Initial revision

mimehead.c

@@ -0,0 +1,306 @@
+
+/* 
+ * MIME header support by Akinori ITO
+ */
+
+#include <sys/types.h>
+#include "Str.h"
+
+#define LINELEN 4096
+
+#define MIME_ENCODED_LINE_LIMIT	80
+#define MIME_ENCODED_WORD_LENGTH_OFFSET 18
+#define MIME_ENCODED_WORD_LENGTH_ESTIMATION(x) \
+	(((x)+2)*4/3+MIME_ENCODED_WORD_LENGTH_OFFSET)
+#define MIME_DECODED_WORD_LENGTH_ESTIMATION(x) \
+	(((x)-MIME_ENCODED_WORD_LENGTH_OFFSET)/4*3)
+#define J_CHARSET "ISO-2022-JP"
+
+#define BAD_BASE64 255
+
+static
+unsigned char
+c2e(char x)
+{
+    if ('A' <= x && x <= 'Z')
+	return (x) - 'A';
+    if ('a' <= x && x <= 'z')
+	return (x) - 'a' + 26;
+    if ('0' <= x && x <= '9')
+	return (x) - '0' + 52;
+    if (x == '+')
+	return 62;
+    if (x == '/')
+	return 63;
+    return BAD_BASE64;
+}
+
+static
+int
+ha2d(char x, char y)
+{
+    int r = 0;
+
+    if ('0' <= x && x <= '9')
+	r = x - '0';
+    else if ('A' <= x && x <= 'F')
+	r = x - 'A' + 10;
+    else if ('a' <= x && x <= 'f')
+	r = x - 'a' + 10;
+
+    r <<= 4;
+
+    if ('0' <= y && y <= '9')
+	r += y - '0';
+    else if ('A' <= y && y <= 'F')
+	r += y - 'A' + 10;
+    else if ('a' <= y && y <= 'f')
+	r += y - 'a' + 10;
+
+    return r;
+
+}
+
+Str
+decodeB(char **ww)
+{
+    unsigned char c[4];
+    char *wp = *ww;
+    char d[3];
+    int i, n_pad;
+    Str ap = Strnew_size(strlen(wp));
+
+    n_pad = 0;
+    while (1) {
+	for (i = 0; i < 4; i++) {
+	    c[i] = *(wp++);
+	    if (*wp == '\0' || *wp == '?') {
+		i++;
+		for (; i < 4; i++) {
+		    c[i] = '=';
+		}
+		break;
+	    }
+	}
+	if (c[3] == '=') {
+	    n_pad++;
+	    c[3] = 'A';
+	    if (c[2] == '=') {
+		n_pad++;
+		c[2] = 'A';
+	    }
+	}
+	for (i = 0; i < 4; i++) {
+	    c[i] = c2e(c[i]);
+	    if (c[i] == BAD_BASE64) {
+		*ww = wp;
+		return ap;
+	    }
+	}
+	d[0] = ((c[0] << 2) | (c[1] >> 4));
+	d[1] = ((c[1] << 4) | (c[2] >> 2));
+	d[2] = ((c[2] << 6) | c[3]);
+	for (i = 0; i < 3 - n_pad; i++) {
+	    Strcat_char(ap, d[i]);
+	}
+	if (n_pad || *wp == '\0' || *wp == '?')
+	    break;
+    }
+    *ww = wp;
+    return ap;
+}
+
+/* RFC2047 (4.2. The "Q" encoding) */
+Str
+decodeQ(char **ww)
+{
+    char *w = *ww;
+    Str a = Strnew_size(strlen(w));
+
+    for (; *w != '\0' && *w != '?'; w++) {
+	if (*w == '=') {
+	    w++;
+	    Strcat_char(a, ha2d(*w, *(w + 1)));
+	    w++;
+	}
+	else if (*w == '_') {
+	    Strcat_char(a, ' ');
+	}
+	else
+	    Strcat_char(a, *w);
+    }
+    *ww = w;
+    return a;
+}
+
+/* RFC2045 (6.7. Quoted-Printable Content-Transfer-Encoding) */
+Str
+decodeQP(char **ww)
+{
+    char *w = *ww;
+    Str a = Strnew_size(strlen(w));
+
+    for (; *w != '\0'; w++) {
+	if (*w == '=') {
+	    w++;
+	    if (*w == '\n' || *w == '\r' || *w == ' ' || *w == '\t') {
+		while (*w != '\n' && *w != '\0')
+		    w++;
+		if (*w == '\0')
+		    break;
+	    }
+	    else {
+		if (*w == '\0' || *(w + 1) == '\0')
+		    break;
+		Strcat_char(a, ha2d(*w, *(w + 1)));
+		w++;
+	    }
+	}
+	else
+	    Strcat_char(a, *w);
+    }
+    *ww = w;
+    return a;
+}
+
+Str
+decodeWord(char **ow)
+{
+    char charset[32];
+    char *p, *w = *ow;
+    char method;
+    Str a = Strnew();
+
+    if (*w != '=' || *(w + 1) != '?')
+	goto convert_fail;
+    w += 2;
+    for (p = charset; *w != '?'; w++) {
+	if (*w == '\0')
+	    goto convert_fail;
+	*(p++) = *w;
+    }
+    *p = '\0';
+    if (strcasecmp(charset, J_CHARSET) != 0) {
+	/* NOT ISO-2022-JP encoding ... don't convert */
+	goto convert_fail;
+    }
+    w++;
+    method = *(w++);
+    if (*w != '?')
+	goto convert_fail;
+    w++;
+    p = w;
+    switch (method) {
+    case 'B':
+	a = decodeB(&w);
+	break;
+    case 'Q':
+	a = decodeQ(&w);
+	break;
+    default:
+	goto convert_fail;
+    }
+    if (p == w)
+	goto convert_fail;
+    if (*w == '?') {
+	w++;
+	if (*w == '=')
+	    w++;
+    }
+    *ow = w;
+    return a;
+
+  convert_fail:
+    return Strnew();
+}
+
+/* 
+ * convert MIME encoded string to the original one
+ */
+Str
+decodeMIME(char *orgstr)
+{
+    char *org = orgstr;
+    char *org0, *p;
+    Str cnv = Strnew_size(strlen(orgstr));
+
+    while (*org) {
+	if (*org == '=' && *(org + 1) == '?') {
+	  nextEncodeWord:
+	    p = org;
+	    Strcat(cnv, decodeWord(&org));
+	    if (org == p) {	/* Convert failure */
+		Strcat_charp(cnv, org);
+		return cnv;
+	    }
+	    org0 = org;
+	  SPCRLoop:
+	    switch (*org0) {
+	    case ' ':
+	    case '\t':
+	    case '\n':
+	    case '\r':
+		org0++;
+		goto SPCRLoop;
+	    case '=':
+		if (org0[1] == '?') {
+		    org = org0;
+		    goto nextEncodeWord;
+		}
+	    default:
+		break;
+	    }
+	}
+	else
+	    Strcat_char(cnv, *(org++));
+    }
+    return cnv;
+}
+
+/* encoding */
+
+static char Base64Table[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
+
+Str
+encodeB(char *a)
+{
+    unsigned char d[3];
+    unsigned char c1, c2, c3, c4;
+    int i, n_pad;
+    Str w = Strnew();
+
+    while (1) {
+	if (*a == '\0')
+	    break;
+	n_pad = 0;
+	d[1] = d[2] = 0;
+	for (i = 0; i < 3; i++) {
+	    d[i] = a[i];
+	    if (a[i] == '\0') {
+		n_pad = 3 - i;
+		break;
+	    }
+	}
+	c1 = d[0] >> 2;
+	c2 = (((d[0] << 4) | (d[1] >> 4)) & 0x3f);
+	if (n_pad == 2) {
+	    c3 = c4 = 64;
+	}
+	else if (n_pad == 1) {
+	    c3 = ((d[1] << 2) & 0x3f);
+	    c4 = 64;
+	}
+	else {
+	    c3 = (((d[1] << 2) | (d[2] >> 6)) & 0x3f);
+	    c4 = (d[2] & 0x3f);
+	}
+	Strcat_char(w, Base64Table[c1]);
+	Strcat_char(w, Base64Table[c2]);
+	Strcat_char(w, Base64Table[c3]);
+	Strcat_char(w, Base64Table[c4]);
+	if (n_pad)
+	    break;
+	a += 3;
+    }
+    return w;
+}