X-Git-Url: http://git.marmaro.de/?a=blobdiff_plain;f=sbr%2Fmessage_id.c;h=bb71313021501967de473e571a3d15de84efaf45;hb=293b37f3c3eab8af5c87c9ad8ee9df89c998cf48;hp=d0a6dd9dbd2da36dc2183124fbc88c4bef24cd42;hpb=9f8f8b1e1d553774865f2c177191c359c3dc652c;p=mmh

diff --git a/sbr/message_id.c b/sbr/message_id.c
index d0a6dd9..bb71313 100644
--- a/sbr/message_id.c
+++ b/sbr/message_id.c
@@ -8,15 +8,15 @@
  */
 
 #include <h/mh.h>
-#include <unistd.h>   /* for getpid() */
-#include <sys/time.h> /* for gettimeofday() */
+#include <unistd.h>    /* for getpid() */
+#include <sys/time.h>  /* for gettimeofday() */
 #include <stdio.h>
 
 
-#define NMH_MESSAGE_ID_LOCALNAME 0
-#define NMH_MESSAGE_ID_RANDOM 1
-
-static int message_id_style = NMH_MESSAGE_ID_LOCALNAME;
+static enum {
+  NMH_MESSAGE_ID_LOCALNAME,
+  NMH_MESSAGE_ID_RANDOM
+} message_id_style = NMH_MESSAGE_ID_LOCALNAME;
 static char message_id_[BUFSIZ];
 
 
@@ -37,51 +37,75 @@ save_message_id_style (const char *value) {
 
 char *
 message_id (time_t tclock, int content_id) {
-  if (message_id_style == NMH_MESSAGE_ID_LOCALNAME) {
-    char *format = content_id  ?  "<%d.%ld.%%d@%s>"  :  "<%d.%ld@%s>";
-
-    snprintf (message_id_, sizeof message_id_, format,
-              (int) getpid (), (long) tclock, LocalName (1));
-  } else if  (message_id_style == NMH_MESSAGE_ID_RANDOM) {
-    char *format = content_id ? "<%d-%ld.%06ld%%d@%s>" : "<%d-%ld.%06ld@%s>";
-    /* Use a sequence of digits divisible by 3 because that will
-       expand to base64 without any waste.  Must be shorter than 58,
-       see below. */
-    unsigned char rnd[12];
-
-    if (m_rand (rnd, sizeof rnd) == 0) {
-      pid_t pid;
-      struct timeval now;
-      /* All we really need is 4 * [sizeof rnd/3] + 2, as long as the
-         base64 encoding stays shorter than 76 bytes so embedded
-         newlines aren't necessary.  But use double the sizeof rnd
-         just to be safe. */
-      unsigned char rnd_base64[2 * sizeof rnd];
-      int i;
-
-      writeBase64 (rnd, sizeof rnd, rnd_base64);
-
-      for (i = strlen ((const char *) rnd_base64) - 1;
-           i > 0  &&  iscntrl (rnd_base64[i]);
-           --i) {
-        /* Remove trailing newline.  rnd_base64 had better be shorter
-           than 76 characters, so don't bother to look for embedded
-           newlines. */
-        rnd_base64[i] = '\0';
-      }
-
-      /* Neither of these can fail according to the POSIX spec. */
-      pid = getpid ();
-      gettimeofday (&now, 0);
+  switch (message_id_style) {
+    case NMH_MESSAGE_ID_LOCALNAME: {
+      char *format = content_id  ?  "<%d.%ld.%%d@%s>"  :  "<%d.%ld@%s>";
 
       snprintf (message_id_, sizeof message_id_, format,
-                pid, (long) now.tv_sec, (long) now.tv_usec, rnd_base64);
+                (int) getpid (), (long) tclock, LocalName (1));
+
+      break;
     }
-  } else {
-    /* Should never get here. */
-    adios (0, "invalid message id style \"%s\"", message_id_style);
-  }
 
+    case NMH_MESSAGE_ID_RANDOM: {
+      char *format = content_id
+        ?  "<%d-%ld.%06ld%%d@%.*s.%.*s.%.*s>"
+        :  "<%d-%ld.%06ld@%.*s.%.*s.%.*s>";
+      /* Use a sequence of digits divisible by 3 because that will
+         expand to base64 without any waste.  Must be shorter than 58,
+         see below. */
+      unsigned char rnd[9];
+      /* The part after the '@' is divided into thirds.  The base64
+         encoded string will be 4/3 the size of rnd. */
+      size_t one_third = sizeof rnd * 4/3/3;
+
+      if (m_rand (rnd, sizeof rnd) == 0) {
+        struct timeval now;
+        /* All we really need is 4 * [sizeof rnd/3] + 2, as long as
+           the base64 encoding stays shorter than 76 bytes so embedded
+           newlines aren't necessary.  But use double the sizeof rnd
+           just to be safe. */
+        unsigned char rnd_base64[2 * sizeof rnd];
+        unsigned char *cp;
+        int i;
+
+        writeBase64 (rnd, sizeof rnd, rnd_base64);
+
+        for (i = strlen ((const char *) rnd_base64) - 1;
+             i > 0  &&  iscntrl (rnd_base64[i]);
+             --i) {
+          /* Remove trailing newline.  rnd_base64 had better be
+             shorter than 76 characters, so don't bother to look for
+             embedded newlines. */
+          rnd_base64[i] = '\0';
+        }
+
+        /* Try to make the base64 string look a little more like a
+           hostname by replacing + with - and / with _. */
+        for (cp = rnd_base64; *cp; ++cp) {
+          if (*cp == '+') {
+            *cp = '-';
+          } else if (*cp == '/') {
+            *cp = '_';
+          }
+        }
+
+        /* gettimeofday() and getpid() shouldn't fail on POSIX platforms. */
+        gettimeofday (&now, 0);
+
+        /* The format string inserts a couple of dots, for the benefit
+           of spam filters that want to see a message id with a final
+           part that resembles a hostname. */
+        snprintf (message_id_, sizeof message_id_, format,
+                  getpid (), (long) now.tv_sec, (long) now.tv_usec,
+                  one_third, rnd_base64,
+                  one_third, &rnd_base64[one_third],
+                  one_third, &rnd_base64[2*one_third]);
+      }
+
+      break;
+    }
+  }
 
   return message_id_;
 }