Contents of /tags/mkinitrd-6_2_3/busybox/mailutils/sendmail.c
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Mon May 31 20:54:44 2010 UTC (14 years, 4 months ago) by niro
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Mon May 31 20:54:44 2010 UTC (14 years, 4 months ago) by niro
File MIME type: text/plain
File size: 9100 byte(s)
tagged 'mkinitrd-6_2_3'
1 | /* vi: set sw=4 ts=4: */ |
2 | /* |
3 | * bare bones sendmail |
4 | * |
5 | * Copyright (C) 2008 by Vladimir Dronnikov <dronnikov@gmail.com> |
6 | * |
7 | * Licensed under GPLv2, see file LICENSE in this tarball for details. |
8 | */ |
9 | #include "libbb.h" |
10 | #include "mail.h" |
11 | |
12 | // limit maximum allowed number of headers to prevent overflows. |
13 | // set to 0 to not limit |
14 | #define MAX_HEADERS 256 |
15 | |
16 | static int smtp_checkp(const char *fmt, const char *param, int code) |
17 | { |
18 | char *answer; |
19 | const char *msg = command(fmt, param); |
20 | // read stdin |
21 | // if the string has a form \d\d\d- -- read next string. E.g. EHLO response |
22 | // parse first bytes to a number |
23 | // if code = -1 then just return this number |
24 | // if code != -1 then checks whether the number equals the code |
25 | // if not equal -> die saying msg |
26 | while ((answer = xmalloc_fgetline(stdin)) != NULL) |
27 | if (strlen(answer) <= 3 || '-' != answer[3]) |
28 | break; |
29 | if (answer) { |
30 | int n = atoi(answer); |
31 | if (timeout) |
32 | alarm(0); |
33 | free(answer); |
34 | if (-1 == code || n == code) |
35 | return n; |
36 | } |
37 | bb_error_msg_and_die("%s failed", msg); |
38 | } |
39 | |
40 | static int smtp_check(const char *fmt, int code) |
41 | { |
42 | return smtp_checkp(fmt, NULL, code); |
43 | } |
44 | |
45 | // strip argument of bad chars |
46 | static char *sane_address(char *str) |
47 | { |
48 | char *s = str; |
49 | char *p = s; |
50 | while (*s) { |
51 | if (isalnum(*s) || '_' == *s || '-' == *s || '.' == *s || '@' == *s) { |
52 | *p++ = *s; |
53 | } |
54 | s++; |
55 | } |
56 | *p = '\0'; |
57 | return str; |
58 | } |
59 | |
60 | static void rcptto(const char *s) |
61 | { |
62 | // N.B. we don't die if recipient is rejected, for the other recipients may be accepted |
63 | if (250 != smtp_checkp("RCPT TO:<%s>", s, -1)) |
64 | bb_error_msg("Bad recipient: <%s>", s); |
65 | } |
66 | |
67 | int sendmail_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
68 | int sendmail_main(int argc UNUSED_PARAM, char **argv) |
69 | { |
70 | char *opt_connect = opt_connect; |
71 | char *opt_from; |
72 | char *s; |
73 | llist_t *list = NULL; |
74 | char *domain = sane_address(safe_getdomainname()); |
75 | unsigned nheaders = 0; |
76 | int code; |
77 | |
78 | enum { |
79 | //--- standard options |
80 | OPT_t = 1 << 0, // read message for recipients, append them to those on cmdline |
81 | OPT_f = 1 << 1, // sender address |
82 | OPT_o = 1 << 2, // various options. -oi IMPLIED! others are IGNORED! |
83 | OPT_i = 1 << 3, // IMPLIED! |
84 | //--- BB specific options |
85 | OPT_w = 1 << 4, // network timeout |
86 | OPT_H = 1 << 5, // use external connection helper |
87 | OPT_S = 1 << 6, // specify connection string |
88 | OPT_a = 1 << 7, // authentication tokens |
89 | }; |
90 | |
91 | // init global variables |
92 | INIT_G(); |
93 | |
94 | // save initial stdin since body is piped! |
95 | xdup2(STDIN_FILENO, 3); |
96 | G.fp0 = xfdopen_for_read(3); |
97 | |
98 | // parse options |
99 | // -f is required. -H and -S are mutually exclusive |
100 | opt_complementary = "f:w+:H--S:S--H:a::"; |
101 | // N.B. since -H and -S are mutually exclusive they do not interfere in opt_connect |
102 | // -a is for ssmtp (http://downloads.openwrt.org/people/nico/man/man8/ssmtp.8.html) compatibility, |
103 | // it is still under development. |
104 | opts = getopt32(argv, "tf:o:iw:H:S:a::", &opt_from, NULL, &timeout, &opt_connect, &opt_connect, &list); |
105 | //argc -= optind; |
106 | argv += optind; |
107 | |
108 | // process -a[upm]<token> options |
109 | if ((opts & OPT_a) && !list) |
110 | bb_show_usage(); |
111 | while (list) { |
112 | char *a = (char *) llist_pop(&list); |
113 | if ('u' == a[0]) |
114 | G.user = xstrdup(a+1); |
115 | if ('p' == a[0]) |
116 | G.pass = xstrdup(a+1); |
117 | // N.B. we support only AUTH LOGIN so far |
118 | //if ('m' == a[0]) |
119 | // G.method = xstrdup(a+1); |
120 | } |
121 | // N.B. list == NULL here |
122 | //bb_info_msg("OPT[%x] AU[%s], AP[%s], AM[%s], ARGV[%s]", opts, au, ap, am, *argv); |
123 | |
124 | // connect to server |
125 | |
126 | // connection helper ordered? -> |
127 | if (opts & OPT_H) { |
128 | const char *args[] = { "sh", "-c", opt_connect, NULL }; |
129 | // plug it in |
130 | launch_helper(args); |
131 | // vanilla connection |
132 | } else { |
133 | int fd; |
134 | // host[:port] not explicitly specified? -> use $SMTPHOST |
135 | // no $SMTPHOST ? -> use localhost |
136 | if (!(opts & OPT_S)) { |
137 | opt_connect = getenv("SMTPHOST"); |
138 | if (!opt_connect) |
139 | opt_connect = (char *)"127.0.0.1"; |
140 | } |
141 | // do connect |
142 | fd = create_and_connect_stream_or_die(opt_connect, 25); |
143 | // and make ourselves a simple IO filter |
144 | xmove_fd(fd, STDIN_FILENO); |
145 | xdup2(STDIN_FILENO, STDOUT_FILENO); |
146 | } |
147 | // N.B. from now we know nothing about network :) |
148 | |
149 | // wait for initial server OK |
150 | // N.B. if we used openssl the initial 220 answer is already swallowed during openssl TLS init procedure |
151 | // so we need to kick the server to see whether we are ok |
152 | code = smtp_check("NOOP", -1); |
153 | // 220 on plain connection, 250 on openssl-helped TLS session |
154 | if (220 == code) |
155 | smtp_check(NULL, 250); // reread the code to stay in sync |
156 | else if (250 != code) |
157 | bb_error_msg_and_die("INIT failed"); |
158 | |
159 | // we should start with modern EHLO |
160 | if (250 != smtp_checkp("EHLO %s", domain, -1)) { |
161 | smtp_checkp("HELO %s", domain, 250); |
162 | } |
163 | if (ENABLE_FEATURE_CLEAN_UP) |
164 | free(domain); |
165 | |
166 | // perform authentication |
167 | if (opts & OPT_a) { |
168 | smtp_check("AUTH LOGIN", 334); |
169 | // we must read credentials unless they are given via -a[up] options |
170 | if (!G.user || !G.pass) |
171 | get_cred_or_die(4); |
172 | encode_base64(NULL, G.user, NULL); |
173 | smtp_check("", 334); |
174 | encode_base64(NULL, G.pass, NULL); |
175 | smtp_check("", 235); |
176 | } |
177 | |
178 | // set sender |
179 | // N.B. we have here a very loosely defined algotythm |
180 | // since sendmail historically offers no means to specify secrets on cmdline. |
181 | // 1) server can require no authentication -> |
182 | // we must just provide a (possibly fake) reply address. |
183 | // 2) server can require AUTH -> |
184 | // we must provide valid username and password along with a (possibly fake) reply address. |
185 | // For the sake of security username and password are to be read either from console or from a secured file. |
186 | // Since reading from console may defeat usability, the solution is either to read from a predefined |
187 | // file descriptor (e.g. 4), or again from a secured file. |
188 | |
189 | // got no sender address? -> use system username as a resort |
190 | // N.B. we marked -f as required option! |
191 | //if (!G.user) { |
192 | // // N.B. IMHO getenv("USER") can be way easily spoofed! |
193 | // G.user = xuid2uname(getuid()); |
194 | // opt_from = xasprintf("%s@%s", G.user, domain); |
195 | //} |
196 | //if (ENABLE_FEATURE_CLEAN_UP) |
197 | // free(domain); |
198 | smtp_checkp("MAIL FROM:<%s>", opt_from, 250); |
199 | |
200 | // process message |
201 | |
202 | // read recipients from message and add them to those given on cmdline. |
203 | // this means we scan stdin for To:, Cc:, Bcc: lines until an empty line |
204 | // and then use the rest of stdin as message body |
205 | code = 0; // set "analyze headers" mode |
206 | while ((s = xmalloc_fgetline(G.fp0)) != NULL) { |
207 | dump: |
208 | // put message lines doubling leading dots |
209 | if (code) { |
210 | // escape leading dots |
211 | // N.B. this feature is implied even if no -i (-oi) switch given |
212 | // N.B. we need to escape the leading dot regardless of |
213 | // whether it is single or not character on the line |
214 | if ('.' == s[0] /*&& '\0' == s[1] */) |
215 | printf("."); |
216 | // dump read line |
217 | printf("%s\r\n", s); |
218 | free(s); |
219 | continue; |
220 | } |
221 | |
222 | // analyze headers |
223 | // To: or Cc: headers add recipients |
224 | if (0 == strncasecmp("To: ", s, 4) || 0 == strncasecmp("Bcc: " + 1, s, 4)) { |
225 | rcptto(sane_address(s+4)); |
226 | goto addheader; |
227 | // Bcc: header adds blind copy (hidden) recipient |
228 | } else if (0 == strncasecmp("Bcc: ", s, 5)) { |
229 | rcptto(sane_address(s+5)); |
230 | free(s); |
231 | // N.B. Bcc: vanishes from headers! |
232 | |
233 | // other headers go verbatim |
234 | |
235 | // N.B. RFC2822 2.2.3 "Long Header Fields" allows for headers to occupy several lines. |
236 | // Continuation is denoted by prefixing additional lines with whitespace(s). |
237 | // Thanks (stefan.seyfried at googlemail.com) for pointing this out. |
238 | } else if (strchr(s, ':') || (list && skip_whitespace(s) != s)) { |
239 | addheader: |
240 | // N.B. we allow MAX_HEADERS generic headers at most to prevent attacks |
241 | if (MAX_HEADERS && ++nheaders >= MAX_HEADERS) |
242 | goto bail; |
243 | llist_add_to_end(&list, s); |
244 | // a line without ":" (an empty line too, by definition) doesn't look like a valid header |
245 | // so stop "analyze headers" mode |
246 | } else { |
247 | reenter: |
248 | // put recipients specified on cmdline |
249 | while (*argv) { |
250 | char *t = sane_address(*argv); |
251 | rcptto(t); |
252 | //if (MAX_HEADERS && ++nheaders >= MAX_HEADERS) |
253 | // goto bail; |
254 | llist_add_to_end(&list, xasprintf("To: %s", t)); |
255 | argv++; |
256 | } |
257 | // enter "put message" mode |
258 | // N.B. DATA fails iff no recipients were accepted (or even provided) |
259 | // in this case just bail out gracefully |
260 | if (354 != smtp_check("DATA", -1)) |
261 | goto bail; |
262 | // dump the headers |
263 | while (list) { |
264 | printf("%s\r\n", (char *) llist_pop(&list)); |
265 | } |
266 | // stop analyzing headers |
267 | code++; |
268 | // N.B. !s means: we read nothing, and nothing to be read in the future. |
269 | // just dump empty line and break the loop |
270 | if (!s) { |
271 | puts("\r"); |
272 | break; |
273 | } |
274 | // go dump message body |
275 | // N.B. "s" already contains the first non-header line, so pretend we read it from input |
276 | goto dump; |
277 | } |
278 | } |
279 | // odd case: we didn't stop "analyze headers" mode -> message body is empty. Reenter the loop |
280 | // N.B. after reenter code will be > 0 |
281 | if (!code) |
282 | goto reenter; |
283 | |
284 | // finalize the message |
285 | smtp_check(".", 250); |
286 | bail: |
287 | // ... and say goodbye |
288 | smtp_check("QUIT", 221); |
289 | // cleanup |
290 | if (ENABLE_FEATURE_CLEAN_UP) |
291 | fclose(G.fp0); |
292 | |
293 | return EXIT_SUCCESS; |
294 | } |