X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~mdw/git/disorder/blobdiff_plain/39d4aa6b1c612305bf06760529e2a1532b9818a5..16fb2830d52c1420afdee555a566d72a065d9616:/lib/mime.c

diff --git a/lib/mime.c b/lib/mime.c
index c8ffe31..6bff61d 100644
--- a/lib/mime.c
+++ b/lib/mime.c
@@ -1,30 +1,26 @@
 /*
  * This file is part of DisOrder
- * Copyright (C) 2005, 2007 Richard Kettlewell
+ * Copyright (C) 2005, 2007, 2008 Richard Kettlewell
  *
- * This program is free software; you can redistribute it and/or modify
+ * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
+ * the Free Software Foundation, either version 3 of the License, or
  * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful, but
- * WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * General Public License for more details.
- *
+ * 
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
  * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
- * USA
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 /** @file lib/mime.c
  * @brief Support for MIME and allied protocols
  */
 
-#include <config.h>
-#include "types.h"
+#include "common.h"
 
-#include <string.h>
 #include <ctype.h>
 
 #include "mem.h"
@@ -32,6 +28,8 @@
 #include "vector.h"
 #include "hex.h"
 #include "log.h"
+#include "base64.h"
+#include "kvp.h"
 
 /** @brief Match whitespace characters */
 static int whitespace(int c) {
@@ -47,7 +45,7 @@ static int whitespace(int c) {
 }
 
 /** @brief Match RFC2045 tspecial characters */
-static int tspecial(int c) {
+int mime_tspecial(int c) {
   switch(c) {
   case '(':
   case ')':
@@ -70,8 +68,8 @@ static int tspecial(int c) {
   }
 }
 
-/** @brief Mathc RFC2616 seprator characters */
-static int http_separator(int c) {
+/** @brief Match RFC2616 separator characters */
+int mime_http_separator(int c) {
   switch(c) {
   case '(':
   case ')':
@@ -104,7 +102,9 @@ static int iscrlf(const char *ptr) {
 }
 
 /** @brief Skip whitespace
+ * @param s Pointer into string
  * @param rfc822_comments If true, skip RFC822 nested comments
+ * @return Pointer into string after whitespace
  */
 static const char *skipwhite(const char *s, int rfc822_comments) {
   int c, depth;
@@ -128,12 +128,14 @@ static const char *skipwhite(const char *s, int rfc822_comments) {
 	case '(': ++depth; break;
 	case ')': --depth; break;
 	case '\\':
-	  if(!*s) return 0;
+	  if(!*s)
+	    return 0;
 	  ++s;
 	  break;
 	}
       }
-      if(depth) return 0;
+      if(depth)
+	return 0;
       break;
     default:
       return s;
@@ -143,7 +145,7 @@ static const char *skipwhite(const char *s, int rfc822_comments) {
 
 /** @brief Test for a word character
  * @param c Character to test
- * @param special tspecial() (MIME/RFC2405) or http_separator() (HTTP/RFC2616)
+ * @param special mime_tspecial() (MIME/RFC2405) or mime_http_separator() (HTTP/RFC2616)
  * @return 1 if @p c is a word character, else 0
  */
 static int iswordchar(int c, int (*special)(int)) {
@@ -153,13 +155,13 @@ static int iswordchar(int c, int (*special)(int)) {
 /** @brief Parse an RFC1521/RFC2616 word
  * @param s Pointer to start of word
  * @param valuep Where to store value
- * @param special tspecial() (MIME/RFC2405) or http_separator() (HTTP/RFC2616)
+ * @param special mime_tspecial() (MIME/RFC2405) or mime_http_separator() (HTTP/RFC2616)
  * @return Pointer just after end of word or NULL if there's no word
  *
  * A word is a token or a quoted-string.
  */
-static const char *parseword(const char *s, char **valuep,
-			     int (*special)(int)) {
+const char *mime_parse_word(const char *s, char **valuep,
+			    int (*special)(int)) {
   struct dynstr value[1];
   int c;
 
@@ -169,13 +171,15 @@ static const char *parseword(const char *s, char **valuep,
     while((c = *s++) != '"') {
       switch(c) {
       case '\\':
-	if(!(c = *s++)) return 0;
+	if(!(c = *s++))
+	  return 0;
       default:
 	dynstr_append(value, c);
 	break;
       }
     }
-    if(!c) return 0;
+    if(!c)
+      return 0;
   } else {
     if(!iswordchar((unsigned char)*s, special))
       return NULL;
@@ -191,59 +195,75 @@ static const char *parseword(const char *s, char **valuep,
 /** @brief Parse an RFC1521/RFC2616 token
  * @param s Pointer to start of token
  * @param valuep Where to store value
- * @param special tspecial() (MIME/RFC2405) or http_separator() (HTTP/RFC2616)
+ * @param special mime_tspecial() (MIME/RFC2405) or mime_http_separator() (HTTP/RFC2616)
  * @return Pointer just after end of token or NULL if there's no token
  */
 static const char *parsetoken(const char *s, char **valuep,
 			      int (*special)(int)) {
-  if(*s == '"') return 0;
-  return parseword(s, valuep, special);
+  if(*s == '"')
+    return 0;
+  return mime_parse_word(s, valuep, special);
 }
 
 /** @brief Parse a MIME content-type field
  * @param s Start of field
  * @param typep Where to store type
- * @param parameternamep Where to store parameter name
- * @param parameternvaluep Wher to store parameter value
+ * @param parametersp Where to store parameter list
  * @return 0 on success, non-0 on error
+ *
+ * See <a href="http://tools.ietf.org/html/rfc2045#section-5">RFC 2045 s5</a>.
  */
 int mime_content_type(const char *s,
 		      char **typep,
-		      char **parameternamep,
-		      char **parametervaluep) {
+		      struct kvp **parametersp) {
   struct dynstr type, parametername;
+  struct kvp *parameters = 0;
+  char *parametervalue;
 
   dynstr_init(&type);
-  if(!(s = skipwhite(s, 1))) return -1;
-  if(!*s) return -1;
-  while(*s && !tspecial(*s) && !whitespace(*s))
+  if(!(s = skipwhite(s, 1)))
+    return -1;
+  if(!*s)
+    return -1;
+  while(*s && !mime_tspecial(*s) && !whitespace(*s))
     dynstr_append(&type, tolower((unsigned char)*s++));
-  if(!(s = skipwhite(s, 1))) return -1;
-  if(*s++ != '/') return -1;
+  if(!(s = skipwhite(s, 1)))
+    return -1;
+  if(*s++ != '/')
+    return -1;
   dynstr_append(&type, '/');
-  if(!(s = skipwhite(s, 1))) return -1;
-  while(*s && !tspecial(*s) && !whitespace(*s))
+  if(!(s = skipwhite(s, 1)))
+    return -1;
+  while(*s && !mime_tspecial(*s) && !whitespace(*s))
     dynstr_append(&type, tolower((unsigned char)*s++));
-  if(!(s = skipwhite(s, 1))) return -1;
+  if(!(s = skipwhite(s, 1)))
+    return -1;
 
-  if(*s == ';') {
+  while(*s == ';') {
     dynstr_init(&parametername);
     ++s;
-    if(!(s = skipwhite(s, 1))) return -1;
-    if(!*s) return -1;
-    while(*s && !tspecial(*s) && !whitespace(*s))
+    if(!(s = skipwhite(s, 1)))
+      return -1;
+    if(!*s)
+      return -1;
+    while(*s && !mime_tspecial(*s) && !whitespace(*s))
       dynstr_append(&parametername, tolower((unsigned char)*s++));
-    if(!(s = skipwhite(s, 1))) return -1;
-    if(*s++ != '=') return -1;
-    if(!(s = skipwhite(s, 1))) return -1;
-    if(!(s = parseword(s, parametervaluep, tspecial))) return -1;
-    if(!(s = skipwhite(s, 1))) return -1;
+    if(!(s = skipwhite(s, 1)))
+      return -1;
+    if(*s++ != '=')
+      return -1;
+    if(!(s = skipwhite(s, 1)))
+      return -1;
+    if(!(s = mime_parse_word(s, &parametervalue, mime_tspecial)))
+      return -1;
+    if(!(s = skipwhite(s, 1)))
+      return -1;
     dynstr_terminate(&parametername);
-    *parameternamep = parametername.vec;
-  } else
-    *parametervaluep = *parameternamep = 0;
+    kvp_set(&parameters, parametername.vec, parametervalue);
+  }
   dynstr_terminate(&type);
   *typep = type.vec;
+  *parametersp = parameters;
   return 0;
 }
 
@@ -251,7 +271,12 @@ int mime_content_type(const char *s,
  * @param s Start of message
  * @param callback Called for each header field
  * @param u Passed to callback
- * @return Pointer to decoded body (might be in original string)
+ * @return Pointer to decoded body (might be in original string), or NULL on error
+ *
+ * This does an RFC 822-style parse and honors Content-Transfer-Encoding as
+ * described in <a href="http://tools.ietf.org/html/rfc2045#section-6">RFC 2045
+ * s6</a>.  @p callback is called for each header field encountered, in order,
+ * with ASCII characters in the header name forced to lower case.
  */
 const char *mime_parse(const char *s,
 		       int (*callback)(const char *name, const char *value,
@@ -263,14 +288,27 @@ const char *mime_parse(const char *s,
   while(*s && !iscrlf(s)) {
     dynstr_init(&name);
     dynstr_init(&value);
-    while(*s && !tspecial(*s) && !whitespace(*s))
+    while(*s && !mime_tspecial(*s) && !whitespace(*s))
       dynstr_append(&name, tolower((unsigned char)*s++));
-    if(!(s = skipwhite(s, 1))) return 0;
-    if(*s != ':') return 0;
+    if(!(s = skipwhite(s, 1)))
+      return 0;
+    if(*s != ':')
+      return 0;
     ++s;
-    while(*s && !(*s == '\n' && !(s[1] == ' ' || s[1] == '\t')))
-      dynstr_append(&value, *s++);
-    if(*s) ++s;
+    while(*s && !(*s == '\n' && !(s[1] == ' ' || s[1] == '\t'))) {
+      const int c = *s++;
+      /* Strip leading whitespace */
+      if(value.nvec || !(c == ' ' || c == '\t' || c == '\n' || c == '\r'))
+	dynstr_append(&value, c);
+    }
+    /* Strip trailing whitespace */
+    while(value.nvec > 0 && (value.vec[value.nvec - 1] == ' '
+			     || value.vec[value.nvec - 1] == '\t'
+			     || value.vec[value.nvec - 1] == '\n'
+			     || value.vec[value.nvec - 1] == '\r'))
+      --value.nvec;
+    if(*s)
+      ++s;
     dynstr_terminate(&name);
     dynstr_terminate(&value);
     if(!strcmp(name.vec, "content-transfer-encoding")) {
@@ -278,16 +316,25 @@ const char *mime_parse(const char *s,
       for(p = cte; *p; p++)
 	*p = tolower((unsigned char)*p);
     }
-    if(callback(name.vec, value.vec, u)) return 0;
+    if(callback(name.vec, value.vec, u))
+      return 0;
   }
-  if(*s) s += 2;
+  if(*s)
+    s += 2;
   if(cte) {
-    if(!strcmp(cte, "base64")) return mime_base64(s);
-    if(!strcmp(cte, "quoted-printable")) return mime_qp(s);
+    if(!strcmp(cte, "base64"))
+      return mime_base64(s, 0);
+    if(!strcmp(cte, "quoted-printable"))
+      return mime_qp(s);
+    if(!strcmp(cte, "7bit") || !strcmp(cte, "8bit"))
+      return s;
+    error(0, "unknown content-transfer-encoding '%s'", cte);
+    return 0;
   }
   return s;
 }
 
+/** @brief Match the boundary string */
 static int isboundary(const char *ptr, const char *boundary, size_t bl) {
   return (ptr[0] == '-'
 	  && ptr[1] == '-'
@@ -295,24 +342,29 @@ static int isboundary(const char *ptr, const char *boundary, size_t bl) {
 	  && (iscrlf(ptr + bl + 2)
 	      || (ptr[bl + 2] == '-'
 		  && ptr[bl + 3] == '-'
-		  && iscrlf(ptr + bl + 4))));
+		  && (iscrlf(ptr + bl + 4) || *(ptr + bl + 4) == 0))));
 }
 
+/** @brief Match the final boundary string */
 static int isfinal(const char *ptr, const char *boundary, size_t bl) {
   return (ptr[0] == '-'
 	  && ptr[1] == '-'
 	  && !strncmp(ptr + 2, boundary, bl)
 	  && ptr[bl + 2] == '-'
 	  && ptr[bl + 3] == '-'
-	  && iscrlf(ptr + bl + 4));
+	  && (iscrlf(ptr + bl + 4) || *(ptr + bl + 4) == 0));
 }
 
 /** @brief Parse a multipart MIME body
  * @param s Start of message
- * @param callback CAllback for each part
+ * @param callback Callback for each part
  * @param boundary Boundary string
  * @param u Passed to callback
  * @return 0 on success, non-0 on error
+ * 
+ * See <a href="http://tools.ietf.org/html/rfc2046#section-5.1">RFC 2046
+ * s5.1</a>.  @p callback is called for each part (not yet decoded in any way)
+ * in succession; you should probably call mime_parse() for each part.
  */
 int mime_multipart(const char *s,
 		   int (*callback)(const char *s, void *u),
@@ -322,12 +374,20 @@ int mime_multipart(const char *s,
   const char *start, *e;
   int ret;
 
-  if(!isboundary(s, boundary, bl)) return -1;
+  /* We must start with a boundary string */
+  if(!isboundary(s, boundary, bl)) {
+    error(0, "mime_multipart: first line is not the boundary string");
+    return -1;
+  }
+  /* Keep going until we hit a final boundary */
   while(!isfinal(s, boundary, bl)) {
     s = strstr(s, "\r\n") + 2;
     start = s;
     while(!isboundary(s, boundary, bl)) {
-      if(!(e = strstr(s, "\r\n"))) return -1;
+      if(!(e = strstr(s, "\r\n"))) {
+	error(0, "mime_multipart: line does not end CRLF");
+	return -1;
+      }
       s = e + 2;
     }
     if((ret = callback(xstrndup(start,
@@ -340,10 +400,13 @@ int mime_multipart(const char *s,
 
 /** @brief Parse an RFC2388-style content-disposition field
  * @param s Start of field
- * @param typep Where to store type
+ * @param dispositionp Where to store disposition
  * @param parameternamep Where to store parameter name
- * @param parameternvaluep Wher to store parameter value
+ * @param parametervaluep Wher to store parameter value
  * @return 0 on success, non-0 on error
+ *
+ * See <a href="http://tools.ietf.org/html/rfc2388#section-3">RFC 2388 s3</a>
+ * and <a href="http://tools.ietf.org/html/rfc2183">RFC 2183</a>.
  */
 int mime_rfc2388_content_disposition(const char *s,
 				     char **dispositionp,
@@ -352,24 +415,34 @@ int mime_rfc2388_content_disposition(const char *s,
   struct dynstr disposition, parametername;
 
   dynstr_init(&disposition);
-  if(!(s = skipwhite(s, 1))) return -1;
-  if(!*s) return -1;
-  while(*s && !tspecial(*s) && !whitespace(*s))
+  if(!(s = skipwhite(s, 1)))
+    return -1;
+  if(!*s)
+    return -1;
+  while(*s && !mime_tspecial(*s) && !whitespace(*s))
     dynstr_append(&disposition, tolower((unsigned char)*s++));
-  if(!(s = skipwhite(s, 1))) return -1;
+  if(!(s = skipwhite(s, 1)))
+    return -1;
 
   if(*s == ';') {
     dynstr_init(&parametername);
     ++s;
-    if(!(s = skipwhite(s, 1))) return -1;
-    if(!*s) return -1;
-    while(*s && !tspecial(*s) && !whitespace(*s))
+    if(!(s = skipwhite(s, 1)))
+      return -1;
+    if(!*s)
+      return -1;
+    while(*s && !mime_tspecial(*s) && !whitespace(*s))
       dynstr_append(&parametername, tolower((unsigned char)*s++));
-    if(!(s = skipwhite(s, 1))) return -1;
-    if(*s++ != '=') return -1;
-    if(!(s = skipwhite(s, 1))) return -1;
-    if(!(s = parseword(s, parametervaluep, tspecial))) return -1;
-    if(!(s = skipwhite(s, 1))) return -1;
+    if(!(s = skipwhite(s, 1)))
+      return -1;
+    if(*s++ != '=')
+      return -1;
+    if(!(s = skipwhite(s, 1)))
+      return -1;
+    if(!(s = mime_parse_word(s, parametervaluep, mime_tspecial)))
+      return -1;
+    if(!(s = skipwhite(s, 1)))
+      return -1;
     dynstr_terminate(&parametername);
     *parameternamep = parametername.vec;
   } else
@@ -382,6 +455,9 @@ int mime_rfc2388_content_disposition(const char *s,
 /** @brief Convert MIME quoted-printable
  * @param s Quoted-printable data
  * @return Decoded data
+ *
+ * See <a href="http://tools.ietf.org/html/rfc2045#section-6.7">RFC 2045
+ * s6.7</a>.
  */
 char *mime_qp(const char *s) {
   struct dynstr d;
@@ -425,45 +501,56 @@ char *mime_qp(const char *s) {
   return d.vec;
 }
 
-/** @brief Convert MIME base64
- * @param s base64 data
- * @return Decoded data
+/** @brief Match cookie separator characters
+ *
+ * This is a subset of the RFC2616 specials, and technically is in breach of
+ * the specification.  However rejecting (in particular) slashes is
+ * unreasonably strict and has broken at least one (admittedly somewhat
+ * obscure) browser, so we're more forgiving.
  */
-char *mime_base64(const char *s) {
-  struct dynstr d;
-  const char *t;
-  int b[4], n, c;
-  static const char table[] =
-    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+static int cookie_separator(int c) {
+  switch(c) {
+  case '(':
+  case ')':
+  case ',':
+  case ';':
+  case '=':
+  case ' ':
+  case '"':
+  case '\t':
+    return 1;
 
-  dynstr_init(&d);
-  n = 0;
-  while((c = (unsigned char)*s++)) {
-    if((t = strchr(table, c))) {
-      b[n++] = t - table;
-      if(n == 4) {
-	dynstr_append(&d, (b[0] << 2) + (b[1] >> 4));
-	dynstr_append(&d, (b[1] << 4) + (b[2] >> 2));
-	dynstr_append(&d, (b[2] << 6) + b[3]);
-	n = 0;
-      }
-    } else if(c == '=') {
-      if(n >= 2) {
-	dynstr_append(&d, (b[0] << 2) + (b[1] >> 4));
-	if(n == 3)
-	  dynstr_append(&d, (b[1] << 4) + (b[2] >> 2));
-      }
-      break;
-    }
+  default:
+    return 0;
+  }
+}
+
+/** @brief Match cookie value separator characters
+ *
+ * Same as cookie_separator() but allows for @c = in cookie values.
+ */
+static int cookie_value_separator(int c) {
+  switch(c) {
+  case '(':
+  case ')':
+  case ',':
+  case ';':
+  case ' ':
+  case '"':
+  case '\t':
+    return 1;
+
+  default:
+    return 0;
   }
-  dynstr_terminate(&d);
-  return d.vec;
 }
 
 /** @brief Parse a RFC2109 Cookie: header
  * @param s Header field value
  * @param cd Where to store result
  * @return 0 on success, non-0 on error
+ *
+ * See <a href="http://tools.ietf.org/html/rfc2109">RFC 2109</a>.
  */
 int parse_cookie(const char *s,
 		 struct cookiedata *cd) {
@@ -478,11 +565,20 @@ int parse_cookie(const char *s,
       s = skipwhite(s, 0);
       continue;
     }
-    if(!(s = parsetoken(s, &n, http_separator))) return -1;
+    if(!(s = parsetoken(s, &n, cookie_separator))) {
+      error(0, "parse_cookie: cannot parse attribute name");
+      return -1;
+    }      
     s = skipwhite(s, 0);
-    if(*s++ != '=') return -1;
+    if(*s++ != '=') {
+      error(0, "parse_cookie: did not find expected '='");
+      return -1;
+    }
     s = skipwhite(s, 0);
-    if(!(s = parseword(s, &v, http_separator))) return -1;
+    if(!(s = mime_parse_word(s, &v, cookie_value_separator))) {
+      error(0, "parse_cookie: cannot parse value for '%s'", n);
+      return -1;
+    }
     if(n[0] == '$') {
       /* Some bit of meta-information */
       if(!strcmp(n, "$Version"))
@@ -536,6 +632,132 @@ const struct cookie *find_cookie(const struct cookiedata *cd,
   return 0;
 }
 
+/** @brief RFC822 quoting
+ * @param s String to quote
+ * @param force If non-0, always quote
+ * @return Possibly quoted string
+ */
+char *quote822(const char *s, int force) {
+  const char *t;
+  struct dynstr d[1];
+  int c;
+
+  if(!force) {
+    /* See if we need to quote */
+    for(t = s; (c = (unsigned char)*t); ++t) {
+      if(mime_tspecial(c) || mime_http_separator(c) || whitespace(c))
+	break;
+    }
+    if(*t)
+      force = 1;
+  }
+
+  if(!force)
+    return xstrdup(s);
+
+  dynstr_init(d);
+  dynstr_append(d, '"');
+  for(t = s; (c = (unsigned char)*t); ++t) {
+    if(c == '"' || c == '\\')
+      dynstr_append(d, '\\');
+    dynstr_append(d, c);
+  }
+  dynstr_append(d, '"');
+  dynstr_terminate(d);
+  return d->vec;
+}
+
+/** @brief Return true if @p ptr points at trailing space */
+static int is_trailing_space(const char *ptr) {
+  if(*ptr == ' ' || *ptr == '\t') {
+    while(*ptr == ' ' || *ptr == '\t')
+      ++ptr;
+    return *ptr == '\n' || *ptr == 0;
+  } else
+    return 0;
+}
+
+/** @brief Encoding text as quoted-printable
+ * @param text String to encode
+ * @return Encoded string
+ *
+ * See <a href="http://tools.ietf.org/html/rfc2045#section-6.7">RFC2045
+ * s6.7</a>.
+ */
+char *mime_to_qp(const char *text) {
+  struct dynstr d[1];
+  int linelength = 0;			/* length of current line */
+  char buffer[10];
+
+  dynstr_init(d);
+  /* The rules are:
+   * 1. Anything except newline can be replaced with =%02X
+   * 2. Newline, 33-60 and 62-126 stand for themselves (i.e. not '=')
+   * 3. Non-trailing space/tab stand for themselves.
+   * 4. Output lines are limited to 76 chars, with =<newline> being used
+   *    as a soft line break
+   * 5. Newlines aren't counted towards the 76 char limit.
+   */
+  while(*text) {
+    const int c = (unsigned char)*text;
+    if(c == '\n') {
+      /* Newline stands as itself */
+      dynstr_append(d, '\n');
+      linelength = 0;
+    } else if((c >= 33 && c <= 126 && c != '=')
+	      || ((c == ' ' || c == '\t')
+		  && !is_trailing_space(text))) {
+      /* Things that can stand for themselves  */
+      dynstr_append(d, c);
+      ++linelength;
+    } else {
+      /* Anything else that needs encoding */
+      snprintf(buffer, sizeof buffer, "=%02X", c);
+      dynstr_append_string(d, buffer);
+      linelength += 3;
+    }
+    ++text;
+    if(linelength > 73 && *text && *text != '\n') {
+      /* Next character might overflow 76 character limit if encoded, so we
+       * insert a soft break */
+      dynstr_append_string(d, "=\n");
+      linelength = 0;
+    }
+  }
+  /* Ensure there is a final newline */
+  if(linelength)
+    dynstr_append(d, '\n');
+  /* That's all */
+  dynstr_terminate(d);
+  return d->vec;
+}
+
+/** @brief Encode text
+ * @param text Underlying UTF-8 text
+ * @param charsetp Where to store charset string
+ * @param encodingp Where to store encoding string
+ * @return Encoded text (might be @p text)
+ */
+const char *mime_encode_text(const char *text,
+			     const char **charsetp,
+			     const char **encodingp) {
+  const char *ptr;
+
+  /* See if there are in fact any non-ASCII characters */
+  for(ptr = text; *ptr; ++ptr)
+    if((unsigned char)*ptr >= 128)
+      break;
+  if(!*ptr) {
+    /* Plain old ASCII, no encoding required */
+    *charsetp = "us-ascii";
+    *encodingp = "7bit";
+    return text;
+  }
+  *charsetp = "utf-8";
+  *encodingp = "quoted-printable";
+  return mime_to_qp(text);
+}
+
 /*
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