| Message ID | cd9a02ba94e9eb59b07d0b95140d5b880f122941.1675711789.git.gitgitgadget@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Enhance credential helper protocol to include auth headers | expand |
On Mon, Feb 06 2023, Matthew John Cheetham via GitGitGadget wrote: > From: Matthew John Cheetham <mjcheetham@outlook.com> > +static inline int skip_iprefix_mem(const char *buf, size_t len, > + const char *prefix, > + const char **out, size_t *outlen) > +{ > + size_t prefix_len = strlen(prefix); Style nit: We typically use \n\n after the end of decls, so an extra newline here before the code. > + if (len < prefix_len) > + return 0; > + > + if (!strncasecmp(buf, prefix, prefix_len)){ Style: ")) {", not ")){".
Matthew John Cheetham via GitGitGadget wrote: > diff --git a/git-compat-util.h b/git-compat-util.h > index a76d0526f79..f11c44517d7 100644 > --- a/git-compat-util.h > +++ b/git-compat-util.h > @@ -1266,6 +1266,28 @@ static inline int skip_iprefix(const char *str, const char *prefix, > return 0; > } > > +/* > + * Like skip_prefix_mem, but compare case-insensitively. Note that the > + * comparison is done via tolower(), so it is strictly ASCII (no multi-byte > + * characters or locale-specific conversions). > + */ > +static inline int skip_iprefix_mem(const char *buf, size_t len, > + const char *prefix, > + const char **out, size_t *outlen) > +{ > + size_t prefix_len = strlen(prefix); > + if (len < prefix_len) > + return 0; > + > + if (!strncasecmp(buf, prefix, prefix_len)){ > + *out = buf + prefix_len; > + *outlen = len - prefix_len; > + return 1; > + } > + > + return 0; > +} > + > static inline int strtoul_ui(char const *s, int base, unsigned int *result) > { > unsigned long ul; > diff --git a/http.c b/http.c > index 8a5ba3f4776..7a56a3db5f7 100644 > --- a/http.c > +++ b/http.c > @@ -183,6 +183,124 @@ size_t fwrite_buffer(char *ptr, size_t eltsize, size_t nmemb, void *buffer_) > return nmemb; > } > > +/* > + * A folded header continuation line starts with at least one single whitespace > + * character. It is not a continuation line if the line is *just* a newline. > + * The RFC for HTTP states that CRLF is the header field line ending, but some > + * servers may use LF only; we accept both. > + */ > +static inline int is_hdr_continuation(const char *ptr, const size_t size) > +{ > + /* totally empty line or normal header */ > + if (!size || !isspace(*ptr)) > + return 0; > + > + /* empty line with LF line ending */ > + if (size == 1 && ptr[0] == '\n') > + return 0; > + > + /* empty line with CRLF line ending */ > + if (size == 2 && ptr[0] == '\r' && ptr[1] == '\n') > + return 0; > + > + return 1; > +} > + > +static size_t fwrite_wwwauth(char *ptr, size_t eltsize, size_t nmemb, void *p) > +{ > + size_t size = eltsize * nmemb; > + struct strvec *values = &http_auth.wwwauth_headers; > + struct strbuf buf = STRBUF_INIT; > + const char *val; > + size_t val_len; > + > + /* > + * Header lines may not come NULL-terminated from libcurl so we must > + * limit all scans to the maximum length of the header line, or leverage > + * strbufs for all operations. > + * > + * In addition, it is possible that header values can be split over > + * multiple lines as per RFC 2616 (even though this has since been > + * deprecated in RFC 7230). A continuation header field value is > + * identified as starting with a space or horizontal tab. > + * > + * The formal definition of a header field as given in RFC 2616 is: > + * > + * message-header = field-name ":" [ field-value ] > + * field-name = token > + * field-value = *( field-content | LWS ) > + * field-content = <the OCTETs making up the field-value > + * and consisting of either *TEXT or combinations > + * of token, separators, and quoted-string> > + */ > + > + /* Start of a new WWW-Authenticate header */ > + if (skip_iprefix_mem(ptr, size, "www-authenticate:", &val, &val_len)) { > + strbuf_add(&buf, val, val_len); > + > + /* > + * Strip the CRLF that should be present at the end of each > + * field as well as any trailing or leading whitespace from the > + * value. > + */ > + strbuf_trim(&buf); > + > + strvec_push(values, buf.buf); > + http_auth.header_is_last_match = 1; > + goto exit; > + } > + > + /* > + * This line could be a continuation of the previously matched header > + * field. If this is the case then we should append this value to the > + * end of the previously consumed value. > + */ > + if (http_auth.header_is_last_match && is_hdr_continuation(ptr, size)) { > + /* > + * Trim the CRLF and any leading or trailing from this line. > + */ > + strbuf_add(&buf, ptr, size); > + strbuf_trim(&buf); > + > + /* > + * At this point we should always have at least one existing > + * value, even if it is empty. Do not bother appending the new > + * value if this continuation header is itself empty. > + */ > + if (!values->nr) { > + BUG("should have at least one existing header value"); > + } else if (buf.len) { > + char *prev = xstrdup(values->v[values->nr - 1]); > + > + /* Join two non-empty values with a single space. */ > + const char *const sp = *prev ? " " : ""; > + > + strvec_pop(values); > + strvec_pushf(values, "%s%s%s", prev, sp, buf.buf); > + free(prev); > + } > + > + goto exit; > + } > + > + /* This is the start of a new header we don't care about */ > + http_auth.header_is_last_match = 0; > + > + /* > + * If this is a HTTP status line and not a header field, this signals > + * a different HTTP response. libcurl writes all the output of all > + * response headers of all responses, including redirects. > + * We only care about the last HTTP request response's headers so clear > + * the existing array. > + */ > + if (!strncasecmp(ptr, "http/", 5)) > + strvec_clear(values); I found this updated version of 'fwrite_wwwauth()' (using 'skip_iprefix_mem()', 'is_hdr_continuation()', and 'strncasecmp()') a bit easier to read than previous iterations - possibly because all the prefix-skipping is done before adding to 'buf', so 'buf' represents *only* the line's header value (possibly with leading/trailing whitespace, which is trimmed). Plus, avoiding unnecessary allocations is always nice. > + > +exit: > + strbuf_release(&buf); > + return size; > +}
diff --git a/credential.c b/credential.c index f6389a50684..897b4679333 100644 --- a/credential.c +++ b/credential.c @@ -22,6 +22,7 @@ void credential_clear(struct credential *c) free(c->username); free(c->password); string_list_clear(&c->helpers, 0); + strvec_clear(&c->wwwauth_headers); credential_init(c); } diff --git a/credential.h b/credential.h index f430e77fea4..6f2e5bc610b 100644 --- a/credential.h +++ b/credential.h @@ -2,6 +2,7 @@ #define CREDENTIAL_H #include "string-list.h" +#include "strvec.h" /** * The credentials API provides an abstracted way of gathering username and @@ -115,6 +116,19 @@ struct credential { */ struct string_list helpers; + /** + * A `strvec` of WWW-Authenticate header values. Each string + * is the value of a WWW-Authenticate header in an HTTP response, + * in the order they were received in the response. + */ + struct strvec wwwauth_headers; + + /** + * Internal use only. Used to keep track of split header fields + * in order to fold multiple lines into one value. + */ + unsigned header_is_last_match:1; + unsigned approved:1, configured:1, quit:1, @@ -130,6 +144,7 @@ struct credential { #define CREDENTIAL_INIT { \ .helpers = STRING_LIST_INIT_DUP, \ + .wwwauth_headers = STRVEC_INIT, \ } /* Initialize a credential structure, setting all fields to empty. */ diff --git a/git-compat-util.h b/git-compat-util.h index a76d0526f79..f11c44517d7 100644 --- a/git-compat-util.h +++ b/git-compat-util.h @@ -1266,6 +1266,28 @@ static inline int skip_iprefix(const char *str, const char *prefix, return 0; } +/* + * Like skip_prefix_mem, but compare case-insensitively. Note that the + * comparison is done via tolower(), so it is strictly ASCII (no multi-byte + * characters or locale-specific conversions). + */ +static inline int skip_iprefix_mem(const char *buf, size_t len, + const char *prefix, + const char **out, size_t *outlen) +{ + size_t prefix_len = strlen(prefix); + if (len < prefix_len) + return 0; + + if (!strncasecmp(buf, prefix, prefix_len)){ + *out = buf + prefix_len; + *outlen = len - prefix_len; + return 1; + } + + return 0; +} + static inline int strtoul_ui(char const *s, int base, unsigned int *result) { unsigned long ul; diff --git a/http.c b/http.c index 8a5ba3f4776..7a56a3db5f7 100644 --- a/http.c +++ b/http.c @@ -183,6 +183,124 @@ size_t fwrite_buffer(char *ptr, size_t eltsize, size_t nmemb, void *buffer_) return nmemb; } +/* + * A folded header continuation line starts with at least one single whitespace + * character. It is not a continuation line if the line is *just* a newline. + * The RFC for HTTP states that CRLF is the header field line ending, but some + * servers may use LF only; we accept both. + */ +static inline int is_hdr_continuation(const char *ptr, const size_t size) +{ + /* totally empty line or normal header */ + if (!size || !isspace(*ptr)) + return 0; + + /* empty line with LF line ending */ + if (size == 1 && ptr[0] == '\n') + return 0; + + /* empty line with CRLF line ending */ + if (size == 2 && ptr[0] == '\r' && ptr[1] == '\n') + return 0; + + return 1; +} + +static size_t fwrite_wwwauth(char *ptr, size_t eltsize, size_t nmemb, void *p) +{ + size_t size = eltsize * nmemb; + struct strvec *values = &http_auth.wwwauth_headers; + struct strbuf buf = STRBUF_INIT; + const char *val; + size_t val_len; + + /* + * Header lines may not come NULL-terminated from libcurl so we must + * limit all scans to the maximum length of the header line, or leverage + * strbufs for all operations. + * + * In addition, it is possible that header values can be split over + * multiple lines as per RFC 2616 (even though this has since been + * deprecated in RFC 7230). A continuation header field value is + * identified as starting with a space or horizontal tab. + * + * The formal definition of a header field as given in RFC 2616 is: + * + * message-header = field-name ":" [ field-value ] + * field-name = token + * field-value = *( field-content | LWS ) + * field-content = <the OCTETs making up the field-value + * and consisting of either *TEXT or combinations + * of token, separators, and quoted-string> + */ + + /* Start of a new WWW-Authenticate header */ + if (skip_iprefix_mem(ptr, size, "www-authenticate:", &val, &val_len)) { + strbuf_add(&buf, val, val_len); + + /* + * Strip the CRLF that should be present at the end of each + * field as well as any trailing or leading whitespace from the + * value. + */ + strbuf_trim(&buf); + + strvec_push(values, buf.buf); + http_auth.header_is_last_match = 1; + goto exit; + } + + /* + * This line could be a continuation of the previously matched header + * field. If this is the case then we should append this value to the + * end of the previously consumed value. + */ + if (http_auth.header_is_last_match && is_hdr_continuation(ptr, size)) { + /* + * Trim the CRLF and any leading or trailing from this line. + */ + strbuf_add(&buf, ptr, size); + strbuf_trim(&buf); + + /* + * At this point we should always have at least one existing + * value, even if it is empty. Do not bother appending the new + * value if this continuation header is itself empty. + */ + if (!values->nr) { + BUG("should have at least one existing header value"); + } else if (buf.len) { + char *prev = xstrdup(values->v[values->nr - 1]); + + /* Join two non-empty values with a single space. */ + const char *const sp = *prev ? " " : ""; + + strvec_pop(values); + strvec_pushf(values, "%s%s%s", prev, sp, buf.buf); + free(prev); + } + + goto exit; + } + + /* This is the start of a new header we don't care about */ + http_auth.header_is_last_match = 0; + + /* + * If this is a HTTP status line and not a header field, this signals + * a different HTTP response. libcurl writes all the output of all + * response headers of all responses, including redirects. + * We only care about the last HTTP request response's headers so clear + * the existing array. + */ + if (!strncasecmp(ptr, "http/", 5)) + strvec_clear(values); + +exit: + strbuf_release(&buf); + return size; +} + size_t fwrite_null(char *ptr, size_t eltsize, size_t nmemb, void *strbuf) { return nmemb; @@ -1864,6 +1982,8 @@ static int http_request(const char *url, fwrite_buffer); } + curl_easy_setopt(slot->curl, CURLOPT_HEADERFUNCTION, fwrite_wwwauth); + accept_language = http_get_accept_language_header(); if (accept_language)