/*
 * uhttpd - Tiny single-threaded httpd - Utility functions
 *
 *   Copyright (C) 2010 Jo-Philipp Wich <xm@subsignal.org>
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

#define _XOPEN_SOURCE 500	/* crypt() */
#define _BSD_SOURCE			/* strcasecmp(), strncasecmp() */

#include "uhttpd.h"
#include "uhttpd-utils.h"

#ifdef HAVE_TLS
#include "uhttpd-tls.h"
#endif


static char *uh_index_files[] = {
	"index.html",
	"index.htm",
	"default.html",
	"default.htm"
};


const char * sa_straddr(void *sa)
{
	static char str[INET6_ADDRSTRLEN];
	struct sockaddr_in *v4 = (struct sockaddr_in *)sa;
	struct sockaddr_in6 *v6 = (struct sockaddr_in6 *)sa;

	if( v4->sin_family == AF_INET )
		return inet_ntop(AF_INET, &(v4->sin_addr), str, sizeof(str));
	else
		return inet_ntop(AF_INET6, &(v6->sin6_addr), str, sizeof(str));
}

const char * sa_strport(void *sa)
{
	static char str[6];
	snprintf(str, sizeof(str), "%i", sa_port(sa));
	return str;
}

int sa_port(void *sa)
{
	return ntohs(((struct sockaddr_in6 *)sa)->sin6_port);
}

/* Simple strstr() like function that takes len arguments for both haystack and needle. */
char *strfind(char *haystack, int hslen, const char *needle, int ndlen)
{
	int match = 0;
	int i, j;

	for( i = 0; i < hslen; i++ )
	{
		if( haystack[i] == needle[0] )
		{
			match = ((ndlen == 1) || ((i + ndlen) <= hslen));

			for( j = 1; (j < ndlen) && ((i + j) < hslen); j++ )
			{
				if( haystack[i+j] != needle[j] )
				{
					match = 0;
					break;
				}
			}

			if( match )
				return &haystack[i];
		}
	}

	return NULL;
}


int uh_tcp_send(struct client *cl, const char *buf, int len)
{
	fd_set writer;
	struct timeval timeout;

	FD_ZERO(&writer);
	FD_SET(cl->socket, &writer);

	timeout.tv_sec = 0;
	timeout.tv_usec = 500000;

	if( select(cl->socket + 1, NULL, &writer, NULL, &timeout) > 0 )
	{
#ifdef HAVE_TLS
		if( cl->tls )
			return SSL_write(cl->tls, buf, len);
		else
#endif
			return send(cl->socket, buf, len, 0);
	}

	return -1;
}

int uh_tcp_peek(struct client *cl, char *buf, int len)
{
	int sz = uh_tcp_recv(cl, buf, len);

	/* store received data in peek buffer */
	if( sz > 0 )
	{
		cl->peeklen = sz;
		memcpy(cl->peekbuf, buf, sz);
	}

	return sz;
}

int uh_tcp_recv(struct client *cl, char *buf, int len)
{
	int sz = 0;
	int rsz = 0;

	/* first serve data from peek buffer */
	if( cl->peeklen > 0 )
	{
		sz = min(cl->peeklen, len);
		len -= sz; cl->peeklen -= sz;

		memcpy(buf, cl->peekbuf, sz);
		memmove(cl->peekbuf, &cl->peekbuf[sz], cl->peeklen);
	}

	/* caller wants more */
	if( len > 0 )
	{
#ifdef HAVE_TLS
		if( cl->tls )
			rsz = SSL_read(cl->tls, (void *)&buf[sz], len);
		else
#endif
			rsz = recv(cl->socket, (void *)&buf[sz], len, 0);

		if( (sz == 0) || (rsz > 0) )
			sz += rsz;
	}

	return sz;
}

#define ensure(x) \
	do { if( x < 0 ) return -1; } while(0)

int uh_http_sendhf(struct client *cl, int code, const char *summary, const char *fmt, ...)
{
	va_list ap;

	char buffer[UH_LIMIT_MSGHEAD];
	int len;

	len = snprintf(buffer, sizeof(buffer),
		"HTTP/1.1 %03i %s\r\n"
		"Connection: close\r\n"
		"Content-Type: text/plain\r\n"
		"Transfer-Encoding: chunked\r\n\r\n",
			code, summary
	);

	ensure(uh_tcp_send(cl, buffer, len));

	va_start(ap, fmt);
	len = vsnprintf(buffer, sizeof(buffer), fmt, ap);
	va_end(ap);

	ensure(uh_http_sendc(cl, buffer, len));
	ensure(uh_http_sendc(cl, NULL, 0));

	return 0;
}


int uh_http_sendc(struct client *cl, const char *data, int len)
{
	char chunk[8];
	int clen;

	if( len == -1 )
		len = strlen(data);

	if( len > 0 )
	{
	 	clen = snprintf(chunk, sizeof(chunk), "%X\r\n", len);
		ensure(uh_tcp_send(cl, chunk, clen));
		ensure(uh_tcp_send(cl, data, len));
		ensure(uh_tcp_send(cl, "\r\n", 2));
	}
	else
	{
		ensure(uh_tcp_send(cl, "0\r\n\r\n", 5));
	}

	return 0;
}

int uh_http_sendf(
	struct client *cl, struct http_request *req, const char *fmt, ...
) {
	va_list ap;
	char buffer[UH_LIMIT_MSGHEAD];
	int len;

	va_start(ap, fmt);
	len = vsnprintf(buffer, sizeof(buffer), fmt, ap);
	va_end(ap);

	if( (req != NULL) && (req->version > 1.0) )
		ensure(uh_http_sendc(cl, buffer, len));
	else if( len > 0 )
		ensure(uh_tcp_send(cl, buffer, len));

	return 0;
}

int uh_http_send(
	struct client *cl, struct http_request *req, const char *buf, int len
) {
	if( len < 0 )
		len = strlen(buf);

	if( (req != NULL) && (req->version > 1.0) )
		ensure(uh_http_sendc(cl, buf, len));
	else if( len > 0 )
		ensure(uh_tcp_send(cl, buf, len));

	return 0;
}


int uh_urldecode(char *buf, int blen, const char *src, int slen)
{
	int i;
	int len = 0;

#define hex(x) \
	(((x) <= '9') ? ((x) - '0') : \
		(((x) <= 'F') ? ((x) - 'A' + 10) : \
			((x) - 'a' + 10)))

	for( i = 0; (i <= slen) && (i <= blen); i++ )
	{
		if( src[i] == '%' )
		{
			if( ((i+2) <= slen) && isxdigit(src[i+1]) && isxdigit(src[i+2]) )
			{
				buf[len++] = (char)(16 * hex(src[i+1]) + hex(src[i+2]));
				i += 2;
			}
			else
			{
				buf[len++] = '%';
			}
		}
		else
		{
			buf[len++] = src[i];
		}
	}

	return len;
}

int uh_urlencode(char *buf, int blen, const char *src, int slen)
{
	int i;
	int len = 0;
	const char hex[] = "0123456789abcdef";

	for( i = 0; (i <= slen) && (i <= blen); i++ )
	{
		if( isalnum(src[i]) || (src[i] == '-') || (src[i] == '_') ||
		    (src[i] == '.') || (src[i] == '~') )
		{
			buf[len++] = src[i];
		}
		else if( (len+3) <= blen )
		{
			buf[len++] = '%';
			buf[len++] = hex[(src[i] >> 4) & 15];
			buf[len++] = hex[(src[i] & 15) & 15];
		}
		else
		{
			break;
		}
	}

	return len;
}

int uh_b64decode(char *buf, int blen, const unsigned char *src, int slen)
{
	int i = 0;
	int len = 0;

	unsigned int cin  = 0;
	unsigned int cout = 0;


	for( i = 0; (i <= slen) && (src[i] != 0); i++ )
	{
		cin = src[i];

		if( (cin >= '0') && (cin <= '9') )
			cin = cin - '0' + 52;
		else if( (cin >= 'A') && (cin <= 'Z') )
			cin = cin - 'A';
		else if( (cin >= 'a') && (cin <= 'z') )
			cin = cin - 'a' + 26;
		else if( cin == '+' )
			cin = 62;
		else if( cin == '/' )
			cin = 63;
		else if( cin == '=' )
			cin = 0;
		else
			continue;

		cout = (cout << 6) | cin;

		if( (i % 4) == 3 )
		{
			if( (len + 3) < blen )
			{
				buf[len++] = (char)(cout >> 16);
				buf[len++] = (char)(cout >> 8);
				buf[len++] = (char)(cout);
			}
			else
			{
				break;
			}
		}
	}

	buf[len++] = 0;
	return len;
}


struct path_info * uh_path_lookup(struct client *cl, const char *url)
{
	static char path_phys[PATH_MAX];
	static char path_info[PATH_MAX];
	static struct path_info p;

	char buffer[UH_LIMIT_MSGHEAD];
	char *docroot = cl->server->conf->docroot;
	char *pathptr = NULL;

	int i = 0;
	struct stat s;


	memset(path_phys, 0, sizeof(path_phys));
	memset(path_info, 0, sizeof(path_info));
	memset(buffer, 0, sizeof(buffer));
	memset(&p, 0, sizeof(p));

	/* copy docroot */
	memcpy(buffer, docroot,
		min(strlen(docroot), sizeof(buffer) - 1));

	/* separate query string from url */
	if( (pathptr = strchr(url, '?')) != NULL )
	{
		p.query = pathptr[1] ? pathptr + 1 : NULL;

		/* urldecode component w/o query */
		if( pathptr > url )
			uh_urldecode(
				&buffer[strlen(docroot)],
				sizeof(buffer) - strlen(docroot) - 1,
				url, (int)(pathptr - url) - 1
			);
	}

	/* no query string, decode all of url */
	else
	{
		uh_urldecode(
			&buffer[strlen(docroot)],
			sizeof(buffer) - strlen(docroot) - 1,
			url, strlen(url)
		);
	}

	/* create canon path */
	for( i = strlen(buffer); i >= 0; i-- )
	{
		if( (buffer[i] == 0) || (buffer[i] == '/') )
		{
			memset(path_info, 0, sizeof(path_info));
			memcpy(path_info, buffer, min(i + 1, sizeof(path_info) - 1));

			if( realpath(path_info, path_phys) )
			{
				memset(path_info, 0, sizeof(path_info));
				memcpy(path_info, &buffer[i],
					min(strlen(buffer) - i, sizeof(path_info) - 1));

				break;
			}
		}
	}

	/* check whether found path is within docroot */
	if( strncmp(path_phys, docroot, strlen(docroot)) ||
	    ((path_phys[strlen(docroot)] != 0) &&
		 (path_phys[strlen(docroot)] != '/'))
	) {
		return NULL;
	}

	/* test current path */
	if( ! stat(path_phys, &p.stat) )
	{
		/* is a regular file */
		if( p.stat.st_mode & S_IFREG )
		{
			p.root = docroot;
			p.phys = path_phys;
			p.name = &path_phys[strlen(docroot)];
			p.info = path_info[0] ? path_info : NULL;
		}

		/* is a directory */
		else if( (p.stat.st_mode & S_IFDIR) && !strlen(path_info) )
		{
			/* ensure trailing slash */
			if( path_phys[strlen(path_phys)-1] != '/' )
				path_phys[strlen(path_phys)] = '/';

			/* try to locate index file */
			memset(buffer, 0, sizeof(buffer));
			memcpy(buffer, path_phys, sizeof(buffer));
			pathptr = &buffer[strlen(buffer)];

			for( i = 0; i < array_size(uh_index_files); i++ )
			{
				strncat(buffer, uh_index_files[i], sizeof(buffer));

				if( !stat(buffer, &s) && (s.st_mode & S_IFREG) )
				{
					memcpy(path_phys, buffer, sizeof(path_phys));
					memcpy(&p.stat, &s, sizeof(p.stat));
					break;
				}

				*pathptr = 0;
			}

			p.root = docroot;
			p.phys = path_phys;
			p.name = &path_phys[strlen(docroot)];
		}
	}

	return p.phys ? &p : NULL;
}


static char uh_realms[UH_LIMIT_AUTHREALMS * sizeof(struct auth_realm)] = { 0 };
static int uh_realm_count = 0;

struct auth_realm * uh_auth_add(char *path, char *user, char *pass)
{
	struct auth_realm *new = NULL;
	struct passwd *pwd;
	struct spwd *spwd;

	if( uh_realm_count < UH_LIMIT_AUTHREALMS )
	{
		new = (struct auth_realm *)
			&uh_realms[uh_realm_count * sizeof(struct auth_realm)];

		memset(new, 0, sizeof(struct auth_realm));

		memcpy(new->path, path,
			min(strlen(path), sizeof(new->path) - 1));

		memcpy(new->user, user,
			min(strlen(user), sizeof(new->user) - 1));

		/* given password refers to a passwd entry */
		if( (strlen(pass) > 3) && !strncmp(pass, "$p$", 3) )
		{
			/* try to resolve shadow entry */
			if( ((spwd = getspnam(&pass[3])) != NULL) && spwd->sp_pwdp )
			{
				memcpy(new->pass, spwd->sp_pwdp,
					min(strlen(spwd->sp_pwdp), sizeof(new->pass) - 1));
			}

			/* try to resolve passwd entry */
			else if( ((pwd = getpwnam(&pass[3])) != NULL) && pwd->pw_passwd &&
				(pwd->pw_passwd[0] != '!') && (pwd->pw_passwd[0] != 0)
			) {
				memcpy(new->pass, pwd->pw_passwd,
					min(strlen(pwd->pw_passwd), sizeof(new->pass) - 1));
			}			
		}

		/* ordinary pwd */
		else
		{
			memcpy(new->pass, pass,
				min(strlen(pass), sizeof(new->pass) - 1));
		}

		uh_realm_count++;
	}

	return new;
}

int uh_auth_check(
	struct client *cl, struct http_request *req, struct path_info *pi
) {
	int i, plen, rlen, protected;
	char buffer[UH_LIMIT_MSGHEAD];
	char *user = NULL;
	char *pass = NULL;

	struct auth_realm *realm = NULL;

	plen = strlen(pi->name);
	protected = 0;

	/* check whether at least one realm covers the requested url */
	for( i = 0; i < uh_realm_count; i++ )
	{
		realm = (struct auth_realm *)
			&uh_realms[i * sizeof(struct auth_realm)];

		rlen = strlen(realm->path);

		if( (plen >= rlen) && !strncasecmp(pi->name, realm->path, rlen) )
		{
			req->realm = realm;
			protected = 1;
			break;
		}
	}

	/* requested resource is covered by a realm */
	if( protected )
	{
		/* try to get client auth info */
		foreach_header(i, req->headers)
		{
			if( !strcasecmp(req->headers[i], "Authorization") &&
				(strlen(req->headers[i+1]) > 6) &&
				!strncasecmp(req->headers[i+1], "Basic ", 6)
			) {
				memset(buffer, 0, sizeof(buffer));
				uh_b64decode(buffer, sizeof(buffer) - 1,
					(unsigned char *) &req->headers[i+1][6],
					strlen(req->headers[i+1]) - 6);

				if( (pass = strchr(buffer, ':')) != NULL )
				{
					user = buffer;
					*pass++ = 0;
				}

				break;
			}
		}

		/* have client auth */
		if( user && pass )
		{
			/* find matching realm */
			for( i = 0, realm = NULL; i < uh_realm_count; i++ )
			{
				realm = (struct auth_realm *)
					&uh_realms[i * sizeof(struct auth_realm)];

				rlen = strlen(realm->path);

				if( (plen >= rlen) &&
				    !strncasecmp(pi->name, realm->path, rlen) &&
				    !strcmp(user, realm->user)
				) {
					req->realm = realm;
					break;
				}

				realm = NULL;
			}

			/* found a realm matching the username */
			if( realm )
			{
				/* is a crypt passwd */
				if( realm->pass[0] == '$' )
					pass = crypt(pass, realm->pass);

				/* check user pass */
				if( !strcmp(pass, realm->pass) )
					return 1;
			}
		}

		/* 401 */
		uh_http_sendf(cl, NULL,
			"HTTP/%.1f 401 Authorization Required\r\n"
			"WWW-Authenticate: Basic realm=\"%s\"\r\n"
			"Content-Type: text/plain\r\n"
			"Content-Length: 23\r\n\r\n"
			"Authorization Required\n",
				req->version, cl->server->conf->realm
		);

		return 0;
	}

	return 1;
}


static char uh_listeners[UH_LIMIT_LISTENERS * sizeof(struct listener)] = { 0 };
static char uh_clients[UH_LIMIT_CLIENTS * sizeof(struct client)] = { 0 };

static int uh_listener_count = 0;
static int uh_client_count = 0;


struct listener * uh_listener_add(int sock, struct config *conf)
{
	struct listener *new = NULL;
	socklen_t sl;

	if( uh_listener_count < UH_LIMIT_LISTENERS )
	{
		new = (struct listener *)
			&uh_listeners[uh_listener_count * sizeof(struct listener)];

		new->socket = sock;
		new->conf   = conf;

		/* get local endpoint addr */
		sl = sizeof(struct sockaddr_in6);
		memset(&(new->addr), 0, sl);
		getsockname(sock, (struct sockaddr *) &(new->addr), &sl);

		uh_listener_count++;
	}

	return new;
}

struct listener * uh_listener_lookup(int sock)
{
	struct listener *cur = NULL;
	int i;

	for( i = 0; i < uh_listener_count; i++ )
	{
		cur = (struct listener *) &uh_listeners[i * sizeof(struct listener)];

		if( cur->socket == sock )
			return cur;
	}

	return NULL;
}


struct client * uh_client_add(int sock, struct listener *serv)
{
	struct client *new = NULL;
	socklen_t sl;

	if( uh_client_count < UH_LIMIT_CLIENTS )
	{
		new = (struct client *)
			&uh_clients[uh_client_count * sizeof(struct client)];

		new->socket = sock;
		new->server = serv;

		/* get remote endpoint addr */
		sl = sizeof(struct sockaddr_in6);
		memset(&(new->peeraddr), 0, sl);
		getpeername(sock, (struct sockaddr *) &(new->peeraddr), &sl);

		/* get local endpoint addr */
		sl = sizeof(struct sockaddr_in6);
		memset(&(new->servaddr), 0, sl);
		getsockname(sock, (struct sockaddr *) &(new->servaddr), &sl);

		uh_client_count++;
	}

	return new;
}

struct client * uh_client_lookup(int sock)
{
	struct client *cur = NULL;
	int i;

	for( i = 0; i < uh_client_count; i++ )
	{
		cur = (struct client *) &uh_clients[i * sizeof(struct client)];

		if( cur->socket == sock )
			return cur;
	}

	return NULL;
}

void uh_client_remove(int sock)
{
	struct client *del = uh_client_lookup(sock);

	if( del )
	{
		memmove(del, del + 1,
			sizeof(uh_clients) - (int)((char *)del - uh_clients) - sizeof(struct client));

		uh_client_count--;
	}
}