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Diffstat (limited to 'rfc822.c')
| -rw-r--r-- | rfc822.c | 193 |
1 files changed, 193 insertions, 0 deletions
diff --git a/rfc822.c b/rfc822.c new file mode 100644 index 0000000..5f1cac8 --- /dev/null +++ b/rfc822.c @@ -0,0 +1,193 @@ +/** + * \file rfc822.c + * Code for slicing and dicing RFC822 mail headers. + * + * How to parse RFC822 headers in C. This is not a fully conformant + * implementation of RFC822 or RFC2822, but it has been in production use in a + * widely-deployed MTA (fetcmail) since 1996 without complaints. Really + * perverse combinations of quoting and commenting could break it. + * + * \author Eric S. Raymond <esr@thyrsus.com>, 1997. This source code example + * is part of fetchmail and the Unix Cookbook, and are released under the MIT + * license. + */ + + +#include <stdio.h> +#include <ctype.h> +#include <string.h> +#include <stdlib.h> + + +#ifndef TRUE +#define TRUE 1 +#define FALSE 0 +#endif + +#define HEADER_END(p) ((p)[0] == '\n' && ((p)[1] != ' ' && (p)[1] != '\t')) + + +/** + * Parse addresses in succession out of a specified RFC822 header. + * + * \param hdr header to be parsed, NUL to continue previous \p hdr. + */ +char *next_address(const char *hdr) +{ + static unsigned char address[BUFSIZ]; + static int tp; + static const unsigned char *hp; + static int state, oldstate; + int parendepth = 0; + +#define START_HDR 0 /* before header colon */ +#define SKIP_JUNK 1 /* skip whitespace, \n, and junk */ +#define BARE_ADDRESS 2 /* collecting address without delimiters */ +#define INSIDE_DQUOTE 3 /* inside double quotes */ +#define INSIDE_PARENS 4 /* inside parentheses */ +#define INSIDE_BRACKETS 5 /* inside bracketed address */ +#define ENDIT_ALL 6 /* after last address */ + +#define NEXTTP() ((tp < sizeof(address)-1) ? tp++ : tp) + + if (hdr) + { + hp = hdr; + state = START_HDR; + tp = 0; + } + + for (; *hp; hp++) + { + + if (state == ENDIT_ALL) /* after last address */ + return(NULL); + else if (HEADER_END(hp)) + { + state = ENDIT_ALL; + if (tp) + { + while (isspace(address[--tp])) + continue; + address[++tp] = '\0'; + tp = 0; + return (address); + } + return((unsigned char *)NULL); + } + else if (*hp == '\\') /* handle RFC822 escaping */ + { + if (state != INSIDE_PARENS) + { + address[NEXTTP()] = *hp++; /* take the escape */ + address[NEXTTP()] = *hp; /* take following unsigned char */ + } + } + else switch (state) + { + case START_HDR: /* before header colon */ + if (*hp == ':') + state = SKIP_JUNK; + break; + + case SKIP_JUNK: /* looking for address start */ + if (*hp == '"') /* quoted string */ + { + oldstate = SKIP_JUNK; + state = INSIDE_DQUOTE; + address[NEXTTP()] = *hp; + } + else if (*hp == '(') /* address comment -- ignore */ + { + parendepth = 1; + oldstate = SKIP_JUNK; + state = INSIDE_PARENS; + } + else if (*hp == '<') /* begin <address> */ + { + state = INSIDE_BRACKETS; + tp = 0; + } + else if (*hp != ',' && !isspace(*hp)) + { + --hp; + state = BARE_ADDRESS; + } + break; + + case BARE_ADDRESS: /* collecting address without delimiters */ + if (*hp == ',') /* end of address */ + { + if (tp) + { + address[NEXTTP()] = '\0'; + state = SKIP_JUNK; + tp = 0; + return(address); + } + } + else if (*hp == '(') /* beginning of comment */ + { + parendepth = 1; + oldstate = BARE_ADDRESS; + state = INSIDE_PARENS; + } + else if (*hp == '<') /* beginning of real address */ + { + state = INSIDE_BRACKETS; + tp = 0; + } + else if (*hp == '"') /* quoted word, copy verbatim */ + { + oldstate = state; + state = INSIDE_DQUOTE; + address[NEXTTP()] = *hp; + } + else if (!isspace(*hp)) /* just take it, ignoring whitespace */ + address[NEXTTP()] = *hp; + break; + + case INSIDE_DQUOTE: /* we're in a quoted string, copy verbatim */ + if (*hp != '"') + address[NEXTTP()] = *hp; + else + { + address[NEXTTP()] = *hp; + state = oldstate; + } + break; + + case INSIDE_PARENS: /* we're in a parenthesized comment, ignore */ + if (*hp == '(') + ++parendepth; + else if (*hp == ')') + --parendepth; + if (parendepth == 0) + state = oldstate; + break; + + case INSIDE_BRACKETS: /* possible <>-enclosed address */ + if (*hp == '>') /* end of address */ + { + address[NEXTTP()] = '\0'; + state = SKIP_JUNK; + ++hp; + tp = 0; + return(address); + } + else if (*hp == '<') /* nested <> */ + tp = 0; + else if (*hp == '"') /* quoted address */ + { + address[NEXTTP()] = *hp; + oldstate = INSIDE_BRACKETS; + state = INSIDE_DQUOTE; + } + else /* just copy address */ + address[NEXTTP()] = *hp; + break; + } + } + + return(NULL); +} |