Add Accept header negotiation to relevant API endpoints (#337)

* start centralizing negotiation logic for API

* swagger document nodeinfo endpoint

* go fmt

* document negotiate function

* use content negotiation

* tidy up negotiation logic

* negotiate content throughout client api

* swagger

* remove attachment on Content

* add accept header to test requests

docs/api/swagger.yaml

@@ -12,6 +12,24 @@ definitions:
     title: A FileHeader describes a file part of a multipart request.
     type: object
     x-go-package: mime/multipart
+  Link:
+    description: See https://webfinger.net/
+    properties:
+      href:
+        type: string
+        x-go-name: Href
+      rel:
+        type: string
+        x-go-name: Rel
+      template:
+        type: string
+        x-go-name: Template
+      type:
+        type: string
+        x-go-name: Type
+    title: Link represents one 'link' in a slice of links returned from a lookup request.
+    type: object
+    x-go-package: github.com/superseriousbusiness/gotosocial/internal/api/model
   MIMEHeader:
     additionalProperties:
       items:
@@ -49,6 +67,48 @@ definitions:
     title: Mention represents a mention of another account.
     type: object
     x-go-package: github.com/superseriousbusiness/gotosocial/internal/api/model
+  NodeInfoServices:
+    properties:
+      inbound:
+        items:
+          type: string
+        type: array
+        x-go-name: Inbound
+      outbound:
+        items:
+          type: string
+        type: array
+        x-go-name: Outbound
+    title: NodeInfoServices represents inbound and outbound services that this node
+      offers connections to.
+    type: object
+    x-go-package: github.com/superseriousbusiness/gotosocial/internal/api/model
+  NodeInfoSoftware:
+    properties:
+      name:
+        example: gotosocial
+        type: string
+        x-go-name: Name
+      version:
+        example: 0.1.2 1234567
+        type: string
+        x-go-name: Version
+    title: NodeInfoSoftware represents the name and version number of the software
+      of this node.
+    type: object
+    x-go-package: github.com/superseriousbusiness/gotosocial/internal/api/model
+  NodeInfoUsage:
+    properties:
+      users:
+        $ref: '#/definitions/NodeInfoUsers'
+    title: NodeInfoUsage represents usage information about this server, such as number
+      of users.
+    type: object
+    x-go-package: github.com/superseriousbusiness/gotosocial/internal/api/model
+  NodeInfoUsers:
+    title: NodeInfoUsers is a stub for usage information, currently empty.
+    type: object
+    x-go-package: github.com/superseriousbusiness/gotosocial/internal/api/model
   Source:
     description: Returned as an additional entity when verifying and updated credentials,
       as an attribute of Account.
@@ -1122,6 +1182,42 @@ definitions:
     type: object
     x-go-name: MediaMeta
     x-go-package: github.com/superseriousbusiness/gotosocial/internal/api/model
+  nodeinfo:
+    description: 'See: https://nodeinfo.diaspora.software/schema.html'
+    properties:
+      metadata:
+        additionalProperties:
+          type: object
+        description: Free form key value pairs for software specific values. Clients
+          should not rely on any specific key present.
+        type: object
+        x-go-name: Metadata
+      openRegistrations:
+        description: Whether this server allows open self-registration.
+        example: false
+        type: boolean
+        x-go-name: OpenRegistrations
+      protocols:
+        description: The protocols supported on this server.
+        items:
+          type: string
+        type: array
+        x-go-name: Protocols
+      services:
+        $ref: '#/definitions/NodeInfoServices'
+      software:
+        $ref: '#/definitions/NodeInfoSoftware'
+      usage:
+        $ref: '#/definitions/NodeInfoUsage'
+      version:
+        description: The schema version
+        example: "2.0"
+        type: string
+        x-go-name: Version
+    title: Nodeinfo represents a version 2.1 or version 2.0 nodeinfo schema.
+    type: object
+    x-go-name: Nodeinfo
+    x-go-package: github.com/superseriousbusiness/gotosocial/internal/api/model
   oauthToken:
     properties:
       access_token:
@@ -1670,6 +1766,28 @@ definitions:
     type: object
     x-go-name: UpdateSource
     x-go-package: github.com/superseriousbusiness/gotosocial/internal/api/model
+  wellKnownResponse:
+    description: See https://webfinger.net/
+    properties:
+      aliases:
+        items:
+          type: string
+        type: array
+        x-go-name: Aliases
+      links:
+        items:
+          $ref: '#/definitions/Link'
+        type: array
+        x-go-name: Links
+      subject:
+        type: string
+        x-go-name: Subject
+    title: |-
+      WellKnownResponse represents the response to either a webfinger request for an 'acct' resource, or a request to nodeinfo.
+      For example, it would be returned from https://example.org/.well-known/webfinger?resource=acct:some_username@example.org
+    type: object
+    x-go-name: WellKnownResponse
+    x-go-package: github.com/superseriousbusiness/gotosocial/internal/api/model
 host: example.org
 info:
   contact:
@@ -1682,6 +1800,43 @@ info:
   title: GoToSocial
   version: 0.0.1
 paths:
+  /.well-known/nodeinfo:
+    get:
+      description: |-
+        eg. `{"links":[{"rel":"http://nodeinfo.diaspora.software/ns/schema/2.0","href":"http://example.org/nodeinfo/2.0"}]}`
+        See: https://nodeinfo.diaspora.software/protocol.html
+      operationId: nodeInfoWellKnownGet
+      produces:
+      - application/json
+      responses:
+        "200":
+          description: ""
+          schema:
+            $ref: '#/definitions/wellKnownResponse'
+      summary: Directs callers to /nodeinfo/2.0.
+      tags:
+      - nodeinfo
+  /.well-known/webfinger:
+    get:
+      description: |-
+        For example, a GET to `https://goblin.technology/.well-known/webfinger?resource=acct:tobi@goblin.technology` would return:
+
+        ```
+        {"subject":"acct:tobi@goblin.technology","aliases":["https://goblin.technology/users/tobi","https://goblin.technology/@tobi"],"links":[{"rel":"http://webfinger.net/rel/profile-page","type":"text/html","href":"https://goblin.technology/@tobi"},{"rel":"self","type":"application/activity+json","href":"https://goblin.technology/users/tobi"}]}
+        ```
+
+        See: https://webfinger.net/
+      operationId: webfingerGet
+      produces:
+      - application/json
+      responses:
+        "200":
+          description: ""
+          schema:
+            $ref: '#/definitions/wellKnownResponse'
+      summary: Handles webfinger account lookup requests.
+      tags:
+      - webfinger
   /api/v1/accounts:
     post:
       consumes:
@@ -3529,6 +3684,20 @@ paths:
       summary: Change the password of authenticated user.
       tags:
       - user
+  /nodeinfo/2.0:
+    get:
+      description: 'See: https://nodeinfo.diaspora.software/schema.html'
+      operationId: nodeInfoGet
+      produces:
+      - application/json; profile="http://nodeinfo.diaspora.software/ns/schema/2.0#"
+      responses:
+        "200":
+          description: ""
+          schema:
+            $ref: '#/definitions/nodeinfo'
+      summary: Returns a compliant nodeinfo response to node info queries.
+      tags:
+      - nodeinfo
   /users/{username}/outbox:
     get:
       description: |-

internal/api/client/account/account_test.go

@@ -95,5 +95,7 @@ func (suite *AccountStandardTestSuite) newContext(recorder *httptest.ResponseRec
 		ctx.Request.Header.Set("Content-Type", bodyContentType)
 	}
 
+	ctx.Request.Header.Set("accept", "application/json")
+
 	return ctx
 }

internal/api/client/account/accountcreate.go

@@ -27,6 +27,7 @@
 	"github.com/spf13/viper"
 
 	"github.com/gin-gonic/gin"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/api/model"
 	"github.com/superseriousbusiness/gotosocial/internal/config"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
@@ -78,6 +79,11 @@ func (m *Module) AccountCreatePOSTHandler(c *gin.Context) {
 		return
 	}
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	l.Trace("parsing request form")
 	form := &model.AccountCreateRequest{}
 	if err := c.ShouldBind(form); err != nil || form == nil {

internal/api/client/account/accountget.go

@@ -22,6 +22,7 @@
 	"net/http"
 
 	"github.com/gin-gonic/gin"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
 )
 
@@ -64,6 +65,11 @@ func (m *Module) AccountGETHandler(c *gin.Context) {
 		return
 	}
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	targetAcctID := c.Param(IDKey)
 	if targetAcctID == "" {
 		c.JSON(http.StatusBadRequest, gin.H{"error": "no account id specified"})

internal/api/client/account/accountupdate.go

@@ -20,11 +20,13 @@
 
 import (
 	"fmt"
-	"github.com/sirupsen/logrus"
 	"net/http"
 	"strconv"
 
+	"github.com/sirupsen/logrus"
+
 	"github.com/gin-gonic/gin"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/api/model"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
 )
@@ -110,6 +112,11 @@ func (m *Module) AccountUpdateCredentialsPATCHHandler(c *gin.Context) {
 	}
 	l.Tracef("retrieved account %+v", authed.Account.ID)
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	form, err := parseUpdateAccountForm(c)
 	if err != nil {
 		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})

internal/api/client/account/accountverify.go

@@ -19,10 +19,12 @@
 package account
 
 import (
-	"github.com/sirupsen/logrus"
 	"net/http"
 
+	"github.com/sirupsen/logrus"
+
 	"github.com/gin-gonic/gin"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
 )
 
@@ -60,6 +62,11 @@ func (m *Module) AccountVerifyGETHandler(c *gin.Context) {
 		return
 	}
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	acctSensitive, err := m.processor.AccountGet(c.Request.Context(), authed, authed.Account.ID)
 	if err != nil {
 		l.Debugf("error getting account from processor: %s", err)

internal/api/client/account/block.go

@@ -22,6 +22,7 @@
 	"net/http"
 
 	"github.com/gin-gonic/gin"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
 )
 
@@ -66,6 +67,11 @@ func (m *Module) AccountBlockPOSTHandler(c *gin.Context) {
 		return
 	}
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	targetAcctID := c.Param(IDKey)
 	if targetAcctID == "" {
 		c.JSON(http.StatusBadRequest, gin.H{"error": "no account id specified"})

internal/api/client/account/follow.go

@@ -22,6 +22,7 @@
 	"net/http"
 
 	"github.com/gin-gonic/gin"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/api/model"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
 )
@@ -87,6 +88,11 @@ func (m *Module) AccountFollowPOSTHandler(c *gin.Context) {
 		return
 	}
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	targetAcctID := c.Param(IDKey)
 	if targetAcctID == "" {
 		c.JSON(http.StatusBadRequest, gin.H{"error": "no account id specified"})

internal/api/client/account/followers.go

@@ -22,6 +22,7 @@
 	"net/http"
 
 	"github.com/gin-gonic/gin"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
 )
 
@@ -68,6 +69,11 @@ func (m *Module) AccountFollowersGETHandler(c *gin.Context) {
 		return
 	}
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	targetAcctID := c.Param(IDKey)
 	if targetAcctID == "" {
 		c.JSON(http.StatusBadRequest, gin.H{"error": "no account id specified"})

internal/api/client/account/following.go

@@ -22,6 +22,7 @@
 	"net/http"
 
 	"github.com/gin-gonic/gin"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
 )
 
@@ -68,6 +69,11 @@ func (m *Module) AccountFollowingGETHandler(c *gin.Context) {
 		return
 	}
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	targetAcctID := c.Param(IDKey)
 	if targetAcctID == "" {
 		c.JSON(http.StatusBadRequest, gin.H{"error": "no account id specified"})

internal/api/client/account/relationships.go

@@ -1,10 +1,12 @@
 package account
 
 import (
-	"github.com/sirupsen/logrus"
 	"net/http"
 
+	"github.com/sirupsen/logrus"
+
 	"github.com/gin-gonic/gin"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/api/model"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
 )
@@ -57,6 +59,11 @@ func (m *Module) AccountRelationshipsGETHandler(c *gin.Context) {
 		return
 	}
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	targetAccountIDs := c.QueryArray("id[]")
 	if len(targetAccountIDs) == 0 {
 		// check fallback -- let's be generous and see if maybe it's just set as 'id'?

internal/api/client/account/statuses.go

@@ -19,11 +19,13 @@
 package account
 
 import (
-	"github.com/sirupsen/logrus"
 	"net/http"
 	"strconv"
 
+	"github.com/sirupsen/logrus"
+
 	"github.com/gin-gonic/gin"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
 )
 
@@ -118,6 +120,11 @@ func (m *Module) AccountStatusesGETHandler(c *gin.Context) {
 		return
 	}
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	targetAcctID := c.Param(IDKey)
 	if targetAcctID == "" {
 		l.Debug("no account id specified in query")

internal/api/client/account/unblock.go

@@ -22,6 +22,7 @@
 	"net/http"
 
 	"github.com/gin-gonic/gin"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
 )
 
@@ -66,6 +67,11 @@ func (m *Module) AccountUnblockPOSTHandler(c *gin.Context) {
 		return
 	}
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	targetAcctID := c.Param(IDKey)
 	if targetAcctID == "" {
 		c.JSON(http.StatusBadRequest, gin.H{"error": "no account id specified"})

internal/api/client/account/unfollow.go

@@ -19,10 +19,12 @@
 package account
 
 import (
-	"github.com/sirupsen/logrus"
 	"net/http"
 
+	"github.com/sirupsen/logrus"
+
 	"github.com/gin-gonic/gin"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
 )
 
@@ -69,6 +71,11 @@ func (m *Module) AccountUnfollowPOSTHandler(c *gin.Context) {
 		return
 	}
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	targetAcctID := c.Param(IDKey)
 	if targetAcctID == "" {
 		l.Debug(err)

internal/api/client/admin/domainblockcreate.go

@@ -8,6 +8,7 @@
 
 	"github.com/gin-gonic/gin"
 	"github.com/sirupsen/logrus"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/api/model"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
 )
@@ -110,6 +111,11 @@ func (m *Module) DomainBlocksPOSTHandler(c *gin.Context) {
 		return
 	}
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	imp := false
 	importString := c.Query(ImportQueryKey)
 	if importString != "" {

internal/api/client/admin/domainblockdelete.go

@@ -5,6 +5,7 @@
 
 	"github.com/gin-gonic/gin"
 	"github.com/sirupsen/logrus"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
 )
 
@@ -62,6 +63,11 @@ func (m *Module) DomainBlockDELETEHandler(c *gin.Context) {
 		return
 	}
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	domainBlockID := c.Param(IDKey)
 	if domainBlockID == "" {
 		c.JSON(http.StatusBadRequest, gin.H{"error": "no domain block id provided"})

internal/api/client/admin/domainblockget.go

@@ -6,6 +6,7 @@
 
 	"github.com/gin-gonic/gin"
 	"github.com/sirupsen/logrus"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
 )
 
@@ -63,6 +64,11 @@ func (m *Module) DomainBlockGETHandler(c *gin.Context) {
 		return
 	}
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	domainBlockID := c.Param(IDKey)
 	if domainBlockID == "" {
 		c.JSON(http.StatusBadRequest, gin.H{"error": "no domain block id provided"})

internal/api/client/admin/domainblocksget.go

@@ -6,6 +6,7 @@
 
 	"github.com/gin-gonic/gin"
 	"github.com/sirupsen/logrus"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
 )
 
@@ -69,6 +70,11 @@ func (m *Module) DomainBlocksGETHandler(c *gin.Context) {
 		return
 	}
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	export := false
 	exportString := c.Query(ExportQueryKey)
 	if exportString != "" {

internal/api/client/admin/emojicreate.go

@@ -25,6 +25,7 @@
 
 	"github.com/gin-gonic/gin"
 	"github.com/sirupsen/logrus"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/api/model"
 	"github.com/superseriousbusiness/gotosocial/internal/media"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
@@ -94,6 +95,11 @@ func (m *Module) emojiCreatePOSTHandler(c *gin.Context) {
 		return
 	}
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	// extract the media create form from the request context
 	l.Tracef("parsing request form: %+v", c.Request.Form)
 	form := &model.EmojiCreateRequest{}

internal/api/client/app/appcreate.go

@@ -25,6 +25,7 @@
 	"github.com/sirupsen/logrus"
 
 	"github.com/gin-gonic/gin"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/api/model"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
 )
@@ -81,6 +82,11 @@ func (m *Module) AppsPOSTHandler(c *gin.Context) {
 		return
 	}
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	form := &model.ApplicationCreateRequest{}
 	if err := c.ShouldBind(form); err != nil {
 		c.JSON(http.StatusUnprocessableEntity, gin.H{"error": err.Error()})

internal/api/client/auth/authorize.go

@@ -21,14 +21,16 @@
 import (
 	"errors"
 	"fmt"
-	"github.com/sirupsen/logrus"
 	"net/http"
 	"net/url"
 	"strings"
 
+	"github.com/sirupsen/logrus"
+
 	"github.com/gin-contrib/sessions"
 	"github.com/gin-gonic/gin"
 	"github.com/google/uuid"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/api/model"
 	"github.com/superseriousbusiness/gotosocial/internal/db"
 	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
@@ -41,6 +43,11 @@ func (m *Module) AuthorizeGETHandler(c *gin.Context) {
 	l := logrus.WithField("func", "AuthorizeGETHandler")
 	s := sessions.Default(c)
 
+	if _, err := api.NegotiateAccept(c, api.HTMLAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	// UserID will be set in the session by AuthorizePOSTHandler if the caller has already gone through the authentication flow
 	// If it's not set, then we don't know yet who the user is, so we need to redirect them to the sign in page.
 	userID, ok := s.Get(sessionUserID).(string)

internal/api/client/auth/signin.go

@@ -21,11 +21,13 @@
 import (
 	"context"
 	"errors"
-	"github.com/sirupsen/logrus"
 	"net/http"
 
+	"github.com/sirupsen/logrus"
+
 	"github.com/gin-contrib/sessions"
 	"github.com/gin-gonic/gin"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/db"
 	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
 	"golang.org/x/crypto/bcrypt"
@@ -43,6 +45,12 @@ type login struct {
 func (m *Module) SignInGETHandler(c *gin.Context) {
 	l := logrus.WithField("func", "SignInGETHandler")
 	l.Trace("entering sign in handler")
+
+	if _, err := api.NegotiateAccept(c, api.HTMLAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	if m.idp != nil {
 		s := sessions.Default(c)
 

internal/api/client/auth/token.go

@@ -19,10 +19,12 @@
 package auth
 
 import (
-	"github.com/sirupsen/logrus"
 	"net/http"
 	"net/url"
 
+	"github.com/sirupsen/logrus"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
+
 	"github.com/gin-gonic/gin"
 )
 
@@ -41,6 +43,11 @@ func (m *Module) TokenPOSTHandler(c *gin.Context) {
 	l := logrus.WithField("func", "TokenPOSTHandler")
 	l.Trace("entered TokenPOSTHandler")
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	form := &tokenBody{}
 	if err := c.ShouldBind(form); err == nil {
 		c.Request.Form = url.Values{}

internal/api/client/blocks/blocksget.go

@@ -19,11 +19,13 @@
 package blocks
 
 import (
-	"github.com/sirupsen/logrus"
 	"net/http"
 	"strconv"
 
+	"github.com/sirupsen/logrus"
+
 	"github.com/gin-gonic/gin"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
 )
 
@@ -94,6 +96,11 @@ func (m *Module) BlocksGETHandler(c *gin.Context) {
 		return
 	}
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	maxID := ""
 	maxIDString := c.Query(MaxIDKey)
 	if maxIDString != "" {

internal/api/client/emoji/emojisget.go

@@ -4,9 +4,15 @@
 	"net/http"
 
 	"github.com/gin-gonic/gin"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 )
 
 // EmojisGETHandler returns a list of custom emojis enabled on the instance
 func (m *Module) EmojisGETHandler(c *gin.Context) {
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	c.JSON(http.StatusOK, []string{})
 }

internal/api/client/favourites/favouritesget.go

@@ -1,11 +1,13 @@
 package favourites
 
 import (
-	"github.com/sirupsen/logrus"
 	"net/http"
 	"strconv"
 
+	"github.com/sirupsen/logrus"
+
 	"github.com/gin-gonic/gin"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
 )
 
@@ -20,6 +22,11 @@ func (m *Module) FavouritesGETHandler(c *gin.Context) {
 		return
 	}
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	maxID := ""
 	maxIDString := c.Query(MaxIDKey)
 	if maxIDString != "" {

internal/api/client/fileserver/servefile.go

@@ -24,6 +24,7 @@
 
 	"github.com/gin-gonic/gin"
 	"github.com/sirupsen/logrus"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/api/model"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
 )
@@ -90,14 +91,14 @@ func (m *FileServer) ServeFile(c *gin.Context) {
 		return
 	}
 
-	// TODO: do proper content negotiation here -- if the requester only accepts text/html we should try to serve them *something*
+	// TODO: if the requester only accepts text/html we should try to serve them *something*.
 	// This is mostly needed because when sharing a link to a gts-hosted file on something like mastodon, the masto servers will
 	// attempt to look up the content to provide a preview of the link, and they ask for text/html.
-	if c.NegotiateFormat(content.ContentType) == "" {
+	format, err := api.NegotiateAccept(c, api.Offer(content.ContentType))
-		l.Debugf("couldn't negotiate content for Accept headers %+v: we have content type %s", c.Request.Header.Get("Accepted"), content.ContentType)
+	if err != nil {
-		c.AbortWithStatus(http.StatusNotAcceptable)
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
 		return
 	}
 
-	c.DataFromReader(http.StatusOK, content.ContentLength, content.ContentType, bytes.NewReader(content.Content), nil)
+	c.DataFromReader(http.StatusOK, content.ContentLength, format, bytes.NewReader(content.Content), nil)
 }

internal/api/client/fileserver/servefile_test.go

@@ -123,6 +123,7 @@ func (suite *ServeFileTestSuite) TestServeOriginalFileSuccessful() {
 	recorder := httptest.NewRecorder()
 	ctx, _ := gin.CreateTestContext(recorder)
 	ctx.Request = httptest.NewRequest(http.MethodGet, targetAttachment.URL, nil)
+	ctx.Request.Header.Set("accept", "*/*")
 
 	// normally the router would populate these params from the path values,
 	// but because we're calling the ServeFile function directly, we need to set them manually.

internal/api/client/filter/filtersget.go

@@ -4,9 +4,15 @@
 	"net/http"
 
 	"github.com/gin-gonic/gin"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 )
 
 // FiltersGETHandler returns a list of filters set by/for the authed account
 func (m *Module) FiltersGETHandler(c *gin.Context) {
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	c.JSON(http.StatusOK, []string{})
 }

internal/api/client/followrequest/authorize.go

@@ -19,10 +19,12 @@
 package followrequest
 
 import (
-	"github.com/sirupsen/logrus"
 	"net/http"
 
+	"github.com/sirupsen/logrus"
+
 	"github.com/gin-gonic/gin"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
 )
 
@@ -76,6 +78,11 @@ func (m *Module) FollowRequestAuthorizePOSTHandler(c *gin.Context) {
 		return
 	}
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	if authed.User.Disabled || !authed.User.Approved || !authed.Account.SuspendedAt.IsZero() {
 		l.Debugf("couldn't auth: %s", err)
 		c.JSON(http.StatusForbidden, gin.H{"error": "account is disabled, not yet approved, or suspended"})

internal/api/client/followrequest/followrequest_test.go

@@ -106,6 +106,7 @@ func (suite *FollowRequestStandardTestSuite) newContext(recorder *httptest.Respo
 	if bodyContentType != "" {
 		ctx.Request.Header.Set("Content-Type", bodyContentType)
 	}
+	ctx.Request.Header.Set("accept", "application/json")
 
 	return ctx
 }

internal/api/client/followrequest/get.go

@@ -19,10 +19,12 @@
 package followrequest
 
 import (
-	"github.com/sirupsen/logrus"
 	"net/http"
 
+	"github.com/sirupsen/logrus"
+
 	"github.com/gin-gonic/gin"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
 )
 
@@ -83,6 +85,11 @@ func (m *Module) FollowRequestGETHandler(c *gin.Context) {
 		return
 	}
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	if authed.User.Disabled || !authed.User.Approved || !authed.Account.SuspendedAt.IsZero() {
 		l.Debugf("couldn't auth: %s", err)
 		c.JSON(http.StatusForbidden, gin.H{"error": "account is disabled, not yet approved, or suspended"})

internal/api/client/followrequest/reject.go

@@ -23,6 +23,7 @@
 
 	"github.com/gin-gonic/gin"
 	"github.com/sirupsen/logrus"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
 )
 
@@ -74,6 +75,11 @@ func (m *Module) FollowRequestRejectPOSTHandler(c *gin.Context) {
 		return
 	}
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	if authed.User.Disabled || !authed.User.Approved || !authed.Account.SuspendedAt.IsZero() {
 		l.Debugf("couldn't auth: %s", err)
 		c.JSON(http.StatusForbidden, gin.H{"error": "account is disabled, not yet approved, or suspended"})

internal/api/client/instance/instanceget.go

@@ -5,6 +5,7 @@
 
 	"github.com/sirupsen/logrus"
 	"github.com/spf13/viper"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/config"
 
 	"github.com/gin-gonic/gin"
@@ -35,6 +36,11 @@
 func (m *Module) InstanceInformationGETHandler(c *gin.Context) {
 	l := logrus.WithField("func", "InstanceInformationGETHandler")
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	host := viper.GetString(config.Keys.Host)
 
 	instance, err := m.processor.InstanceGet(c.Request.Context(), host)

internal/api/client/instance/instancepatch.go

@@ -1,10 +1,12 @@
 package instance
 
 import (
-	"github.com/sirupsen/logrus"
 	"net/http"
 
+	"github.com/sirupsen/logrus"
+
 	"github.com/gin-gonic/gin"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/api/model"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
 )
@@ -93,6 +95,11 @@ func (m *Module) InstanceUpdatePATCHHandler(c *gin.Context) {
 		return
 	}
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	// only admins can update instance settings
 	if !authed.User.Admin {
 		l.Debug("user is not an admin so cannot update instance settings")

internal/api/client/list/listsgets.go

@@ -4,9 +4,15 @@
 	"net/http"
 
 	"github.com/gin-gonic/gin"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 )
 
 // ListsGETHandler returns a list of lists created by/for the authed account
 func (m *Module) ListsGETHandler(c *gin.Context) {
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	c.JSON(http.StatusOK, []string{})
 }

internal/api/client/media/mediacreate.go

@@ -27,6 +27,7 @@
 	"github.com/spf13/viper"
 
 	"github.com/gin-gonic/gin"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/api/model"
 	"github.com/superseriousbusiness/gotosocial/internal/config"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
@@ -93,6 +94,11 @@ func (m *Module) MediaCreatePOSTHandler(c *gin.Context) {
 		return
 	}
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	// extract the media create form from the request context
 	l.Tracef("parsing request form: %s", c.Request.Form)
 	form := &model.AttachmentRequest{}

internal/api/client/media/mediacreate_test.go

@@ -149,6 +149,7 @@ func (suite *MediaCreateTestSuite) TestStatusCreatePOSTImageHandlerSuccessful()
 	}
 	ctx.Request = httptest.NewRequest(http.MethodPost, fmt.Sprintf("http://localhost:8080/%s", mediamodule.BasePath), bytes.NewReader(buf.Bytes())) // the endpoint we're hitting
 	ctx.Request.Header.Set("Content-Type", w.FormDataContentType())
+	ctx.Request.Header.Set("accept", "application/json")
 
 	// do the actual request
 	suite.mediaModule.MediaCreatePOSTHandler(ctx)

internal/api/client/media/mediaget.go

@@ -19,10 +19,12 @@
 package media
 
 import (
-	"github.com/sirupsen/logrus"
 	"net/http"
 
+	"github.com/sirupsen/logrus"
+
 	"github.com/gin-gonic/gin"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
 )
 
@@ -70,6 +72,11 @@ func (m *Module) MediaGETHandler(c *gin.Context) {
 		return
 	}
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	attachmentID := c.Param(IDKey)
 	if attachmentID == "" {
 		c.JSON(http.StatusBadRequest, gin.H{"error": "no attachment ID given in request"})

internal/api/client/media/mediaupdate.go

@@ -27,6 +27,7 @@
 	"github.com/spf13/viper"
 
 	"github.com/gin-gonic/gin"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/api/model"
 	"github.com/superseriousbusiness/gotosocial/internal/config"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
@@ -102,6 +103,11 @@ func (m *Module) MediaPUTHandler(c *gin.Context) {
 		return
 	}
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	attachmentID := c.Param(IDKey)
 	if attachmentID == "" {
 		c.JSON(http.StatusBadRequest, gin.H{"error": "no attachment ID given in request"})

internal/api/client/notification/notificationsget.go

@@ -24,6 +24,7 @@
 
 	"github.com/gin-gonic/gin"
 	"github.com/sirupsen/logrus"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
 )
 
@@ -44,6 +45,11 @@ func (m *Module) NotificationsGETHandler(c *gin.Context) {
 		return
 	}
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	limit := 20
 	limitString := c.Query(LimitKey)
 	if limitString != "" {

internal/api/client/search/searchget.go

@@ -25,6 +25,7 @@
 
 	"github.com/gin-gonic/gin"
 	"github.com/sirupsen/logrus"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/api/model"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
 )
@@ -71,6 +72,11 @@ func (m *Module) SearchGETHandler(c *gin.Context) {
 		return
 	}
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	accountID := c.Query(AccountIDKey)
 	maxID := c.Query(MaxIDKey)
 	minID := c.Query(MinIDKey)

internal/api/client/status/statusboost.go

@@ -23,6 +23,7 @@
 
 	"github.com/gin-gonic/gin"
 	"github.com/sirupsen/logrus"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
 )
 
@@ -74,13 +75,18 @@ func (m *Module) StatusBoostPOSTHandler(c *gin.Context) {
 	})
 	l.Debugf("entering function")
 
-	authed, err := oauth.Authed(c, true, false, true, true) // we don't really need an app here but we want everything else
+	authed, err := oauth.Authed(c, true, true, true, true)
 	if err != nil {
 		l.Debug("not authed so can't boost status")
 		c.JSON(http.StatusUnauthorized, gin.H{"error": "not authorized"})
 		return
 	}
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	targetStatusID := c.Param(IDKey)
 	if targetStatusID == "" {
 		c.JSON(http.StatusBadRequest, gin.H{"error": "no status id provided"})

internal/api/client/status/statusboost_test.go

@@ -51,6 +51,7 @@ func (suite *StatusBoostTestSuite) TestPostBoost() {
 	ctx.Set(oauth.SessionAuthorizedUser, suite.testUsers["local_account_1"])
 	ctx.Set(oauth.SessionAuthorizedAccount, suite.testAccounts["local_account_1"])
 	ctx.Request = httptest.NewRequest(http.MethodPost, fmt.Sprintf("http://localhost:8080%s", strings.Replace(status.ReblogPath, ":id", targetStatus.ID, 1)), nil) // the endpoint we're hitting
+	ctx.Request.Header.Set("accept", "application/json")
 
 	// normally the router would populate these params from the path values,
 	// but because we're calling the function directly, we need to set them manually.
@@ -117,6 +118,7 @@ func (suite *StatusBoostTestSuite) TestPostUnboostable() {
 	ctx.Set(oauth.SessionAuthorizedUser, suite.testUsers["local_account_1"])
 	ctx.Set(oauth.SessionAuthorizedAccount, suite.testAccounts["local_account_1"])
 	ctx.Request = httptest.NewRequest(http.MethodPost, fmt.Sprintf("http://localhost:8080%s", strings.Replace(status.ReblogPath, ":id", targetStatus.ID, 1)), nil) // the endpoint we're hitting
+	ctx.Request.Header.Set("accept", "application/json")
 
 	// normally the router would populate these params from the path values,
 	// but because we're calling the function directly, we need to set them manually.
@@ -155,6 +157,7 @@ func (suite *StatusBoostTestSuite) TestPostNotVisible() {
 	ctx.Set(oauth.SessionAuthorizedUser, suite.testUsers["local_account_2"])
 	ctx.Set(oauth.SessionAuthorizedAccount, suite.testAccounts["local_account_2"])
 	ctx.Request = httptest.NewRequest(http.MethodPost, fmt.Sprintf("http://localhost:8080%s", strings.Replace(status.ReblogPath, ":id", targetStatus.ID, 1)), nil) // the endpoint we're hitting
+	ctx.Request.Header.Set("accept", "application/json")
 
 	// normally the router would populate these params from the path values,
 	// but because we're calling the function directly, we need to set them manually.

internal/api/client/status/statuscontext.go

@@ -23,6 +23,7 @@
 
 	"github.com/gin-gonic/gin"
 	"github.com/sirupsen/logrus"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
 )
 
@@ -80,6 +81,11 @@ func (m *Module) StatusContextGETHandler(c *gin.Context) {
 		return
 	}
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	targetStatusID := c.Param(IDKey)
 	if targetStatusID == "" {
 		c.JSON(http.StatusBadRequest, gin.H{"error": "no status id provided"})

internal/api/client/status/statuscreate.go

@@ -27,6 +27,7 @@
 	"github.com/spf13/viper"
 
 	"github.com/gin-gonic/gin"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/api/model"
 	"github.com/superseriousbusiness/gotosocial/internal/config"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
@@ -71,13 +72,18 @@
 //      description: internal error
 func (m *Module) StatusCreatePOSTHandler(c *gin.Context) {
 	l := logrus.WithField("func", "statusCreatePOSTHandler")
-	authed, err := oauth.Authed(c, true, true, true, true) // posting a status is serious business so we want *everything*
+	authed, err := oauth.Authed(c, true, true, true, true)
 	if err != nil {
 		l.Debugf("couldn't auth: %s", err)
 		c.JSON(http.StatusForbidden, gin.H{"error": err.Error()})
 		return
 	}
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	// First check this user/account is permitted to post new statuses.
 	// There's no point continuing otherwise.
 	if authed.User.Disabled || !authed.User.Approved || !authed.Account.SuspendedAt.IsZero() {

internal/api/client/status/statuscreate_test.go

@@ -65,6 +65,7 @@ func (suite *StatusCreateTestSuite) TestPostNewStatus() {
 	ctx.Set(oauth.SessionAuthorizedUser, suite.testUsers["local_account_1"])
 	ctx.Set(oauth.SessionAuthorizedAccount, suite.testAccounts["local_account_1"])
 	ctx.Request = httptest.NewRequest(http.MethodPost, fmt.Sprintf("http://localhost:8080/%s", status.BasePath), nil) // the endpoint we're hitting
+	ctx.Request.Header.Set("accept", "application/json")
 	ctx.Request.Form = url.Values{
 		"status":       {"this is a brand new status! #helloworld"},
 		"spoiler_text": {"hello hello"},
@@ -119,6 +120,7 @@ func (suite *StatusCreateTestSuite) TestPostAnotherNewStatus() {
 	ctx.Set(oauth.SessionAuthorizedUser, suite.testUsers["local_account_1"])
 	ctx.Set(oauth.SessionAuthorizedAccount, suite.testAccounts["local_account_1"])
 	ctx.Request = httptest.NewRequest(http.MethodPost, fmt.Sprintf("http://localhost:8080/%s", status.BasePath), nil) // the endpoint we're hitting
+	ctx.Request.Header.Set("accept", "application/json")
 	ctx.Request.Form = url.Values{
 		"status": {statusWithLinksAndTags},
 	}
@@ -154,6 +156,7 @@ func (suite *StatusCreateTestSuite) TestPostNewStatusWithEmoji() {
 	ctx.Set(oauth.SessionAuthorizedUser, suite.testUsers["local_account_1"])
 	ctx.Set(oauth.SessionAuthorizedAccount, suite.testAccounts["local_account_1"])
 	ctx.Request = httptest.NewRequest(http.MethodPost, fmt.Sprintf("http://localhost:8080/%s", status.BasePath), nil) // the endpoint we're hitting
+	ctx.Request.Header.Set("accept", "application/json")
 	ctx.Request.Form = url.Values{
 		"status": {"here is a rainbow emoji a few times! :rainbow: :rainbow: :rainbow: \n here's an emoji that isn't in the db: :test_emoji: "},
 	}
@@ -195,6 +198,7 @@ func (suite *StatusCreateTestSuite) TestReplyToNonexistentStatus() {
 	ctx.Set(oauth.SessionAuthorizedUser, suite.testUsers["local_account_1"])
 	ctx.Set(oauth.SessionAuthorizedAccount, suite.testAccounts["local_account_1"])
 	ctx.Request = httptest.NewRequest(http.MethodPost, fmt.Sprintf("http://localhost:8080/%s", status.BasePath), nil) // the endpoint we're hitting
+	ctx.Request.Header.Set("accept", "application/json")
 	ctx.Request.Form = url.Values{
 		"status":         {"this is a reply to a status that doesn't exist"},
 		"spoiler_text":   {"don't open cuz it won't work"},
@@ -226,6 +230,7 @@ func (suite *StatusCreateTestSuite) TestReplyToLocalStatus() {
 	ctx.Set(oauth.SessionAuthorizedUser, suite.testUsers["local_account_1"])
 	ctx.Set(oauth.SessionAuthorizedAccount, suite.testAccounts["local_account_1"])
 	ctx.Request = httptest.NewRequest(http.MethodPost, fmt.Sprintf("http://localhost:8080/%s", status.BasePath), nil) // the endpoint we're hitting
+	ctx.Request.Header.Set("accept", "application/json")
 	ctx.Request.Form = url.Values{
 		"status":         {fmt.Sprintf("hello @%s this reply should work!", testrig.NewTestAccounts()["local_account_2"].Username)},
 		"in_reply_to_id": {testrig.NewTestStatuses()["local_account_2_status_1"].ID},
@@ -268,6 +273,7 @@ func (suite *StatusCreateTestSuite) TestAttachNewMediaSuccess() {
 	ctx.Set(oauth.SessionAuthorizedUser, suite.testUsers["local_account_1"])
 	ctx.Set(oauth.SessionAuthorizedAccount, suite.testAccounts["local_account_1"])
 	ctx.Request = httptest.NewRequest(http.MethodPost, fmt.Sprintf("http://localhost:8080/%s", status.BasePath), nil) // the endpoint we're hitting
+	ctx.Request.Header.Set("accept", "application/json")
 	ctx.Request.Form = url.Values{
 		"status":    {"here's an image attachment"},
 		"media_ids": {attachment.ID},

internal/api/client/status/statusdelete.go

@@ -23,6 +23,7 @@
 
 	"github.com/gin-gonic/gin"
 	"github.com/sirupsen/logrus"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
 )
 
@@ -73,13 +74,18 @@ func (m *Module) StatusDELETEHandler(c *gin.Context) {
 	})
 	l.Debugf("entering function")
 
-	authed, err := oauth.Authed(c, true, false, true, true) // we don't really need an app here but we want everything else
+	authed, err := oauth.Authed(c, true, true, true, true)
 	if err != nil {
 		l.Debug("not authed so can't delete status")
 		c.JSON(http.StatusUnauthorized, gin.H{"error": "not authorized"})
 		return
 	}
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	targetStatusID := c.Param(IDKey)
 	if targetStatusID == "" {
 		c.JSON(http.StatusBadRequest, gin.H{"error": "no status id provided"})

internal/api/client/status/statusfave.go

@@ -23,6 +23,7 @@
 
 	"github.com/gin-gonic/gin"
 	"github.com/sirupsen/logrus"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
 )
 
@@ -70,13 +71,18 @@ func (m *Module) StatusFavePOSTHandler(c *gin.Context) {
 	})
 	l.Debugf("entering function")
 
-	authed, err := oauth.Authed(c, true, false, true, true) // we don't really need an app here but we want everything else
+	authed, err := oauth.Authed(c, true, true, true, true)
 	if err != nil {
 		l.Debug("not authed so can't fave status")
 		c.JSON(http.StatusUnauthorized, gin.H{"error": "not authorized"})
 		return
 	}
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	targetStatusID := c.Param(IDKey)
 	if targetStatusID == "" {
 		c.JSON(http.StatusBadRequest, gin.H{"error": "no status id provided"})

internal/api/client/status/statusfave_test.go

@@ -55,6 +55,7 @@ func (suite *StatusFaveTestSuite) TestPostFave() {
 	ctx.Set(oauth.SessionAuthorizedUser, suite.testUsers["local_account_1"])
 	ctx.Set(oauth.SessionAuthorizedAccount, suite.testAccounts["local_account_1"])
 	ctx.Request = httptest.NewRequest(http.MethodPost, fmt.Sprintf("http://localhost:8080%s", strings.Replace(status.FavouritePath, ":id", targetStatus.ID, 1)), nil) // the endpoint we're hitting
+	ctx.Request.Header.Set("accept", "application/json")
 
 	// normally the router would populate these params from the path values,
 	// but because we're calling the function directly, we need to set them manually.
@@ -103,6 +104,7 @@ func (suite *StatusFaveTestSuite) TestPostUnfaveable() {
 	ctx.Set(oauth.SessionAuthorizedUser, suite.testUsers["local_account_1"])
 	ctx.Set(oauth.SessionAuthorizedAccount, suite.testAccounts["local_account_1"])
 	ctx.Request = httptest.NewRequest(http.MethodPost, fmt.Sprintf("http://localhost:8080%s", strings.Replace(status.FavouritePath, ":id", targetStatus.ID, 1)), nil) // the endpoint we're hitting
+	ctx.Request.Header.Set("accept", "application/json")
 
 	// normally the router would populate these params from the path values,
 	// but because we're calling the function directly, we need to set them manually.

internal/api/client/status/statusfavedby.go

@@ -23,6 +23,7 @@
 
 	"github.com/gin-gonic/gin"
 	"github.com/sirupsen/logrus"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
 )
 
@@ -71,13 +72,18 @@ func (m *Module) StatusFavedByGETHandler(c *gin.Context) {
 	})
 	l.Debugf("entering function")
 
-	authed, err := oauth.Authed(c, false, false, false, false) // we don't really need an app here but we want everything else
+	authed, err := oauth.Authed(c, true, true, true, true) // we don't really need an app here but we want everything else
 	if err != nil {
 		l.Errorf("error authing status faved by request: %s", err)
 		c.JSON(http.StatusBadRequest, gin.H{"error": "not authed"})
 		return
 	}
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	targetStatusID := c.Param(IDKey)
 	if targetStatusID == "" {
 		c.JSON(http.StatusBadRequest, gin.H{"error": "no status id provided"})

internal/api/client/status/statusfavedby_test.go

@@ -53,6 +53,7 @@ func (suite *StatusFavedByTestSuite) TestGetFavedBy() {
 	ctx.Set(oauth.SessionAuthorizedUser, suite.testUsers["local_account_2"])
 	ctx.Set(oauth.SessionAuthorizedAccount, suite.testAccounts["local_account_2"])
 	ctx.Request = httptest.NewRequest(http.MethodPost, fmt.Sprintf("http://localhost:8080%s", strings.Replace(status.FavouritedPath, ":id", targetStatus.ID, 1)), nil) // the endpoint we're hitting
+	ctx.Request.Header.Set("accept", "application/json")
 
 	// normally the router would populate these params from the path values,
 	// but because we're calling the function directly, we need to set them manually.

internal/api/client/status/statusget.go

@@ -23,6 +23,7 @@
 
 	"github.com/gin-gonic/gin"
 	"github.com/sirupsen/logrus"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
 )
 
@@ -70,13 +71,18 @@ func (m *Module) StatusGETHandler(c *gin.Context) {
 	})
 	l.Debugf("entering function")
 
-	authed, err := oauth.Authed(c, false, false, false, false) // we don't really need an app here but we want everything else
+	authed, err := oauth.Authed(c, false, false, false, false)
 	if err != nil {
 		l.Errorf("error authing status faved by request: %s", err)
 		c.JSON(http.StatusBadRequest, gin.H{"error": "not authed"})
 		return
 	}
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	targetStatusID := c.Param(IDKey)
 	if targetStatusID == "" {
 		c.JSON(http.StatusBadRequest, gin.H{"error": "no status id provided"})

internal/api/client/status/statusunboost.go

@@ -23,6 +23,7 @@
 
 	"github.com/gin-gonic/gin"
 	"github.com/sirupsen/logrus"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
 )
 
@@ -71,13 +72,18 @@ func (m *Module) StatusUnboostPOSTHandler(c *gin.Context) {
 	})
 	l.Debugf("entering function")
 
-	authed, err := oauth.Authed(c, true, false, true, true) // we don't really need an app here but we want everything else
+	authed, err := oauth.Authed(c, true, true, true, true)
 	if err != nil {
 		l.Debug("not authed so can't unboost status")
 		c.JSON(http.StatusUnauthorized, gin.H{"error": "not authorized"})
 		return
 	}
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	targetStatusID := c.Param(IDKey)
 	if targetStatusID == "" {
 		c.JSON(http.StatusBadRequest, gin.H{"error": "no status id provided"})

internal/api/client/status/statusunfave.go

@@ -23,6 +23,7 @@
 
 	"github.com/gin-gonic/gin"
 	"github.com/sirupsen/logrus"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
 )
 
@@ -70,13 +71,18 @@ func (m *Module) StatusUnfavePOSTHandler(c *gin.Context) {
 	})
 	l.Debugf("entering function")
 
-	authed, err := oauth.Authed(c, true, false, true, true) // we don't really need an app here but we want everything else
+	authed, err := oauth.Authed(c, true, true, true, true)
 	if err != nil {
 		l.Debug("not authed so can't unfave status")
 		c.JSON(http.StatusUnauthorized, gin.H{"error": "not authorized"})
 		return
 	}
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	targetStatusID := c.Param(IDKey)
 	if targetStatusID == "" {
 		c.JSON(http.StatusBadRequest, gin.H{"error": "no status id provided"})

internal/api/client/status/statusunfave_test.go

@@ -56,6 +56,7 @@ func (suite *StatusUnfaveTestSuite) TestPostUnfave() {
 	ctx.Set(oauth.SessionAuthorizedUser, suite.testUsers["local_account_1"])
 	ctx.Set(oauth.SessionAuthorizedAccount, suite.testAccounts["local_account_1"])
 	ctx.Request = httptest.NewRequest(http.MethodPost, fmt.Sprintf("http://localhost:8080%s", strings.Replace(status.UnfavouritePath, ":id", targetStatus.ID, 1)), nil) // the endpoint we're hitting
+	ctx.Request.Header.Set("accept", "application/json")
 
 	// normally the router would populate these params from the path values,
 	// but because we're calling the function directly, we need to set them manually.
@@ -105,6 +106,7 @@ func (suite *StatusUnfaveTestSuite) TestPostAlreadyNotFaved() {
 	ctx.Set(oauth.SessionAuthorizedUser, suite.testUsers["local_account_1"])
 	ctx.Set(oauth.SessionAuthorizedAccount, suite.testAccounts["local_account_1"])
 	ctx.Request = httptest.NewRequest(http.MethodPost, fmt.Sprintf("http://localhost:8080%s", strings.Replace(status.UnfavouritePath, ":id", targetStatus.ID, 1)), nil) // the endpoint we're hitting
+	ctx.Request.Header.Set("accept", "application/json")
 
 	// normally the router would populate these params from the path values,
 	// but because we're calling the function directly, we need to set them manually.

internal/api/client/timeline/home.go

@@ -19,11 +19,13 @@
 package timeline
 
 import (
-	"github.com/sirupsen/logrus"
 	"net/http"
 	"strconv"
 
+	"github.com/sirupsen/logrus"
+
 	"github.com/gin-gonic/gin"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
 )
 
@@ -112,6 +114,11 @@ func (m *Module) HomeTimelineGETHandler(c *gin.Context) {
 		return
 	}
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	maxID := ""
 	maxIDString := c.Query(MaxIDKey)
 	if maxIDString != "" {

internal/api/client/timeline/public.go

@@ -19,11 +19,13 @@
 package timeline
 
 import (
-	"github.com/sirupsen/logrus"
 	"net/http"
 	"strconv"
 
+	"github.com/sirupsen/logrus"
+
 	"github.com/gin-gonic/gin"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
 )
 
@@ -112,6 +114,11 @@ func (m *Module) PublicTimelineGETHandler(c *gin.Context) {
 		return
 	}
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	maxID := ""
 	maxIDString := c.Query(MaxIDKey)
 	if maxIDString != "" {

internal/api/client/user/passwordchange.go

@@ -23,6 +23,7 @@
 
 	"github.com/gin-gonic/gin"
 	"github.com/sirupsen/logrus"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/api/model"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
 )
@@ -71,6 +72,11 @@ func (m *Module) PasswordChangePOSTHandler(c *gin.Context) {
 		return
 	}
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	// First check this user/account is active.
 	if authed.User.Disabled || !authed.User.Approved || !authed.Account.SuspendedAt.IsZero() {
 		l.Debugf("couldn't auth: %s", err)

internal/api/client/user/passwordchange_test.go

@@ -50,6 +50,7 @@ func (suite *PasswordChangeTestSuite) TestPasswordChangePOST() {
 	ctx.Set(oauth.SessionAuthorizedUser, suite.testUsers["local_account_1"])
 	ctx.Set(oauth.SessionAuthorizedAccount, suite.testAccounts["local_account_1"])
 	ctx.Request = httptest.NewRequest(http.MethodPost, fmt.Sprintf("http://localhost:8080/%s", user.PasswordChangePath), nil)
+	ctx.Request.Header.Set("accept", "application/json")
 	ctx.Request.Form = url.Values{
 		"old_password": {"password"},
 		"new_password": {"peepeepoopoopassword"},
@@ -83,6 +84,7 @@ func (suite *PasswordChangeTestSuite) TestPasswordMissingOldPassword() {
 	ctx.Set(oauth.SessionAuthorizedUser, suite.testUsers["local_account_1"])
 	ctx.Set(oauth.SessionAuthorizedAccount, suite.testAccounts["local_account_1"])
 	ctx.Request = httptest.NewRequest(http.MethodPost, fmt.Sprintf("http://localhost:8080/%s", user.PasswordChangePath), nil)
+	ctx.Request.Header.Set("accept", "application/json")
 	ctx.Request.Form = url.Values{
 		"new_password": {"peepeepoopoopassword"},
 	}
@@ -109,6 +111,7 @@ func (suite *PasswordChangeTestSuite) TestPasswordIncorrectOldPassword() {
 	ctx.Set(oauth.SessionAuthorizedUser, suite.testUsers["local_account_1"])
 	ctx.Set(oauth.SessionAuthorizedAccount, suite.testAccounts["local_account_1"])
 	ctx.Request = httptest.NewRequest(http.MethodPost, fmt.Sprintf("http://localhost:8080/%s", user.PasswordChangePath), nil)
+	ctx.Request.Header.Set("accept", "application/json")
 	ctx.Request.Form = url.Values{
 		"old_password": {"notright"},
 		"new_password": {"peepeepoopoopassword"},
@@ -136,6 +139,7 @@ func (suite *PasswordChangeTestSuite) TestPasswordWeakNewPassword() {
 	ctx.Set(oauth.SessionAuthorizedUser, suite.testUsers["local_account_1"])
 	ctx.Set(oauth.SessionAuthorizedAccount, suite.testAccounts["local_account_1"])
 	ctx.Request = httptest.NewRequest(http.MethodPost, fmt.Sprintf("http://localhost:8080/%s", user.PasswordChangePath), nil)
+	ctx.Request.Header.Set("accept", "application/json")
 	ctx.Request.Form = url.Values{
 		"old_password": {"password"},
 		"new_password": {"peepeepoopoo"},

internal/api/model/well-known.go

@@ -22,6 +22,8 @@
 // For example, it would be returned from https://example.org/.well-known/webfinger?resource=acct:some_username@example.org
 //
 // See https://webfinger.net/
+//
+// swagger:model wellKnownResponse
 type WellKnownResponse struct {
 	Subject string   `json:"subject,omitempty"`
 	Aliases []string `json:"aliases,omitempty"`
@@ -40,8 +42,11 @@ type Link struct {
 
 // Nodeinfo represents a version 2.1 or version 2.0 nodeinfo schema.
 // See: https://nodeinfo.diaspora.software/schema.html
+//
+// swagger:model nodeinfo
 type Nodeinfo struct {
 	// The schema version
+	// example: 2.0
 	Version string `json:"version"`
 	// Metadata about server software in use.
 	Software NodeInfoSoftware `json:"software"`
@@ -50,6 +55,7 @@ type Nodeinfo struct {
 	// The third party sites this server can connect to via their application API.
 	Services NodeInfoServices `json:"services"`
 	// Whether this server allows open self-registration.
+	// example: false
 	OpenRegistrations bool `json:"openRegistrations"`
 	// Usage statistics for this server.
 	Usage NodeInfoUsage `json:"usage"`
@@ -59,7 +65,9 @@ type Nodeinfo struct {
 
 // NodeInfoSoftware represents the name and version number of the software of this node.
 type NodeInfoSoftware struct {
-	Name    string `json:"name"`
+	// example: gotosocial
+	Name string `json:"name"`
+	// example: 0.1.2 1234567
 	Version string `json:"version"`
 }
 

internal/api/negotiate.go

@@ -0,0 +1,96 @@
+/*
+   GoToSocial
+   Copyright (C) 2021 GoToSocial Authors admin@gotosocial.org
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Affero General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU Affero General Public License for more details.
+
+   You should have received a copy of the GNU Affero General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+package api
+
+import (
+	"errors"
+	"fmt"
+
+	"github.com/gin-gonic/gin"
+)
+
+// Offer represents an offered mime-type.
+type Offer string
+
+const (
+	AppJSON           Offer = `application/json`                                                     // AppJSON is the mime type for 'application/json'.
+	AppActivityJSON   Offer = `application/activity+json`                                            // AppActivityJSON is the mime type for 'application/activity+json'.
+	AppActivityLDJSON Offer = `application/ld+json; profile="https://www.w3.org/ns/activitystreams"` // AppActivityLDJSON is the mime type for 'application/ld+json; profile="https://www.w3.org/ns/activitystreams"'
+	TextHTML          Offer = `text/html`                                                            // TextHTML is the mime type for 'text/html'.
+)
+
+// ActivityPubAcceptHeaders represents the Accept headers mentioned here:
+// https://www.w3.org/TR/activitypub/#retrieving-objects
+var ActivityPubAcceptHeaders = []Offer{
+	AppActivityJSON,
+	AppActivityLDJSON,
+}
+
+// JSONAcceptHeaders is a slice of offers that just contains application/json types.
+var JSONAcceptHeaders = []Offer{
+	AppJSON,
+}
+
+// HTMLAcceptHeaders is a slice of offers that just contains text/html types.
+var HTMLAcceptHeaders = []Offer{
+	TextHTML,
+}
+
+// NegotiateAccept takes the *gin.Context from an incoming request, and a
+// slice of Offers, and performs content negotiation for the given request
+// with the given content-type offers. It will return a string representation
+// of the first suitable content-type, or an error if something goes wrong or
+// a suiteable content-type cannot be matched.
+//
+// For example, if the request in the *gin.Context has Accept headers of value
+// [application/json, text/html], and the provided offers are of value
+// [application/json, application/xml], then the returned string will be
+// 'application/json', which indicates the content-type that should be returned.
+//
+// If there are no Accept headers in the request, or the length of offers is 0,
+// then an error will be returned, so this function should only be called in places
+// where format negotiation is actually needed and headers are expected to be present
+// on incoming requests.
+//
+// Callers can use the offer slices exported in this package as shortcuts for
+// often-used Accept types.
+//
+// See https://developer.mozilla.org/en-US/docs/Web/HTTP/Content_negotiation#server-driven_content_negotiation
+func NegotiateAccept(c *gin.Context, offers ...Offer) (string, error) {
+	if len(offers) == 0 {
+		return "", errors.New("no format offered")
+	}
+
+	accepts := c.Request.Header.Values("Accept")
+	if len(accepts) == 0 {
+		return "", fmt.Errorf("no Accept header(s) set on incoming request; this endpoint offers %s", offers)
+	}
+
+	strings := []string{}
+	for _, o := range offers {
+		strings = append(strings, string(o))
+	}
+
+	format := c.NegotiateFormat(strings...)
+	if format == "" {
+		return "", fmt.Errorf("no format can be offered for requested Accept header(s) %s; this endpoint offers %s", accepts, offers)
+	}
+
+	return format, nil
+}

internal/api/s2s/nodeinfo/nodeinfoget.go

@@ -19,20 +19,42 @@
 package nodeinfo
 
 import (
+	"encoding/json"
 	"net/http"
 
 	"github.com/gin-gonic/gin"
 	"github.com/sirupsen/logrus"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 )
 
-// NodeInfoGETHandler returns a compliant nodeinfo response to node info queries.
+// NodeInfoGETHandler swagger:operation GET /nodeinfo/2.0 nodeInfoGet
-// See: https://nodeinfo.diaspora.software/
+//
+// Returns a compliant nodeinfo response to node info queries.
+//
+// See: https://nodeinfo.diaspora.software/schema.html
+//
+// ---
+// tags:
+// - nodeinfo
+//
+// produces:
+// - application/json; profile="http://nodeinfo.diaspora.software/ns/schema/2.0#"
+//
+// responses:
+//   '200':
+//     schema:
+//       "$ref": "#/definitions/nodeinfo"
 func (m *Module) NodeInfoGETHandler(c *gin.Context) {
 	l := logrus.WithFields(logrus.Fields{
 		"func":       "NodeInfoGETHandler",
 		"user-agent": c.Request.UserAgent(),
 	})
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	ni, err := m.processor.GetNodeInfo(c.Request.Context(), c.Request)
 	if err != nil {
 		l.Debugf("error with get node info request: %s", err)
@@ -40,5 +62,10 @@ func (m *Module) NodeInfoGETHandler(c *gin.Context) {
 		return
 	}
 
-	c.JSON(http.StatusOK, ni)
+	b, jsonErr := json.Marshal(ni)
+	if jsonErr != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": jsonErr.Error()})
+	}
+
+	c.Data(http.StatusOK, `application/json; profile="http://nodeinfo.diaspora.software/ns/schema/2.0#"`, b)
 }

internal/api/s2s/nodeinfo/wellknownget.go

@@ -23,16 +23,37 @@
 
 	"github.com/gin-gonic/gin"
 	"github.com/sirupsen/logrus"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 )
 
-// NodeInfoWellKnownGETHandler returns a well known response to a query to /.well-known/nodeinfo,
+// NodeInfoWellKnownGETHandler swagger:operation GET /.well-known/nodeinfo nodeInfoWellKnownGet
-// directing (but not redirecting...) callers to the NodeInfoGETHandler.
+//
+// Directs callers to /nodeinfo/2.0.
+//
+// eg. `{"links":[{"rel":"http://nodeinfo.diaspora.software/ns/schema/2.0","href":"http://example.org/nodeinfo/2.0"}]}`
+// See: https://nodeinfo.diaspora.software/protocol.html
+//
+// ---
+// tags:
+// - nodeinfo
+//
+// produces:
+// - application/json
+//
+// responses:
+//   '200':
+//     schema:
+//       "$ref": "#/definitions/wellKnownResponse"
 func (m *Module) NodeInfoWellKnownGETHandler(c *gin.Context) {
 	l := logrus.WithFields(logrus.Fields{
-		"func":       "NodeInfoWellKnownGETHandler",
+		"func": "NodeInfoWellKnownGETHandler",
-		"user-agent": c.Request.UserAgent(),
 	})
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	niRel, err := m.processor.GetNodeInfoRel(c.Request.Context(), c.Request)
 	if err != nil {
 		l.Debugf("error with get node info rel request: %s", err)

internal/api/s2s/user/common.go

@@ -20,19 +20,11 @@
 
 import (
 	"context"
-	"fmt"
 
 	"github.com/gin-gonic/gin"
 	"github.com/superseriousbusiness/gotosocial/internal/util"
 )
 
-// ActivityPubAcceptHeaders represents the Accept headers mentioned here:
-// https://www.w3.org/TR/activitypub/#retrieving-objects
-var ActivityPubAcceptHeaders = []string{
-	`application/activity+json`,
-	`application/ld+json; profile="https://www.w3.org/ns/activitystreams"`,
-}
-
 // transferContext transfers the signature verifier and signature from the gin context to the request context
 func transferContext(c *gin.Context) context.Context {
 	ctx := c.Request.Context()
@@ -50,14 +42,6 @@ func transferContext(c *gin.Context) context.Context {
 	return ctx
 }
 
-func negotiateFormat(c *gin.Context) (string, error) {
-	format := c.NegotiateFormat(ActivityPubAcceptHeaders...)
-	if format == "" {
-		return "", fmt.Errorf("no format can be offered for Accept headers %s", c.Request.Header.Get("Accept"))
-	}
-	return format, nil
-}
-
 // SwaggerCollection represents an activitypub collection.
 // swagger:model swaggerCollection
 type SwaggerCollection struct {

internal/api/s2s/user/followers.go

@@ -25,6 +25,7 @@
 
 	"github.com/gin-gonic/gin"
 	"github.com/sirupsen/logrus"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 )
 
 // FollowersGETHandler returns a collection of URIs for followers of the target user, formatted so that other AP servers can understand it.
@@ -40,9 +41,9 @@ func (m *Module) FollowersGETHandler(c *gin.Context) {
 		return
 	}
 
-	format, err := negotiateFormat(c)
+	format, err := api.NegotiateAccept(c, api.ActivityPubAcceptHeaders...)
 	if err != nil {
-		c.JSON(http.StatusNotAcceptable, gin.H{"error": fmt.Sprintf("could not negotiate format with given Accept header(s): %s", err)})
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
 		return
 	}
 	l.Tracef("negotiated format: %s", format)

internal/api/s2s/user/following.go

@@ -25,6 +25,7 @@
 
 	"github.com/gin-gonic/gin"
 	"github.com/sirupsen/logrus"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 )
 
 // FollowingGETHandler returns a collection of URIs for accounts that the target user follows, formatted so that other AP servers can understand it.
@@ -40,9 +41,9 @@ func (m *Module) FollowingGETHandler(c *gin.Context) {
 		return
 	}
 
-	format, err := negotiateFormat(c)
+	format, err := api.NegotiateAccept(c, api.ActivityPubAcceptHeaders...)
 	if err != nil {
-		c.JSON(http.StatusNotAcceptable, gin.H{"error": fmt.Sprintf("could not negotiate format with given Accept header(s): %s", err)})
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
 		return
 	}
 	l.Tracef("negotiated format: %s", format)

internal/api/s2s/user/outboxget.go

@@ -26,6 +26,7 @@
 
 	"github.com/gin-gonic/gin"
 	"github.com/sirupsen/logrus"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 )
 
 // OutboxGETHandler swagger:operation GET /users/{username}/outbox s2sOutboxGet
@@ -113,9 +114,9 @@ func (m *Module) OutboxGETHandler(c *gin.Context) {
 		maxID = maxIDString
 	}
 
-	format, err := negotiateFormat(c)
+	format, err := api.NegotiateAccept(c, api.ActivityPubAcceptHeaders...)
 	if err != nil {
-		c.JSON(http.StatusNotAcceptable, gin.H{"error": fmt.Sprintf("could not negotiate format with given Accept header(s): %s", err)})
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
 		return
 	}
 	l.Tracef("negotiated format: %s", format)

internal/api/s2s/user/outboxget_test.go

@@ -54,6 +54,7 @@ func (suite *OutboxGetTestSuite) TestGetOutbox() {
 	recorder := httptest.NewRecorder()
 	ctx, _ := gin.CreateTestContext(recorder)
 	ctx.Request = httptest.NewRequest(http.MethodGet, targetAccount.OutboxURI, nil) // the endpoint we're hitting
+	ctx.Request.Header.Set("accept", "application/activity+json")
 	ctx.Request.Header.Set("Signature", signedRequest.SignatureHeader)
 	ctx.Request.Header.Set("Date", signedRequest.DateHeader)
 
@@ -108,6 +109,7 @@ func (suite *OutboxGetTestSuite) TestGetOutboxFirstPage() {
 	recorder := httptest.NewRecorder()
 	ctx, _ := gin.CreateTestContext(recorder)
 	ctx.Request = httptest.NewRequest(http.MethodGet, targetAccount.OutboxURI+"?page=true", nil) // the endpoint we're hitting
+	ctx.Request.Header.Set("accept", "application/activity+json")
 	ctx.Request.Header.Set("Signature", signedRequest.SignatureHeader)
 	ctx.Request.Header.Set("Date", signedRequest.DateHeader)
 
@@ -162,6 +164,7 @@ func (suite *OutboxGetTestSuite) TestGetOutboxNextPage() {
 	recorder := httptest.NewRecorder()
 	ctx, _ := gin.CreateTestContext(recorder)
 	ctx.Request = httptest.NewRequest(http.MethodGet, targetAccount.OutboxURI+"?page=true&max_id=01F8MHAMCHF6Y650WCRSCP4WMY", nil) // the endpoint we're hitting
+	ctx.Request.Header.Set("accept", "application/activity+json")
 	ctx.Request.Header.Set("Signature", signedRequest.SignatureHeader)
 	ctx.Request.Header.Set("Date", signedRequest.DateHeader)
 

internal/api/s2s/user/publickeyget.go

@@ -25,6 +25,7 @@
 
 	"github.com/gin-gonic/gin"
 	"github.com/sirupsen/logrus"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 )
 
 // PublicKeyGETHandler should be served at eg https://example.org/users/:username/main-key.
@@ -44,9 +45,9 @@ func (m *Module) PublicKeyGETHandler(c *gin.Context) {
 		return
 	}
 
-	format, err := negotiateFormat(c)
+	format, err := api.NegotiateAccept(c, api.ActivityPubAcceptHeaders...)
 	if err != nil {
-		c.JSON(http.StatusNotAcceptable, gin.H{"error": fmt.Sprintf("could not negotiate format with given Accept header(s): %s", err)})
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
 		return
 	}
 	l.Tracef("negotiated format: %s", format)

internal/api/s2s/user/repliesget.go

@@ -26,6 +26,7 @@
 
 	"github.com/gin-gonic/gin"
 	"github.com/sirupsen/logrus"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 )
 
 // StatusRepliesGETHandler swagger:operation GET /users/{username}/statuses/{status}/replies s2sRepliesGet
@@ -131,9 +132,9 @@ func (m *Module) StatusRepliesGETHandler(c *gin.Context) {
 		minID = minIDString
 	}
 
-	format, err := negotiateFormat(c)
+	format, err := api.NegotiateAccept(c, api.ActivityPubAcceptHeaders...)
 	if err != nil {
-		c.JSON(http.StatusNotAcceptable, gin.H{"error": fmt.Sprintf("could not negotiate format with given Accept header(s): %s", err)})
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
 		return
 	}
 	l.Tracef("negotiated format: %s", format)

internal/api/s2s/user/repliesget_test.go

@@ -57,6 +57,7 @@ func (suite *RepliesGetTestSuite) TestGetReplies() {
 	recorder := httptest.NewRecorder()
 	ctx, _ := gin.CreateTestContext(recorder)
 	ctx.Request = httptest.NewRequest(http.MethodGet, targetStatus.URI+"/replies", nil) // the endpoint we're hitting
+	ctx.Request.Header.Set("accept", "application/activity+json")
 	ctx.Request.Header.Set("Signature", signedRequest.SignatureHeader)
 	ctx.Request.Header.Set("Date", signedRequest.DateHeader)
 
@@ -117,6 +118,7 @@ func (suite *RepliesGetTestSuite) TestGetRepliesNext() {
 	recorder := httptest.NewRecorder()
 	ctx, _ := gin.CreateTestContext(recorder)
 	ctx.Request = httptest.NewRequest(http.MethodGet, targetStatus.URI+"/replies?only_other_accounts=false&page=true", nil) // the endpoint we're hitting
+	ctx.Request.Header.Set("accept", "application/activity+json")
 	ctx.Request.Header.Set("Signature", signedRequest.SignatureHeader)
 	ctx.Request.Header.Set("Date", signedRequest.DateHeader)
 
@@ -180,6 +182,7 @@ func (suite *RepliesGetTestSuite) TestGetRepliesLast() {
 	recorder := httptest.NewRecorder()
 	ctx, _ := gin.CreateTestContext(recorder)
 	ctx.Request = httptest.NewRequest(http.MethodGet, targetStatus.URI+"/replies?only_other_accounts=false&page=true&min_id=01FF25D5Q0DH7CHD57CTRS6WK0", nil) // the endpoint we're hitting
+	ctx.Request.Header.Set("accept", "application/activity+json")
 	ctx.Request.Header.Set("Signature", signedRequest.SignatureHeader)
 	ctx.Request.Header.Set("Date", signedRequest.DateHeader)
 

internal/api/s2s/user/statusget.go

@@ -25,6 +25,7 @@
 
 	"github.com/gin-gonic/gin"
 	"github.com/sirupsen/logrus"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 )
 
 // StatusGETHandler serves the target status as an activitystreams NOTE so that other AP servers can parse it.
@@ -46,9 +47,9 @@ func (m *Module) StatusGETHandler(c *gin.Context) {
 		return
 	}
 
-	format, err := negotiateFormat(c)
+	format, err := api.NegotiateAccept(c, api.ActivityPubAcceptHeaders...)
 	if err != nil {
-		c.JSON(http.StatusNotAcceptable, gin.H{"error": fmt.Sprintf("could not negotiate format with given Accept header(s): %s", err)})
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
 		return
 	}
 	l.Tracef("negotiated format: %s", format)

internal/api/s2s/user/userget.go

@@ -25,6 +25,7 @@
 
 	"github.com/gin-gonic/gin"
 	"github.com/sirupsen/logrus"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 )
 
 // UsersGETHandler should be served at https://example.org/users/:username.
@@ -48,9 +49,9 @@ func (m *Module) UsersGETHandler(c *gin.Context) {
 		return
 	}
 
-	format, err := negotiateFormat(c)
+	format, err := api.NegotiateAccept(c, api.ActivityPubAcceptHeaders...)
 	if err != nil {
-		c.JSON(http.StatusNotAcceptable, gin.H{"error": fmt.Sprintf("could not negotiate format with given Accept header(s): %s", err)})
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
 		return
 	}
 	l.Tracef("negotiated format: %s", format)

internal/api/s2s/user/userget_test.go

@@ -55,6 +55,7 @@ func (suite *UserGetTestSuite) TestGetUser() {
 	recorder := httptest.NewRecorder()
 	ctx, _ := gin.CreateTestContext(recorder)
 	ctx.Request = httptest.NewRequest(http.MethodGet, targetAccount.URI, nil) // the endpoint we're hitting
+	ctx.Request.Header.Set("accept", "application/activity+json")
 	ctx.Request.Header.Set("Signature", signedRequest.SignatureHeader)
 	ctx.Request.Header.Set("Date", signedRequest.DateHeader)
 

internal/api/s2s/webfinger/webfingerget.go

@@ -27,26 +27,54 @@
 	"github.com/gin-gonic/gin"
 	"github.com/sirupsen/logrus"
 	"github.com/spf13/viper"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/config"
 	"github.com/superseriousbusiness/gotosocial/internal/util"
 )
 
-// WebfingerGETRequest handles requests to, for example, https://example.org/.well-known/webfinger?resource=acct:some_user@example.org
+// WebfingerGETRequest swagger:operation GET /.well-known/webfinger webfingerGet
+//
+// Handles webfinger account lookup requests.
+//
+// For example, a GET to `https://goblin.technology/.well-known/webfinger?resource=acct:tobi@goblin.technology` would return:
+//
+// ```
+//  {"subject":"acct:tobi@goblin.technology","aliases":["https://goblin.technology/users/tobi","https://goblin.technology/@tobi"],"links":[{"rel":"http://webfinger.net/rel/profile-page","type":"text/html","href":"https://goblin.technology/@tobi"},{"rel":"self","type":"application/activity+json","href":"https://goblin.technology/users/tobi"}]}
+// ```
+//
+// See: https://webfinger.net/
+//
+// ---
+// tags:
+// - webfinger
+//
+// produces:
+// - application/json
+//
+// responses:
+//   '200':
+//     schema:
+//       "$ref": "#/definitions/wellKnownResponse"
 func (m *Module) WebfingerGETRequest(c *gin.Context) {
 	l := logrus.WithFields(logrus.Fields{
 		"func":       "WebfingerGETRequest",
 		"user-agent": c.Request.UserAgent(),
 	})
 
-	q, set := c.GetQuery("resource")
+	resourceQuery, set := c.GetQuery("resource")
-	if !set || q == "" {
+	if !set || resourceQuery == "" {
 		l.Debug("aborting request because no resource was set in query")
 		c.JSON(http.StatusBadRequest, gin.H{"error": "no 'resource' in request query"})
 		return
 	}
 
+	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": err.Error()})
+		return
+	}
+
 	// remove the acct: prefix if it's present
-	trimAcct := strings.TrimPrefix(q, "acct:")
+	trimAcct := strings.TrimPrefix(resourceQuery, "acct:")
 	// remove the first @ in @whatever@example.org if it's present
 	namestring := strings.TrimPrefix(trimAcct, "@")
 

internal/api/s2s/webfinger/webfingerget_test.go

@@ -50,6 +50,7 @@ func (suite *WebfingerGetTestSuite) TestFingerUser() {
 	recorder := httptest.NewRecorder()
 	ctx, _ := gin.CreateTestContext(recorder)
 	ctx.Request = httptest.NewRequest(http.MethodGet, requestPath, nil) // the endpoint we're hitting
+	ctx.Request.Header.Set("accept", "application/json")
 
 	// trigger the function being tested
 	suite.webfingerModule.WebfingerGETRequest(ctx)
@@ -83,6 +84,7 @@ func (suite *WebfingerGetTestSuite) TestFingerUserWithDifferentAccountDomainByHo
 	recorder := httptest.NewRecorder()
 	ctx, _ := gin.CreateTestContext(recorder)
 	ctx.Request = httptest.NewRequest(http.MethodGet, requestPath, nil) // the endpoint we're hitting
+	ctx.Request.Header.Set("accept", "application/json")
 
 	// trigger the function being tested
 	suite.webfingerModule.WebfingerGETRequest(ctx)
@@ -116,6 +118,7 @@ func (suite *WebfingerGetTestSuite) TestFingerUserWithDifferentAccountDomainByAc
 	recorder := httptest.NewRecorder()
 	ctx, _ := gin.CreateTestContext(recorder)
 	ctx.Request = httptest.NewRequest(http.MethodGet, requestPath, nil) // the endpoint we're hitting
+	ctx.Request.Header.Set("accept", "application/json")
 
 	// trigger the function being tested
 	suite.webfingerModule.WebfingerGETRequest(ctx)
@@ -141,6 +144,7 @@ func (suite *WebfingerGetTestSuite) TestFingerUserWithoutAcct() {
 	recorder := httptest.NewRecorder()
 	ctx, _ := gin.CreateTestContext(recorder)
 	ctx.Request = httptest.NewRequest(http.MethodGet, requestPath, nil) // the endpoint we're hitting
+	ctx.Request.Header.Set("accept", "application/json")
 
 	// trigger the function being tested
 	suite.webfingerModule.WebfingerGETRequest(ctx)

mkdocs.yml

@@ -21,7 +21,7 @@ nav:
     - "configuration/index.md"
     - "configuration/general.md"
     - "configuration/database.md"
-    - "configuration/template.md"
+    - "configuration/web.md"
     - "configuration/accounts.md"
     - "configuration/media.md"
     - "configuration/storage.md"