index/mbox/mbox-md5-apop3d.c

/* Copyright (c) 2004-2018 Dovecot authors, see the included COPYING file */

#include "lib.h"
#include "md5.h"
#include "message-parser.h"
#include "mbox-md5.h"


struct mbox_md5_context {
    struct md5_context hdr_md5_ctx;
    bool seen_received_hdr;
};

struct mbox_md5_header_func {
    const char *header;
    bool (*func)(struct mbox_md5_context *ctx,
             struct message_header_line *hdr);
};

static bool parse_date(struct mbox_md5_context *ctx,
               struct message_header_line *hdr)
{
    if (!ctx->seen_received_hdr) {
        /* Received-header contains date too, and more trusted one */
        md5_update(&ctx->hdr_md5_ctx, hdr->value, hdr->value_len);
    }
    return TRUE;
}

static bool parse_delivered_to(struct mbox_md5_context *ctx,
                   struct message_header_line *hdr)
{
    md5_update(&ctx->hdr_md5_ctx, hdr->value, hdr->value_len);
    return TRUE;
}

static bool parse_message_id(struct mbox_md5_context *ctx,
                 struct message_header_line *hdr)
{
    if (!ctx->seen_received_hdr) {
        /* Received-header contains unique ID too,
           and more trusted one */
        md5_update(&ctx->hdr_md5_ctx, hdr->value, hdr->value_len);
    }
    return TRUE;
}

static bool parse_received(struct mbox_md5_context *ctx,
               struct message_header_line *hdr)
{
    if (!ctx->seen_received_hdr) {
        /* get only the first received-header */
        md5_update(&ctx->hdr_md5_ctx, hdr->value, hdr->value_len);
        if (!hdr->continues)
            ctx->seen_received_hdr = TRUE;
    }
    return TRUE;
}

static bool parse_x_delivery_id(struct mbox_md5_context *ctx,
                struct message_header_line *hdr)
{
    /* Let the local delivery agent help generate unique ID's but don't
       blindly trust this header alone as it could just as easily come from
       the remote. */
    md5_update(&ctx->hdr_md5_ctx, hdr->value, hdr->value_len);
    return TRUE;
}


static struct mbox_md5_header_func md5_header_funcs[] = {
    { "Date", parse_date },
    { "Delivered-To", parse_delivered_to },
    { "Message-ID", parse_message_id },
    { "Received", parse_received },
    { "X-Delivery-ID", parse_x_delivery_id }
};

static int bsearch_header_func_cmp(const void *p1, const void *p2)
{
    const char *key = p1;
    const struct mbox_md5_header_func *func = p2;

    return strcasecmp(key, func->header);
}

static struct mbox_md5_context *mbox_md5_apop3d_init(void)
{
    struct mbox_md5_context *ctx;

    ctx = i_new(struct mbox_md5_context, 1);
    md5_init(&ctx->hdr_md5_ctx);
    return ctx;
}

static void mbox_md5_apop3d_more(struct mbox_md5_context *ctx,
                 struct message_header_line *hdr)
{
    struct mbox_md5_header_func *func;

    func = bsearch(hdr->name, md5_header_funcs,
               N_ELEMENTS(md5_header_funcs), sizeof(*md5_header_funcs),
               bsearch_header_func_cmp);
    if (func != NULL)
        (void)func->func(ctx, hdr);
}

static void mbox_md5_apop3d_finish(struct mbox_md5_context *ctx,
                   unsigned char result[STATIC_ARRAY 16])
{
    md5_final(&ctx->hdr_md5_ctx, result);
    i_free(ctx);
}

struct mbox_md5_vfuncs mbox_md5_apop3d = {
    mbox_md5_apop3d_init,
    mbox_md5_apop3d_more,
    mbox_md5_apop3d_finish
};