[pkg/ottl] Added ottl functions for hashing strings (#22968)

* [pkg/ottl] Added ottl functions for hashing strings

* [pkg/ottl] Return nil on errors

* Documentation and test changes for the hash functions

Co-authored-by: Tyler Helmuth <12352919+TylerHelmuth@users.noreply.github.com>

---------

Co-authored-by: Tyler Helmuth <12352919+TylerHelmuth@users.noreply.github.com>

.chloggen/ottl_hash_functions.yaml

@@ -0,0 +1,20 @@
+# Use this changelog template to create an entry for release notes.
+# If your change doesn't affect end users, such as a test fix or a tooling change,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: pkg/ottl
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: "Add hash converters/functions for OTTL"
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [22725]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:

pkg/ottl/ottlfuncs/README.md

@@ -263,10 +263,13 @@ Unlike functions, they do not modify any input telemetry and always return a val
 Available Converters:
 - [Concat](#concat)
 - [ConvertCase](#convertcase)
+- [FNV](#fnv)
 - [Int](#int)
 - [IsMatch](#ismatch)
 - [Log](#log)
 - [ParseJSON](#parsejson)
+- [SHA1](#sha1)
+- [SHA256](#sha256)
 - [SpanID](#spanid)
 - [Split](#split)
 - [TraceID](#traceid)
@@ -316,6 +319,25 @@ Examples:
 
 - `ConvertCase(metric.name, "snake")`
 
+### FNV
+
+`FNV(value)`
+
+The `FNV` Converter converts the `value` to an FNV hash/digest.
+
+The returned type is int64.
+
+`value` is either a path expression to a string telemetry field or a literal string. If `value` is another type an error is returned.
+
+If an error occurs during hashing it will be returned.
+
+Examples:
+
+- `FNV(attributes["device.name"])`
+
+
+- `FNV("name")`
+
 ### Int
 
 `Int(value)`
@@ -424,6 +446,48 @@ Examples:
 
 - `ParseJSON(body)`
 
+### SHA1
+
+`SHA1(value)`
+
+The `SHA1` Converter converts the `value` to a sha1 hash/digest.
+
+The returned type is string.
+
+`value` is either a path expression to a string telemetry field or a literal string. If `value` is another type an error is returned.
+
+If an error occurs during hashing it will be returned.
+
+Examples:
+
+- `SHA1(attributes["device.name"])`
+
+
+- `SHA1("name")`
+
+**Note:** According to the National Institute of Standards and Technology (NIST), SHA1 is no longer a recommended hash function. It should be avoided except when required for compatibility. New uses should prefer FNV whenever possible.
+
+### SHA256
+
+`SHA256(value)`
+
+The `SHA256` Converter converts the `value` to a sha256 hash/digest.
+
+The returned type is string.
+
+`value` is either a path expression to a string telemetry field or a literal string. If `value` is another type an error is returned.
+
+If an error occurs during hashing it will be returned.
+
+Examples:
+
+- `SHA256(attributes["device.name"])`
+
+
+- `SHA256("name")`
+
+**Note:** According to the National Institute of Standards and Technology (NIST), SHA256 is no longer a recommended hash function. It should be avoided except when required for compatibility. New uses should prefer FNV whenever possible.
+
 ### SpanID
 
 `SpanID(bytes)`

pkg/ottl/ottlfuncs/func_fnv.go

@@ -0,0 +1,47 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package ottlfuncs // import "github.com/open-telemetry/opentelemetry-collector-contrib/pkg/ottl/ottlfuncs"
+
+import (
+	"context"
+	"fmt"
+	"hash/fnv"
+
+	"github.com/open-telemetry/opentelemetry-collector-contrib/pkg/ottl"
+)
+
+type FnvArguments[K any] struct {
+	Target ottl.StringGetter[K] `ottlarg:"0"`
+}
+
+func NewFnvFactory[K any]() ottl.Factory[K] {
+	return ottl.NewFactory("FNV", &FnvArguments[K]{}, createFnvFunction[K])
+}
+
+func createFnvFunction[K any](_ ottl.FunctionContext, oArgs ottl.Arguments) (ottl.ExprFunc[K], error) {
+	args, ok := oArgs.(*FnvArguments[K])
+
+	if !ok {
+		return nil, fmt.Errorf("FNVFactory args must be of type *FnvArguments[K]")
+	}
+
+	return FNVHashString(args.Target)
+}
+
+func FNVHashString[K any](target ottl.StringGetter[K]) (ottl.ExprFunc[K], error) {
+
+	return func(ctx context.Context, tCtx K) (interface{}, error) {
+		val, err := target.Get(ctx, tCtx)
+		if err != nil {
+			return nil, err
+		}
+		hash := fnv.New64a()
+		_, err = hash.Write([]byte(val))
+		if err != nil {
+			return nil, err
+		}
+		hashValue := hash.Sum64()
+		return int64(hashValue), nil
+	}, nil
+}

pkg/ottl/ottlfuncs/func_fnv_test.go

@@ -0,0 +1,82 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package ottlfuncs
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"github.com/open-telemetry/opentelemetry-collector-contrib/pkg/ottl"
+)
+
+func Test_FNV(t *testing.T) {
+	tests := []struct {
+		name     string
+		value    interface{}
+		expected interface{}
+		err      bool
+	}{
+		{
+			name:     "string",
+			value:    "hello world",
+			expected: int64(8618312879776256743),
+		},
+		{
+			name:     "empty string",
+			value:    "",
+			expected: int64(-3750763034362895579),
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			exprFunc, err := FNVHashString[interface{}](&ottl.StandardStringGetter[interface{}]{
+				Getter: func(context.Context, interface{}) (interface{}, error) {
+					return tt.value, nil
+				},
+			})
+			assert.NoError(t, err)
+			result, err := exprFunc(nil, nil)
+			if tt.err {
+				assert.Error(t, err)
+			} else {
+				assert.NoError(t, err)
+			}
+			assert.Equal(t, tt.expected, result)
+		})
+	}
+}
+
+func Test_FNVError(t *testing.T) {
+	tests := []struct {
+		name          string
+		value         interface{}
+		err           bool
+		expectedError string
+	}{
+		{
+			name:          "non-string",
+			value:         10,
+			expectedError: "expected string but got int",
+		},
+		{
+			name:          "nil",
+			value:         nil,
+			expectedError: "expected string but got nil",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			exprFunc, err := FNVHashString[interface{}](&ottl.StandardStringGetter[interface{}]{
+				Getter: func(context.Context, interface{}) (interface{}, error) {
+					return tt.value, nil
+				},
+			})
+			assert.NoError(t, err)
+			_, err = exprFunc(nil, nil)
+			assert.ErrorContains(t, err, tt.expectedError)
+		})
+	}
+}

pkg/ottl/ottlfuncs/func_sha1.go

@@ -0,0 +1,48 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package ottlfuncs // import "github.com/open-telemetry/opentelemetry-collector-contrib/pkg/ottl/ottlfuncs"
+
+import (
+	"context"
+	"crypto/sha1" // #nosec
+	"encoding/hex"
+	"fmt"
+
+	"github.com/open-telemetry/opentelemetry-collector-contrib/pkg/ottl"
+)
+
+type SHA1Arguments[K any] struct {
+	Target ottl.StringGetter[K] `ottlarg:"0"`
+}
+
+func NewSHA1Factory[K any]() ottl.Factory[K] {
+	return ottl.NewFactory("SHA1", &SHA1Arguments[K]{}, createSHA1Function[K])
+}
+
+func createSHA1Function[K any](_ ottl.FunctionContext, oArgs ottl.Arguments) (ottl.ExprFunc[K], error) {
+	args, ok := oArgs.(*SHA1Arguments[K])
+
+	if !ok {
+		return nil, fmt.Errorf("SHA1Factory args must be of type *SHA1Arguments[K]")
+	}
+
+	return SHA1HashString(args.Target)
+}
+
+func SHA1HashString[K any](target ottl.StringGetter[K]) (ottl.ExprFunc[K], error) {
+
+	return func(ctx context.Context, tCtx K) (interface{}, error) {
+		val, err := target.Get(ctx, tCtx)
+		if err != nil {
+			return nil, err
+		}
+		hash := sha1.New() // #nosec
+		_, err = hash.Write([]byte(val))
+		if err != nil {
+			return nil, err
+		}
+		hashValue := hex.EncodeToString(hash.Sum(nil))
+		return hashValue, nil
+	}, nil
+}

pkg/ottl/ottlfuncs/func_sha1_test.go

@@ -0,0 +1,82 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package ottlfuncs
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"github.com/open-telemetry/opentelemetry-collector-contrib/pkg/ottl"
+)
+
+func Test_SHA1(t *testing.T) {
+	tests := []struct {
+		name     string
+		value    interface{}
+		expected interface{}
+		err      bool
+	}{
+		{
+			name:     "string",
+			value:    "hello world",
+			expected: "2aae6c35c94fcfb415dbe95f408b9ce91ee846ed",
+		},
+		{
+			name:     "empty string",
+			value:    "",
+			expected: "da39a3ee5e6b4b0d3255bfef95601890afd80709",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			exprFunc, err := SHA1HashString[interface{}](&ottl.StandardStringGetter[interface{}]{
+				Getter: func(context.Context, interface{}) (interface{}, error) {
+					return tt.value, nil
+				},
+			})
+			assert.NoError(t, err)
+			result, err := exprFunc(nil, nil)
+			if tt.err {
+				assert.Error(t, err)
+			} else {
+				assert.NoError(t, err)
+			}
+			assert.Equal(t, tt.expected, result)
+		})
+	}
+}
+
+func Test_SHA1Error(t *testing.T) {
+	tests := []struct {
+		name          string
+		value         interface{}
+		err           bool
+		expectedError string
+	}{
+		{
+			name:          "non-string",
+			value:         10,
+			expectedError: "expected string but got int",
+		},
+		{
+			name:          "nil",
+			value:         nil,
+			expectedError: "expected string but got nil",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			exprFunc, err := SHA1HashString[interface{}](&ottl.StandardStringGetter[interface{}]{
+				Getter: func(context.Context, interface{}) (interface{}, error) {
+					return tt.value, nil
+				},
+			})
+			assert.NoError(t, err)
+			_, err = exprFunc(nil, nil)
+			assert.ErrorContains(t, err, tt.expectedError)
+		})
+	}
+}