mirror of https://github.com/jb55/nostril.git
427 lines
9.5 KiB
C
427 lines
9.5 KiB
C
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#include <stdio.h>
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#include <time.h>
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#include <stdlib.h>
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#include <assert.h>
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#include <errno.h>
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#include <inttypes.h>
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#include <secp256k1.h>
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#include <secp256k1_schnorrsig.h>
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#include "cursor.h"
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#include "hex.h"
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#include "sha256.h"
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#include "random.h"
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#define MAX_TAGS 32
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#define MAX_TAG_ELEMS 16
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#define HAS_CREATED_AT (1<<1)
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#define HAS_KIND (1<<2)
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#define HAS_ENVELOPE (1<<2)
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struct key {
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secp256k1_keypair pair;
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unsigned char pubkey[32];
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};
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struct args {
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unsigned int flags;
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int kind;
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const char *sec;
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const char *content;
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uint64_t created_at;
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};
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struct nostr_tag {
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const char *strs[MAX_TAG_ELEMS];
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int num_elems;
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};
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struct nostr_event {
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unsigned char id[32];
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unsigned char pubkey[32];
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unsigned char sig[64];
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const char *content;
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uint64_t created_at;
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int kind;
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struct nostr_tag tags[MAX_TAGS];
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int num_tags;
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};
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void usage()
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{
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printf("usage: nostril <content>\n");
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exit(1);
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}
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inline static int cursor_push_escaped_char(struct cursor *cur, char c)
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{
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switch (c) {
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case '"': return cursor_push_str(cur, "\\\"");
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case '\\': return cursor_push_str(cur, "\\\\");
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case '\b': return cursor_push_str(cur, "\\b");
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case '\f': return cursor_push_str(cur, "\\f");
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case '\n': return cursor_push_str(cur, "\\n");
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case '\r': return cursor_push_str(cur, "\\r");
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case '\t': return cursor_push_str(cur, "\\t");
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// TODO: \u hex hex hex hex
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}
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return cursor_push_byte(cur, c);
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}
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static int cursor_push_jsonstr(struct cursor *cur, const char *str)
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{
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int i;
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int len;
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len = strlen(str);
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if (!cursor_push_byte(cur, '"'))
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return 0;
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for (i = 0; i < len; i++) {
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if (!cursor_push_escaped_char(cur, str[i]))
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return 0;
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}
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if (!cursor_push_byte(cur, '"'))
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return 0;
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return 1;
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}
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static int cursor_push_tag(struct cursor *cur, struct nostr_tag *tag)
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{
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int i;
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if (!cursor_push_byte(cur, '['))
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return 0;
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for (i = 0; i < tag->num_elems; i++) {
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if (!cursor_push_jsonstr(cur, tag->strs[i]))
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return 0;
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if (i != tag->num_elems-1) {
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if (!cursor_push_byte(cur, ','))
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return 0;
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}
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}
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return cursor_push_byte(cur, ']');
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}
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static int cursor_push_tags(struct cursor *cur, struct nostr_event *ev)
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{
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int i;
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if (!cursor_push_byte(cur, '['))
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return 0;
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for (i = 0; i < ev->num_tags; i++) {
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if (!cursor_push_tag(cur, &ev->tags[i]))
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return 0;
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if (i != ev->num_tags-1) {
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if (!cursor_push_str(cur, ","))
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return 0;
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}
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}
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return cursor_push_byte(cur, ']');
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}
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int event_commitment(struct nostr_event *ev, unsigned char *buf, int buflen)
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{
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char timebuf[16] = {0};
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char kindbuf[16] = {0};
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char pubkey[65];
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struct cursor cur;
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int ok;
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ok = hex_encode(ev->pubkey, sizeof(ev->pubkey), pubkey, sizeof(pubkey));
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assert(ok);
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make_cursor(buf, buf + buflen, &cur);
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snprintf(timebuf, sizeof(timebuf), "%" PRIu64 "", ev->created_at);
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snprintf(kindbuf, sizeof(kindbuf), "%d", ev->kind);
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ok =
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cursor_push_str(&cur, "[0,\"") &&
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cursor_push_str(&cur, pubkey) &&
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cursor_push_str(&cur, "\",") &&
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cursor_push_str(&cur, timebuf) &&
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cursor_push_str(&cur, ",") &&
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cursor_push_str(&cur, kindbuf) &&
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cursor_push_str(&cur, ",") &&
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cursor_push_tags(&cur, ev) &&
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cursor_push_str(&cur, ",") &&
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cursor_push_jsonstr(&cur, ev->content) &&
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cursor_push_str(&cur, "]");
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if (!ok)
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return 0;
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return cur.p - cur.start;
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}
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static int make_sig(secp256k1_context *ctx, struct key *key,
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unsigned char *id, unsigned char sig[64])
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{
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unsigned char aux[32];
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if (!fill_random(aux, sizeof(aux))) {
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return 0;
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}
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return secp256k1_schnorrsig_sign(ctx, sig, id, &key->pair, aux);
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}
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static int create_key(secp256k1_context *ctx, struct key *key, unsigned char seckey[32])
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{
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secp256k1_xonly_pubkey pubkey;
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/* Try to create a keypair with a valid context, it should only
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* fail if the secret key is zero or out of range. */
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if (!secp256k1_keypair_create(ctx, &key->pair, seckey))
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return 0;
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if (!secp256k1_keypair_xonly_pub(ctx, &pubkey, NULL, &key->pair))
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return 0;
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/* Serialize the public key. Should always return 1 for a valid public key. */
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return secp256k1_xonly_pubkey_serialize(ctx, key->pubkey, &pubkey);
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}
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static int decode_key(secp256k1_context *ctx, const char *secstr, struct key *key)
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{
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unsigned char seckey[32];
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int ok;
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if (!hex_decode(secstr, strlen(secstr), seckey, 32)) {
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fprintf(stderr, "could not hex decode secret key\n");
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return 0;
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}
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return create_key(ctx, key, seckey);
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}
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static int generate_key(secp256k1_context *ctx, struct key *key)
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{
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unsigned char seckey[32];
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/* If the secret key is zero or out of range (bigger than secp256k1's
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* order), we try to sample a new key. Note that the probability of this
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* happening is negligible. */
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if (!fill_random(seckey, sizeof(seckey))) {
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return 0;
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}
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return create_key(ctx, key, seckey);
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}
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static int init_secp_context(secp256k1_context **ctx)
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{
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unsigned char randomize[32];
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*ctx = secp256k1_context_create(SECP256K1_CONTEXT_SIGN | SECP256K1_CONTEXT_VERIFY);
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if (!fill_random(randomize, sizeof(randomize))) {
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return 0;
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}
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/* Randomizing the context is recommended to protect against side-channel
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* leakage See `secp256k1_context_randomize` in secp256k1.h for more
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* information about it. This should never fail. */
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return secp256k1_context_randomize(*ctx, randomize);
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}
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static int generate_event_id(struct nostr_event *ev)
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{
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static unsigned char buf[32000];
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int len;
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if (!(len = event_commitment(ev, buf, sizeof(buf)))) {
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fprintf(stderr, "event_commitment: buffer out of space\n");
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return 0;
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}
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fprintf(stderr, "commitment: '%.*s'\n", len, buf);
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sha256((struct sha256*)ev->id, buf, len);
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return 1;
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}
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static int sign_event(secp256k1_context *ctx, struct key *key, struct nostr_event *ev)
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{
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if (!make_sig(ctx, key, ev->id, ev->sig)) {
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fprintf(stderr, "Signature generation failed\n");
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return 0;
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}
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return 1;
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}
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static int print_event(struct nostr_event *ev, int envelope)
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{
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unsigned char buf[32000];
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char pubkey[65];
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char id[65];
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char sig[129];
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struct cursor cur;
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int ok;
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ok = hex_encode(ev->id, sizeof(ev->id), id, sizeof(id)) &&
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hex_encode(ev->pubkey, sizeof(ev->pubkey), pubkey, sizeof(pubkey)) &&
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hex_encode(ev->sig, sizeof(ev->sig), sig, sizeof(sig));
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assert(ok);
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make_cursor(buf, buf+sizeof(buf), &cur);
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if (!cursor_push_tags(&cur, ev))
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return 0;
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if (envelope)
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printf("[\"EVENT\",");
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printf("{\"id\": \"%s\",", id);
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printf("\"pubkey\": \"%s\",", pubkey);
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printf("\"created_at\": %" PRIu64 ",", ev->created_at);
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printf("\"kind\": %d,", ev->kind);
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printf("\"tags\": %.*s,", (int)cursor_len(&cur), cur.start);
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reset_cursor(&cur);
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if (!cursor_push_jsonstr(&cur, ev->content))
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return 0;
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printf("\"content\": %.*s,", (int)cursor_len(&cur), cur.start);
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printf("\"sig\": \"%s\"}", sig);
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if (envelope)
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printf("]");
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printf("\n");
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return 1;
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}
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static void make_event_from_args(struct nostr_event *ev, struct args *args)
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{
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ev->tags[0].strs[0] = "tag";
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ev->tags[0].strs[1] = "a";
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ev->tags[0].num_elems = 2;
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ev->num_tags = 0;
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ev->created_at = args->flags & HAS_CREATED_AT? args->created_at : time(NULL);
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ev->content = args->content;
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ev->kind = 1;
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}
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static int parse_num(const char *arg, uint64_t *t)
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{
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*t = strtol(arg, NULL, 10);
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return errno != EINVAL;
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}
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static int parse_args(int argc, const char *argv[], struct args *args)
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{
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const char *arg;
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uint64_t n;
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argv++; argc--;
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for (; argc; ) {
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arg = *argv++; argc--;
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if (!argc) {
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args->content = arg;
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return 1;
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}
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if (!strcmp(arg, "--sec")) {
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args->sec = *argv++; argc--;
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} else if (!strcmp(arg, "--created-at")) {
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arg = *argv++; argc--;
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if (!parse_num(arg, &args->created_at)) {
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fprintf(stderr, "created-at must be a unix timestamp\n");
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return 0;
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} else {
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args->flags |= HAS_CREATED_AT;
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}
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} else if (!strcmp(arg, "--kind")) {
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if (!parse_num(arg, &n)) {
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fprintf(stderr, "kind should be a number, got '%s'\n", arg);
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return 0;
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}
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args->kind = (int)n;
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args->flags |= HAS_KIND;
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} else if (!strcmp(arg, "--envelope")) {
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args->flags |= HAS_ENVELOPE;
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} else if (!strncmp(arg, "--", 2)) {
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fprintf(stderr, "unknown argument: %s\n", arg);
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return 0;
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}
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}
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return 1;
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}
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int main(int argc, const char *argv[])
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{
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struct args args = {0};
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struct nostr_event ev = {0};
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struct key key;
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secp256k1_context *ctx;
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int ok;
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if (argc < 2)
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usage();
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if (!init_secp_context(&ctx))
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return 2;
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if (!parse_args(argc, argv, &args))
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return 10;
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make_event_from_args(&ev, &args);
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if (args.sec) {
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if (!decode_key(ctx, args.sec, &key)) {
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return 8;
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}
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} else {
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if (!generate_key(ctx, &key)) {
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fprintf(stderr, "could not generate key");
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return 4;
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}
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}
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// set the event's pubkey
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memcpy(ev.pubkey, key.pubkey, 32);
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if (!generate_event_id(&ev)) {
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fprintf(stderr, "could not generate event id\n");
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return 5;
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}
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if (!sign_event(ctx, &key, &ev)) {
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fprintf(stderr, "could not sign event\n");
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return 6;
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}
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if (!print_event(&ev, args.flags & HAS_ENVELOPE)) {
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fprintf(stderr, "buffer too small\n");
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return 88;
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}
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return 0;
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}
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