first commit

.gitignore

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+*.core
+*.o
+posta
+config.h

COPYING

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+BSD 3-Clause License
+
+Copyright (c) 2023, 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:
+
+* Redistributions of source code must retain the above copyright notice, this
+  list of conditions and the following disclaimer.
+
+* 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.
+
+* Neither the name of the copyright holder 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 THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 THE COPYRIGHT HOLDER OR CONTRIBUTORS 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.

Makefile

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

config.def.h

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+#ifndef CONFIG_H
+#define CONFIG_H
+
+
+#endif

config.mk

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+# posta version
+VERSION = 1.0
+
+# Customize below to fit your system
+
+# paths
+PREFIX = /usr
+MANPREFIX = ${PREFIX}/share/man
+
+# OpenBSD (uncomment)
+MANPREFIX = ${PREFIX}/man
+
+# includes and libs
+INCS =
+LIBS = -lssl -lcrypto
+
+# flags
+CPPFLAGS = -g -D_DEFAULT_SOURCE -D_BSD_SOURCE -D_XOPEN_SOURCE=700L -DVERSION=\"${VERSION}\" ${XINERAMAFLAGS}
+#CFLAGS   = -g -std=c99 -pedantic -Wall -O0 ${INCS} ${CPPFLAGS}
+CFLAGS   = -g -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

imap.c

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+#include "imap.h"
+#include "utils.h"
+#include <stdlib.h>
+#include <sys/socket.h>
+#include <arpa/inet.h>
+#include <stdio.h>
+#include <netdb.h>
+#include <string.h>
+#include <unistd.h>
+#include <openssl/err.h>
+
+imap_t *imap_connect(const char *addr, const char *port)
+{
+	int sock;
+	char *res;
+	FILE *sockfile;
+	imap_t *state;
+	struct addrinfo* address = NULL;
+
+    getaddrinfo(addr, port, 0, &address);
+	struct sockaddr_in *p = (struct sockaddr_in *)address->ai_addr;
+
+	if ((sock = create_connection(p)) == -1)
+		return NULL;
+
+	if ((sockfile = fdopen(sock, "r")) == NULL)
+		return NULL;
+
+	state = (imap_t *) malloc(sizeof(imap_t));
+	state->sock = sock;
+	state->sockfile = sockfile;
+
+	if (strcmp(port, "993") == 0) {
+		state->tls = 1;
+		imap_starttls(state);
+	} else {
+		state->tls = 0;
+	}
+	
+	res = imap_response(state);
+
+	if (res[2] != 'O' || res[3] != 'K')
+		return NULL;
+
+	free(res);
+
+	return state;
+}
+
+void imap_close(imap_t *state)
+{
+	close_connection(state->sock);
+	fclose(state->sockfile);
+
+	free(state);
+}
+
+char *imap_response(imap_t *state)
+{
+	size_t len;
+	char *res;
+	char c;
+	int i;
+
+	len = 15;
+	res = (char *) calloc(len, sizeof(char));
+ 	
+	i = 0;
+
+	if (!state->tls) {
+		c = fgetc(state->sockfile);
+	} else {
+		SSL_read(state->ssl, &c, 1);	
+	}
+
+	while (c != '\n') {
+		res[i] = c;
+		i++;
+
+		if (i > len) {
+			len = i+5;
+			res = (char *) reallocarray(res, len, sizeof(char));
+		}
+		if (!state->tls) {
+			c = fgetc(state->sockfile);
+		} else {
+			SSL_read(state->ssl, &c, 1);	
+		}
+	}
+
+	if (i < len)
+		res = (char *) reallocarray(res, i+1, sizeof(char));
+
+	res[i] = '\0';
+
+	return res;
+}
+
+int imap_send(imap_t *state, char *cmd)
+{
+	if (!state->tls) {
+		return send(state->sock, (const void *)cmd, strlen(cmd), 0);
+	} else {
+		return SSL_write(state->ssl, (const void *)cmd, strlen(cmd)) > 0;
+	}
+}
+
+int imap_capability(imap_t *state)
+{
+	state->capabilities = 0;
+	char *cmd, *res, *token;
+
+	cmd = "A0 CAPABILITY\n";
+	imap_send(state, cmd);	
+	res = imap_response(state);
+	token = get_token(res);
+
+	if (!imap_match_token(token, "*"))
+		return -1;	
+
+	token = get_token(NULL);
+
+	if (!imap_match_token(token, TOK_CAPABILITY))
+		return -1;	
+
+	while ((token = get_token(NULL)) != NULL) {
+		if (imap_match_token(token, TOK_IMAP4))
+			state->capabilities |= IMAP4;
+		else if (imap_match_token(token, TOK_STARTTLS))
+			state->capabilities |= STARTTLS;
+	}
+
+	free(res);
+	res = imap_response(state);
+	free(res);
+
+	return 0;
+}
+
+int imap_match_token(char *t1, const char *t2)
+{
+	return strcmp(t1, t2) == 0;
+}
+
+int imap_starttls(imap_t* state)
+{
+	if (!state->tls) {
+		char *cmd, *res, *token;
+
+		cmd = "A1 STARTTLS\n";
+		imap_send(state, cmd);	
+		res = imap_response(state);
+		token = get_token(res);
+
+		if (!imap_match_token(token, "A1"))
+			return 1;	
+
+		token = get_token(NULL);
+
+		if (!imap_match_token(token, "OK"))
+			return 2;
+
+	}
+
+	state->ssl_ctx = SSL_CTX_new(TLSv1_2_client_method());
+	state->ssl = SSL_new(state->ssl_ctx);
+	SSL_set_fd(state->ssl, state->sock);
+	if (SSL_connect(state->ssl) == 0) {
+		return -1;
+	}
+
+	state->tls = 1;
+
+	return 0;
+}
+
+int imap_login(imap_t* state, char *username, char *password)
+{
+	char *cmd, *res, *token;
+
+	size_t datalen = strlen(username) + strlen(password) + 12;
+	cmd = calloc(datalen, sizeof(char));
+	snprintf(cmd, datalen, "A2 LOGIN %s %s\n", username, password);
+	imap_send(state, cmd);	
+	res = imap_response(state);
+	token = get_token(res);
+
+	if (!imap_match_token(token, "*"))
+		return -1;	
+
+	token = get_token(NULL);
+
+	if (!imap_match_token(token, TOK_CAPABILITY))
+		return -1;	
+
+	while ((token = get_token(NULL)) != NULL) {
+		if (imap_match_token(token, TOK_IMAP4))
+			state->capabilities |= IMAP4;
+		else if (imap_match_token(token, TOK_STARTTLS))
+			state->capabilities |= STARTTLS;
+	}
+
+	free(res);
+
+
+	res = imap_response(state);
+	token = get_token(res);
+
+	if (!imap_match_token(token, "A2"))
+		return 1;	
+
+	token = get_token(NULL);
+	
+	if (!imap_match_token(token, TOK_OK))
+		return 1;	
+
+	return 0;
+}

imap.h

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+#ifndef IMAP_H
+#define IMAP_H
+
+#include <stdio.h>
+#include <openssl/ssl.h>
+
+#define TOK_OK "OK"
+#define TOK_BAD "BAD"
+#define TOK_CAPABILITY "CAPABILITY"
+#define TOK_IMAP4 "IMAP4rev1"
+#define TOK_STARTTLS "STARTTLS"
+
+enum imap_caps {
+	IMAP4 = 1 << 0,
+	STARTTLS = 1 << 1,	
+};
+
+/* IMAP connection */
+typedef struct {
+	int sock;
+	int capabilities;
+	int tls;
+	FILE *sockfile;
+	SSL *ssl;
+	SSL_CTX *ssl_ctx;
+} imap_t;
+
+/* Connect to an IMAP server */
+imap_t *imap_connect(const char *addr, const char *port);
+
+/* Close the connection to the IMAP server, automatically free used memory */
+void imap_close(imap_t *state);
+
+/* Get the server response as a string */
+char *imap_response(imap_t *state);
+
+int imap_send(imap_t *state, char *cmd);
+
+/* Query for server capabilities */
+int imap_capability(imap_t *state);
+
+/* Check for token matching */
+int imap_match_token(char *t1, const char *t2);
+
+/* Init TLS connection */
+int imap_starttls(imap_t* state);
+
+/* Login to the IMAP server */
+int imap_login(imap_t* state, char *username, char *password);
+
+#endif

posta.c

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+#include <stdio.h>
+#include <stdlib.h>
+#include <openssl/ssl.h>
+#include "utils.h"
+#include "imap.h"
+
+int main(void)
+{
+	SSL_library_init();
+
+	imap_t *state = imap_connect("sagittarius-a.org", "993");
+
+	/*
+	if (imap_starttls(state) == 0) {
+		printf("TLS connection enstablished!\n");
+	} else {
+		printf("Can't enstablish TLS connection\n");
+		exit(-1);
+	}*/
+
+	if (imap_capability(state) != 0) {
+		printf("Can't get server capabilities!\n");
+		exit(-1);
+	}
+
+	if (state->capabilities & IMAP4) {
+		printf("IMAP4rev1 found\n");
+	}
+
+	if (imap_login(state, "", "") != 0) {
+		printf("Login failed!\n");
+	} else {
+		printf("Logged successfully!\n");
+	}
+
+	imap_close(state);
+
+	return 0;
+}

utils.c

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+#include "utils.h"
+#include <netinet/in.h>
+#include <sys/socket.h>
+#include <stdint.h>
+#include <unistd.h>
+#include <string.h>
+#include <stdio.h>
+#include <arpa/inet.h>
+
+int create_connection(struct sockaddr_in *endpoint)
+{
+	int fd, status;
+
+	if ((fd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
+		return -1;
+	}
+
+	if ((status = connect(fd, (struct sockaddr*)endpoint, sizeof(*endpoint))) < 0) {
+		printf("Failed to connect!\n");
+		return -1;
+	}
+
+	return fd;
+}
+
+void close_connection(int socket)
+{
+	close(socket);
+}
+
+char *get_token(char *s)
+{	
+	const char sep[4] = " ";
+	return strtok(s, sep);
+}

utils.h

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+#ifndef UTILS_H
+#define UTILS_H
+
+#include <netinet/in.h>
+#include <stdlib.h>
+#include <sys/socket.h>
+
+int create_connection(struct sockaddr_in *addr);
+void close_connection(int socket);
+
+char *get_token(char *s);
+
+#endif