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/* snac - A simple, minimalistic ActivityPub instance */
/* copyright (c) 2022 - 2023 grunfink / MIT license */
#include "xs.h"
#include "xs_io.h"
#include "xs_encdec.h"
#include "xs_openssl.h"
#include "xs_curl.h"
#include "xs_time.h"
#include "xs_json.h"
#include "snac.h"
xs_dict *http_signed_request_raw(const char *keyid, const char *seckey,
const char *method, const char *url,
xs_dict *headers,
const char *body, int b_size,
int *status, xs_str **payload, int *p_size,
int timeout)
/* does a signed HTTP request */
{
xs *l1 = NULL;
xs *date = NULL;
xs *digest = NULL;
xs *s64 = NULL;
xs *signature = NULL;
xs *hdrs = NULL;
char *host;
char *target;
char *k, *v;
xs_dict *response;
date = xs_str_utctime(0, "%a, %d %b %Y %H:%M:%S GMT");
{
xs *s = xs_replace(url, "https:/" "/", "");
l1 = xs_split_n(s, "/", 1);
}
/* strip the url to get host and target */
host = xs_list_get(l1, 0);
if (xs_list_len(l1) == 2)
target = xs_list_get(l1, 1);
else
target = "";
/* digest */
{
xs *s;
if (body != NULL)
s = xs_sha256_base64(body, b_size);
else
s = xs_sha256_base64("", 0);
digest = xs_fmt("SHA-256=%s", s);
}
{
/* build the string to be signed */
xs *s = xs_fmt("(request-target): %s /%s\n"
"host: %s\n"
"digest: %s\n"
"date: %s",
strcmp(method, "POST") == 0 ? "post" : "get",
target, host, digest, date);
s64 = xs_evp_sign(seckey, s, strlen(s));
}
/* build now the signature header */
signature = xs_fmt("keyId=\"%s#main-key\","
"algorithm=\"rsa-sha256\","
"headers=\"(request-target) host digest date\","
"signature=\"%s\"",
keyid, s64);
/* transfer the original headers */
hdrs = xs_dict_new();
while (xs_dict_iter(&headers, &k, &v))
hdrs = xs_dict_append(hdrs, k, v);
/* add the new headers */
if (strcmp(method, "POST") == 0)
hdrs = xs_dict_append(hdrs, "content-type", "application/activity+json");
else
hdrs = xs_dict_append(hdrs, "accept", "application/activity+json");
xs *user_agent = xs_fmt("%s; +%s/", USER_AGENT, srv_baseurl);
hdrs = xs_dict_append(hdrs, "date", date);
hdrs = xs_dict_append(hdrs, "signature", signature);
hdrs = xs_dict_append(hdrs, "digest", digest);
hdrs = xs_dict_append(hdrs, "host", host);
hdrs = xs_dict_append(hdrs, "user-agent", user_agent);
response = xs_http_request(method, url, hdrs,
body, b_size, status, payload, p_size, timeout);
srv_archive("SEND", url, hdrs, body, b_size, *status, response, *payload, *p_size);
return response;
}
xs_dict *http_signed_request(snac *snac, const char *method, const char *url,
xs_dict *headers,
const char *body, int b_size,
int *status, xs_str **payload, int *p_size,
int timeout)
/* does a signed HTTP request */
{
char *seckey = xs_dict_get(snac->key, "secret");
xs_dict *response;
response = http_signed_request_raw(snac->actor, seckey, method, url,
headers, body, b_size, status, payload, p_size, timeout);
return response;
}
int check_signature(snac *snac, xs_dict *req, xs_str **err)
/* check the signature */
{
char *sig_hdr = xs_dict_get(req, "signature");
xs *keyId = NULL;
xs *headers = NULL;
xs *signature = NULL;
xs *created = NULL;
xs *expires = NULL;
char *pubkey;
char *p;
{
/* extract the values */
xs *l = xs_split(sig_hdr, ",");
xs_list *p;
xs_val *v;
p = l;
while (xs_list_iter(&p, &v)) {
if (xs_startswith(v, "keyId"))
keyId = xs_crop_i(xs_dup(v), 7, -1);
else
if (xs_startswith(v, "headers"))
headers = xs_crop_i(xs_dup(v), 9, -1);
else
if (xs_startswith(v, "signature"))
signature = xs_crop_i(xs_dup(v), 11, -1);
else
if (xs_startswith(v, "created"))
created = xs_crop_i(xs_dup(v), 9, -1);
else
if (xs_startswith(v, "expires"))
expires = xs_crop_i(xs_dup(v), 9, -1);
}
}
if (keyId == NULL || headers == NULL || signature == NULL) {
*err = xs_fmt("bad signature header");
return 0;
}
/* strip the # from the keyId */
if ((p = strchr(keyId, '#')) != NULL)
*p = '\0';
xs *actor = NULL;
if (!valid_status(actor_request(snac, keyId, &actor))) {
*err = xs_fmt("unknown actor %s", keyId);
return 0;
}
if ((p = xs_dict_get(actor, "publicKey")) == NULL ||
((pubkey = xs_dict_get(p, "publicKeyPem")) == NULL)) {
*err = xs_fmt("cannot get pubkey from %s", keyId);
return 0;
}
/* now build the string to be signed */
xs *sig_str = xs_str_new(NULL);
{
xs *l = xs_split(headers, " ");
xs_list *p;
xs_val *v;
p = l;
while (xs_list_iter(&p, &v)) {
char *hc;
xs *ss = NULL;
if (*sig_str != '\0')
sig_str = xs_str_cat(sig_str, "\n");
if (strcmp(v, "(request-target)") == 0) {
ss = xs_fmt("%s: post %s", v, xs_dict_get(req, "path"));
}
else
if (strcmp(v, "(created)") == 0) {
ss = xs_fmt("%s: %s", v, created);
}
else
if (strcmp(v, "(expires)") == 0) {
ss = xs_fmt("%s: %s", v, expires);
}
else {
/* add the header */
if ((hc = xs_dict_get(req, v)) == NULL) {
*err = xs_fmt("cannot find header '%s'", v);
return 0;
}
ss = xs_fmt("%s: %s", v, hc);
}
sig_str = xs_str_cat(sig_str, ss);
}
}
if (xs_evp_verify(pubkey, sig_str, strlen(sig_str), signature) != 1) {
*err = xs_fmt("RSA verify error %s", keyId);
return 0;
}
return 1;
}
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