diff options
Diffstat (limited to '')
| -rw-r--r-- | src/lib-mail/message-snippet.c | 207 |
1 files changed, 207 insertions, 0 deletions
diff --git a/src/lib-mail/message-snippet.c b/src/lib-mail/message-snippet.c new file mode 100644 index 0000000..2982e2e --- /dev/null +++ b/src/lib-mail/message-snippet.c @@ -0,0 +1,207 @@ +/* Copyright (c) 2015-2018 Dovecot authors, see the included COPYING file */ + +#include "lib.h" +#include "buffer.h" +#include "str.h" +#include "istream.h" +#include "mail-html2text.h" +#include "message-parser.h" +#include "message-decoder.h" +#include "message-snippet.h" + +#include <ctype.h> + +enum snippet_state { + /* beginning of the line */ + SNIPPET_STATE_NEWLINE = 0, + /* within normal text */ + SNIPPET_STATE_NORMAL, + /* within quoted text - skip until EOL */ + SNIPPET_STATE_QUOTED +}; + +struct snippet_data { + string_t *snippet; + unsigned int chars_left; +}; + +struct snippet_context { + struct snippet_data snippet; + struct snippet_data quoted_snippet; + enum snippet_state state; + bool add_whitespace; + struct mail_html2text *html2text; + buffer_t *plain_output; +}; + +static void snippet_add_content(struct snippet_context *ctx, + struct snippet_data *target, + const unsigned char *data, size_t size, + size_t *count_r) +{ + i_assert(target != NULL); + if (size == 0) + return; + if (size >= 3 && + ((data[0] == 0xEF && data[1] == 0xBB && data[2] == 0xBF) || + (data[0] == 0xBF && data[1] == 0xBB && data[2] == 0xEF))) { + *count_r = 3; + return; + } + if (data[0] == '\0') { + /* skip NULs without increasing snippet size */ + return; + } + if (i_isspace(*data)) { + /* skip any leading whitespace */ + if (str_len(target->snippet) > 0) + ctx->add_whitespace = TRUE; + if (data[0] == '\n') + ctx->state = SNIPPET_STATE_NEWLINE; + return; + } + if (target->chars_left == 0) + return; + target->chars_left--; + if (ctx->add_whitespace) { + if (target->chars_left == 0) { + /* don't add a trailing whitespace */ + return; + } + str_append_c(target->snippet, ' '); + ctx->add_whitespace = FALSE; + target->chars_left--; + } + *count_r = uni_utf8_char_bytes(data[0]); + i_assert(*count_r <= size); + str_append_data(target->snippet, data, *count_r); +} + +static bool snippet_generate(struct snippet_context *ctx, + const unsigned char *data, size_t size) +{ + size_t i, count; + struct snippet_data *target; + + if (ctx->html2text != NULL) { + buffer_set_used_size(ctx->plain_output, 0); + mail_html2text_more(ctx->html2text, data, size, + ctx->plain_output); + data = ctx->plain_output->data; + size = ctx->plain_output->used; + } + + if (ctx->state == SNIPPET_STATE_QUOTED) + target = &ctx->quoted_snippet; + else + target = &ctx->snippet; + + /* message-decoder should feed us only valid and complete + UTF-8 input */ + + for (i = 0; i < size; i += count) { + count = 1; + switch (ctx->state) { + case SNIPPET_STATE_NEWLINE: + if (data[i] == '>') { + ctx->state = SNIPPET_STATE_QUOTED; + i++; + target = &ctx->quoted_snippet; + } else { + ctx->state = SNIPPET_STATE_NORMAL; + target = &ctx->snippet; + } + /* fallthrough */ + case SNIPPET_STATE_NORMAL: + case SNIPPET_STATE_QUOTED: + snippet_add_content(ctx, target, CONST_PTR_OFFSET(data, i), + size-i, &count); + /* break here if we have enough non-quoted data, + quoted data does not need to break here as it's + only used if the actual snippet is left empty. */ + if (ctx->snippet.chars_left == 0) + return FALSE; + break; + } + } + return TRUE; +} + +static void snippet_copy(const char *src, string_t *dst) +{ + while (*src != '\0' && i_isspace(*src)) src++; + str_append(dst, src); +} + +int message_snippet_generate(struct istream *input, + unsigned int max_snippet_chars, + string_t *snippet) +{ + const struct message_parser_settings parser_set = { .flags = 0 }; + struct message_parser_ctx *parser; + struct message_part *parts; + struct message_part *skip_part = NULL; + struct message_decoder_context *decoder; + struct message_block raw_block, block; + struct snippet_context ctx; + pool_t pool; + int ret; + + i_zero(&ctx); + pool = pool_alloconly_create("message snippet", 2048); + ctx.snippet.snippet = str_new(pool, max_snippet_chars); + ctx.snippet.chars_left = max_snippet_chars; + ctx.quoted_snippet.snippet = str_new(pool, max_snippet_chars); + ctx.quoted_snippet.chars_left = max_snippet_chars - 1; /* -1 for '>' */ + parser = message_parser_init(pool_datastack_create(), input, &parser_set); + decoder = message_decoder_init(NULL, 0); + while ((ret = message_parser_parse_next_block(parser, &raw_block)) > 0) { + if (raw_block.part == skip_part) + continue; + if (!message_decoder_decode_next_block(decoder, &raw_block, &block)) + continue; + if (block.size == 0) { + const char *ct; + + if (block.hdr != NULL) + continue; + + /* We already have a snippet, don't look for more in + subsequent parts. */ + if (ctx.snippet.snippet->used != 0 || + ctx.quoted_snippet.snippet->used != 0) + break; + + skip_part = NULL; + + /* end of headers - verify that we can use this + Content-Type. we get here only once, because we + always handle only one non-multipart MIME part. */ + ct = message_decoder_current_content_type(decoder); + if (ct == NULL) + /* text/plain */ ; + else if (mail_html2text_content_type_match(ct)) { + mail_html2text_deinit(&ctx.html2text); + ctx.html2text = mail_html2text_init(0); + if (ctx.plain_output == NULL) { + ctx.plain_output = + buffer_create_dynamic(pool, 1024); + } + } else if (strncasecmp(ct, "text/", 5) != 0) + skip_part = raw_block.part; + } else if (!snippet_generate(&ctx, block.data, block.size)) + break; + } + i_assert(ret != 0); + message_decoder_deinit(&decoder); + message_parser_deinit(&parser, &parts); + mail_html2text_deinit(&ctx.html2text); + if (ctx.snippet.snippet->used != 0) + snippet_copy(str_c(ctx.snippet.snippet), snippet); + else if (ctx.quoted_snippet.snippet->used != 0) { + str_append_c(snippet, '>'); + snippet_copy(str_c(ctx.quoted_snippet.snippet), snippet); + } + pool_unref(&pool); + return input->stream_errno == 0 ? 0 : -1; +} |