/*

 * HTTP authentication

 * Copyright (c) 2010 Martin Storsjo

 *

 * This file is part of FFmpeg.

 *

 * FFmpeg is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * FFmpeg is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with FFmpeg; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

 */

#include "httpauth.h"

#include "libavutil/base64.h"

#include "libavutil/avstring.h"

#include "libavutil/mem.h"

#include "internal.h"

#include "libavutil/random_seed.h"

#include "libavutil/md5.h"

#include "urldecode.h"

static void handle_basic_params(HTTPAuthState *state, const char *key,

                                int key_len, char **dest, int *dest_len)

{

    if (!strncmp(key, "realm=", key_len)) {

        *dest     =        state->realm;

        *dest_len = sizeof(state->realm);

    }

}

static void handle_digest_params(HTTPAuthState *state, const char *key,

                                 int key_len, char **dest, int *dest_len)

{

    DigestParams *digest = &state->digest_params;

    if (!strncmp(key, "realm=", key_len)) {

        *dest     =        state->realm;

        *dest_len = sizeof(state->realm);

    } else if (!strncmp(key, "nonce=", key_len)) {

        *dest     =        digest->nonce;

        *dest_len = sizeof(digest->nonce);

    } else if (!strncmp(key, "opaque=", key_len)) {

        *dest     =        digest->opaque;

        *dest_len = sizeof(digest->opaque);

    } else if (!strncmp(key, "algorithm=", key_len)) {

        *dest     =        digest->algorithm;

        *dest_len = sizeof(digest->algorithm);

    } else if (!strncmp(key, "qop=", key_len)) {

        *dest     =        digest->qop;

        *dest_len = sizeof(digest->qop);

    } else if (!strncmp(key, "stale=", key_len)) {

        *dest     =        digest->stale;

        *dest_len = sizeof(digest->stale);

    }

}

static void handle_digest_update(HTTPAuthState *state, const char *key,

                                 int key_len, char **dest, int *dest_len)

{

    DigestParams *digest = &state->digest_params;

    if (!strncmp(key, "nextnonce=", key_len)) {

        *dest     =        digest->nonce;

        *dest_len = sizeof(digest->nonce);

    }

}

static void choose_qop(char *qop, int size)

{

    char *ptr = strstr(qop, "auth");

    char *end = ptr + strlen("auth");

    if (ptr && (!*end || av_isspace(*end) || *end == ',') &&

        (ptr == qop || av_isspace(ptr[-1]) || ptr[-1] == ',')) {

        av_strlcpy(qop, "auth", size);

    } else {

        qop[0] = 0;

    }

}

void ff_http_auth_handle_header(HTTPAuthState *state, const char *key,

                                const char *value)

{

    if (!av_strcasecmp(key, "WWW-Authenticate") || !av_strcasecmp(key, "Proxy-Authenticate")) {

        const char *p;

        if (av_stristart(value, "Basic ", &p) &&

            state->auth_type <= HTTP_AUTH_BASIC) {

            state->auth_type = HTTP_AUTH_BASIC;

            state->realm[0] = 0;

            state->stale = 0;

            ff_parse_key_value(p, (ff_parse_key_val_cb) handle_basic_params,

                               state);

        } else if (av_stristart(value, "Digest ", &p) &&

                   state->auth_type <= HTTP_AUTH_DIGEST) {

            state->auth_type = HTTP_AUTH_DIGEST;

            memset(&state->digest_params, 0, sizeof(DigestParams));

            state->realm[0] = 0;

            state->stale = 0;

            ff_parse_key_value(p, (ff_parse_key_val_cb) handle_digest_params,

                               state);

            choose_qop(state->digest_params.qop,

                       sizeof(state->digest_params.qop));

            if (!av_strcasecmp(state->digest_params.stale, "true"))

                state->stale = 1;

        }

    } else if (!av_strcasecmp(key, "Authentication-Info")) {

        ff_parse_key_value(value, (ff_parse_key_val_cb) handle_digest_update,

                           state);

    }

}

static void update_md5_strings(struct AVMD5 *md5ctx, ...)

{

    va_list vl;

    va_start(vl, md5ctx);

    while (1) {

        const char* str = va_arg(vl, const char*);

        if (!str)

            break;

        av_md5_update(md5ctx, str, strlen(str));

    }

    va_end(vl);

}

/* Generate a digest reply, according to RFC 2617. */

static char *make_digest_auth(HTTPAuthState *state, const char *username,

                              const char *password, const char *uri,

                              const char *method)

{

    DigestParams *digest = &state->digest_params;

    int len;

    uint32_t cnonce_buf[2];

    char cnonce[17];

    char nc[9];

    int i;

    char A1hash[33], A2hash[33], response[33];

    struct AVMD5 *md5ctx;

    uint8_t hash[16];

    char *authstr;

    digest->nc++;

    snprintf(nc, sizeof(nc), "%08x", digest->nc);

    /* Generate a client nonce. */

    for (i = 0; i < 2; i++)

        cnonce_buf[i] = av_get_random_seed();

    ff_data_to_hex(cnonce, (const uint8_t*) cnonce_buf, sizeof(cnonce_buf), 1);

    md5ctx = av_md5_alloc();

    if (!md5ctx)

        return NULL;

    av_md5_init(md5ctx);

    update_md5_strings(md5ctx, username, ":", state->realm, ":", password, NULL);

    av_md5_final(md5ctx, hash);

    ff_data_to_hex(A1hash, hash, 16, 1);

    if (!strcmp(digest->algorithm, "") || !strcmp(digest->algorithm, "MD5")) {

    } else if (!strcmp(digest->algorithm, "MD5-sess")) {

        av_md5_init(md5ctx);

        update_md5_strings(md5ctx, A1hash, ":", digest->nonce, ":", cnonce, NULL);

        av_md5_final(md5ctx, hash);

        ff_data_to_hex(A1hash, hash, 16, 1);

    } else {

        /* Unsupported algorithm */

        av_free(md5ctx);

        return NULL;

    }

    av_md5_init(md5ctx);

    update_md5_strings(md5ctx, method, ":", uri, NULL);

    av_md5_final(md5ctx, hash);

    ff_data_to_hex(A2hash, hash, 16, 1);

    av_md5_init(md5ctx);

    update_md5_strings(md5ctx, A1hash, ":", digest->nonce, NULL);

    if (!strcmp(digest->qop, "auth") || !strcmp(digest->qop, "auth-int")) {

        update_md5_strings(md5ctx, ":", nc, ":", cnonce, ":", digest->qop, NULL);

    }

    update_md5_strings(md5ctx, ":", A2hash, NULL);

    av_md5_final(md5ctx, hash);

    ff_data_to_hex(response, hash, 16, 1);

    av_free(md5ctx);

    if (!strcmp(digest->qop, "") || !strcmp(digest->qop, "auth")) {

    } else if (!strcmp(digest->qop, "auth-int")) {

        /* qop=auth-int not supported */

        return NULL;

    } else {

        /* Unsupported qop value. */

        return NULL;

    }

    len = strlen(username) + strlen(state->realm) + strlen(digest->nonce) +

              strlen(uri) + strlen(response) + strlen(digest->algorithm) +

              strlen(digest->opaque) + strlen(digest->qop) + strlen(cnonce) +

              strlen(nc) + 150;

    authstr = av_malloc(len);

    if (!authstr)

        return NULL;

    snprintf(authstr, len, "Authorization: Digest ");

    /* TODO: Escape the quoted strings properly. */

    av_strlcatf(authstr, len, "username=\"%s\"",   username);

    av_strlcatf(authstr, len, ", realm=\"%s\"",     state->realm);

    av_strlcatf(authstr, len, ", nonce=\"%s\"",     digest->nonce);

    av_strlcatf(authstr, len, ", uri=\"%s\"",       uri);

    av_strlcatf(authstr, len, ", response=\"%s\"",  response);

    // we are violating the RFC and use "" because all others seem to do that too.

    if (digest->algorithm[0])

        av_strlcatf(authstr, len, ", algorithm=\"%s\"",  digest->algorithm);

    if (digest->opaque[0])

        av_strlcatf(authstr, len, ", opaque=\"%s\"", digest->opaque);

    if (digest->qop[0]) {

        av_strlcatf(authstr, len, ", qop=\"%s\"",    digest->qop);

        av_strlcatf(authstr, len, ", cnonce=\"%s\"", cnonce);

        av_strlcatf(authstr, len, ", nc=%s",         nc);

    }

    av_strlcatf(authstr, len, "\r\n");

    return authstr;

}

char *ff_http_auth_create_response(HTTPAuthState *state, const char *auth,

                                   const char *path, const char *method)

{

    char *authstr = NULL;

    /* Clear the stale flag, we assume the auth is ok now. It is reset

     * by the server headers if there's a new issue. */

    state->stale = 0;

    if (!auth || !strchr(auth, ':'))

        return NULL;

    if (state->auth_type == HTTP_AUTH_BASIC) {

        int auth_b64_len, len;

        char *ptr, *decoded_auth = ff_urldecode(auth, 0);

        if (!decoded_auth)

            return NULL;

        auth_b64_len = AV_BASE64_SIZE(strlen(decoded_auth));

        len = auth_b64_len + 30;

        authstr = av_malloc(len);

        if (!authstr) {

            av_free(decoded_auth);

            return NULL;

        }

        snprintf(authstr, len, "Authorization: Basic ");

        ptr = authstr + strlen(authstr);

        av_base64_encode(ptr, auth_b64_len, decoded_auth, strlen(decoded_auth));

        av_strlcat(ptr, "\r\n", len - (ptr - authstr));

        av_free(decoded_auth);

    } else if (state->auth_type == HTTP_AUTH_DIGEST) {

        char *username = ff_urldecode(auth, 0), *password;

        if (!username)

            return NULL;

        if ((password = strchr(username, ':'))) {

            *password++ = 0;

            authstr = make_digest_auth(state, username, password, path, method);

        }

        av_free(username);

    }

    return authstr;

}