys that have changed. To get values (or determine absence), the server must be
@ -299,15 +416,17 @@ type Annotation struct {
Value []byte
}
// ../rfc/5464:683
type UntaggedMetadataAnnotations struct {
// ../rfc/5464:683
Mailbox string // Empty means not specific to mailbox.
Annotations []Annotation
}
// ../rfc/9051:7059 ../9208:712
type StatusAttr string
// ../rfc/9051:7059 ../9208:712
const (
StatusMessages StatusAttr = "MESSAGES"
StatusUIDNext StatusAttr = "UIDNEXT"
@ -326,6 +445,7 @@ type UntaggedNamespace struct {
}
type UntaggedLsub struct {
// ../rfc/3501:4833
Flags []string
Separator byte
Mailbox string
@ -395,6 +515,7 @@ type EsearchDataExt struct {
type NamespaceDescr struct {
// ../rfc/9051:6769
Prefix string
Separator byte // If 0 then separator was absent.
Exts []NamespaceExtension
@ -402,13 +523,14 @@ type NamespaceDescr struct {
type NamespaceExtension struct {
// ../rfc/9051:6773
Key string
Values []string
}
// FetchAttr represents a FETCH response attribute.
type FetchAttr interface {
Attr() string // Name of attribute.
Attr() string // Name of attribute in upper case, e.g. "UID".
}
type NumSet struct {
@ -435,14 +557,14 @@ func (ns NumSet) String() string {
}
func ParseNumSet(s string) (ns NumSet, rerr error) {
c := Conn{br: bufio.NewReader(strings.NewReader(s))}
c := Proto{br: bufio.NewReader(strings.NewReader(s))}
defer c.recover(&rerr)
ns = c.xsequenceSet()
return
}
func ParseUIDRange(s string) (nr NumRange, rerr error) {
c := Conn{br: bufio.NewReader(strings.NewReader(s))}
c := Proto{br: bufio.NewReader(strings.NewReader(s))}
defer c.recover(&rerr)
nr = c.xuidrange()
return
@ -481,6 +603,7 @@ type TaggedExtComp struct {
type TaggedExtVal struct {
// ../rfc/9051:7111
Number *int64
SeqSet *NumSet
Comp *TaggedExtComp // If SimpleNumber and SimpleSeqSet is nil, this is a Comp. But Comp is optional and can also be nil. Not great.
@ -488,6 +611,7 @@ type TaggedExtVal struct {
type MboxListExtendedItem struct {
// ../rfc/9051:6699
Tag string
Val TaggedExtVal
}
@ -522,8 +646,10 @@ type FetchInternalDate struct {
func (f FetchInternalDate) Attr() string { return "INTERNALDATE" }
// "SAVEDATE" fetch response. ../rfc/8514:265
// "SAVEDATE" fetch response.
type FetchSaveDate struct {
// ../rfc/8514:265
SaveDate *time.Time // nil means absent for message.
}
@ -552,6 +678,7 @@ func (f FetchRFC822Text) Attr() string { return "RFC822.TEXT" }
// "BODYSTRUCTURE" fetch response.
type FetchBodystructure struct {
// ../rfc/9051:6355
RespAttr string
Body any // BodyType*
}
@ -561,6 +688,7 @@ func (f FetchBodystructure) Attr() string { return f.RespAttr }
// "BODY" fetch response.
type FetchBody struct {
// ../rfc/9051:6756 ../rfc/9051:6985
RespAttr string
Section string // todo: parse more ../rfc/9051:6985
Offset int32
@ -580,6 +708,7 @@ type BodyFields struct {
// subparts and the multipart media subtype. Used in a FETCH response.
type BodyTypeMpart struct {
// ../rfc/9051:6411
Bodies []any // BodyTypeBasic, BodyTypeMsg, BodyTypeText
MediaSubtype string
Ext *BodyExtensionMpart
@ -589,6 +718,7 @@ type BodyTypeMpart struct {
// response.
type BodyTypeBasic struct {
// ../rfc/9051:6407
MediaType, MediaSubtype string
BodyFields BodyFields
Ext *BodyExtension1Part
@ -598,6 +728,7 @@ type BodyTypeBasic struct {
// response.
type BodyTypeMsg struct {
// ../rfc/9051:6415
MediaType, MediaSubtype string
BodyFields BodyFields
Envelope Envelope
@ -610,6 +741,7 @@ type BodyTypeMsg struct {
// response.
type BodyTypeText struct {
// ../rfc/9051:6418
MediaType, MediaSubtype string
BodyFields BodyFields
Lines int64
@ -618,26 +750,42 @@ type BodyTypeText struct {
// BodyExtension1Part has the extensible form fields of a BODYSTRUCTURE for
// multiparts.
//
// Fields in this struct are optional in IMAP4, and can be NIL or contain a value.
// The first field is always present, otherwise the "parent" struct would have a
// nil *BodyExtensionMpart. The second and later fields are nil when absent. For
// non-reference types (e.g. strings), an IMAP4 NIL is represented as a pointer to
// (*T)(nil). For reference types (e.g. slices), an IMAP4 NIL is represented by a
// pointer to nil.
type BodyExtensionMpart struct {
// ../rfc/9051:5986 ../rfc/3501:4161 ../rfc/9051:6371 ../rfc/3501:4599
Params [][2]string
Disposition string
DispositionParams [][2]string
Language []string
Location string
More []BodyExtension
Disposition **string
DispositionParams *[][2]string
Language *[]string
Location **string
More []BodyExtension // Nil if absent.
}
// BodyExtension1Part has the extensible form fields of a BODYSTRUCTURE for
// non-multiparts.
//
// Fields in this struct are optional in IMAP4, and can be NIL or contain a value.
// The first field is always present, otherwise the "parent" struct would have a
// nil *BodyExtensionMpart. The second and later fields are nil when absent. For
// non-reference types (e.g. strings), an IMAP4 NIL is represented as a pointer to
// (*T)(nil). For reference types (e.g. slices), an IMAP4 NIL is represented by a
// pointer to nil.
type BodyExtension1Part struct {
// ../rfc/9051:6023 ../rfc/3501:4191 ../rfc/9051:6366 ../rfc/3501:4584
MD5 string
Disposition string
DispositionParams [][2]string
Language []string
Location string
More []BodyExtension
MD5 *string
Disposition **string
DispositionParams *[][2]string
Language *[]string
Location **string
More []BodyExtension // Nil means absent.
}
// BodyExtension has the additional extension fields for future expansion of