FastAPI OAuth2 ইমপ্লিমেন্টেশন: একটি বিস্তৃত প্রমাণীকরণ ফ্লো গাইড

            pip install fastapi uvicorn python-multipart passlib[bcrypt] python-jose[cryptography]
            

              
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            from fastapi import Depends, FastAPI, HTTPException, status
from fastapi.security import OAuth2PasswordRequestForm
from jose import JWTError, jwt
from passlib.context import CryptContext
from datetime import datetime, timedelta

app = FastAPI()

# Replace with a strong, randomly generated secret key
SECRET_KEY = "YOUR_SECRET_KEY"
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_MINUTES = 30

# Password hashing configuration
pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")

# Dummy user database (replace with a real database in production)
users = {
    "johndoe": {
        "username": "johndoe",
        "hashed_password": pwd_context.hash("password123"),
        "scopes": ["read", "write"]
    }
}

# Function to verify password
def verify_password(plain_password, hashed_password):
    return pwd_context.verify(plain_password, hashed_password)

# Function to create access token
def create_access_token(data: dict, expires_delta: timedelta):
    to_encode = data.copy()
    expire = datetime.utcnow() + expires_delta
    to_encode.update({"exp": expire})
    encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
    return encoded_jwt

# OAuth2 endpoint for token generation
@app.post("/token")
async def login(form_data: OAuth2PasswordRequestForm = Depends()):
    user = users.get(form_data.username)
    if not user:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Incorrect username or password",
            headers={"WWW-Authenticate": "Bearer"},
        )
    if not verify_password(form_data.password, user["hashed_password"]):
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Incorrect username or password",
            headers={"WWW-Authenticate": "Bearer"},
        )
    access_token_expires = timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)
    access_token = create_access_token(
        data={"sub": user["username"], "scopes": user["scopes"]},
        expires_delta=access_token_expires,
    )
    return {"access_token": access_token, "token_type": "bearer"}

# Dependency to authenticate requests
async def get_current_user(token: str):
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )
    try:
        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
        username: str = payload.get("sub")
        if username is None:
            raise credentials_exception
    except JWTError:
        raise credentials_exception
    user = users.get(username)
    if user is None:
        raise credentials_exception
    return user

async def get_current_active_user(current_user = Depends(get_current_user)):
    return current_user

# Example protected endpoint
@app.get("/users/me")
async def read_users_me(current_user = Depends(get_current_active_user)):
    return {"username": current_user["username"], "scopes": current_user["scopes"]}

            

              
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            from fastapi import Depends, FastAPI, HTTPException, status
from fastapi.security import OAuth2AuthorizationCodeBearer
from jose import JWTError, jwt

app = FastAPI()

# Replace with a strong, randomly generated secret key
SECRET_KEY = "YOUR_SECRET_KEY"
ALGORITHM = "HS256"

# Dummy user database (replace with a real database in production)
users = {
    "johndoe": {
        "username": "johndoe",
        "scopes": ["read", "write"]
    }
}

# OAuth2 scheme - using AuthorizationCodeBearer for token verification
oauth2_scheme = OAuth2AuthorizationCodeBearer(authorizationUrl="/auth", tokenUrl="/token") # These URLs are handled by the Authorization Server (not this FastAPI app).

# Dependency to authenticate requests
async def get_current_user(token: str = Depends(oauth2_scheme)):
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )
    try:
        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
        username: str = payload.get("sub")
        if username is None:
            raise credentials_exception
    except JWTError:
        raise credentials_exception
    user = users.get(username)
    if user is None:
        raise credentials_exception
    return user

async def get_current_active_user(current_user = Depends(get_current_user)):
    return current_user

# Example protected endpoint
@app.get("/users/me")
async def read_users_me(current_user = Depends(get_current_active_user)):
    return {"username": current_user["username"], "scopes": current_user["scopes"]}

            

              
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            from fastapi import Depends, FastAPI, HTTPException, status
from fastapi.security import OAuth2AuthorizationCodeBearer
from jose import JWTError, jwt

app = FastAPI()

# Replace with a strong, randomly generated secret key
SECRET_KEY = "YOUR_SECRET_KEY"
ALGORITHM = "HS256"

# Dummy user database (replace with a real database in production)
users = {
    "johndoe": {
        "username": "johndoe",
        "scopes": ["read", "write"]
    }
}

# OAuth2 scheme - using AuthorizationCodeBearer for token verification
oauth2_scheme = OAuth2AuthorizationCodeBearer(authorizationUrl="/auth", tokenUrl="/token") # These URLs are handled by the Authorization Server.

# Dependency to authenticate requests
async def get_current_user(token: str = Depends(oauth2_scheme)):
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )
    try:
        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
        username: str = payload.get("sub")
        if username is None:
            raise credentials_exception
    except JWTError:
        raise credentials_exception
    user = users.get(username)
    if user is None:
        raise credentials_exception
    return user

async def get_current_active_user(current_user = Depends(get_current_user)):
    return current_user

# Example protected endpoint
@app.get("/users/me")
async def read_users_me(current_user = Depends(get_current_active_user)):
    return {"username": current_user["username"], "scopes": current_user["scopes"]}

            

              
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            from fastapi import Depends, FastAPI, HTTPException, status
from fastapi.security import HTTPBasic, HTTPBasicCredentials
from jose import JWTError, jwt
from datetime import datetime, timedelta

app = FastAPI()

# Replace with a strong, randomly generated secret key
SECRET_KEY = "YOUR_SECRET_KEY"
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_MINUTES = 30

# Dummy client database (replace with a real database in production)
clients = {
    "client_id": {
        "client_secret": "client_secret",
        "scopes": ["read", "write"]
    }
}

# Function to create access token
def create_access_token(data: dict, expires_delta: timedelta):
    to_encode = data.copy()
    expire = datetime.utcnow() + expires_delta
    to_encode.update({"exp": expire})
    encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
    return encoded_jwt

# HTTP Basic Authentication scheme
security = HTTPBasic()

# Endpoint for token generation
@app.post("/token")
async def login(credentials: HTTPBasicCredentials = Depends(security)):
    client = clients.get(credentials.username)
    if not client:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Incorrect client ID or secret",
            headers={"WWW-Authenticate": "Basic"},
        )
    if credentials.password != client["client_secret"]:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Incorrect client ID or secret",
            headers={"WWW-Authenticate": "Basic"},
        )
    access_token_expires = timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)
    access_token = create_access_token(
        data={"sub": credentials.username, "scopes": client["scopes"]},
        expires_delta=access_token_expires,
    )
    return {"access_token": access_token, "token_type": "bearer"}

# Dependency to authenticate requests
async def get_current_client(token: str):
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )
    try:
        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
        client_id: str = payload.get("sub")
        if client_id is None:
            raise credentials_exception
    except JWTError:
        raise credentials_exception
    client = clients.get(client_id)
    if client is None:
        raise credentials_exception
    return client

async def get_current_active_client(current_client = Depends(get_current_client)):
    return current_client

# Example protected endpoint
@app.get("/data")
async def read_data(current_client = Depends(get_current_active_client)):
    return {"message": "Data accessed by client: " + current_client["client_secret"]}

            

              
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            from fastapi import Depends, FastAPI, HTTPException, status
from fastapi.security import OAuth2PasswordRequestForm
from jose import JWTError, jwt
from passlib.context import CryptContext
from datetime import datetime, timedelta
import secrets  # For generating secure random strings

app = FastAPI()

# Replace with a strong, randomly generated secret key
SECRET_KEY = "YOUR_SECRET_KEY"
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_MINUTES = 30
REFRESH_TOKEN_EXPIRE_DAYS = 30  # Longer lifetime for refresh tokens

# Password hashing configuration
pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")

# Dummy user database (replace with a real database in production)
users = {
    "johndoe": {
        "username": "johndoe",
        "hashed_password": pwd_context.hash("password123"),
        "scopes": ["read", "write"],
        "refresh_token": None  # Store refresh token here
    }
}

# Function to verify password (same as before)
def verify_password(plain_password, hashed_password):
    return pwd_context.verify(plain_password, hashed_password)

# Function to create access token (same as before)
def create_access_token(data: dict, expires_delta: timedelta):
    to_encode = data.copy()
    expire = datetime.utcnow() + expires_delta
    to_encode.update({"exp": expire})
    encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
    return encoded_jwt

# Function to create refresh token
def create_refresh_token():
    return secrets.token_urlsafe(32)  # Generate a secure random string

# OAuth2 endpoint for token generation
@app.post("/token")
async def login(form_data: OAuth2PasswordRequestForm = Depends()):
    user = users.get(form_data.username)
    if not user:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Incorrect username or password",
            headers={"WWW-Authenticate": "Bearer"},
        )
    if not verify_password(form_data.password, user["hashed_password"]):
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Incorrect username or password",
            headers={"WWW-Authenticate": "Bearer"},
        )

    # Create refresh token and store it (securely in a database in real-world)
    refresh_token = create_refresh_token()
    user["refresh_token"] = refresh_token  # Store it in the user object for now (INSECURE for production)

    access_token_expires = timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)
    access_token = create_access_token(
        data={"sub": user["username"], "scopes": user["scopes"]},
        expires_delta=access_token_expires,
    )
    return {"access_token": access_token, "token_type": "bearer", "refresh_token": refresh_token}

# Endpoint for refreshing the access token
@app.post("/refresh_token")
async def refresh_access_token(refresh_token: str):
    # Find user by refresh token (securely query the database)
    user = next((user for user in users.values() if user["refresh_token"] == refresh_token), None)

    if not user:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Invalid refresh token",
            headers={"WWW-Authenticate": "Bearer"},
        )

    # Create a new access token
    access_token_expires = timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)
    access_token = create_access_token(
        data={"sub": user["username"], "scopes": user["scopes"]},
        expires_delta=access_token_expires,
    )

    return {"access_token": access_token, "token_type": "bearer"}

# Dependency to authenticate requests (same as before)
async def get_current_user(token: str):
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )
    try:
        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
        username: str = payload.get("sub")
        if username is None:
            raise credentials_exception
    except JWTError:
        raise credentials_exception
    user = next((user for user in users.values() if user["username"] == username), None)
    if user is None:
        raise credentials_exception
    return user

async def get_current_active_user(current_user = Depends(get_current_user)):
    return current_user

# Example protected endpoint (same as before)
@app.get("/users/me")
async def read_users_me(current_user = Depends(get_current_active_user)):
    return {"username": current_user["username"], "scopes": current_user["scopes"]}

            

              
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