Improper type assignation
Need
Enforce proper type assignment in the source code
Context
- Usage of Go 1.16 for developing high-performance and efficient applications
- Usage of gin-gonic/gin for building web applications in Go
- Usage of net/http for building HTTP servers in a Node.js application
Description
Non compliant code
package main
import (
"github.com/gin-gonic/gin"
"net/http"
)
func main() {
r := gin.Default()
r.GET("/example", func(c *gin.Context) {
var data = c.MustGet("data")
c.JSON(http.StatusOK, gin.H{
"data": data,
})
})
r.Run()
}
In the above code, the variable data
is declared without a specific type. This is done using the var
keyword followed by the variable name data
and then assigning the value using the =
operator. The value is retrieved from the context c
of the gin framework using the MustGet
function with the key "data".
This is a vulnerability because the data type of data
is not explicitly defined, and it will be inferred from the value returned by c.MustGet("data")
. This can lead to unexpected behavior if the value associated with the key "data" in the context c
is not of the type that the rest of the code expects.
For example, if the rest of the code expects data
to be a string and tries to perform string operations on it, but the value associated with the key "data" in the context c
is actually an integer, a runtime error will occur.
Moreover, this code is inefficient because every time data
is used, the Go runtime has to determine its data type dynamically. This can slow down the execution of the program, especially if data
is used frequently.
Steps
- Identify the specific type of data that is being stored in the 'data' variable
- Declare the 'data' variable with the appropriate type
- Assign the value from 'c.MustGet('data')' to the 'data' variable with the correct type
- Update the JSON response to use the 'data' variable with the correct type
Compliant code
package main
import (
"github.com/gin-gonic/gin"
"net/http"
)
func main() {
r := gin.Default()
r.GET("/example", func(c *gin.Context) {
data, exists := c.Get("data")
if !exists {
c.JSON(http.StatusBadRequest, gin.H{"error": "No data provided"})
return
}
strData, ok := data.(string) // assuming the data is of type string
if !ok {
c.JSON(http.StatusBadRequest, gin.H{"error": "Invalid data type"})
return
}
c.JSON(http.StatusOK, gin.H{
"data": strData,
})
})
r.Run()
}
The original code had a vulnerability due to improper type assignation. The variable data
was declared without a specific type, which can be inefficient and potentially unsafe.
The fixed code first checks if the data
exists in the context using c.Get("data")
. If it doesn't exist, it returns a 400 Bad Request
status with an error message.
Next, it tries to assert the type of data
to string
(assuming the data is expected to be a string). If the type assertion fails (i.e., the data is not a string), it returns a 400 Bad Request
status with an error message.
Finally, if the data exists and is of the correct type, it returns a 200 OK
status with the data.
This way, the code is safer and more efficient because it doesn't need to identify and cast the variable's data type every time it's used.