fix(routing/http/client): avoid escaping comma query separator (#688)

CHANGELOG.md

@@ -22,6 +22,8 @@ The following emojis are used to highlight certain changes:
 
 ### Fixed
 
+- `routing/http/client`: optional address and protocol filter parameters from [IPIP-484](https://github.com/ipfs/specs/pull/484) use human-readable `,` instead of `%2C`. [#688](https://github.com/ipfs/boxo/pull/688)
+
 ### Security
 
 ## [v0.24.0]

routing/http/filters/filters.go

@@ -39,7 +39,13 @@ func AddFiltersToURL(baseURL string, protocolFilter, addrFilter []string) string
 		query.Set("filter-addrs", strings.Join(addrFilter, ","))
 	}
 
-	parsedURL.RawQuery = query.Encode()
+	// The comma is in the "sub-delims" set of characters that don't need to be
+	// encoded in most parts of a URL, including query parameters. Golang
+	// standard library percent-escapes it for consistency, but we prefer
+	// human-readable /routing/v1 URLs, and real comma is restored here to
+	// ensure human and machine requests hit the same HTTP cache keys.
+	parsedURL.RawQuery = strings.ReplaceAll(query.Encode(), "%2C", ",")
+
 	return parsedURL.String()
 }
 

routing/http/filters/filters_test.go

@@ -30,21 +30,21 @@ func TestAddFiltersToURL(t *testing.T) {
 			baseURL:        "https://example.com/routing/v1/providers/bafybeigdyrzt5sfp7udm7hu76uh7y26nf3efuylqabf3oclgtqy55fbzdi",
 			protocolFilter: []string{"transport-bitswap", "transport-ipfs-gateway-http"},
 			addrFilter:     nil,
-			expected:       "https://example.com/routing/v1/providers/bafybeigdyrzt5sfp7udm7hu76uh7y26nf3efuylqabf3oclgtqy55fbzdi?filter-protocols=transport-bitswap%2Ctransport-ipfs-gateway-http",
+			expected:       "https://example.com/routing/v1/providers/bafybeigdyrzt5sfp7udm7hu76uh7y26nf3efuylqabf3oclgtqy55fbzdi?filter-protocols=transport-bitswap,transport-ipfs-gateway-http",
 		},
 		{
 			name:           "Only addr filter",
 			baseURL:        "https://example.com/routing/v1/providers/bafybeigdyrzt5sfp7udm7hu76uh7y26nf3efuylqabf3oclgtqy55fbzdi",
 			protocolFilter: nil,
 			addrFilter:     []string{"ip4", "ip6"},
-			expected:       "https://example.com/routing/v1/providers/bafybeigdyrzt5sfp7udm7hu76uh7y26nf3efuylqabf3oclgtqy55fbzdi?filter-addrs=ip4%2Cip6",
+			expected:       "https://example.com/routing/v1/providers/bafybeigdyrzt5sfp7udm7hu76uh7y26nf3efuylqabf3oclgtqy55fbzdi?filter-addrs=ip4,ip6",
 		},
 		{
 			name:           "Both filters",
 			baseURL:        "https://example.com/routing/v1/providers/bafybeigdyrzt5sfp7udm7hu76uh7y26nf3efuylqabf3oclgtqy55fbzdi",
 			protocolFilter: []string{"transport-bitswap", "transport-graphsync-filecoinv1"},
 			addrFilter:     []string{"ip4", "ip6"},
-			expected:       "https://example.com/routing/v1/providers/bafybeigdyrzt5sfp7udm7hu76uh7y26nf3efuylqabf3oclgtqy55fbzdi?filter-addrs=ip4%2Cip6&filter-protocols=transport-bitswap%2Ctransport-graphsync-filecoinv1",
+			expected:       "https://example.com/routing/v1/providers/bafybeigdyrzt5sfp7udm7hu76uh7y26nf3efuylqabf3oclgtqy55fbzdi?filter-addrs=ip4,ip6&filter-protocols=transport-bitswap,transport-graphsync-filecoinv1",
 		},
 		{
 			name:           "URL with existing query parameters",