perf: use textproto.TrimString for HTTP header parsing to improve performance

[1911860538]

Replaced strings.TrimSpace with textproto.TrimString in HTTP header parsing functions to improve performance and better align with HTTP spec.
textproto.TrimString, which is widely used in net/http, trims only ASCII whitespace—making it both sufficient and more efficient for HTTP headers like X-Forwarded-For and Accept.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.92%. Comparing base (3dc1cd6) to head (84814fa).
Report is 129 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4257      +/-   ##
==========================================
- Coverage   99.21%   98.92%   -0.30%     
==========================================
  Files          42       44       +2     
  Lines        3182     3434     +252     
==========================================
+ Hits         3157     3397     +240     
- Misses         17       26       +9     
- Partials        8       11       +3     

Flag	Coverage Δ
	?
--ldflags="-checklinkname=0" -tags sonic	98.85% <100.00%> (?)
-tags go_json	98.85% <100.00%> (?)
-tags nomsgpack	98.90% <100.00%> (?)
go-1.18	?
go-1.19	?
go-1.20	?
go-1.21	?
go-1.23	98.92% <100.00%> (?)
go-1.24	98.92% <100.00%> (?)
macos-latest	98.92% <100.00%> (-0.30%)	⬇️
ubuntu-latest	98.92% <100.00%> (-0.30%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[1911860538]

test code

package main

import (
	"net"
	"net/textproto"
	"strings"
	"testing"
)

func validateHeaderOriginal(header string) (clientIP string, valid bool) {
	if header == "" {
		return "", false
	}
	items := strings.Split(header, ",")
	for i := len(items) - 1; i >= 0; i-- {
		ipStr := strings.TrimSpace(items[i])
		ip := net.ParseIP(ipStr)
		if ip == nil {
			break
		}
		if (i == 0) || (!isTrustedProxy(ip)) {
			return ipStr, true
		}
	}
	return "", false
}

func validateHeaderOptimized(header string) (clientIP string, valid bool) {
	if header == "" {
		return "", false
	}
	items := strings.Split(header, ",")
	for i := len(items) - 1; i >= 0; i-- {
		ipStr := textproto.TrimString(items[i])
		ip := net.ParseIP(ipStr)
		if ip == nil {
			break
		}
		if (i == 0) || (!isTrustedProxy(ip)) {
			return ipStr, true
		}
	}
	return "", false
}

func parseAcceptOriginal(acceptHeader string) []string {
	parts := strings.Split(acceptHeader, ",")
	out := make([]string, 0, len(parts))
	for _, part := range parts {
		if i := strings.IndexByte(part, ';'); i > 0 {
			part = part[:i]
		}
		if part = strings.TrimSpace(part); part != "" {
			out = append(out, part)
		}
	}
	return out
}

func parseAcceptOptimized(acceptHeader string) []string {
	parts := strings.Split(acceptHeader, ",")
	out := make([]string, 0, len(parts))
	for _, part := range parts {
		if i := strings.IndexByte(part, ';'); i > 0 {
			part = part[:i]
		}
		if part = textproto.TrimString(part); part != "" {
			out = append(out, part)
		}
	}
	return out
}

func isTrustedProxy(_ net.IP) bool {
	// For benchmarking, assume all proxies are untrusted
	return false
}

func BenchmarkValidateHeader(b *testing.B) {
	header := " 192.168.1.1 ,  10.0.0.1 , 172.16.0.1 "

	b.Run("original", func(b *testing.B) {
		for i := 0; i < b.N; i++ {
			validateHeaderOriginal(header)
		}
	})

	b.Run("optimized", func(b *testing.B) {
		for i := 0; i < b.N; i++ {
			validateHeaderOptimized(header)
		}
	})
}

func BenchmarkParseAccept(b *testing.B) {
	accept := "text/html ; q=0.9 , application/json , image/png ; q=0.8"

	b.Run("original", func(b *testing.B) {
		for i := 0; i < b.N; i++ {
			parseAcceptOriginal(accept)
		}
	})

	b.Run("optimized", func(b *testing.B) {
		for i := 0; i < b.N; i++ {
			parseAcceptOptimized(accept)
		}
	})
}

validateHeader benchmark result

goos: darwin
goarch: amd64
pkg: github.com/gin-gonic/gin/test/trimespace
cpu: Intel(R) Core(TM) i7-8569U CPU @ 2.80GHz
BenchmarkValidateHeader
BenchmarkValidateHeader/original
BenchmarkValidateHeader/original-8         	10694073	       112.3 ns/op
BenchmarkValidateHeader/optimized
BenchmarkValidateHeader/optimized-8        	 9857858	       106.4 ns/op
PASS

Process finished with the exit code 0

parseAccept benchmark result

goos: darwin
goarch: amd64
pkg: github.com/gin-gonic/gin/test/trimespace
cpu: Intel(R) Core(TM) i7-8569U CPU @ 2.80GHz
BenchmarkParseAccept
BenchmarkParseAccept/original
BenchmarkParseAccept/original-8         	 8826144	       137.4 ns/op
BenchmarkParseAccept/optimized
BenchmarkParseAccept/optimized-8        	 8665436	       128.1 ns/op
PASS

Process finished with the exit code 0