Fetching new Gmail emails after a timestamp - go

I am going through Gmail API docs(https://developers.google.com/gmail/api), I am able to read all the user emails which are present in the inbox.
eg snippet (reading complete list of emails):
for {
req := svc.Users.Messages.List("me")
r, _ := req.Do()
for _, m := range r.Messages {
msg, _ := svc.Users.Messages.Get("me", m.Id).Do()
date := ""
for _, h := range msg.Payload.Headers {
if h.Name == "Date" {
date = h.Value
break
}
}
msgs = append(msgs, message{
...
})
}
}
Now, when new emails come I want to read them as well (either immediately or after some time). I can write a scheduled job for that purpose, But I am not sure if I can fetch email after a particular timestamp or after an email identifier. I don't want to read a whole bunch of emails, again and again, to figure out the new emails, in this way, there is a lot of unnecessary computation being involved. Is there any way I can make this task easier?

Looking at the docs, it looks like it supports a query parameter, q.
The query parameter supports the same options as available in the Gmail search bar:
Only return messages matching the specified query. Supports the same query format as the Gmail search box. For example, "from:someuser#example.com rfc822msgid:somemsgid#example.com is:unread". Parameter cannot be used when accessing the api using the gmail.metadata scope.
This means you can do something like "after:YYYY/MM/DD" or with a timestamp "after:1616819452".
req := svc.Users.Messages.List("me").Q("after:2021/01/01")
See the full usage here https://pkg.go.dev/google.golang.org/api/gmail/v1#UsersMessagesListCall.Q

Related

Whatsmeow conversation data [closed]

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I'm trying to build a tui client for WhatsApp using whatsmeow.
After half a day of searching and reading through the docs, I still can't find a way to get the conversation data of individual contacts. Any help is appreciated.
I found ParseWebMessage but I'm not really sure how to use this.
chatJID, err := types.ParseJID(conv.GetId())
for _, historyMsg := range conv.GetMessages() {
evt, err := cli.ParseWebMessage(chatJID, historyMsg.GetMessage())
yourNormalEventHandler(evt)
}
Matter of fact I'm not even sure if this is what I'm looking for
Well, you basically linked to the part of the docs that contains the information you're looking for. The return type of the ParseWebMessage call is events.Message, documented here. It contains an Info field of type MessageInfo (again, documented here). In turn, this MessageInfo type embeds the MessageSource type see docs here which looks like this:
type MessageSource struct {
Chat JID // The chat where the message was sent.
Sender JID // The user who sent the message.
IsFromMe bool // Whether the message was sent by the current user instead of someone else.
IsGroup bool // Whether the chat is a group chat or broadcast list.
// When sending a read receipt to a broadcast list message, the Chat is the broadcast list
// and Sender is you, so this field contains the recipient of the read receipt.
BroadcastListOwner JID
}
So to get the contact who sent a given message, given your code evt, err := cli.ParseWebMessage(), you need to check:
evt, err := cli.ParseWebMessage(chatJID, historyMsg.GetMessage())
if err != nil {
// handle error, of course
}
fmt.Printf("Sender ID: %s\nSent in Chat: %s\n", evt.Info.Sender, evt.Info.Chat)
if evt.Info.IsGroup {
fmt.Printf("%s is a group chat\n", evt.Info.Chat)
}
You can also skip messages you sent by simply doing this:
if evt.Info.IsFromMe {
continue
}
The evt.Info.Chat and evt.Info.Sender fields are all of type JID, documented here. There essentially are 2 variations of this ID type: user and server JID's and AD-JIDs (user, agent, and device). You can distinguish between the two by checking the JID.AD flag.
I haven't used this module at all, I only scanned through the docs briefly, but as I understand it, this module allows you to write a handler which will receive an events.Message type for everything you receive. By checking the evt.Info.IsGroup, you can work out whether the message we sent in a group chat, or in your person-to-person conversation thing. Based on evt.Info.Sender and evt.Info.Chat, you can work out who sent the message. The evt.Info.Sender being a JID in turn allows you to call the GetUserInfo method, passing in the JID, which gets you a UserInfo object in return as documented here, showing the name, picture, status, etc...
So I guess you're looking for something along these lines:
// some map of all messages from a given person, sent directly to you
contacts := cli.GetAllContacts() // returns map[JID]ContactInfo
personMsg := map[string][]*events.Message
evt, err := cli.ParseWebMessage(chatJID, historyMsg.GetMessage())
if err != nil {
// handle
}
if !evt.Info.IsFromMe && !evt.Info.IsGroup {// not a group, not sent by me
info, _ := cli.GetUserInfo([]types.JID{evt.Info.Sender})
if contact, ok := contacts[info[evt.Info.Sender]; ok {
msgs, ok := personMsg[contact.PushName]
if !ok {
msgs := []*events.Message{}
}
personMsg[contact.PushName] = append(msgs, evt)
}
}
Note the ContatInfo type didn't show up in the docs right away, but I stumbled across it in the repo.
Either way, I'm not quite sure what you're trying to do, and how/why you're stuck. All it took to find this information was to check the return type of the ParseWebMessage method you mentioned, check a couple of types, and scroll through some of the listed/documented methods to get a rough idea of how you can get all the data you could possibly need...

When create JWT token inside loop getting same token in jwt-go

I am creating jwt tokens using jwt-go library. Later wrote a script to load test. I have noticed when I send the many concurrent request getting same token. To check more about this I created token inside for loop and result is same.
The library that I use is https://github.com/dgrijalva/jwt-go, go version is 1.12.9.
expirationTime := time.Now().Add(time.Duration(60) * time.Minute)
for i := 1; i < 5; i++ {
claims := &jwt.StandardClaims{
ExpiresAt: expirationTime.Unix(),
Issuer:"telescope",
}
_token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
var jwtKey = []byte("secret_key")
auth_token, _ := _token.SignedString(jwtKey)
fmt.Println(auth_token)
}
A JWT contains three parts: a mostly-fixed header, a set of claims, and a signature. RFC 7519 has the actual details. If the header is fixed and the claims are identical between two tokens, then the signature will be identical too, and you can easily get duplicated tokens. The two timestamp claims "iat" and "exp" are only at a second granularity, so if you issue multiple tokens with your code during the same second you will get identical results (even if you move the expirationTime calculation inside the loop).
The jwt-go library exports the StandardClaims listed in RFC 7519 ยง4.1 as a structure, which is what you're using in your code. Digging through the library code, there's nothing especially subtle here: StandardClaims uses ordinary "encoding/json" annotations, and then when a token is written out, the claims are JSON encoded and then base64-encoded. So given a fixed input, you'll get a fixed output.
If you want every token to be "different" in some way, the standard "jti" claim is a place to provide a unique ID. This isn't part of the StandardClaims, so you need to create your own custom claim type that includes it.
type UniqueClaims struct {
jwt.StandardClaims
TokenId string `json:"jti,omitempty"`
}
Then when you create the claims structure, you need to generate a unique TokenId yourself.
import (
"crypto/rand"
"encoding/base64"
)
bits := make([]byte, 12)
_, err := rand.Read(bits)
if err != nil {
panic(err)
}
claims := UniqueClaims{
StandardClaims: jwt.StandardClaims{...},
TokenId: base64.StdEncoding.EncodeToString(bits),
}
https://play.golang.org/p/zDnkamwsCi- has a complete example; every time you run it you will get a different token, even if you run it multiple times in the same second. You can base64 decode the middle part of the token by hand to see the claims, or use a tool like the https://jwt.io/ debugger to decode it.
I changed your code:
Moved calculation of expirationTime in the loop
Added 1 sec delay on each step of loop
for i := 1; i < 5; i++ {
expirationTime := time.Now().Add(time.Duration(60) * time.Minute)
claims := &jwt.StandardClaims{
ExpiresAt: expirationTime.Unix(),
Issuer: "telescope",
}
_token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
var jwtKey = []byte("secret_key")
auth_token, _ := _token.SignedString(jwtKey)
fmt.Println(auth_token)
time.Sleep(time.Duration(1) * time.Second)
}
In this case we get different tokens:
eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJleHAiOjE1NjcyNDcwNDgsImlzcyI6InRlbGVzY29wZSJ9.G7wV-zsCYjysLEdgYAq_92JGDPsgqqOz9lZxdh5gcX8
eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJleHAiOjE1NjcyNDcwNDksImlzcyI6InRlbGVzY29wZSJ9.yPNV20EN3XJbGiHhe-wGTdiluJyVHXj3nIqEsfwDZ0Q
eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJleHAiOjE1NjcyNDcwNTAsImlzcyI6InRlbGVzY29wZSJ9.W3xFXEiVwh8xK47dZinpXFpKuvUl1LFUAiaLZZzZ2L0
eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJleHAiOjE1NjcyNDcwNTEsImlzcyI6InRlbGVzY29wZSJ9.wYUbzdXm_VQGdFH9RynAVVouW9h6KI1tHRFJ0Y322i4
Sorry, I am not big expert in JWT and I hope somebody who is explain us this behavior from RFC point of view.
I want to get different tokens. eg : same person login in to system using different browser. so I want to keep many tokens.
It is the same user and we can get him the same token. If we want to give it another one we need to revoke previous one or the client must refresh it.

How to output json format errors in Golang rest, specifically referencing the bad fields

I have the following requirement: return errors from a REST API in the following format:
Error format
422
{
"name-of-field": [
"can't be blank",
"is too silly"
]
}
My code looks like this:
var PostFeedback = func(w http.ResponseWriter, r *http.Request) {
params := mux.Vars(r)
surveyId := params["id"]
feedback := &models.Feedback{}
err := json.NewDecoder(r.Body).Decode(feedback)
if err != nil {
jsonError := fmt.Sprintf(`{
"%s": [
"%s"
]
}`, "errors", err)
log.Printf("invalid input format, %v", jsonError)
resp := map[string]interface{}{"error": jsonError}
u.Respond(w, resp)
return
}
Questions:
How do I get the names of the offending fields?
How do I satisfy the requirement best?
The encoding/json package doesn't provide validation for "blank", nor "silly" values. It will return an error only if the data in the body is not a valid json, or if the field types in the json do not, according to the package's spec, match the field types of the structure into which you're trying to decode that json.
The 1st type of error would be the json.SyntaxError, if you get this it is not always possible to satisfy your requirements since there may be no actual fields which you could use in your response, or if there are json fields, they, and their values, may be perfectly valid json, but the cause of the error may lie elsewhere (see example).
In cases where the data holds actual json fields but it has, for example, non-json values you could use the Offset field of the SyntaxError type to find the closest preceding field in the data stream. Using strings.LastIndex you can implement a naive solution to look backwards for the field.
data := []byte(`{"foobar": i'm not json}`)
err := json.Unmarshal(data, &T{})
se, ok := err.(*json.SyntaxError)
if !ok {
panic(err)
}
field := string(data[:se.Offset])
if i := strings.LastIndex(field, `":`); i >= 0 {
field = field[:i]
if j := strings.LastIndex(field, `"`); j >= 0 {
field = field[j+1:]
}
}
fmt.Println(field) // outputs foobar
Playground link
NOTE: As you can see, for you to be able to look for the field, you need to have access to the data, but when you're using json.NewDecoder and passing it the request's body directly, without first storing its contents somewhere, you'll loose access to that data once the decoder's Decode method is done. This is because the body is a stream of bytes wrapped in a io.ReadCloser that does not support "rewinding", i.e. you cannot re-read bytes that the decoder already read. To avoid this you can use ioutil.ReadAll to read the full contents of the body and then json.Unmarshal to do the decoding.
The 2nd type of error would be the json.UnmarshalTypeError. If you look at the documentation of the error type and its fields you'll know that all you need to do is to type assert the returned value and you're done. Example
Validation against "blank" and "silly" values would be done after the json has been successfully decoded into your structure. How you do that is up to you. For example you could use a 3rd party package that's designed for validating structs, or you can implement an in-house solution yourself, etc. I actually don't have an opinion on which one of them is the "best" so I can't help you with that.
What I can say is that the most basic approach would be to simply look at each field of the structure and check if its value is valid or not according to the requirements for that field.

LoadRelated of a list in beego

I am wondering how the correct approach is to load related fields in beego.
The doc explains it like this:
type User struct {
Id int
Name string
Posts []*Post `orm:"reverse(many)"`
}
user := User{Id: 1}
err := dORM.Read(&user)
num, err := dORM.LoadRelated(&user, "Posts")
This makes sense as long as I only query one record. What is the correct way to fetch related fields when I query all users?
A possible solution would be like this:
var users []*User
o.QueryTable(new(User)).All(&users)
for _, user := range users {
o.LoadRelated(controlCategory, "Posts")
}
However, this means I have to loop everytime over the complete list and make for every record a DB query to load all records.
Any suggestions? Thanks!

How to fetch body from imap server in Go

I successfully fetched a list of email headers using the sample code from this url: https://godoc.org/code.google.com/p/go-imap/go1/imap#example-Client . However, I still haven't been able to fetch the body of the emails. Can anyone show some working sample code that could fetch the body of the emails from a imap server in Golang?
I figured out how to get the body text now.
cmd, _ = c.UIDFetch(set, "RFC822.HEADER", "RFC822.TEXT")
// Process responses while the command is running
fmt.Println("\nMost recent messages:")
for cmd.InProgress() {
// Wait for the next response (no timeout)
c.Recv(-1)
// Process command data
for _, rsp = range cmd.Data {
header := imap.AsBytes(rsp.MessageInfo().Attrs["RFC822.HEADER"])
uid := imap.AsNumber((rsp.MessageInfo().Attrs["UID"]))
body := imap.AsBytes(rsp.MessageInfo().Attrs["RFC822.TEXT"])
if msg, _ := mail.ReadMessage(bytes.NewReader(header)); msg != nil {
fmt.Println("|--", msg.Header.Get("Subject"))
fmt.Println("UID: ", uid)
fmt.Println(string(body))
}
}
cmd.Data = nil
c.Data = nil
}
The example code you've linked to demonstrates the use of the IMAP FETCH command to fetch the RFC822.HEADER message data item for a message. The RFC contains a list of standard data items you can fetch from a message.
If you want the entire mime formatted message (both headers and body), then requesting BODY should do. You can get the headers and message body separately by requesting BODY[HEADER] and BODY[TEXT] respectively. Modifying the sample program to use one of these data items should get the data you are after.

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