漫话Redis源码之七十四

SSL大家应该很熟悉，就是为了确保安全的，openssl应该听说过吧：

/* Wrapper around redisSecureConnection to avoid hiredis_ssl dependencies if
 * not building with TLS support.
 */
int cliSecureConnection(redisContext *c, cliSSLconfig config, const char **err) {
#ifdef USE_OPENSSL
    static SSL_CTX *ssl_ctx = NULL;
 
    if (!ssl_ctx) {
        ssl_ctx = SSL_CTX_new(SSLv23_client_method());
        if (!ssl_ctx) {
            *err = "Failed to create SSL_CTX";
            goto error;
        }
        SSL_CTX_set_options(ssl_ctx, SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3);
        SSL_CTX_set_verify(ssl_ctx, config.skip_cert_verify ? SSL_VERIFY_NONE : SSL_VERIFY_PEER, NULL);
 
        if (config.cacert || config.cacertdir) {
            if (!SSL_CTX_load_verify_locations(ssl_ctx, config.cacert, config.cacertdir)) {
                *err = "Invalid CA Certificate File/Directory";
                goto error;
            }
        } else {
            if (!SSL_CTX_set_default_verify_paths(ssl_ctx)) {
                *err = "Failed to use default CA paths";
                goto error;
            }
        }
 
        if (config.cert && !SSL_CTX_use_certificate_chain_file(ssl_ctx, config.cert)) {
            *err = "Invalid client certificate";
            goto error;
        }
 
        if (config.key && !SSL_CTX_use_PrivateKey_file(ssl_ctx, config.key, SSL_FILETYPE_PEM)) {
            *err = "Invalid private key";
            goto error;
        }
        if (config.ciphers && !SSL_CTX_set_cipher_list(ssl_ctx, config.ciphers)) {
            *err = "Error while configuring ciphers";
            goto error;
        }
#ifdef TLS1_3_VERSION
        if (config.ciphersuites && !SSL_CTX_set_ciphersuites(ssl_ctx, config.ciphersuites)) {
            *err = "Error while setting cypher suites";
            goto error;
        }
#endif
    }
 
    SSL *ssl = SSL_new(ssl_ctx);
    if (!ssl) {
        *err = "Failed to create SSL object";
        return REDIS_ERR;
    }
 
    if (config.sni && !SSL_set_tlsext_host_name(ssl, config.sni)) {
        *err = "Failed to configure SNI";
        SSL_free(ssl);
        return REDIS_ERR;
    }
 
    return redisInitiateSSL(c, ssl);
 
error:
    SSL_CTX_free(ssl_ctx);
    ssl_ctx = NULL;
    return REDIS_ERR;
#else
    (void) config;
    (void) c;
    (void) err;
    return REDIS_OK;
#endif
}
 
/* Wrapper around hiredis to allow arbitrary reads and writes.
 *
 * We piggybacks on top of hiredis to achieve transparent TLS support,
 * and use its internal buffers so it can co-exist with commands
 * previously/later issued on the connection.
 *
 * Interface is close to enough to read()/write() so things should mostly
 * work transparently.
 */
 
/* Write a raw buffer through a redisContext. If we already have something
 * in the buffer (leftovers from hiredis operations) it will be written
 * as well.
 */
ssize_t cliWriteConn(redisContext *c, const char *buf, size_t buf_len)
{
    int done = 0;
 
    /* Append data to buffer which is *usually* expected to be empty
     * but we don't assume that, and write.
     */
    c->obuf = sdscatlen(c->obuf, buf, buf_len);
    if (redisBufferWrite(c, &done) == REDIS_ERR) {
        if (!(c->flags & REDIS_BLOCK))
            errno = EAGAIN;
 
        /* On error, we assume nothing was written and we roll back the
         * buffer to its original state.
         */
        if (sdslen(c->obuf) > buf_len)
            sdsrange(c->obuf, 0, -(buf_len+1));
        else
            sdsclear(c->obuf);
 
        return -1;
    }
 
    /* If we're done, free up everything. We may have written more than
     * buf_len (if c->obuf was not initially empty) but we don't have to
     * tell.
     */
    if (done) {
        sdsclear(c->obuf);
        return buf_len;
    }
 
    /* Write was successful but we have some leftovers which we should
     * remove from the buffer.
     *
     * Do we still have data that was there prior to our buf? If so,
     * restore buffer to it's original state and report no new data was
     * writen.
     */
    if (sdslen(c->obuf) > buf_len) {
        sdsrange(c->obuf, 0, -(buf_len+1));
        return 0;
    }
 
    /* At this point we're sure no prior data is left. We flush the buffer
     * and report how much we've written.
     */
    size_t left = sdslen(c->obuf);
    sdsclear(c->obuf);
    return buf_len - left;
}
 
/* Wrapper around OpenSSL (libssl and libcrypto) initialisation
 */
int cliSecureInit()
{
#ifdef USE_OPENSSL
    ERR_load_crypto_strings();
    SSL_load_error_strings();
    SSL_library_init();
#endif
    return REDIS_OK;
}