src/lib-mail/message-address.c

/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */

#include "lib.h"
#include "str.h"
#include "strescape.h"
#include "smtp-address.h"
#include "message-parser.h"
#include "message-address.h"
#include "rfc822-parser.h"

struct message_address_parser_context {
    pool_t pool;
    struct rfc822_parser_context parser;

    struct message_address *first_addr, *last_addr, addr;
    string_t *str;

    bool fill_missing;
};

static void add_address(struct message_address_parser_context *ctx)
{
    struct message_address *addr;

    addr = p_new(ctx->pool, struct message_address, 1);

    memcpy(addr, &ctx->addr, sizeof(ctx->addr));
    i_zero(&ctx->addr);

    if (ctx->first_addr == NULL)
        ctx->first_addr = addr;
    else
        ctx->last_addr->next = addr;
    ctx->last_addr = addr;
}

/* quote with "" and escape all '\', '"' and "'" characters if need */
static void str_append_maybe_escape(string_t *dest, const char *cstr, bool escape_dot)
{
    const char *p;

    /* see if we need to quote it */
    for (p = cstr; *p != '\0'; p++) {
        if (!IS_ATEXT(*p) && (escape_dot || *p != '.'))
            break;
    }

    if (*p == '\0') {
        str_append_data(dest, cstr, (size_t) (p - cstr));
        return;
    }

    /* see if we need to escape it */
    for (p = cstr; *p != '\0'; p++) {
        if (IS_ESCAPED_CHAR(*p))
            break;
    }

    if (*p == '\0') {
        /* only quote */
        str_append_c(dest, '"');
        str_append_data(dest, cstr, (size_t) (p - cstr));
        str_append_c(dest, '"');
        return;
    }

    /* quote and escape */
    str_append_c(dest, '"');
    str_append_data(dest, cstr, (size_t) (p - cstr));

    for (; *p != '\0'; p++) {
        if (IS_ESCAPED_CHAR(*p))
            str_append_c(dest, '\\');
        str_append_c(dest, *p);
    }

    str_append_c(dest, '"');
}

static int parse_local_part(struct message_address_parser_context *ctx)
{
    int ret;

    /*
       local-part      = dot-atom / quoted-string / obs-local-part
       obs-local-part  = word *("." word)
    */
    i_assert(ctx->parser.data != ctx->parser.end);

    str_truncate(ctx->str, 0);
    if (*ctx->parser.data == '"')
        ret = rfc822_parse_quoted_string(&ctx->parser, ctx->str);
    else
        ret = rfc822_parse_dot_atom(&ctx->parser, ctx->str);
    if (ret < 0)
        return -1;

    ctx->addr.mailbox = p_strdup(ctx->pool, str_c(ctx->str));
    return ret;
}

static int parse_domain(struct message_address_parser_context *ctx)
{
    int ret;

    str_truncate(ctx->str, 0);
    if ((ret = rfc822_parse_domain(&ctx->parser, ctx->str)) < 0)
        return -1;

    ctx->addr.domain = p_strdup(ctx->pool, str_c(ctx->str));
    return ret;
}

static int parse_domain_list(struct message_address_parser_context *ctx)
{
    int ret;

    /* obs-domain-list = "@" domain *(*(CFWS / "," ) [CFWS] "@" domain) */
    str_truncate(ctx->str, 0);
    for (;;) {
        if (ctx->parser.data == ctx->parser.end)
            return 0;

        if (*ctx->parser.data != '@')
            break;

        if (str_len(ctx->str) > 0)
            str_append_c(ctx->str, ',');

        str_append_c(ctx->str, '@');
        if ((ret = rfc822_parse_domain(&ctx->parser, ctx->str)) <= 0)
            return ret;

        while (rfc822_skip_lwsp(&ctx->parser) > 0 &&
               *ctx->parser.data == ',')
            ctx->parser.data++;
    }
    ctx->addr.route = p_strdup(ctx->pool, str_c(ctx->str));
    return 1;
}

static int parse_angle_addr(struct message_address_parser_context *ctx)
{
    int ret;

    /* "<" [ "@" route ":" ] local-part "@" domain ">" */
    i_assert(*ctx->parser.data == '<');
    ctx->parser.data++;

    if ((ret = rfc822_skip_lwsp(&ctx->parser)) <= 0)
        return ret;

    if (*ctx->parser.data == '@') {
        if (parse_domain_list(ctx) <= 0 || *ctx->parser.data != ':') {
            if (ctx->fill_missing)
                ctx->addr.route = "INVALID_ROUTE";
            if (ctx->parser.data == ctx->parser.end)
                return -1;
            /* try to continue anyway */
        } else {
            ctx->parser.data++;
        }
        if ((ret = rfc822_skip_lwsp(&ctx->parser)) <= 0)
            return ret;
    }

    if (*ctx->parser.data == '>') {
        /* <> address isn't valid */
    } else {
        if ((ret = parse_local_part(ctx)) <= 0)
            return ret;
        if (*ctx->parser.data == '@') {
            if ((ret = parse_domain(ctx)) <= 0)
                return ret;
        }
    }

    if (*ctx->parser.data != '>')
        return -1;
    ctx->parser.data++;

    return rfc822_skip_lwsp(&ctx->parser);
}

static int parse_name_addr(struct message_address_parser_context *ctx)
{
    /*
       name-addr       = [display-name] angle-addr
       display-name    = phrase
    */
    str_truncate(ctx->str, 0);
    if (rfc822_parse_phrase(&ctx->parser, ctx->str) <= 0 ||
        *ctx->parser.data != '<')
        return -1;

    ctx->addr.name = p_strdup(ctx->pool, str_c(ctx->str));
    if (*ctx->addr.name == '\0') {
        /* Cope with "<address>" without display name */
        ctx->addr.name = NULL;
    }
    if (parse_angle_addr(ctx) < 0) {
        /* broken */
        if (ctx->fill_missing)
            ctx->addr.domain = "SYNTAX_ERROR";
        ctx->addr.invalid_syntax = TRUE;
    }
    return ctx->parser.data != ctx->parser.end ? 1 : 0;
}

static int parse_addr_spec(struct message_address_parser_context *ctx)
{
    /* addr-spec       = local-part "@" domain */
    int ret, ret2 = -2;

    i_assert(ctx->parser.data != ctx->parser.end);

    str_truncate(ctx->parser.last_comment, 0);

    bool quoted_string = *ctx->parser.data == '"';
    ret = parse_local_part(ctx);
    if (ret <= 0) {
        /* end of input or parsing local-part failed */
        ctx->addr.invalid_syntax = TRUE;
    }
    if (ret != 0 && *ctx->parser.data == '@') {
        ret2 = parse_domain(ctx);
        if (ret2 <= 0)
            ret = ret2;
    }

    if (str_len(ctx->parser.last_comment) > 0)
        ctx->addr.name = p_strdup(ctx->pool, str_c(ctx->parser.last_comment));
    else if (ret2 == -2) {
        /* So far we've read user without @domain and without
           (Display Name). We'll assume that a single "user" (already
           read into addr.mailbox) is a mailbox, but if it's followed
           by anything else it's a display-name. */
        str_append_c(ctx->str, ' ');
        size_t orig_str_len = str_len(ctx->str);
        (void)rfc822_parse_phrase(&ctx->parser, ctx->str);
        if (str_len(ctx->str) != orig_str_len) {
            ctx->addr.mailbox = NULL;
            ctx->addr.name = p_strdup(ctx->pool, str_c(ctx->str));
        } else {
            if (!quoted_string)
                ctx->addr.domain = "";
        }
        ctx->addr.invalid_syntax = TRUE;
        ret = -1;
    }
    return ret;
}

static void add_fixed_address(struct message_address_parser_context *ctx)
{
    if (ctx->addr.mailbox == NULL) {
        ctx->addr.mailbox = !ctx->fill_missing ? "" : "MISSING_MAILBOX";
        ctx->addr.invalid_syntax = TRUE;
    }
    if (ctx->addr.domain == NULL || ctx->addr.domain[0] == '\0') {
        ctx->addr.domain = !ctx->fill_missing ? "" : "MISSING_DOMAIN";
        ctx->addr.invalid_syntax = TRUE;
    }
    add_address(ctx);
}

static int parse_mailbox(struct message_address_parser_context *ctx)
{
    const unsigned char *start;
    int ret;

    /* mailbox         = name-addr / addr-spec */
    start = ctx->parser.data;
    if ((ret = parse_name_addr(ctx)) < 0) {
        /* nope, should be addr-spec */
        ctx->parser.data = start;
        ret = parse_addr_spec(ctx);
        if (ctx->addr.invalid_syntax && ctx->addr.name == NULL &&
            ctx->addr.mailbox != NULL && ctx->addr.domain == NULL) {
            ctx->addr.name = ctx->addr.mailbox;
            ctx->addr.mailbox = NULL;
        }
    }

    if (ret < 0)
        ctx->addr.invalid_syntax = TRUE;
    add_fixed_address(ctx);
    return ret;
}

static int parse_group(struct message_address_parser_context *ctx)
{
    int ret;

    /*
       group           = display-name ":" [mailbox-list / CFWS] ";" [CFWS]
       display-name    = phrase
    */
    str_truncate(ctx->str, 0);
    if (rfc822_parse_phrase(&ctx->parser, ctx->str) <= 0 ||
        *ctx->parser.data != ':')
        return -1;

    /* from now on don't return -1 even if there are problems, so that
       the caller knows this is a group */
    ctx->parser.data++;
    if ((ret = rfc822_skip_lwsp(&ctx->parser)) <= 0)
        ctx->addr.invalid_syntax = TRUE;

    ctx->addr.mailbox = p_strdup(ctx->pool, str_c(ctx->str));
    add_address(ctx);

    if (ret > 0 && *ctx->parser.data != ';') {
        for (;;) {
            /* mailbox-list    =
                (mailbox *("," mailbox)) / obs-mbox-list */
            if (parse_mailbox(ctx) <= 0) {
                /* broken mailbox - try to continue anyway. */
            }
            if (ctx->parser.data == ctx->parser.end ||
                *ctx->parser.data != ',')
                break;
            ctx->parser.data++;
            if (rfc822_skip_lwsp(&ctx->parser) <= 0) {
                ret = -1;
                break;
            }
        }
    }
    if (ret >= 0) {
        if (ctx->parser.data == ctx->parser.end ||
            *ctx->parser.data != ';')
            ret = -1;
        else {
            ctx->parser.data++;
            ret = rfc822_skip_lwsp(&ctx->parser);
        }
    }
    if (ret < 0)
        ctx->addr.invalid_syntax = TRUE;

    add_address(ctx);
    return ret == 0 ? 0 : 1;
}

static int parse_address(struct message_address_parser_context *ctx)
{
    const unsigned char *start;
    int ret;

    /* address         = mailbox / group */
    start = ctx->parser.data;
    if ((ret = parse_group(ctx)) < 0) {
        /* not a group, try mailbox */
        ctx->parser.data = start;
        ret = parse_mailbox(ctx);
    }
    return ret;
}

static int parse_address_list(struct message_address_parser_context *ctx,
                  unsigned int max_addresses)
{
    int ret = 0;

    /* address-list    = (address *("," address)) / obs-addr-list */
    while (max_addresses > 0) {
        max_addresses--;
        if ((ret = parse_address(ctx)) == 0)
            break;
        if (ctx->parser.data == ctx->parser.end ||
            *ctx->parser.data != ',') {
            ret = -1;
            break;
        }
        ctx->parser.data++;
        if ((ret = rfc822_skip_lwsp(&ctx->parser)) <= 0) {
            if (ret < 0) {
                /* ends with some garbage */
                add_fixed_address(ctx);
            }
            break;
        }
    }
    return ret;
}

static struct message_address *
message_address_parse_real(pool_t pool, const unsigned char *data, size_t size,
               unsigned int max_addresses, bool fill_missing)
{
    struct message_address_parser_context ctx;

    i_zero(&ctx);

    rfc822_parser_init(&ctx.parser, data, size, t_str_new(128));
    ctx.pool = pool;
    ctx.str = t_str_new(128);
    ctx.fill_missing = fill_missing;

    if (rfc822_skip_lwsp(&ctx.parser) <= 0) {
        /* no addresses */
        return NULL;
    }
    (void)parse_address_list(&ctx, max_addresses);
    return ctx.first_addr;
}

static int
message_address_parse_path_real(pool_t pool, const unsigned char *data,
                size_t size, struct message_address **addr_r)
{
    struct message_address_parser_context ctx;
    int ret;

    i_zero(&ctx);
    *addr_r = NULL;

    rfc822_parser_init(&ctx.parser, data, size, NULL);
    ctx.pool = pool;
    ctx.str = t_str_new(128);

    if (rfc822_skip_lwsp(&ctx.parser) <= 0)
        return -1;
    if ((ret=parse_angle_addr(&ctx)) < 0 ||
        (ctx.addr.mailbox != NULL && ctx.addr.domain == NULL)) {
        ctx.addr.invalid_syntax = TRUE;
        ret = -1;
    }
    add_address(&ctx);
    *addr_r = ctx.first_addr;
    return (ret < 0 ? -1 : 0);
}

struct message_address *
message_address_parse(pool_t pool, const unsigned char *data, size_t size,
              unsigned int max_addresses, bool fill_missing)
{
    struct message_address *addr;

    if (pool->datastack_pool) {
        return message_address_parse_real(pool, data, size,
                          max_addresses, fill_missing);
    }
    T_BEGIN {
        addr = message_address_parse_real(pool, data, size,
                          max_addresses, fill_missing);
    } T_END;
    return addr;
}

int message_address_parse_path(pool_t pool, const unsigned char *data,
                   size_t size, struct message_address **addr_r)
{
    int ret;

    if (pool->datastack_pool) {
        return message_address_parse_path_real(pool, data, size, addr_r);
    }
    T_BEGIN {
        ret = message_address_parse_path_real(pool, data, size, addr_r);
    } T_END;
    return ret;
}

void message_address_write(string_t *str, const struct message_address *addr)
{
    const char *tmp;
    bool first = TRUE, in_group = FALSE;

    /* <> path */
    if (addr->mailbox == NULL && addr->domain == NULL) {
        i_assert(addr->next == NULL);
        str_append(str, "<>");
        return;
    }

    /* a) mailbox@domain
       b) name <@route:mailbox@domain>
       c) group: .. ; */

    while (addr != NULL) {
        if (first)
            first = FALSE;
        else
            str_append(str, ", ");

        if (addr->domain == NULL) {
            if (!in_group) {
                /* beginning of group. mailbox is the group
                   name, others are NULL. */
                if (addr->mailbox != NULL && *addr->mailbox != '\0') {
                    /* check for MIME encoded-word */
                    if (strstr(addr->mailbox, "=?") != NULL)
                        /* MIME encoded-word MUST NOT appear within a 'quoted-string'
                           so escaping and quoting of phrase is not possible, instead
                           use obsolete RFC822 phrase syntax which allow spaces */
                        str_append(str, addr->mailbox);
                    else
                        str_append_maybe_escape(str, addr->mailbox, TRUE);
                } else {
                    /* empty group name needs to be quoted */
                    str_append(str, "\"\"");
                }
                str_append(str, ": ");
                first = TRUE;
            } else {
                /* end of group. all fields should be NULL. */
                i_assert(addr->mailbox == NULL);

                /* cut out the ", " */
                tmp = str_c(str)+str_len(str)-2;
                i_assert((tmp[0] == ',' || tmp[0] == ':') && tmp[1] == ' ');
                if (tmp[0] == ',' && tmp[1] == ' ')
                    str_truncate(str, str_len(str)-2);
                else if (tmp[0] == ':' && tmp[1] == ' ')
                    str_truncate(str, str_len(str)-1);
                str_append_c(str, ';');
            }

            in_group = !in_group;
        } else {
            /* "Display Name" <mailbox@domain> */
            i_assert(addr->mailbox != NULL);

            if (addr->name != NULL) {
                /* check for MIME encoded-word */
                if (strstr(addr->name, "=?") != NULL)
                    /* MIME encoded-word MUST NOT appear within a 'quoted-string'
                       so escaping and quoting of phrase is not possible, instead
                       use obsolete RFC822 phrase syntax which allow spaces */
                    str_append(str, addr->name);
                else
                    str_append_maybe_escape(str, addr->name, TRUE);
            }
            if (addr->route != NULL ||
                addr->mailbox[0] != '\0' ||
                addr->domain[0] != '\0') {
                if (addr->name != NULL && addr->name[0] != '\0')
                    str_append_c(str, ' ');
                str_append_c(str, '<');
                if (addr->route != NULL) {
                    str_append(str, addr->route);
                    str_append_c(str, ':');
                }
                if (addr->mailbox[0] == '\0')
                    str_append(str, "\"\"");
                else
                    str_append_maybe_escape(str, addr->mailbox, FALSE);
                if (addr->domain[0] != '\0') {
                    str_append_c(str, '@');
                    str_append(str, addr->domain);
                }
                str_append_c(str, '>');
            }
        }

        addr = addr->next;
    }
}

const char *message_address_to_string(const struct message_address *addr)
{
    string_t *str = t_str_new(256);
    message_address_write(str, addr);
    return str_c(str);
}

const char *message_address_first_to_string(const struct message_address *addr)
{
    struct message_address first_addr;

    first_addr = *addr;
    first_addr.next = NULL;
    first_addr.route = NULL;
    return message_address_to_string(&first_addr);
}

void message_address_init(struct message_address *addr,
    const char *name, const char *mailbox, const char *domain)
{
    i_zero(addr);
    addr->name = name;
    addr->mailbox = mailbox;
    addr->domain = domain;
}

void message_address_init_from_smtp(struct message_address *addr,
    const char *name, const struct smtp_address *smtp_addr)
{
    i_zero(addr);
    addr->name = name;
    addr->mailbox = smtp_addr->localpart;
    addr->domain = smtp_addr->domain;
}

static const char *address_headers[] = {
    "From", "Sender", "Reply-To",
    "To", "Cc", "Bcc",
    "Resent-From", "Resent-Sender", "Resent-To", "Resent-Cc", "Resent-Bcc"
};

bool message_header_is_address(const char *hdr_name)
{
    unsigned int i;

    for (i = 0; i < N_ELEMENTS(address_headers); i++) {
        if (strcasecmp(hdr_name, address_headers[i]) == 0)
            return TRUE;
    }
    return FALSE;
}