ttyd/src/http.c

#include <string.h>
#include <libwebsockets.h>

#include "server.h"
#include "html.h"

int
check_auth(struct lws *wsi) {
    if (server->credential == NULL)
        return 0;

    int hdr_length = lws_hdr_total_length(wsi, WSI_TOKEN_HTTP_AUTHORIZATION);
    char buf[hdr_length + 1];
    int len = lws_hdr_copy(wsi, buf, sizeof(buf), WSI_TOKEN_HTTP_AUTHORIZATION);
    if (len > 0) {
        // extract base64 text from authorization header
        char *ptr = &buf[0];
        char *token, *b64_text = NULL;
        int i = 1;
        while ((token = strsep(&ptr, " ")) != NULL) {
            if (strlen(token) == 0)
                continue;
            if (i++ == 2) {
                b64_text = token;
                break;
            }
        }
        if (b64_text != NULL && !strcmp(b64_text, server->credential))
            return 0;
    }

    unsigned char buffer[1024 + LWS_PRE], *p, *end;
    p = buffer + LWS_PRE;
    end = p + sizeof(buffer) - LWS_PRE;

    if (lws_add_http_header_status(wsi, HTTP_STATUS_UNAUTHORIZED, &p, end))
        return 1;
    if (lws_add_http_header_by_token(wsi,
                                     WSI_TOKEN_HTTP_WWW_AUTHENTICATE,
                                     (unsigned char *) "Basic realm=\"ttyd\"",
                                     18, &p, end))
        return 1;
    if (lws_add_http_header_content_length(wsi, 0, &p, end))
        return 1;
    if (lws_finalize_http_header(wsi, &p, end))
        return 1;
    if (lws_write(wsi, buffer + LWS_PRE, p - (buffer + LWS_PRE), LWS_WRITE_HTTP_HEADERS) < 0)
        return 1;

    return -1;
}

int
callback_http(struct lws *wsi, enum lws_callback_reasons reason, void *user, void *in, size_t len) {
    struct pss_http *pss = (struct pss_http *) user;
    unsigned char buffer[4096 + LWS_PRE], *p, *end;
    char buf[256], name[100], rip[50];

    switch (reason) {
        case LWS_CALLBACK_HTTP:
            // only GET method is allowed
            if (!lws_hdr_total_length(wsi, WSI_TOKEN_GET_URI) || len < 1) {
                lws_return_http_status(wsi, HTTP_STATUS_BAD_REQUEST, NULL);
                return 0;
            }

            snprintf(pss->path, sizeof(pss->path), "%s", (const char *)in);
            lws_get_peer_addresses(wsi, lws_get_socket_fd(wsi), name, sizeof(name), rip, sizeof(rip));
            lwsl_notice("HTTP %s - %s (%s)\n", (char *) in, rip, name);

            switch (check_auth(wsi)) {
                case 0:
                    break;
                case -1:
                    return 0;
                case 1:
                default:
                    return 1;
            }

            p = buffer + LWS_PRE;
            end = p + sizeof(buffer) - LWS_PRE;

            if (strncmp(pss->path, "/auth_token.js", 14) == 0) {
                size_t n = server->credential != NULL ? sprintf(buf, "var tty_auth_token = '%s';", server->credential) : 0;

                if (lws_add_http_header_status(wsi, HTTP_STATUS_OK, &p, end))
                    return 1;
                if (lws_add_http_header_by_token(wsi,
                                                 WSI_TOKEN_HTTP_CONTENT_TYPE,
                                                 (unsigned char *) "application/javascript",
                                                 22, &p, end))
                    return 1;
                if (lws_add_http_header_content_length(wsi, (unsigned long) n, &p, end))
                    return 1;
                if (lws_finalize_http_header(wsi, &p, end))
                    return 1;
                if (lws_write(wsi, buffer + LWS_PRE, p - (buffer + LWS_PRE), LWS_WRITE_HTTP_HEADERS) < 0)
                    return 1;
                if (n > 0) {
                    pss->buffer = strdup(buf);
                    pss->len = n;
                    lws_callback_on_writable(wsi);
                }
                return 0;
            }

            if (strcmp(pss->path, "/") != 0) {
                lws_return_http_status(wsi, HTTP_STATUS_NOT_FOUND, NULL);
                return 0;
            }

            const char* content_type = "text/html";
            if (server->index != NULL) {
                int n = lws_serve_http_file(wsi, server->index, content_type, NULL, 0);
                if (n < 0 || (n > 0 && lws_http_transaction_completed(wsi)))
                    return 1;
            } else {
                if (lws_add_http_header_status(wsi, HTTP_STATUS_OK, &p, end))
                    return 1;
                if (lws_add_http_header_by_token(wsi, WSI_TOKEN_HTTP_CONTENT_TYPE, (const unsigned char *) content_type, 9, &p, end))
                    return 1;
                if (lws_add_http_header_content_length(wsi, (unsigned long) index_html_len, &p, end))
                    return 1;
                if (lws_finalize_http_header(wsi, &p, end))
                    return 1;
                if (lws_write(wsi, buffer + LWS_PRE, p - (buffer + LWS_PRE), LWS_WRITE_HTTP_HEADERS) < 0)
                    return 1;

                pss->buffer = (char *) index_html;
                pss->len = index_html_len;
                lws_callback_on_writable(wsi);
                return 0;
            }
            break;
        case LWS_CALLBACK_HTTP_WRITEABLE:
            if (pss->len > 0) {
                int n = lws_write_http(wsi, pss->buffer, pss->len);
                if (strncmp(pss->path, "/", 1) != 0)
                    free(pss->buffer);
                if (n < pss->len)
                    return 1;
            }
            if (lws_http_transaction_completed(wsi))
                return -1;
            break;
        case LWS_CALLBACK_OPENSSL_PERFORM_CLIENT_CERT_VERIFICATION:
            if (!len || (SSL_get_verify_result((SSL *) in) != X509_V_OK)) {
                int err = X509_STORE_CTX_get_error((X509_STORE_CTX *) user);
                int depth = X509_STORE_CTX_get_error_depth((X509_STORE_CTX *) user);
                const char *msg = X509_verify_cert_error_string(err);
                lwsl_err("client certificate verification error: %s (%d), depth: %d\n", msg, err, depth);
                return 1;
            }
            break;
        default:
            break;
    }

    return 0;
}