Add first working version

2 files changed, 396 insertions, 0 deletions

diff --git a/imbox.1 b/imbox.1
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+++ b/imbox.1
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+.Dd December 20, 2019
+.Dt IMBOX 1
+.Os
+.
+.Sh NAME
+.Nm imbox
+.Nd IMAP to mboxrd
+.
+.Sh SYNOPSIS
+.Nm
+.Op Fl vw
+.Op Fl h Ar host
+.Op Fl m Ar mailbox
+.Op Fl p Ar port
+.Op Fl s Ar search
+.Ar user
+.
+.Sh DESCRIPTION
+The
+.Nm
+utility exports messages from an IMAP mailbox
+to the mboxrd format on standard output.
+IMAP login is performed as
+.Ar user
+with a password read from
+.Pa /dev/tty ,
+or standard input if
+.Fl w
+is used.
+.
+.Pp
+The arguments are as follows:
+.Bl -tag -width Ds
+.It Fl h Ar host
+Connect to
+.Ar host .
+The default host is
+.Li imap.fastmail.com .
+TLS without STARTTLS is assumed.
+.
+.It Fl m Ar mailbox
+Export messages from
+.Ar mailbox .
+The default mailbox is INBOX.
+.
+.It Fl p Ar port
+Connect to
+.Ar port .
+The default port is 993.
+.
+.It Fl s Ar search
+Export messages matching
+.Ar search .
+The default search is
+.Ql SUBJECT \(dq[PATCH\(dq .
+.
+.It Fl v
+Log IMAP protocol to standard error.
+.
+.It Fl w
+Read the IMAP password from standard input.
+.El
+.
+.Sh EXAMPLES
+.Bd -literal
+imbox june@causal.agency | git am
+.Ed
+.
+.Sh STANDARDS
+.Bl -item
+.It
+.Rs
+.%A M. Crispin
+.%Q University of Washington
+.%T INTERNET MESSAGE ACCESS PROTOCOL - VERSION 4rev1
+.%I IETF
+.%N RFC 3501
+.%D March 2003
+.%U https://tools.ietf.org/html/rfc3501
+.Re
+.It
+.Rs
+.%A E. Hall
+.%T The application/mbox Media Type
+.%I IETF
+.%N RFC 4155
+.%D September 2005
+.%U https://tools.ietf.org/html/rfc4155
+.Re
+.El
diff --git a/imbox.c b/imbox.c
new file mode 100644
index 0000000..9f46983
--- /dev/null
+++ b/imbox.c
@@ -0,0 +1,306 @@
+/* Copyright (C) 2019  C. McEnroe <june@causal.agency>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <ctype.h>
+#include <err.h>
+#include <readpassphrase.h>
+#include <regex.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sysexits.h>
+#include <tls.h>
+#include <unistd.h>
+
+#define ARRAY_LEN(a) (sizeof(a) / sizeof((a)[0]))
+
+static void compile(regex_t *regex, const char *pattern) {
+	if (regex->re_nsub) return;
+	int error = regcomp(regex, pattern, REG_EXTENDED | REG_NEWLINE);
+	if (!error) return;
+	char buf[256];
+	regerror(error, regex, buf, sizeof(buf));
+	errx(EX_SOFTWARE, "regcomp: %s: %s", buf, pattern);
+}
+
+static void mboxrd(const char *headers, const char *body) {
+	static regex_t fromRegex;
+	compile(&fromRegex, "^From: .*<([^>]+)>");
+
+	regmatch_t from[2];
+	int error = regexec(&fromRegex, headers, 2, from, 0);
+	if (error) errx(EX_DATAERR, "missing From header");
+	printf(
+		"From %.*s ",
+		(int)(from[1].rm_eo - from[1].rm_so), &headers[from[1].rm_so]
+	);
+
+	static regex_t dateRegex;
+	compile(&dateRegex, "^Date: (...), (..) (...) (....) (.{8})");
+
+	regmatch_t date[6];
+	error = regexec(&dateRegex, headers, 6, date, 0);
+	if (error) errx(EX_DATAERR, "missing Date header");
+	printf(
+		"%.*s %.*s %.*s %.*s %.*s\r\n",
+		(int)(date[1].rm_eo - date[1].rm_so), &headers[date[1].rm_so],
+		(int)(date[3].rm_eo - date[3].rm_so), &headers[date[3].rm_so],
+		(int)(date[2].rm_eo - date[2].rm_so), &headers[date[2].rm_so],
+		(int)(date[5].rm_eo - date[5].rm_so), &headers[date[5].rm_so],
+		(int)(date[4].rm_eo - date[4].rm_so), &headers[date[4].rm_so]
+	);
+
+	printf("%s", headers);
+	// FIXME: There seems to sometimes be some garbage data at the end of the
+	// headers?
+
+	static regex_t quoteRegex;
+	compile(&quoteRegex, "^>*From ");
+	regmatch_t match = {0};
+	for (const char *ptr = body;; ptr += match.rm_eo) {
+		regmatch_t match;
+		error = regexec(
+			&quoteRegex, body, 1, &match, (ptr > body ? REG_NOTBOL : 0)
+		);
+		if (error) {
+			printf("%s", ptr);
+			break;
+		}
+		printf(
+			"%.*s>%.*s",
+			(int)match.rm_so, ptr,
+			(int)(match.rm_eo - match.rm_so), &ptr[match.rm_so]
+		);
+	}
+
+	// FIXME: mbox technically shouldn't use \r\n but everything else does...
+	printf("\r\n");
+}
+
+static bool verbose;
+
+int tlsRead(void *_tls, char *ptr, int len) {
+	struct tls *tls = _tls;
+	ssize_t ret;
+	do {
+		ret = tls_read(tls, ptr, len);
+	} while (ret == TLS_WANT_POLLIN || ret == TLS_WANT_POLLOUT);
+	if (ret < 0) errx(EX_IOERR, "tls_read: %s", tls_error(tls));
+	if (verbose) fprintf(stderr, "%.*s", (int)ret, ptr);
+	return ret;
+}
+
+int tlsWrite(void *_tls, const char *ptr, int len) {
+	struct tls *tls = _tls;
+	ssize_t ret;
+	do {
+		ret = tls_write(tls, ptr, len);
+	} while (ret == TLS_WANT_POLLIN || ret == TLS_WANT_POLLOUT);
+	if (ret < 0) errx(EX_IOERR, "tls_write: %s", tls_error(tls));
+	if (verbose) fprintf(stderr, "%.*s", (int)ret, ptr);
+	return ret;
+}
+
+int tlsClose(void *_tls) {
+	struct tls *tls = _tls;
+	int error = tls_close(tls);
+	if (error) errx(EX_IOERR, "tls_close: %s", tls_error(tls));
+	return error;
+}
+
+#define ENUM_ATOM \
+	X(Unknown, "") \
+	X(Untagged, "*") \
+	X(Ok, "OK") \
+	X(No, "NO") \
+	X(Bad, "BAD") \
+	X(Bye, "BYE") \
+	X(Login, "LOGIN") \
+	X(Select, "SELECT") \
+	X(Search, "SEARCH") \
+	X(Fetch, "FETCH")
+
+enum Atom {
+#define X(id, _) id,
+	ENUM_ATOM
+#undef X
+};
+
+static const char *Atoms[] = {
+#define X(id, str) [id] = str,
+	ENUM_ATOM
+#undef X
+};
+
+static enum Atom atom(const char *str) {
+	if (!str) return Unknown;
+	for (size_t i = 0; i < ARRAY_LEN(Atoms); ++i) {
+		if (!strcmp(str, Atoms[i])) return i;
+	}
+	return Unknown;
+}
+
+static char *readLiteral(FILE *imap, const char *line) {
+	char *prefix = strrchr(line, '{');
+	if (!prefix) errx(EX_PROTOCOL, "no literal prefix");
+
+	size_t size = strtoul(prefix + 1, NULL, 10);
+	if (!size) errx(EX_PROTOCOL, "invalid literal size");
+
+	char *literal = malloc(size);
+	if (!literal) err(EX_OSERR, "malloc");
+
+	size_t count = fread(literal, size, 1, imap);
+	if (!count) errx(EX_PROTOCOL, "could not read literal");
+
+	return literal;
+}
+
+int main(int argc, char *argv[]) {
+	const char *host = "imap.fastmail.com";
+	const char *port = "993";
+	const char *mailbox = "INBOX";
+	const char *search = "SUBJECT \"[PATCH\"";
+	int rppFlags = 0;
+
+	int opt;
+	while (0 < (opt = getopt(argc, argv, "h:m:p:s:vw"))) {
+		switch (opt) {
+			break; case 'h': host = optarg;
+			break; case 'm': mailbox = optarg;
+			break; case 'p': port = optarg;
+			break; case 's': search = optarg;
+			break; case 'v': verbose = true;
+			break; case 'w': rppFlags |= RPP_STDIN;
+			break; default:  return EX_USAGE;
+		}
+	}
+
+	const char *user = argv[optind];
+	if (!user) errx(EX_USAGE, "username required");
+
+	char buf[1024];
+	char *pass = readpassphrase(
+		(rppFlags & RPP_STDIN ? "" : "Password: "),
+		buf, sizeof(buf), rppFlags
+	);
+	if (!pass) err(EX_UNAVAILABLE, "readpassphrase");
+
+	struct tls *client = tls_client();
+	if (!client) errx(EX_SOFTWARE, "tls_client");
+
+	struct tls_config *config = tls_config_new();
+	if (!config) errx(EX_SOFTWARE, "tls_config_new");
+
+	int error = tls_configure(client, config);
+	if (error) errx(EX_SOFTWARE, "tls_configure: %s", tls_error(client));
+	tls_config_free(config);
+
+	error = tls_connect(client, host, port);
+	if (error) errx(EX_NOHOST, "tls_connect: %s", tls_error(client));
+
+	FILE *imap = funopen(client, tlsRead, tlsWrite, NULL, tlsClose);
+	if (!imap) err(EX_SOFTWARE, "funopen");
+
+	bool login = false;
+	char *uids = NULL;
+
+	char *line = NULL;
+	size_t cap = 0;
+	while (0 < getline(&line, &cap, imap)) {
+		if (strchr(line, '\r')) *strchr(line, '\r') = '\0';
+
+		char *rest = line;
+		enum Atom tag = atom(strsep(&rest, " "));
+		if (rest && isdigit(rest[0])) strsep(&rest, " ");
+		enum Atom resp = atom(strsep(&rest, " "));
+
+		if (resp == No || resp == Bad) {
+			errx(
+				EX_CONFIG, "%s: %s %s",
+				Atoms[tag], Atoms[resp], (rest ? rest : "")
+			);
+		} else if (resp == Bye) {
+			errx(EX_UNAVAILABLE, "unexpected BYE: %s", (rest ? rest : ""));
+		}
+
+		switch (tag) {
+			break; case Untagged: {
+				if (login) break;
+				fprintf(imap, "%s LOGIN %s %s\r\n", Atoms[Login], user, pass);
+				login = true;
+			}
+			break; case Login: {
+				fprintf(imap, "%s SELECT %s\r\n", Atoms[Select], mailbox);
+			}
+			break; case Select: {
+				fprintf(
+					imap, "%s UID SEARCH CHARSET UTF-8 %s\r\n",
+					Atoms[Search], search
+				);
+			}
+			break; case Search: {
+				if (!uids) errx(EX_PROTOCOL, "no search response");
+				for (char *ch = uids; *ch; ++ch) {
+					if (*ch == ' ') *ch = ',';
+				}
+				// FIXME: Grab Content-Encoding as well?
+				fprintf(
+					imap,
+					"%s UID FETCH %s ("
+					"BODY[HEADER.FIELDS (Date From Subject Message-Id)] "
+					"BODY[TEXT]"
+					")\r\n",
+					Atoms[Fetch], uids
+				);
+			}
+			break; case Fetch: {
+				fprintf(imap, "ayy LOGOUT\r\n");
+				fclose(imap);
+				return EX_OK;
+			}
+			break; default:;
+		}
+
+		switch (resp) {
+			break; case Search: {
+				if (!rest) errx(EX_TEMPFAIL, "no messages match");
+				uids = strdup(rest);
+				if (!uids) err(EX_OSERR, "strdup");
+			}
+			break; case Fetch: {
+				char *headers = readLiteral(imap, rest);
+
+				ssize_t len = getline(&line, &cap, imap);
+				if (len <= 0) errx(EX_PROTOCOL, "unexpected eof");
+
+				char *body = readLiteral(imap, line);
+
+				len = getline(&line, &cap, imap);
+				if (len <= 0) errx(EX_PROTOCOL, "unexpected eof");
+				if (strcmp(line, ")\r\n")) {
+					errx(EX_PROTOCOL, "trailing fetch data");
+				}
+
+				mboxrd(headers, body);
+				free(headers);
+				free(body);
+			}
+			break; default:;
+		}
+	}
+}