Move HTTP service to public for plugin use (#27284)

* Move httpservice for use in plugins

* Adapt httpservice for plugin use

* Fix lint

server/public/shared/httpservice/httpservice.go

@@ -0,0 +1,119 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package httpservice
+
+import (
+	"net"
+	"net/http"
+	"strings"
+	"time"
+	"unicode"
+
+	"github.com/mattermost/mattermost/server/public/model"
+	"github.com/mattermost/mattermost/server/public/plugin"
+)
+
+// HTTPService wraps the functionality for making http requests to provide some improvements to the default client
+// behaviour.
+type HTTPService interface {
+	// MakeClient returns an http client constructed with a RoundTripper as returned by MakeTransport.
+	MakeClient(trustURLs bool) *http.Client
+
+	// MakeTransport returns a RoundTripper that is suitable for making requests to external resources. The default
+	// implementation provides:
+	// - A shorter timeout for dial and TLS handshake (defined as constant "ConnectTimeout")
+	// - A timeout for end-to-end requests
+	// - A Mattermost-specific user agent header
+	// - Additional security for untrusted and insecure connections
+	MakeTransport(trustURLs bool) *MattermostTransport
+}
+
+type getConfig interface {
+	Config() *model.Config
+}
+
+type HTTPServiceImpl struct {
+	configService getConfig
+
+	RequestTimeout time.Duration
+}
+
+func splitFields(c rune) bool {
+	return unicode.IsSpace(c) || c == ','
+}
+
+func MakeHTTPService(configService getConfig) HTTPService {
+	return &HTTPServiceImpl{
+		configService,
+		RequestTimeout,
+	}
+}
+
+type pluginAPIConfigServiceAdapter struct {
+	pluginAPIConfigService plugin.API
+}
+
+func (p *pluginAPIConfigServiceAdapter) Config() *model.Config {
+	return p.pluginAPIConfigService.GetConfig()
+}
+
+func MakeHTTPServicePlugin(configService plugin.API) HTTPService {
+	return MakeHTTPService(&pluginAPIConfigServiceAdapter{configService})
+}
+
+func (h *HTTPServiceImpl) MakeClient(trustURLs bool) *http.Client {
+	return &http.Client{
+		Transport: h.MakeTransport(trustURLs),
+		Timeout:   h.RequestTimeout,
+	}
+}
+
+func (h *HTTPServiceImpl) MakeTransport(trustURLs bool) *MattermostTransport {
+	insecure := h.configService.Config().ServiceSettings.EnableInsecureOutgoingConnections != nil && *h.configService.Config().ServiceSettings.EnableInsecureOutgoingConnections
+
+	if trustURLs {
+		return NewTransport(insecure, nil, nil)
+	}
+
+	allowHost := func(host string) bool {
+		if h.configService.Config().ServiceSettings.AllowedUntrustedInternalConnections == nil {
+			return false
+		}
+		for _, allowed := range strings.FieldsFunc(*h.configService.Config().ServiceSettings.AllowedUntrustedInternalConnections, splitFields) {
+			if host == allowed {
+				return true
+			}
+		}
+		return false
+	}
+
+	allowIP := func(ip net.IP) bool {
+		reservedIP := IsReservedIP(ip)
+		ownIP, err := IsOwnIP(ip)
+
+		// If there is an error getting the self-assigned IPs, default to the secure option
+		if err != nil {
+			return false
+		}
+
+		// If it's not a reserved IP and it's not self-assigned IP, accept the IP
+		if !reservedIP && !ownIP {
+			return true
+		}
+
+		if h.configService.Config().ServiceSettings.AllowedUntrustedInternalConnections == nil {
+			return false
+		}
+
+		// In the case it's the self-assigned IP, enforce that it needs to be explicitly added to the AllowedUntrustedInternalConnections
+		for _, allowed := range strings.FieldsFunc(*h.configService.Config().ServiceSettings.AllowedUntrustedInternalConnections, splitFields) {
+			if _, ipRange, err := net.ParseCIDR(allowed); err == nil && ipRange.Contains(ip) {
+				return true
+			}
+		}
+		return false
+	}
+
+	return NewTransport(insecure, allowHost, allowIP)
+}