Added a webfinger handler.

Makefile

@@ -2,7 +2,7 @@ CFLAGS=-g -Wall
 
 all: snac
 
-snac: snac.o main.o data.o http.o httpd.o
+snac: snac.o main.o data.o http.o httpd.o webfinger.o
 	$(CC) -L/usr/local/lib *.o -lcurl -lcrypto -o $@
 
 .c.o:
@@ -21,3 +21,4 @@ httpd.o: httpd.c xs.h xs_io.h xs_encdec.h xs_json.h xs_socket.h \
 main.o: main.c xs.h xs_encdec.h xs_json.h snac.h
 snac.o: snac.c xs.h xs_io.h xs_encdec.h xs_json.h xs_curl.h \
   xs_openssl.h xs_socket.h xs_httpd.h snac.h
+webfinger.o: webfinger.c xs.h xs_encdec.h xs_json.h snac.h

httpd.c

@@ -109,6 +109,9 @@ void httpd_connection(int rs)
         /* cascade through */
         if (status == 0)
             server_get_handler(req, q_path, &status, &body, &b_size, &ctype);
+
+        if (status == 0)
+            webfinger_get_handler(req, q_path, &status, &body, &b_size, &ctype);
     }
     else
     if (strcmp(method, "POST") == 0) {

snac.h

@@ -69,3 +69,6 @@ d_char *http_signed_request(snac *snac, char *method, char *url,
                         int *status, d_char **payload, int *p_size);
 
 void httpd(void);
+
+void webfinger_get_handler(d_char *req, char *q_path, int *status,
+                        char **body, int *b_size, char **ctype);

webfinger.c

@@ -0,0 +1,94 @@
+/* snac - A simple, minimalistic ActivityPub instance */
+/* copyright (c) 2022 grunfink - MIT license */
+
+#include "xs.h"
+#include "xs_encdec.h"
+#include "xs_json.h"
+
+#include "snac.h"
+
+void webfinger_get_handler(d_char *req, char *q_path, int *status,
+                        char **body, int *b_size, char **ctype)
+/* serves webfinger queries */
+{
+    if (strcmp(q_path, "/.well-known/webfinger") != 0)
+        return;
+
+    char *q_vars   = xs_dict_get(req, "q_vars");
+    char *resource = xs_dict_get(q_vars, "resource");
+
+    if (resource == NULL) {
+        *status = 400;
+        return;
+    }
+
+    snac snac;
+    int found = 0;
+
+    if (xs_startswith(resource, "https:/" "/")) {
+        /* actor search: find a user with this actor */
+        xs *list = user_list();
+        char *p, *uid;
+
+        p = list;
+        while (xs_list_iter(&p, &uid)) {
+            if (user_open(&snac, uid)) {
+                if (strcmp(snac.actor, resource) == 0) {
+                    found = 1;
+                    break;
+                }
+
+                user_free(&snac);
+            }
+        }
+    }
+    else
+    if (xs_startswith(resource, "acct:")) {
+        /* it's an account name */
+        xs *an = xs_replace(resource, "acct:", "");
+        xs *l = NULL;
+
+        /* strip a possible leading @ */
+        if (xs_startswith(an, "@"))
+            an = xs_crop(an, 1, 0);
+
+        l = xs_split_n(an, "@", 1);
+
+        if (xs_list_len(l) == 2) {
+            char *uid  = xs_list_get(l, 0);
+            char *host = xs_list_get(l, 1);
+
+            if (strcmp(host, xs_dict_get(srv_config, "host")) == 0)
+                found = user_open(&snac, uid);
+        }
+    }
+
+    if (found) {
+        /* build the object */
+        xs *acct;
+        xs *aaj   = xs_dict_new();
+        xs *links = xs_list_new();
+        xs *obj   = xs_dict_new();
+        d_char *j;
+
+        acct = xs_fmt("acct:%s@%s",
+            xs_dict_get(snac.config, "uid"), xs_dict_get(srv_config, "host"));
+
+        aaj = xs_dict_append(aaj, "rel",  "self");
+        aaj = xs_dict_append(aaj, "type", "application/activity+json");
+        aaj = xs_dict_append(aaj, "href", snac.actor);
+
+        links = xs_list_append(links, aaj);
+
+        obj = xs_dict_append(obj, "subject", acct);
+        obj = xs_dict_append(obj, "links",   links);
+
+        j = xs_json_dumps_pp(obj, 4);
+
+        user_free(&snac);
+
+        *status = 200;
+        *body   = j;
+        *ctype  = "application/json";
+    }
+}