Improvements to #44: Implement #22 and #9 (#51)

This pull request makes a very small commit on top of #44.

Closes #44.
Closes #9.
Closes #22.

Co-authored-by: LoaD Accumulator <lda@freetards.xyz>
Co-authored-by: lda <lda@freetards.xyz>
Co-authored-by: lda <lda@noreply.git.telodendria.io>
Reviewed-on: Telodendria/Telodendria#51

docs/CHANGELOG.md

@@ -41,6 +41,8 @@ will now be maintained separately and have its own releases as well.
 custom scripts.
 - Greatly simplified some endpoint code by using Cytoplasm's `j2s` for
 parsing request bodies.
+- Create a parser API for grammars found in Matrix, and refactor the 
+User API to use it.
 
 ### New Features
 
@@ -58,6 +60,10 @@ the ability to change only a subset of the configuration.
     - **GET** `/_telodendria/admin/tokens/[token]`
     - **POST** `/_telodendria/admin/tokens`
     - **DELETE** `/_telodendria/admin/tokens/[token]`
+    - **GET** `/_matrix/client/v3/directory/room/[alias]`
+    - **PUT** `/_matrix/client/v3/directory/room/[alias]`
+    - **DELETE** `/_matrix/client/v3/directory/room/[alias]`
+    - **GET** `/_matrix/client/v3/rooms/[id]/aliases`
 
 ## v0.3.0
 

docs/user/admin/privileges.md

@@ -16,10 +16,10 @@ registration tokens.
 configuration.
 - **GRANT_PRIVILEGES:** Allows a user to modify his or her own
 privileges or the privileges of other local users.
-- **ALIAS:** Allows a user to modify room aliases created by other
+- **ALIAS:** Allows a user to modify and see room aliases created by 
-users. By default, users can only manage their own room aliases, but
+other users. By default, users can only manage their own room aliases, 
-an administrator may wish to take over an alias or remove an offensive
+but an administrator may wish to take over an alias or remove an 
-alias.
+offensive alias.
 - **PROC_CONTROL:** Allows a user to get statistics on the running
 process, as well as shutdown and resetart the Telodendria daemon
 itself. Typically this will pair well with **CONFIG**, because there

src/Parser.c

@@ -0,0 +1,503 @@
+/*
+ * Copyright (C) 2022-2024 Jordan Bancino <@jordan:bancino.net> with
+ * other valuable contributors. See CONTRIBUTORS.txt for the full list.
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation files
+ * (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge,
+ * publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include <Parser.h>
+
+#include <Cytoplasm/Memory.h>
+#include <Cytoplasm/Str.h>
+#include <Cytoplasm/Int.h>
+
+#include <string.h>
+#include <stdlib.h>
+#include <ctype.h>
+
+
+/* Iterate through a char **. */
+#define Iterate(s) (*(*s)++)
+
+/* Parse an extended localpart */
+static int
+ParseUserLocalpart(char **str, char **out)
+{
+    char c;
+    char *start;
+    size_t length;
+
+    if (!str || !out)
+    {
+        return 0;
+    }
+    /* An extended localpart contains every ASCII printable character, 
+     * except an ':'. */
+    start = *str;
+    while (isascii((c = Iterate(str))) && c != ':' && c)
+    {
+        /* Do nothing */
+    }
+    length = (size_t) (*str - start) - 1;
+    if (length < 1)
+    {
+        *str = start;
+        return 0;
+    }
+    if (c == ':')
+    {
+        --(*str);
+    }
+
+    *out = Malloc(length + 1);
+    memcpy(*out, start, length);
+    (*out)[length] = '\0';
+
+    return 1;
+}
+/* Parses an IPv4 address. */
+static int
+ParseIPv4(char **str, char **out)
+{
+    /* Be *very* careful with this buffer */
+    char buffer[4];
+    char *start;
+    size_t length;
+    char c;
+
+    int digit = 0;
+    int digits = 0;
+
+    memset(buffer, 0, sizeof(buffer));
+    start = *str;
+
+    /* An IPv4 address is made of 4 blocks between 1-3 digits, like so:
+     * (1-3)*DIGIT.(1-3)*DIGIT.(1-3)*DIGIT.(1-3)*DIGIT */
+    while ((isdigit(c = Iterate(str)) || c == '.') && c && digits < 4)
+    {
+        if (isdigit(c))
+        {
+            digit++;
+            continue;
+        }
+        if (digit < 1 || digit > 3)
+        {
+            /* Current digit is too long for the spec! */
+            *str = start;
+            return 0;
+        }
+        memcpy(buffer, *str - digit - 1, digit);
+        if (atoi(buffer) > 255)
+        {
+            /* Current digit is too large for the spec! */
+            *str = start;
+            return 0;
+        }
+        memset(buffer, 0, sizeof(buffer));
+        digit = 0;
+        digits++; /* We have parsed a digit. */
+    }
+    if (c == '.' || digits != 3)
+    {
+        *str = start;
+        return 0;
+    }
+    length = (size_t) (*str - start) - 1;
+    *out = Malloc(length + 1);
+    memcpy(*out, start, length);
+    (*str)--;
+    return 1;
+}
+static int
+IsIPv6Char(char c)
+{
+    return isxdigit(c) || c == ':' || c == '.';
+}
+static int
+ParseIPv6(char **str, char **out)
+{
+    char *start;
+    size_t length;
+    char c;
+
+    int filled = 0;
+    int digit = 0;
+    int digits = 0;
+
+    start = *str;
+    length = 0;
+
+    if (Iterate(str) != '[')
+    {
+        goto fail;
+    }
+
+    while ((c = Iterate(str)) && IsIPv6Char(c))
+    {
+        char *ipv4;
+        if (isxdigit(c))
+        {
+            digit++;
+            length++;
+            continue;
+        }
+        if (c == ':')
+        {
+            if (**str == ':')
+            {
+                digit = 0;
+                if (!filled)
+                {
+                    filled = 1;
+                    length++;
+                    c = Iterate(str); /* Skip over the character */
+                    continue;
+                }
+                /* RFC3513 says the following:
+                 * > 'The "::" can only appear once in an address.' */
+                *str = start;
+                return 0;
+            }
+            if (digit < 1 || digit > 4)
+            {
+                goto fail;
+            }
+            /* We do not have to check whenever the digit here is valid, 
+             * because it has to be. */
+            digit = 0;
+            digits++;
+
+            length++;
+            continue;
+        }
+        /* The only remaining character being '.', we are probably dealing 
+         * with an IPv4 literal. */
+        *str -= digit + 1;
+        length -= digit + 1;
+        if (ParseIPv4(str, &ipv4))
+        {
+            length += strlen(ipv4);
+            Free(ipv4);
+            c = Iterate(str);
+            filled = 1;
+            goto end;
+        }
+    }
+end:
+    --(*str);
+    if (Iterate(str) != ']')
+    {
+        goto fail;
+    }
+
+    length = (size_t) (*str - start);
+    if (length < 4 || length > 47)
+    {
+        goto fail;
+    }
+    *out = Malloc(length + 1);
+    memset(*out, '\0', length + 1);
+    memcpy(*out, start, length);
+
+    return 1;
+fail:
+    *str = start;
+    return 0;
+}
+static int
+ParseHostname(char **str, char **out)
+{
+    char *start;
+    size_t length = 0;
+    char c;
+
+    start = *str;
+    while ((c = Iterate(str)) && 
+        (isalnum(c) || c == '.' || c == '-') && 
+        ++length < 256)
+    {
+        /* Do nothing. */
+    }
+    if (length < 1 || length > 255)
+    {
+        *str = start;
+        return 0;
+    }
+    length = (size_t) (*str - start) - 1;
+    *out = Malloc(length + 1);
+    memcpy(*out, start, length);
+    (*str)--;
+    return 1;
+}
+
+static int
+ParseServerName(char **str, ServerPart *out)
+{
+    char c;
+    char *start;
+    char *startPort;
+    size_t chars = 0;
+
+    char *host = NULL;
+    char *port = NULL;
+
+    if (!str || !out)
+    {
+        return 0;
+    }
+
+    start = *str;
+
+    if (!host)
+    {
+        /* If we can parse an IPv4 address, use that. */
+        ParseIPv4(str, &host);
+    }
+    if (!host)
+    {
+        /* If we can parse an IPv6 address, use that. */
+        ParseIPv6(str, &host);
+    }
+    if (!host)
+    {
+        /* If we can parse an hostname, use that. */
+        ParseHostname(str, &host);
+    }
+    if (!host)
+    {
+        /* Can't parse a valid server name. */
+        return 0;
+    }
+    /* Now, there's only 2 options: a ':', or the end(everything else.) */
+    if (**str != ':')
+    {
+        /* We're done. */
+        out->hostname = host;
+        out->port = NULL;
+        return 1;
+    }
+    /* TODO: Separate this out */
+    startPort = ++(*str);
+    while(isdigit(c = Iterate(str)) && c && ++chars < 5)
+    {
+        /* Do nothing. */
+    }
+    if (chars < 1 || chars > 5)
+    {
+        *str = start;
+        Free(host);
+        host = NULL;
+        return 0;
+    }
+
+    port = Malloc(chars + 1);
+    memcpy(port, startPort, chars);
+    port[chars] = '\0';
+    if (atol(port) > 65535)
+    {
+        Free(port);
+        Free(host);
+        *str = start;
+        return 0;
+    }
+
+    out->hostname = host;
+    out->port = port;
+
+    return 1;
+}
+int
+ParseServerPart(char *str, ServerPart *part)
+{
+    /* This is a wrapper behind the internal ParseServerName. */
+    if (!str || !part)
+    {
+        return 0;
+    }
+    return ParseServerName(&str, part);
+}
+void
+ServerPartFree(ServerPart part)
+{
+    if (part.hostname)
+    {
+        Free(part.hostname);
+    }
+    if (part.port)
+    {
+        Free(part.port);
+    }
+}
+
+int
+ParseCommonID(char *str, CommonID *id)
+{
+    char sigil;
+
+    if (!str || !id)
+    {
+        return 0;
+    }
+    
+    /* There must at least be 2 chararacters: the sigil and a string.*/
+    if (strlen(str) < 2)
+    {
+        return 0;
+    }
+
+    sigil = *str++;
+    /* Some sigils have the following restriction:
+     * > MUST NOT exceed 255 bytes (including the # sigil and the domain).
+     */
+    if ((sigil == '#' || sigil == '@') && strlen(str) > 255)
+    {
+        return 0;
+    }
+    id->sigil = sigil;
+    id->local = NULL;
+    id->server.hostname = NULL;
+    id->server.port = NULL;
+    
+    switch (sigil)
+    {
+        case '$':
+            /* For event IDs, it depends on the version, so we're just 
+             * accepting it all. */
+            if (!ParseUserLocalpart(&str, &id->local))
+            {
+                return 0;
+            }
+            if (*str == ':')
+            {
+                (*str)++;
+                if (!ParseServerName(&str, &id->server))
+                {
+                    Free(id->local);
+                    id->local = NULL;
+                    return 0;
+                }
+                return 1;
+            }
+            break;
+        case '!':
+        case '#': /* It seems like the localpart should be the same as the 
+                     user's: everything, except ':'. */
+        case '@':
+            if (!ParseUserLocalpart(&str, &id->local))
+            {
+                return 0;
+            }
+            if (*str++ != ':')
+            {
+                Free(id->local);
+                id->local = NULL;
+                return 0;
+            }
+            if (!ParseServerName(&str, &id->server))
+            {
+                Free(id->local);
+                id->local = NULL;
+                return 0;
+            }
+            break;
+    }
+    return 1;
+}
+
+void
+CommonIDFree(CommonID id)
+{
+    if (id.local)
+    {
+        Free(id.local);
+    }
+    ServerPartFree(id.server);
+}
+int
+ValidCommonID(char *str, char sigil)
+{
+    CommonID id;
+    int ret;
+    memset(&id, 0, sizeof(CommonID));
+    if (!str)
+    {
+        return 0;
+    }
+
+    ret = ParseCommonID(str, &id) && id.sigil == sigil;
+    
+    CommonIDFree(id);
+    return ret;
+}
+char *
+ParserRecomposeServerPart(ServerPart serverPart)
+{
+    if (serverPart.hostname && serverPart.port)
+    {
+        return StrConcat(3, serverPart.hostname, ":", serverPart.port);
+    }
+    if (serverPart.hostname)
+    {
+        return StrDuplicate(serverPart.hostname);
+    }
+    return NULL;
+}
+char *
+ParserRecomposeCommonID(CommonID id)
+{
+    char *ret = Malloc(2 * sizeof(char));
+    ret[0] = id.sigil;
+    ret[1] = '\0';
+
+    if (id.local)
+    {
+        char *tmp = StrConcat(2, ret, id.local);
+        Free(ret);
+
+        ret = tmp;
+    }
+    if (id.server.hostname)
+    {
+        char *server = ParserRecomposeServerPart(id.server);
+        char *tmp = StrConcat(4, "@", ret, ":", server);
+        Free(ret);
+        Free(server);
+
+        ret = tmp;
+    }
+    return ret;
+}
+int
+ParserServerNameEquals(ServerPart serverPart, char *str)
+{
+    char *idServer;
+    int ret;
+    if (!str)
+    {
+        return 0;
+    }
+    idServer = ParserRecomposeServerPart(serverPart);
+
+    ret = StrEquals(idServer, str);
+    Free(idServer);
+    
+    return ret;
+}

src/Routes/RouteAliasDirectory.c

@@ -25,8 +25,12 @@
 
 #include <Routes.h>
 
+#include <Cytoplasm/Memory.h>
 #include <Cytoplasm/Json.h>
 #include <Cytoplasm/Str.h>
+
+#include <Config.h>
+#include <Parser.h>
 #include <User.h>
 
 ROUTE_IMPL(RouteAliasDirectory, path, argp)
@@ -38,20 +42,40 @@ ROUTE_IMPL(RouteAliasDirectory, path, argp)
     HashMap *response;
 
     Db *db = args->matrixArgs->db;
-    DbRef *ref;
+    DbRef *ref = NULL;
     HashMap *aliases;
+    HashMap *idObject;
     JsonValue *val;
+    Array *arr;
 
     char *token;
+    char *msg;
     User *user = NULL;
 
-    /* TODO: Return HTTP 400 M_INVALID_PARAM if alias is invalid */
+    CommonID aliasID;
+    Config config;
+
+    aliasID.sigil = '\0';
+    aliasID.local = NULL;
+    aliasID.server.hostname = NULL;
+    aliasID.server.port = NULL;
+
+    ConfigLock(db, &config);
+
+    if (!ParseCommonID(alias, &aliasID) || aliasID.sigil != '#')
+    {
+        msg = "Invalid room alias.";
+        HttpResponseStatus(args->context, HTTP_BAD_REQUEST);
+        response = MatrixErrorCreate(M_INVALID_PARAM, msg);
+        goto finish;
+    }
 
     ref = DbLock(db, 1, "aliases");
     if (!ref && !(ref = DbCreate(db, 1, "aliases")))
     {
+        msg = "Unable to access alias database.",
         HttpResponseStatus(args->context, HTTP_INTERNAL_SERVER_ERROR);
-        response = MatrixErrorCreate(M_UNKNOWN, "Unable to access alias database.");
+        response = MatrixErrorCreate(M_UNKNOWN, msg);
         goto finish;
     }
 
@@ -69,8 +93,9 @@ ROUTE_IMPL(RouteAliasDirectory, path, argp)
             }
             else
             {
+                msg = "There is no mapped room ID for this room alias.";
                 HttpResponseStatus(args->context, HTTP_NOT_FOUND);
-                response = MatrixErrorCreate(M_NOT_FOUND, "There is no mapped room ID for this room alias.");
+                response = MatrixErrorCreate(M_NOT_FOUND, msg);
             }
             break;
         case HTTP_PUT:
@@ -92,9 +117,21 @@ ROUTE_IMPL(RouteAliasDirectory, path, argp)
             if (HttpRequestMethodGet(args->context) == HTTP_PUT)
             {
                 HashMap *newAlias;
+                char *id;
+                char *serverPart;
 
-                /* TODO: Validate alias domain and make sure it matches
+                serverPart = ParserRecomposeServerPart(aliasID.server);
-                 * server name and is well formed. */
+                if (!StrEquals(serverPart, config.serverName))
+                {
+                    msg = "Invalid server name.";
+                    HttpResponseStatus(args->context, HTTP_BAD_REQUEST);
+                    response = MatrixErrorCreate(M_INVALID_PARAM, msg);
+
+                    Free(serverPart);
+                    goto finish;
+                }
+
+                Free(serverPart);
 
                 if (JsonGet(aliases, 2, "alias", alias))
                 {
@@ -111,40 +148,81 @@ ROUTE_IMPL(RouteAliasDirectory, path, argp)
                     goto finish;
                 }
 
-                if (!JsonValueAsString(HashMapGet(request, "room_id")))
+                id = JsonValueAsString(HashMapGet(request, "room_id"));
+                if (!id)
                 {
                     HttpResponseStatus(args->context, HTTP_BAD_REQUEST);
                     response = MatrixErrorCreate(M_BAD_JSON, "Missing or invalid room_id.");
                     goto finish;
                 }
-
+                
-                /* TODO: Validate room ID to make sure it is well
+                if (!ValidCommonID(id, '!'))
-                 * formed. */
+                {
+                    msg = "Invalid room ID.";
+                    HttpResponseStatus(args->context, HTTP_BAD_REQUEST);
+                    response = MatrixErrorCreate(M_INVALID_PARAM, msg);
+                    goto finish;
+                }
 
                 newAlias = HashMapCreate();
                 HashMapSet(newAlias, "createdBy", JsonValueString(UserGetName(user)));
-                HashMapSet(newAlias, "id", JsonValueDuplicate(HashMapGet(request, "room_id")));
+                HashMapSet(newAlias, "id", JsonValueString(id));
                 HashMapSet(newAlias, "servers", JsonValueArray(ArrayCreate()));
 
                 JsonSet(aliases, JsonValueObject(newAlias), 2, "alias", alias);
+
+                if (!(idObject = JsonValueAsObject(JsonGet(aliases, 2, "id", id))))
+                {
+                    arr = ArrayCreate();
+                    idObject = HashMapCreate();
+                    HashMapSet(idObject, "aliases", JsonValueArray(arr));
+                    JsonSet(aliases, JsonValueObject(idObject), 2, "id", id);
+                }
+                val = HashMapGet(idObject, "aliases");
+                arr = JsonValueAsArray(val);
+                ArrayAdd(arr, JsonValueString(alias));
+
             }
             else
             {
-                if (!JsonGet(aliases, 2, "alias", alias))
+                HashMap *roomAlias;
+                char *id;
+
+                if (!(val = JsonGet(aliases, 2, "alias", alias)))
                 {
                     HttpResponseStatus(args->context, HTTP_NOT_FOUND);
                     response = MatrixErrorCreate(M_NOT_FOUND, "Room alias not found.");
                     goto finish;
                 }
+                roomAlias = JsonValueAsObject(val);
+                id = StrDuplicate(JsonValueAsString(HashMapGet(roomAlias, "id")));
 
-                if (!(UserGetPrivileges(user) & USER_ALIAS) && !StrEquals(UserGetName(user), JsonValueAsString(JsonGet(aliases, 3, "alias", alias, "createdBy"))))
+                if (!(UserGetPrivileges(user) & USER_ALIAS) && !StrEquals(UserGetName(user), JsonValueAsString(JsonGet(roomAlias, 1, "createdBy"))))
                 {
                     HttpResponseStatus(args->context, HTTP_UNAUTHORIZED);
                     response = MatrixErrorCreate(M_UNAUTHORIZED, NULL);
+                    Free(id);
                     goto finish;
                 }
 
                 JsonValueFree(HashMapDelete(JsonValueAsObject(HashMapGet(aliases, "alias")), alias));
+
+                idObject = JsonValueAsObject(JsonGet(aliases, 2, "id", id));
+                if (idObject)
+                {
+                    size_t i;
+                    val = HashMapGet(idObject, "aliases");
+                    arr = JsonValueAsArray(val);
+                    for (i = 0; i < ArraySize(arr); i++)
+                    {
+                        if (StrEquals(JsonValueAsString(ArrayGet(arr, i)), alias))
+                        {
+                            JsonValueFree(ArrayDelete(arr, i));
+                            break;
+                        }
+                    }
+                }
+                Free(id);
             }
             response = HashMapCreate();
 
@@ -156,6 +234,8 @@ ROUTE_IMPL(RouteAliasDirectory, path, argp)
     }
 
 finish:
+    CommonIDFree(aliasID);
+    ConfigUnlock(&config);
     UserUnlock(user);
     DbUnlock(db, ref);
     JsonFree(request);

src/Routes/RouteFilter.c

@@ -64,7 +64,7 @@ ROUTE_IMPL(RouteFilter, path, argp)
     HashMap *response = NULL;
 
     User *user = NULL;
-    UserId *id = NULL;
+    CommonID *id = NULL;
     char *token = NULL;
 
     char *serverName = NULL;
@@ -97,7 +97,7 @@ ROUTE_IMPL(RouteFilter, path, argp)
         goto finish;
     }
 
-    if (!StrEquals(id->server, serverName))
+    if (!ParserServerNameEquals(id->server, serverName))
     {
         msg = "Cannot use /filter for non-local users.";
         HttpResponseStatus(args->context, HTTP_UNAUTHORIZED);
@@ -119,7 +119,7 @@ ROUTE_IMPL(RouteFilter, path, argp)
         goto finish;
     }
 
-    if (!StrEquals(id->localpart, UserGetName(user)))
+    if (!StrEquals(id->local, UserGetName(user)))
     {
         msg = "Unauthorized to use /filter.";
         HttpResponseStatus(args->context, HTTP_UNAUTHORIZED);

src/Routes/RouteLogin.c

@@ -49,7 +49,7 @@ ROUTE_IMPL(RouteLogin, path, argp)
     LoginRequest loginRequest;
     LoginRequestUserIdentifier userIdentifier;
 
-    UserId *userId = NULL;
+    CommonID *userId = NULL;
 
     Db *db = args->matrixArgs->db;
 
@@ -160,8 +160,8 @@ ROUTE_IMPL(RouteLogin, path, argp)
                 break;
             }
 
-            if (!StrEquals(userId->server, config.serverName)
+            if (!ParserServerNameEquals(userId->server, config.serverName)
-                || !UserExists(db, userId->localpart))
+                || !UserExists(db, userId->local))
             {
                 msg = "Unknown user ID.";
                 HttpResponseStatus(args->context, HTTP_FORBIDDEN);
@@ -175,7 +175,7 @@ ROUTE_IMPL(RouteLogin, path, argp)
             password = loginRequest.password;
             refreshToken = loginRequest.refresh_token;
 
-            user = UserLock(db, userId->localpart);
+            user = UserLock(db, userId->local);
 
             if (!user)
             {

src/Routes/RouteRoomAliases.c

@@ -25,25 +25,80 @@
 
 #include <Routes.h>
 
+#include <Cytoplasm/Memory.h>
 #include <Cytoplasm/Json.h>
+#include <Cytoplasm/Db.h>
+
+#include <Matrix.h>
+#include <User.h>
 
 ROUTE_IMPL(RouteRoomAliases, path, argp)
 {
     RouteArgs *args = argp;
     char *roomId = ArrayGet(path, 0);
+    char *token;
+    char *msg;
 
-    HashMap *request = NULL;
     HashMap *response = NULL;
+    HashMap *aliases = NULL;
+    HashMap *reversealias = NULL;
+
+    JsonValue *val;
 
     Db *db = args->matrixArgs->db;
     DbRef *ref = NULL;
 
-    (void) roomId;
+    User *user = NULL;
 
-    /* TODO: Placeholder; remove. */
+    if (HttpRequestMethodGet(args->context) != HTTP_GET)
-    goto finish;
+    {
+        msg = "Route only accepts GET.";
+        HttpResponseStatus(args->context, HTTP_FORBIDDEN);
+        response = MatrixErrorCreate(M_FORBIDDEN, msg);
+        goto finish;
+    }
+
+    response = MatrixGetAccessToken(args->context, &token);
+    if (response)
+    {
+        goto finish;
+    }
+    user = UserAuthenticate(db, token);
+    if (!user)
+    {
+        HttpResponseStatus(args->context, HTTP_UNAUTHORIZED);
+        response = MatrixErrorCreate(M_UNKNOWN_TOKEN, NULL);
+        goto finish;
+    }
+
+    /* TODO: Check whenever the user is in the room or if its world readable 
+     * once this is implemented instead of just checking for the ALIAS 
+     * privilege. */
+    if (!(UserGetPrivileges(user) & USER_ALIAS))
+    {
+        msg = "User is not allowed to get this room's aliases.";
+        HttpResponseStatus(args->context, HTTP_FORBIDDEN);
+        response = MatrixErrorCreate(M_FORBIDDEN, msg);
+        goto finish;
+    }
+
+    ref = DbLock(db, 1, "aliases");
+    aliases = DbJson(ref);
+    reversealias = JsonValueAsObject(JsonGet(aliases, 2, "id", roomId));
+    if (!reversealias)
+    {
+        /* We do not know about the room ID. */
+        msg = "Unknown room ID.";
+        HttpResponseStatus(args->context, HTTP_BAD_REQUEST);
+        response = MatrixErrorCreate(M_INVALID_PARAM, msg);
+        goto finish;
+    }
+
+    response = HashMapCreate();
+    val = JsonGet(reversealias, 1, "aliases");
+    HashMapSet(response, "aliases", JsonValueDuplicate(val));
 finish:
     DbUnlock(db, ref);
-    JsonFree(request);
+    UserUnlock(user);
     return response;
 }

src/Routes/RouteUserProfile.c

@@ -40,7 +40,7 @@ ROUTE_IMPL(RouteUserProfile, path, argp)
     HashMap *request = NULL;
     HashMap *response = NULL;
 
-    UserId *userId = NULL;
+    CommonID *userId = NULL;
     User *user = NULL;
 
     char *serverName;
@@ -73,7 +73,7 @@ ROUTE_IMPL(RouteUserProfile, path, argp)
         response = MatrixErrorCreate(M_INVALID_PARAM, msg);
         goto finish;
     }
-    if (strcmp(userId->server, serverName))
+    if (!ParserServerNameEquals(userId->server, serverName))
     {
         /* TODO: Implement lookup over federation. */
         msg =   "User profile endpoint currently doesn't support lookup over "
@@ -87,7 +87,7 @@ ROUTE_IMPL(RouteUserProfile, path, argp)
     switch (HttpRequestMethodGet(args->context))
     {
         case HTTP_GET:
-            user = UserLock(db, userId->localpart);
+            user = UserLock(db, userId->local);
             if (!user)
             {
                 msg = "Couldn't lock user.";
@@ -147,11 +147,11 @@ ROUTE_IMPL(RouteUserProfile, path, argp)
                     StrEquals(entry, "avatar_url"))
                 {
                     /* Check if user has privilege to do that action. */
-                    if (StrEquals(userId->localpart, UserGetName(user)))
+                    if (StrEquals(userId->local, UserGetName(user)))
                     {
                         value = JsonValueAsString(HashMapGet(request, entry));
-                        /* TODO: Make UserSetProfile notify other
+                        /* TODO: Make UserSetProfile notify other parties of 
-                         * parties of the change */
+                         * the change */
                         UserSetProfile(user, entry, value);
                         response = HashMapCreate();
                         goto finish;

src/Routes/RouteVersions.c

@@ -37,9 +37,14 @@ ROUTE_IMPL(RouteVersions, path, argp)
     (void) argp;
 
 #define DECLARE_SPEC_VERSION(x) ArrayAdd(versions, JsonValueString(x))
+    DECLARE_SPEC_VERSION("v1.2");
+    DECLARE_SPEC_VERSION("v1.3");
+    DECLARE_SPEC_VERSION("v1.4");
+    DECLARE_SPEC_VERSION("v1.5");
+    DECLARE_SPEC_VERSION("v1.6");
 
+    /* The curently supported version. */
     DECLARE_SPEC_VERSION("v1.7");
-    /* Declare additional spec version support here. */
 
 #undef DECLARE_SPEC_VERSION
 

src/Routes/RouteWhoami.c

@@ -43,7 +43,6 @@ ROUTE_IMPL(RouteWhoami, path, argp)
     char *token;
     char *userID;
     char *deviceID;
-    char *msg;
 
     Config config;
 

src/Uia.c

@@ -351,7 +351,7 @@ UiaComplete(Array * flows, HttpServerContext * context, Db * db,
         char *password = JsonValueAsString(HashMapGet(auth, "password"));
         HashMap *identifier = JsonValueAsObject(HashMapGet(auth, "identifier"));
         char *type;
-        UserId *userId;
+        CommonID *userId;
         User *user;
 
         if (!password || !identifier)
@@ -366,7 +366,8 @@ UiaComplete(Array * flows, HttpServerContext * context, Db * db,
                              config.serverName);
 
         if (!type || !StrEquals(type, "m.id.user")
-         || !userId || !StrEquals(userId->server, config.serverName))
+         || !userId
+         || !ParserServerNameEquals(userId->server, config.serverName))
         {
             HttpResponseStatus(context, HTTP_UNAUTHORIZED);
             ret = BuildResponse(flows, db, response, session, dbRef);
@@ -374,7 +375,7 @@ UiaComplete(Array * flows, HttpServerContext * context, Db * db,
             goto finish;
         }
 
-        user = UserLock(db, userId->localpart);
+        user = UserLock(db, userId->local);
         if (!user)
         {
             HttpResponseStatus(context, HTTP_UNAUTHORIZED);

src/User.c

@@ -31,6 +31,8 @@
 #include <Cytoplasm/Int64.h>
 #include <Cytoplasm/UInt64.h>
 
+#include <Parser.h>
+
 #include <string.h>
 
 struct User
@@ -882,10 +884,11 @@ finish:
     return arr;
 }
 
-UserId *
+CommonID *
 UserIdParse(char *id, char *defaultServer)
 {
-    UserId *userId;
+    CommonID *userId;
+    char *server;
 
     if (!id)
     {
@@ -898,48 +901,38 @@ UserIdParse(char *id, char *defaultServer)
         return NULL;
     }
 
-    userId = Malloc(sizeof(UserId));
+    userId = Malloc(sizeof(CommonID));
     if (!userId)
     {
         goto finish;
     }
+    memset(userId, 0, sizeof(CommonID));
 
     /* Fully-qualified user ID */
     if (*id == '@')
     {
-        char *localStart = id + 1;
+        if (!ParseCommonID(id, userId) || !userId->server.hostname)
-        char *serverStart = localStart;
-
-        while (*serverStart != ':' && *serverStart != '\0')
         {
-            serverStart++;
+            UserIdFree(userId);
-        }
 
-        if (*serverStart == '\0')
-        {
-            Free(userId);
             userId = NULL;
             goto finish;
         }
-
-        *serverStart = '\0';
-        serverStart++;
-
-        userId->localpart = StrDuplicate(localStart);
-        userId->server = StrDuplicate(serverStart);
     }
     else
     {
         /* Treat it as just a localpart */
-        userId->localpart = StrDuplicate(id);
+        userId->local = StrDuplicate(id);
-        userId->server = StrDuplicate(defaultServer);
+        ParseServerPart(defaultServer, &userId->server);
     }
 
-    if (!UserHistoricalValidate(userId->localpart, userId->server))
+    server = ParserRecomposeServerPart(userId->server);
+    if (!UserHistoricalValidate(userId->local, server))
     {
         UserIdFree(userId);
         userId = NULL;
     }
+    Free(server);
 
 finish:
     Free(id);
@@ -947,12 +940,11 @@ finish:
 }
 
 void
-UserIdFree(UserId * id)
+UserIdFree(CommonID * id)
 {
     if (id)
     {
-        Free(id->localpart);
+        CommonIDFree(*id);
-        Free(id->server);
         Free(id);
     }
 }

src/include/Parser.h

@@ -0,0 +1,106 @@
+/*
+ * Copyright (C) 2022-2024 Jordan Bancino <@jordan:bancino.net> with
+ * other valuable contributors. See CONTRIBUTORS.txt for the full list.
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation files
+ * (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge,
+ * publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+#ifndef TELODENDRIA_PARSER_H
+#define TELODENDRIA_PARSER_H
+
+/***
+ * @Nm Parser
+ * @Nd Functions for dealing with grammars found in Matrix
+ * @Dd November 25 2023
+ * @Xr User
+ *
+ * The
+ * .Nm
+ * API provides an interface for parsing grammars within the 
+ * Matrix specification
+ */
+
+/**
+ * The host[:port] format in a servername.
+ */
+typedef struct ServerPart {
+    char *hostname;
+    char *port;
+} ServerPart;
+/**
+ * A common identifier in the form '&local[:server]', where & determines the 
+ * *type* of the identifier.
+ */
+typedef struct CommonID {
+    char sigil;
+    char *local;
+    ServerPart server;
+} CommonID;
+
+/** 
+ * Parses a common identifier, as per the Common Identifier Format as defined 
+ * by the [matrix] specification.
+ */
+extern int ParseCommonID(char *, CommonID *);
+
+/** 
+ * Parses the server part in a common identifier.
+ */
+extern int ParseServerPart(char *, ServerPart *);
+
+/** 
+ * Checks whenever the string is a valid common ID with the correct sigil.
+ */
+extern int ValidCommonID(char *, char);
+
+/** 
+ * Frees a CommonID's values. Note that it doesn't free the CommonID itself.
+ */
+extern void CommonIDFree(CommonID);
+
+/** 
+ * Frees a ServerPart's values. Note that it doesn't free the ServerPart 
+ * itself, and that 
+ * .Fn CommonIDFree 
+ * automatically deals with its server part.
+ */
+extern void ServerPartFree(ServerPart);
+
+/**
+ * Recompose a Common ID into a string which lives in the heap, and must 
+ * therefore be freed with 
+ * .Fn Free .
+ */
+extern char * ParserRecomposeCommonID(CommonID);
+
+/**
+ * Recompose a server part into a string which lives in the heap, and must 
+ * therefore be freed with 
+ * .Fn Free .
+ */
+extern char * ParserRecomposeServerPart(ServerPart);
+
+/**
+ * Compares whenever a ServerName is equivalent to a server name string.
+ */
+extern int ParserServerNameEquals(ServerPart, char *);
+
+
+#endif                             /* TELODENDRIA_PARSER_H */

src/include/User.h

@@ -43,6 +43,8 @@
 #include <Cytoplasm/Db.h>
 #include <Cytoplasm/Json.h>
 
+#include <Parser.h>
+
 /**
  * Many functions here operate on an opaque user structure.
  */
@@ -88,15 +90,6 @@ typedef struct UserLoginInfo
     char *refreshToken;
 } UserLoginInfo;
 
-/**
- * A description of a Matrix user ID.
- */
-typedef struct UserId
-{
-    char *localpart;
-    char *server;
-} UserId;
-
 /**
  * Take a localpart and domain as separate parameters and validate them
  * against the rules of the Matrix specification. The reasion the
@@ -303,15 +296,15 @@ extern Array *UserEncodePrivileges(int);
 extern int UserDecodePrivilege(const char *);
 
 /**
- * Parse either a localpart or a fully qualified Matrix ID. If the
+ * Parse either a localpart or a fully qualified Matrix common ID. If the
  * first argument is a localpart, then the second argument is used as
  * the server name.
  */
-extern UserId * UserIdParse(char *, char *);
+extern CommonID * UserIdParse(char *, char *);
 
 /**
- * Free the memory associated with the parsed Matrix ID.
+ * Frees the user's common ID and the memory allocated for it.
  */
-extern void UserIdFree(UserId *);
+extern void UserIdFree(CommonID *);
 
 #endif                             /* TELODENDRIA_USER_H */