Add RFC 5988 link header parser
Extract link header parsing into a reusable pkg/rfc5988 package with Parse and FindByRel functions, used by Sentry and GitHub drivers for pagination. Signed-off-by: Aurélien Sibiril <81782+aureliensibiril@users.noreply.github.com>
This commit is contained in:
Aurélien Sibiril
88
pkg/rfc5988/rfc5988.go
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88
pkg/rfc5988/rfc5988.go
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// Copyright (c) 2026 Probo Inc <hello@getprobo.com>.
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//
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// Permission to use, copy, modify, and/or distribute this software for any
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// purpose with or without fee is hereby granted, provided that the above
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// copyright notice and this permission notice appear in all copies.
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//
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// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
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// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
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// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
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// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
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// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
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// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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// PERFORMANCE OF THIS SOFTWARE.
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// Package rfc5988 provides a parser for HTTP Link headers as defined in
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// RFC 5988 (Web Linking).
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package rfc5988
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import "strings"
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// Link represents a single entry in an HTTP Link header.
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type Link struct {
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URL string
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Params map[string]string
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}
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// Parse parses an HTTP Link header value into individual Link entries.
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// Each entry has the form <URL>; param1="value1"; param2="value2".
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func Parse(header string) []Link {
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if header == "" {
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return nil
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}
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var links []Link
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for part := range strings.SplitSeq(header, ",") {
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part = strings.TrimSpace(part)
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if part == "" {
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continue
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}
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start := strings.Index(part, "<")
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end := strings.Index(part, ">")
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if start == -1 || end == -1 || end <= start {
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continue
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}
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link := Link{
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URL: part[start+1 : end],
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Params: make(map[string]string),
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}
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rest := part[end+1:]
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for segment := range strings.SplitSeq(rest, ";") {
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segment = strings.TrimSpace(segment)
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if segment == "" {
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continue
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}
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key, value, ok := strings.Cut(segment, "=")
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if !ok {
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continue
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}
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key = strings.TrimSpace(key)
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value = strings.TrimSpace(value)
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value = strings.Trim(value, `"`)
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link.Params[key] = value
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}
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links = append(links, link)
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}
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return links
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}
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// FindByRel returns the URL of the first Link entry whose "rel" parameter
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// matches the given value. It returns an empty string if no match is found.
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func FindByRel(header string, rel string) string {
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for _, link := range Parse(header) {
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if link.Params["rel"] == rel {
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return link.URL
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}
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}
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return ""
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}
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116
pkg/rfc5988/rfc5988_test.go
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pkg/rfc5988/rfc5988_test.go
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// Copyright (c) 2026 Probo Inc <hello@getprobo.com>.
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//
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// Permission to use, copy, modify, and/or distribute this software for any
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// purpose with or without fee is hereby granted, provided that the above
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// copyright notice and this permission notice appear in all copies.
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//
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// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
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// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
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// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
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// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
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// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
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// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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// PERFORMANCE OF THIS SOFTWARE.
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package rfc5988_test
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import (
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"testing"
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"github.com/stretchr/testify/assert"
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"github.com/stretchr/testify/require"
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"go.probo.inc/probo/pkg/rfc5988"
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)
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func TestParse(t *testing.T) {
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t.Parallel()
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t.Run("empty header", func(t *testing.T) {
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t.Parallel()
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links := rfc5988.Parse("")
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assert.Nil(t, links)
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})
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t.Run("single link", func(t *testing.T) {
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t.Parallel()
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links := rfc5988.Parse(`<https://api.example.com/items?page=2>; rel="next"`)
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require.Len(t, links, 1)
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assert.Equal(t, "https://api.example.com/items?page=2", links[0].URL)
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assert.Equal(t, "next", links[0].Params["rel"])
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})
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t.Run("multiple links", func(t *testing.T) {
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t.Parallel()
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header := `<https://api.example.com/items?page=2>; rel="next", <https://api.example.com/items?page=5>; rel="last"`
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links := rfc5988.Parse(header)
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require.Len(t, links, 2)
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assert.Equal(t, "https://api.example.com/items?page=2", links[0].URL)
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assert.Equal(t, "next", links[0].Params["rel"])
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assert.Equal(t, "https://api.example.com/items?page=5", links[1].URL)
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assert.Equal(t, "last", links[1].Params["rel"])
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})
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t.Run("multiple params per link", func(t *testing.T) {
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t.Parallel()
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header := `<https://sentry.io/api/0/?cursor=abc>; rel="next"; results="true"; cursor="abc"`
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links := rfc5988.Parse(header)
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require.Len(t, links, 1)
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assert.Equal(t, "https://sentry.io/api/0/?cursor=abc", links[0].URL)
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assert.Equal(t, "next", links[0].Params["rel"])
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assert.Equal(t, "true", links[0].Params["results"])
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assert.Equal(t, "abc", links[0].Params["cursor"])
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})
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t.Run("github style link header", func(t *testing.T) {
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t.Parallel()
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header := `<https://api.github.com/orgs/foo/members?page=2>; rel="next", <https://api.github.com/orgs/foo/members?page=3>; rel="last"`
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links := rfc5988.Parse(header)
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require.Len(t, links, 2)
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assert.Equal(t, "next", links[0].Params["rel"])
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assert.Equal(t, "last", links[1].Params["rel"])
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})
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t.Run("sentry style link header", func(t *testing.T) {
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t.Parallel()
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header := `<https://sentry.io/api/0/orgs/slug/members/?cursor=prev>; rel="previous"; results="false"; cursor="prev", <https://sentry.io/api/0/orgs/slug/members/?cursor=next>; rel="next"; results="true"; cursor="next"`
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links := rfc5988.Parse(header)
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require.Len(t, links, 2)
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assert.Equal(t, "previous", links[0].Params["rel"])
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assert.Equal(t, "false", links[0].Params["results"])
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assert.Equal(t, "next", links[1].Params["rel"])
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assert.Equal(t, "true", links[1].Params["results"])
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})
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}
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func TestFindByRel(t *testing.T) {
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t.Parallel()
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t.Run("empty header", func(t *testing.T) {
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t.Parallel()
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url := rfc5988.FindByRel("", "next")
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assert.Empty(t, url)
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})
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t.Run("found", func(t *testing.T) {
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t.Parallel()
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header := `<https://api.example.com/items?page=2>; rel="next", <https://api.example.com/items?page=5>; rel="last"`
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url := rfc5988.FindByRel(header, "next")
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assert.Equal(t, "https://api.example.com/items?page=2", url)
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})
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t.Run("not found", func(t *testing.T) {
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t.Parallel()
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header := `<https://api.example.com/items?page=2>; rel="prev"`
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url := rfc5988.FindByRel(header, "next")
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assert.Empty(t, url)
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})
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}
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