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Lorenzo Torres 2024-08-19 22:49:04 +02:00
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config.h
**/*.swp
**/*~
**/*.o
**/*.core
sis

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Copyright (c) 2024, Lorenzo Torres
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
3. Neither the name of the <organization> nor the
names of its contributors may be used to endorse or promote products
derived from this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY <COPYRIGHT HOLDER> ''AS IS'' AND ANY
EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

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# sis - simple imap server
# See LICENSE file for copyright and license details.
include config.mk
SRC = sis.c imap.c
HDR = config.def.h
OBJ = ${SRC:.c=.o}
all: options sis
options:
@echo sis build options:
@echo "CFLAGS = ${CFLAGS}"
@echo "LDFLAGS = ${LDFLAGS}"
@echo "CC = ${CC}"
.c.o:
${CC} -c ${CFLAGS} $<
${OBJ}: config.h config.mk
config.h:
cp config.def.h $@
sis: ${OBJ}
${CC} -o $@ ${OBJ} ${LDFLAGS}
clean:
rm -f sis ${OBJ} sis-${VERSION}.tar.gz
dist: clean
mkdir -p sis-${VERSION}
cp -R LICENSE Makefile README config.mk\
sis.1 ${HDR} ${SRC} sis-${VERSION}
tar -cf sis-${VERSION}.tar sis-${VERSION}
gzip sis-${VERSION}.tar
rm -rf sis-${VERSION}
install: all
mkdir -p ${DESTDIR}${PREFIX}/bin
cp -f sis ${DESTDIR}${PREFIX}/bin
chmod 755 ${DESTDIR}${PREFIX}/bin/sis
mkdir -p ${DESTDIR}${MANPREFIX}/man1
sed "s/VERSION/${VERSION}/g" < sis.1 > ${DESTDIR}${MANPREFIX}/man1/sis.1
chmod 644 ${DESTDIR}${MANPREFIX}/man1/sis.1
uninstall:
rm -f ${DESTDIR}${PREFIX}/bin/dwm\
${DESTDIR}${MANPREFIX}/man1/dwm.1
.PHONY: all options clean dist install uninstall

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sis - simple imap server
============================
sis is an IMAP server, following the unix philosophy,
trying to be as small as possible while providing
a reliable service.
Requirements
------------
In order to build sis you need... a computer
Installation
------------
Edit config.mk to match your local setup (sis is installed into
the /usr/local namespace by default).
Afterwards enter the following command to build and install sis (if
necessary as root):
make clean install
Running sis
-----------
By default, sis runs in daemon mode, if you want to avoid detaching use the -d option
sis -d
Configuration
-------------
The configuration of sis is done by creating a custom config.h
and (re)compiling the source code.

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/* See LICENSE file for copyright and license details. */
/* network */
#define IMAP_PORT 143
#define IMAPS_PORT 993
/*-
* Maximum number of connected clients,
* NOTE: each one of these is a currently
* connected client! Unless your server
* has to manage a lot of accounts you
* should be good with the default value.
*/
#define MAX_CLIENTS 30
/*-
* Maximum size for the command buffer.
* IMAP sends plain text commands, so
* the default value can receive up to
* 8000 characters long commands.
* It should be enough but feel free to
* modify this.
*/
#define CMD_MAX_SIZE 8000

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# sis version
VERSION = 0.1
# Customize below to fit your system
# paths
PREFIX = /usr
MANPREFIX = ${PREFIX}/share/man
# OpenBSD (uncomment)
#MANPREFIX = ${PREFIX}/man
# includes and libs
INCS = -I.
LIBS =
# flags
CPPFLAGS = -DVERSION=\"${VERSION}\"
CFLAGS = -g -std=c99 -pedantic -Wall -O0 ${INCS} ${CPPFLAGS}
#CFLAGS = -std=c99 -pedantic -Wall -Wno-deprecated-declarations -Os ${INCS} ${CPPFLAGS}
LDFLAGS = ${LIBS}
# Solaris
#CFLAGS = -fast ${INCS} -DVERSION=\"${VERSION}\"
#LDFLAGS = ${LIBS}
# compiler and linker
CC = cc

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/*-
* Copyright (c) 2024, Lorenzo Torres
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the <organization> nor the
* names of its contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED ''AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/select.h>
#include <syslog.h>
#include <errno.h>
#include <config.h>
#include <imap.h>
uint8_t imap_init(uint8_t daemon, imap_t *instance)
{
imap_t imap;
/* Create a new socket using IPv4 protocol */
if ((imap.socket = socket(PF_INET, SOCK_STREAM, 0)) < 0) {
perror("socker");
return 1;
}
bzero(&imap.addr, sizeof(struct sockaddr_in));
imap.addr.sin_family = AF_INET;
/* From config.h */
imap.addr.sin_port = htons(IMAP_PORT);
if (INADDR_ANY) {
imap.addr.sin_addr.s_addr = htonl(INADDR_ANY);
}
/* Bind the socket to the specified address */
if ((bind(imap.socket, (struct sockaddr *)&imap.addr, sizeof(imap.addr)) < 0)) {
perror("bind");
return 2;
}
/* If daemon mode is activated, detach */
if (daemon) {
switch (fork()) {
case -1:
perror("fork");
return 3;
break;
default:
close(imap.socket);
free(instance);
exit(0);
break;
case 0:
break;
}
}
memcpy(instance, &imap, sizeof(imap));
return 0;
}
int imap_get_max_fd(client_list *list, int master)
{
int max_fd = 0;
client_list *node = list;
while (node != NULL) {
if (max_fd < node->socket) {
max_fd = node->socket;
}
node = node->next;
}
return max_fd > master ? max_fd : master;
}
client_list *imap_add_client(client_list *list, int sock)
{
client_list *node = (client_list *) malloc(sizeof(client_list));
node->socket = sock;
node->next = list;
node->prev = NULL;
if (list != NULL) {
list->prev = node;
}
return node;
}
client_list *imap_remove_client(client_list *list, client_list *node)
{
if (node->next != NULL) {
node->next->prev = node->prev;
}
if (node->prev != NULL) {
node->prev->next = node->next;
}
close(node->socket);
if (node == list) {
return NULL;
}
return list;
}
client_list *imap_remove_sock(client_list *list, int sock)
{
client_list *node = list;
while (node != NULL && node->socket != sock) {
node = node->next;
}
if (node != NULL) {
imap_remove_client(list, node);
}
return node;
}
void imap_start(imap_t *instance)
{
int activity, max_fd, connection;
size_t bytes_read;
char buf[CMD_MAX_SIZE];
/* List of all the file descriptors (sockets) being used. */
fd_set fds;
instance->clients = NULL;
client_list *node = instance->clients;
client_list *tmp = instance->clients;
listen(instance->socket, BACKLOG);
syslog(LOG_INFO, "Listening on %d.", IMAP_PORT);
for (;;) {
FD_ZERO(&fds);
FD_SET(instance->socket, &fds);
node = instance->clients;
while (node != NULL) {
FD_SET(node->socket, &fds);
node = node->next;
}
max_fd = imap_get_max_fd(instance->clients, instance->socket);
activity = select(max_fd + 1, &fds, NULL, NULL, NULL);
if ((activity < 0) && (errno!=EINTR)) {
perror("select");
}
/* New connection. */
if (FD_ISSET(instance->socket, &fds)) {
if ((connection = accept(instance->socket, NULL, NULL)) < 0) {
perror("accept");
syslog(LOG_ERR, "Connection failed.");
imap_close(instance);
exit(EXIT_FAILURE);
}
instance->clients = imap_add_client(instance->clients, connection);
syslog(LOG_INFO, "Connection enstablished.");
FD_SET(connection, &fds);
}
node = instance->clients;
tmp = node;
while (node != NULL) {
connection = node->socket;
tmp = node->next;
if (FD_ISSET(connection, &fds)) {
/* Error occured. */
if ((bytes_read = read(connection, buf, CMD_MAX_SIZE)) < 0) {
perror("recv");
instance->clients = imap_remove_client(instance->clients, node);
free(node);
FD_CLR(connection, &fds);
syslog(LOG_ERR, "Failed to receive data.");
/* Somebody disconnected */
} else if (bytes_read == 0) {
instance->clients = imap_remove_client(instance->clients, node);
free(node);
FD_CLR(connection, &fds);
syslog(LOG_INFO, "Connection closed.");
} else {
buf[bytes_read] = '\0';
}
}
node = tmp;
}
}
}
void imap_close(imap_t *instance)
{
client_list *node = instance->clients;
client_list *tmp = node;
while (node != NULL) {
close(node->socket);
tmp = node->next;
free(node);
node = tmp;
}
close(instance->socket);
free(instance);
}

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/*-
* Copyright (c) 2024, Lorenzo Torres
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the <organization> nor the
* names of its contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED ''AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef IMAP_H
#define IMAP_H
#include <stdint.h>
#include <stddef.h>
#include <netinet/in.h>
#define BACKLOG 4
typedef struct _client_list {
int32_t socket;
struct _client_list *next;
struct _client_list *prev;
} client_list;
typedef struct imap {
int32_t socket;
client_list *clients;
struct sockaddr_in addr;
} imap_t;
/* Create a new imap_t instance and initialize the server. */
uint8_t imap_init(uint8_t daemon, imap_t *instance);
/* Start the IMAP server. */
void imap_start(imap_t *instance);
/* Close all connections and free the allocated memory. */
void imap_close(imap_t *instance);
/* Add client to client list */
client_list *imap_add_client(client_list *list, int sock);
/* Close connection with client */
client_list *imap_remove_client(client_list *list, client_list *node);
client_list *imap_remove_sock(client_list *list, int sock);
/* Get the higher file descriptor in the client list */
int imap_get_max_fd(client_list *list, int master);
#endif /* ifndef IMAP_H */

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/*-
* Copyright (c) 2024, Lorenzo Torres
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the <organization> nor the
* names of its contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED ''AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <signal.h>
#include <syslog.h>
#include <imap.h>
static imap_t *instance;
void int_handler(int sig)
{
if (instance != NULL) {
imap_close(instance);
}
}
int main(void)
{
signal(SIGINT, int_handler);
openlog("sis", LOG_PID, LOG_MAIL);
syslog(LOG_INFO, "Starting sis %s.", VERSION);
int status = 0;
instance = (imap_t *) malloc(sizeof(imap_t));
if ((status = imap_init(0, instance)) != 0) {
perror("imap_init");
goto ret;
}
imap_start(instance);
ret:
if (instance != NULL) {
imap_close(instance);
}
closelog();
return status;
}